Streaming Data Processing with Apache Storm

Apache Storm is a big data technology that enables software, data, and infrastructure engineers to process high velocity, high volume data in real time and extract useful information. Any project that involves processing high velocity data streams in real time can benefit from it.

Zookeeper is a critical distributed systems technology that Storm depends on to function correctly.

Some use cases where Storm is a good solution:

• Twitter data analytics (for example, trend prediction or sentiment analysis)
• Stock market analysis
• Analysis of server logs
• Internet of Things (IoT) sensor data processing

This guide explains how to create Storm clusters on the Linode cloud using a set of shell scripts that use Linode’s Application Programming Interface (APIs) to programmatically create and configure large clusters. The scripts are all provided by the author of this guide via GitHub repository. This application stack could also benefit from large amounts of disk space, so consider using our Block Storage service with this setup.

The deployed architecture will look like this:

From an application standpoint, the flow of data is depicted below:

The application flow begins, from the client side, with the Storm client, which provides a user interface. This contacts a Nimbus node, which is central to the operation of the Storm cluster. The Nimbus node gets the current state of the cluster, including a list of the supervisor nodes and topologies from the Zookeeper cluster. The Storm cluster’s supervisor nodes constantly update their states to the Zookeeper nodes, which ensure that the system remains synced.

The method by which Storm handles and processes data is called a topology. A topology is a network of components that perform individual operations, and is made up of spouts, which are sources of data, and bolts, which accept the incoming data and perform operations such as running functions or transformations. The data itself, called a stream in Storm terminology, comes in the form of unbounded sequences of tuples.

This guide will explain how to configure a working Storm cluster and its Zookeeper nodes, but it will not provide information on how to develop custom topologies for data processing. For more information on creating and deploying Storm topologies, see the Apache Storm tutorial.

Before You Begin

OS Requirements

• This article assumes that the workstation used for the initial setup of the cluster manager Linode is running Ubuntu 14.04 LTS or Debian 8. This can be your local computer, or another Linode acting as your remote workstation. Other distributions and operating systems have not been tested.
• After the initial setup, any SSH capable workstation can be used to log in to the cluster manager Linode or cluster nodes.
• The cluster manager Linode can have either Ubuntu 14.04 LTS or Debian 8 installed.
• A Zookeeper or Storm cluster can have either Ubuntu 14.04 LTS or Debian 8 installed on its nodes. Its distribution does not need to be the same one as the one installed on the cluster manager Linode.

Naming Conventions

Throughout this guide, we will use the following names as examples that refer to the images and clusters we will be creating:

• zk-image1 - Zookeeper image
• zk-cluster1 - Zookeeper cluster
• storm-image1 - Storm image
• storm-cluster1 - Storm cluster

These are the names we’ll use, but you are welcome to choose your own when creating your own images and clusters. This guide will use these names in all example commands, so be sure to substitute your own names where applicable.

Get a Linode API Key

Follow the steps in Generating an API Key and save your key securely. It will be entered into configuration files in upcoming steps.

If the key expires or is removed, remember to create a new one and update the api_env_linode.conf API environment configuration file on the cluster manager Linode. This will be explained further in the next section.

Set Up the Cluster Manager

The first step is setting up a central Cluster Manager to store details of all Storm clusters, and enable authorized users to create, manage or access those clusters. This can be a local workstation or a Linode, but in this guide will be a Linode.

1. The scripts used in this guide communicate with Linode’s API using Python. On your workstation, install Git, Python 2.7 and curl:

   sudo apt-get install python2.7 curl git
   

2. Download the project git repository:

   git clone "https://github.com/pathbreak/storm-linode"
   cd storm-linode
   git checkout $(git describe $(git rev-list --tags='release*' --max-count=1))
   

3. Make the shell and Python scripts executable:

   chmod +x *.sh *.py
   

4. Make a working copy of the API environment configuration file:

   cp api_env_example.conf api_env_linode.conf
   

5. Open api_env_linode.conf in a text editor, and set LINODE_KEY to the API key previously created (see Get a Linode API key).

   File: ~/storm-linode/api_env_linode.conf

   1	export LINODE_KEY=fnxaZ5HMsaImTTRO8SBtg48...

6. Open ~/storm-linode/cluster_manager.sh in a text editor and change the following configuration settings to customize where and how the Cluster Manager Linode is created:

   • ROOT_PASSWORD: This will be the root user’s password on the Cluster Manager Linode and is required to create the node. Set this to a secure password of your choice. Linode requires the root password to contain at least 2 of these 4 character types:

     • lower case characters
     • upper case characters
     • numeric characters
     • symbolic characters

     If you have spaces in your password, make sure the entire password is enclosed in double quotes ("). If you have double quotes, dollar characters or backslashes in your password, escape each of them with a backslash (\).

   • PLAN_ID: The default value of 1 creates the Cluster Manager Linode as a 2GB node, the smallest plan. This is usually sufficient. However, if you want a more powerful Linode, use the following commands to see a list of all available plans and their IDs:

      source ~/storm-linode/api_env_linode.conf
      ~/storm-linode/linode_api.py plans
     

     Note

     You only need to run source on this file once in a single terminal session, unless you make changes to it.

   • DATACENTER: This specifies the Linode data center where the Cluster Manager Linode is created. Set it to the ID of the data center that is nearest to your location, to reduce network latency. It’s also recommended to create the cluster manager node in the same data center where the images and cluster nodes will be created, so that it can communicate with them using low latency private IP addresses and reduce data transfer usage.

     To view the list of data centers and their IDs:

      source ~/storm-linode/api_env_linode.conf
      ~/storm-linode/linode_api.py datacenters table
     

   • DISTRIBUTION: This is the ID of the distribution to install on the Cluster Manager Linode. This guide has been tested only on Ubuntu 14.04 or Debian 8; other distributions are not supported.

     The default value of 124 selects Ubuntu 14.04 LTS 64-bit. If you’d like to use Debian 8 instead, change this value to 140.

     Note

     The values represented in this guide are current as of publication, but are subject to change in the future. You can run ~/storm-linode/linode_api.py distributions to see a list of all available distributions and their values in the API.

   • KERNEL: This is the ID of the Linux kernel to install on the Cluster Manager Linode. The default value of 138 selects the latest 64-bit Linux kernel available from Linode. It is recommended not to change this setting.

   • DISABLE_SSH_PASSWORD_AUTHENTICATION: This disables SSH password authentication and allows only key-based SSH authentication for the Cluster Manager Linode. Password authentication is considered less secure, and is hence disabled by default. To enable password authentication, you can change this value to no.

   Note

   The options shown in this section are generated by the linode_api.py script, and differ slightly from the options shown using the Linode CLI tool. Do not use the Linode CLI tool to configure your Manager Node.

   When you’ve finished making changes, save and close the editor.

7. Now, create and set up the Cluster Manager Linode:

   ./cluster_manager.sh create-linode api_env_linode.conf
   

   Once the node is created, you should see output like this:

   

   Note the public IP address of the Cluster Manager Linode. You will need this when you log into the cluster manager to create or manage clusters.

8. The cluster_manager.sh script we ran in the previous step creates three users on the Cluster Manager Linode, and generates authentication keypairs for all of them on your workstation, as shown in this illustration:

   • ~/.ssh/clustermgrroot is the private key for Cluster Manager Linode’s root user. Access to this user’s credentials should be as restricted as possible.

   • ~/.ssh/clustermgr is the private key for the Cluster Manager Linode’s clustermgr user. This is a privileged administrative user who can create and manage Storm or Zookeeper clusters. Access to this user’s credentials should be as restricted as possible.

   • ~/.ssh/clustermgrguest is the private key for Cluster Manager Linode’s clustermgrguest user. This is an unprivileged user for use by anybody who need information about Storm clusters, but not the ability to manage them. These are typically developers, who need to know a cluster’s client node IP address to submit topologies to it.

   SSH password authentication to the cluster manager is disabled by default. It is recommended to leave the default setting. However, if you want to enable password authentication for just clustermgrguest users for convenience, log in to the newly created cluster manager as root and append the following line to the end of /etc/ssh/sshd_config:

   File: /etc/ssh/sshd_config

   1 2	Match User clustermgrguest PasswordAuthentication yes

   Restart the SSH service to enable this change:

   service ssh restart
   

   Important

   Since access to the cluster manager provides access to all Storm and Zookeeper clusters and any sensitive data they are processing, its security configuration should be considered critical, and access should be as restrictive as possible.

9. Log in to the cluster manager Linode as the root user, using the public IP address shown when you created it:

   ssh -i ~/.ssh/clustermgrroot root@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE
   

10. Change the hostname to something more descriptive. Here, we are changing it to clustermgr, but you may substitute a different name if you like:

    sed -i -r "s/127.0.1.1.*$/127.0.1.1\tclustermgr/" /etc/hosts
    echo clustermgr > /etc/hostname
    hostname clustermgr
    

11. Set passwords for the clustermgr and clustermgrguest users:

    passwd clustermgr
    passwd clustermgrguest
    

    Any administrator logging in as the clustermgr user should know this password because they will be asked to enter the password when attempting a privileged command.

12. Delete cluster_manager.sh from root user’s directory and close the SSH session:

    rm cluster_manager.sh
    exit
    

13. Log back in to the Cluster Manager Linode - this time as clustermgr user - using its public IP address and the private key for clustermgr user:

    ssh -i ~/.ssh/clustermgr clustermgr@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE
    

14. Navigate to your storm-linode directory and make a working copy of api_env_example.conf. In this example, we’ll call it api_env_linode.conf:

    cd storm-linode
    cp api_env_example.conf api_env_linode.conf
    

15. Open the newly created api_env_linode.conf in a text editor and set LINODE_KEY to your API key.

    Set CLUSTER_MANAGER_NODE_PASSWORD to the password you set for the clustermgr user in Step 11.

    File: ~/storm-linode/api_env_linode.conf

    1 2 3

    export LINODE_KEY=fnxaZ5HMsaImTTRO8SBtg48... ... export CLUSTER_MANAGER_NODE_PASSWORD=changeme

    Save your changes and close the editor.

16. The cluster manager Linode is now ready to create Apache Storm clusters. Add the public keys of anyone who will manage the clusters to /home/clustermgr/.ssh/authorized_keys, so that they can connect via SSH to the Cluster Manager Linode as user clustermgr.

Create a Storm Cluster

Creating a new Storm cluster involves four main steps, some of which are necessary only the first time and can be skipped when creating subsequent clusters.

Create a Zookeeper Image

A Zookeeper image is a master disk image with all necessary Zookeeper software and libraries installed. We’ll create our using Linode Images The benefits of using a Zookeeper image include:

• Quick creation of a Zookeeper cluster by simply cloning it to create as many nodes as required, each a perfect copy of the image
• Distribution packages and third party software packages are identical on all nodes, preventing version mismatch errors
• Reduced network usage, because downloads and updates are executed only once when preparing the image instead of repeating them on each node

1. Log in to the Cluster Manager Linode as clustermgr and navigate to the storm-linode directory:

   ssh -i ~/.ssh/clustermgr clustermgr@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE
   cd storm-linode
   

2. Choose a unique name for your image and create a configuration directory for the new image using the new-image-conf command. In this example, we’ll call our new image zk-image1:

   ./zookeeper-cluster-linode.sh new-image-conf zk-image1
   

   This creates a directory named zk-image1 containing the files that make up the image configuration:

   • zk-image1.conf - This is the main image configuration file, and the one you’ll be modifying the most. Its properties are described in the next step. This file is named zk-image1.conf in our example, but if you chose a different image name, yours may vary.

   • zoo.cfg - This is the primary Zookeeper configuration file. See the official Zookeeper Configuration Parameters documentation for details on what parameters can be customized. It’s not necessary to enter the cluster’s node list in this file. That’s done automatically by the script during cluster creation.

   • log4j.properties - This file sets the default logging levels for Zookeeper components. You can also customize these at the node level when a cluster is created.

   • zk-supervisord.conf - The Zookeeper daemon is run under supervision so that if it shuts down unexpectedly, it’s automatically restarted by Supervisord. There is nothing much to customize here, but you can refer to the Supervisord Configuration documentation if you want to learn more about the options.

3. Open the image configuration file (in this example, ./zk-image1/zk-image1.conf) in a text editor. Enter or edit values of configuration properties as required. Properties that must be entered or changed from their default values are marked as REQUIRED:

   • DISTRIBUTION_FOR_IMAGE

     Specify either Ubuntu 14.04 or Debian 8 to use for this image. This guide has not been tested on any other versions or distributions.

     All nodes of all clusters created from this image will have this distribution. The default value is 124 corresponding to Ubuntu 14.04 LTS 64-bit. For Debian 8 64-bit, change this value to 140.

     Note

     The values represented in this guide are current as of publication, but are subject to change in the future. You can run ~/storm-linode/linode_api.py distributions to see a list of all available distributions and their values in the API.
     
     

   • LABEL_FOR_IMAGE

     A label to help you differentiate this image from others. This name will be shown if you edit or view your images in the Linode Manager.

     
     

   • KERNEL_FOR_IMAGE

     The kernel version provided by Linode to use in this image. The default value is 138, corresponding to the latest 64-bit kernel provided by Linode. It is recommended that you leave this as the default setting.

     
     

   • DATACENTER_FOR_IMAGE

     The Linode data center where this image will be created. This can be any Linode data center, but cluster creation is faster if the image is created in the same data center where the cluster will be created. It’s also recommended to create the image in the same data center as the Cluster Manager Linode. Select a data center that is geographically close to your premises, to reduce network latency. If left unchanged, the Linode will be created in the Newark data center.

     This value can either be the data center’s ID or location or abbreviation. To see a list of all data centers:

      ./zookeeper-cluster-linode.sh datacenters api_env_linode.conf
     

     
     

   • IMAGE_ROOT_PASSWORD - REQUIRED

     The default root user password for the image. All nodes of any clusters created from this image will have this as the root password, unless it’s overridden in a cluster’s configuration file.

     
     

   • IMAGE_ROOT_SSH_PUBLIC_KEY and IMAGE_ROOT_SSH_PRIVATE_KEY

     The keypair files for SSH public key authentication as root user. Any user who logs in with this private key can be authenticated as root.

     By default, the cluster_manager.sh setup has already created a keypair named clusterroot and clusterroot.pub under ~/.ssh/. If you wish to replace these with your own keypair, you may create your own keys and set their full paths here.

     
     

   • IMAGE_DISABLE_SSH_PASSWORD_AUTHENTICATION

     This disables SSH password authentication and allows only key based SSH authentication for the cluster nodes. Password authentication is considered less secure, and is hence disabled by default. To enable password authentication, you can change this value to no.

     
     

   • IMAGE_ADMIN_USER

     Administrators or developers may have to log in to the cluster nodes for maintenance. Instead of logging in as root users, it’s better to log in as a privileged non-root user. The script creates a privileged user with this name in the image (and in all cluster nodes based on this image).

     
     

   • IMAGE_ADMIN_PASSWORD - REQUIRED

     Sets the password for the IMAGE_ADMIN_USER.

     
     

   • IMAGE_ADMIN_SSH_AUTHORIZED_KEYS

     A file that contains public keys of all personnel authorized to log in to cluster nodes as IMAGE_ADMIN_USER. This file should be in the same format as the standard SSH authorized_keys file. All the entries in this file are appended to the image’s authorized_keys file, and get inherited into all nodes based on this image.

     By default, the cluster_manager.sh setup creates a new clusteradmin keypair, and this variable is set to the path of the public key. You can either retain this generated keypair and distribute the generated private key file ~/.ssh/clusteradmin to authorized personnel. Alternatively, you can collect public keys of authorized personnel and append them to ~/.ssh/clusteradmin.pub.

     
     

   • IMAGE_DISK_SIZE

     The size of the image disk in MB. The default value of 5000MB is generally sufficient, since the installation only consists of the OS with Java and Zookeeper software installed.

     
     

   • UPGRADE_OS

     If yes, the distribution’s packages are updated and upgraded before installing any software. It is recommended to leave the default setting to avoid any installation or dependency issues.

     
     

   • INSTALL_ZOOKEEPER_DISTRIBUTION

     The Zookeeper version to install. By default, cluster_manager.sh has already downloaded version 3.4.6. If you wish to install a different version, download it manually and change this variable. However, it is recommended to leave the default value as this guide has not been tested against other versions.

     
     

   • ZOOKEEPER_INSTALL_DIRECTORY

     The directory where Zookeeper will be installed on the image (and on all cluster nodes created from this image).

     
     

   • ZOOKEEPER_USER

     The username under which the Zookeeper daemon runs. This is a security feature to avoid privilege escalation by exploiting some vulnerability in the Zookeeper daemon.

     
     

   • ZOOKEEPER_MAX_HEAP_SIZE

     The maximum Java heap size for the JVM hosting the Zookeeper daemon. This value can be either a percentage, or a fixed value. If the fixed value is not suffixed with any character, it is interpreted as bytes. If it is suffixed with K, M, or G, it is interpreted as kilobytes, megabytes or gigabytes, respectively.

     If this is too low, it may result in out of memory errors, and cause data losses or delays in the Storm cluster. If it is set too high, the memory for the OS and its processes will be limited, resulting in disk thrashing, which will have a significant negative impact on Zookeeper’s performance.

     The default value is 75%, which means at most 75% of the Linode’s RAM can be reserved for the JVM, and remaining 25% for the rest of the OS and other processes. It is strongly recommended not to change this default setting.

     
     

   • ZOOKEEPER_MIN_HEAP_SIZE

     The minimum Java heap size to commit for the JVM hosting the Zookeeper daemon. This value can be either a percentage, or a fixed value. If the fixed value is not suffixed with any character, it is interpreted as bytes. If it is suffixed with K, M, or G, it is interpreted as kilobytes, megabytes, or gigabytes, respectively.

     If this value is lower than ZOOKEEPER_MAX_HEAP_SIZE, this amount of memory is committed, and additional memory up to ZOOKEEPER_MAX_HEAP_SIZE is allocated only when the JVM requests it from OS. This can lead to memory allocation delays during operation. So do not set it too low.

     This value should never be more than ZOOKEEPER_MAX_HEAP_SIZE. If it is, the Zookeeper daemon will not start.

     The default value is 75%, which means 75% of the Linode’s RAM is committed – not just reserved - to the JVM and unavailable to any other process. It is strongly recommended not to change this default setting.

   When you’ve finished making changes, save and close the editor.

4. Create the image using create-image command, specifying the name of the newly created image and the API environment file:

   ./zookeeper-cluster-linode.sh create-image zk-image1 api_env_linode.conf
   

   If the image is created successfully, the output will look something like this at the end:

   Deleting the temporary linode xxxxxx
   
   Finished creating Zookeeper template image yyyyyy
   

   If the process fails, ensure that you do not already have an existing Linode with the same name in the Linode Manager. If you do, delete it and run the command again, or recreate this image with a different name.

   Note

   During this process, a temporary, short-lived 2GB Linode is created and deleted. This will entail a small cost in your monthly invoice and trigger an event notification email to be sent to the address you have registered with Linode. This is expected behavior.

Create a Zookeeper Cluster

In this section, you will learn how to create a new Zookeeper cluster in which every node is a replica of an existing Zookeeper image. If you have not already created a Zookeeper image, do so first by following Create a Zookeeper image.

1. Log in to the Cluster Manager Linode as clustermgr and navigate to the storm-linode directory:

   ssh -i ~/.ssh/clustermgr clustermgr@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE
   cd storm-linode
   

2. Choose a unique name for your cluster and create a configuration directory using the new-cluster-conf command. In this example, we’ll call our new cluster configuration zk-cluster1:

   ./zookeeper-cluster-linode.sh new-cluster-conf zk-cluster1
   

   This creates a directory named zk-cluster1 that contains the main configuration file, zk-cluster1.conf, which will be described in the next step. If you chose a different name when you ran the previous command, your directory and configuration file will be named accordingly.

3. Open the newly created zk-cluster1.conf file and make changes as described below. Properties that must be entered or changed from their default values are marked as REQUIRED:

   • DATACENTER_FOR_CLUSTER

     The Linode data center where the nodes of this cluster will be created. All nodes of a cluster have to be in the same data center; they cannot span multiple data centers since they will use private network traffic to communicate.

     This can be any Linode data center, but cluster creation may be faster if it is created in the same data center where the image and Cluster Manager Linode are created. It is recommended to select a data center that is geographically close to your premises to reduce network latency.

     This value can either be the data center’s ID or location or abbreviation. To see a list of all data centers:

      ./zookeeper-cluster-linode.sh datacenters api_env_linode.conf
     

     
     

   • CLUSTER_SIZE

     The types and number of nodes that constitute this cluster. The syntax is:

     plan:count plan:count ...

     A plan is one of 2GB | 4GB | ... | 120GB (see Linode plans for all plans) and count is the number of nodes with that plan.

     Examples:

     • For a cluster with three 4GB nodes:

        CLUSTER_SIZE="4GB:3"
       

     • For a cluster with three nodes of different plans:

        CLUSTER_SIZE="2GB:1 4GB:1 8GB:1"
       

     The total number of nodes in a Zookeeper cluster must be an odd number. Although cluster can have nodes of different plans, it’s recommended to use the same plan for all nodes. It is recommended to avoid very large clusters. A cluster with 3-9 nodes is sufficient for most use cases. 11-19 nodes would be considered “large”. Anything more than 19 nodes would be counterproductive, because at that point, Zookeeper would slow down all the Storm clusters that depend on it.

     Size the cluster carefully, because as of version 3.4.6, Zookeeper does not support dynamic expansion. The only way to resize would be to take it down and create a new cluster, creating downtime for any Storm clusters that depend on it.

     
     

   • ZK_IMAGE_CONF - REQUIRED

     Path of the Zookeeper image directory or configuration file to use as a template for creating nodes of this cluster. Every node’s disk will be a replica of this image.

     The path can either be an absolute path, or a path that is relative to the cluster configuration directory. Using our example, the absolute path would be /home/clustermgr/storm-linode/zk-image1 and the relative path would be ../zk-image1.

     
     

   • NODE_DISK_SIZE

     Size of each node’s disk in MB. This must be at least as large as the selected image’s disk, otherwise the image will not copy properly.

     
     

   • NODE_ROOT_PASSWORD

     Optionally, you can specify a root password for the nodes. If this is empty, the root password will be the IMAGE_ROOT_PASSWORD in the image configuration file.

     
     

   • NODE_ROOT_SSH_PUBLIC_KEY and NODE_ROOT_SSH_PRIVATE_KEY

     Optionally, you can specify a custom SSH public key file and private key file for root user authentication. If this is empty, the keys will be the keys specified in image configuration file.

     If you wish to specify your own keypair, select a descriptive filename for this new keypair (example: zkcluster1root), generate them using ssh-keygen, and set their full paths here.

     
     

   • PUBLIC_HOST_NAME_PREFIX

     Every Linode in the cluster has a public IP address, which can be reached from anywhere on the Internet, and a private IP address, which can be reached only from other nodes of the same user inside the same data center.

     Accordingly, every node is given a public hostname that resolves to its public IP address. Each node’s public hostname will use this value followed by a number (for example, public-host1, public-host2, etc.) If the cluster manager node is in a different Linode data center from the cluster nodes, it uses the public hostnames and public IP addresses to communicate with cluster nodes.

     
     

   • PRIVATE_HOST_NAME_PREFIX

     Every Linode in the cluster is given a private hostname that resolves to its private IP address. Each node’s private hostname will use this value followed by a number (for example, private-host1, private-host2, etc.). All the nodes of a cluster communicate with one another through their private hostnames. This is also the actual hostname set for the node using the host’s hostname command and saved in /etc/hostname.

     
     

   • CLUSTER_MANAGER_USES_PUBLIC_IP

     Set this value to false if the cluster manager node is located in the same Linode data center as the cluster nodes. This is the recommended value. Change to true only if the cluster manager node is located in a different Linode data center from the cluster nodes.

     Important

     It’s important to set this correctly to avoid critical cluster creation failures.
     
     

   • ZOOKEEPER_LEADER_CONNECTION_PORT

     The port used by a Zookeeper node to connect its followers to the leader. When a new leader is elected, each follower opens a TCP connection to the leader at this port. There’s no need to change this unless you plan to customize the firewall.

     
     

   • ZOOKEEPER_LEADER_ELECTION_PORT

     The port used for Zookeeper leader election during quorum. There’s no need to change this, unless you plan to customize the firewall.

     
     

   • IPTABLES_V4_RULES_TEMPLATE

     Absolute or relative path of the IPv4 iptables firewall rules file. Modify this if you plan to customize the firewall configuration.

     
     

   • IPTABLES_V6_RULES_TEMPLATE

     Absolute or relative path of the IPv6 iptables firewall rules file. IPv6 is completely disabled on all nodes, and no services listen on IPv6 addresses. Modify this if you plan to customize the firewall configuration.

   When you’ve finished making changes, save and close the editor.

4. Create the cluster using the create command:

   ./zookeeper-cluster-linode.sh create zk-cluster1 api_env_linode.conf
   

   If the cluster is created successfully, a success message is printed:

   Zookeeper cluster successfully created
   

   Details of the created cluster can be viewed using the describe command:

   ./zookeeper-cluster-linode.sh describe zk-cluster1
   

   Cluster nodes are shut down soon after creation. They are started only when any of the Storm clusters starts.

Create a Storm Image

A Storm image is a master disk with all necessary Storm software and libraries downloaded and installed. The benefits of creating a Storm image include:

• Quick creation of a Storm cluster by simply cloning it to create as many nodes as required, each a perfect copy of the image
• Distribution packages and third party software packages are identical on all nodes, and prevent version mismatch errors
• Reduced network usage, because downloads and updates are executed only once when preparing the image, instead of repeating them on each node

1. Log in to the Cluster Manager Linode as clustermgr and navigate to the storm-linode directory:

   ssh -i ~/.ssh/clustermgr clustermgr@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE
   cd storm-linode
   

2. Choose a unique name for your image and create a configuration directory for the new image using new-image-conf command. In this example, we’ll call our new image storm-image1:

   ./storm-cluster-linode.sh new-image-conf storm-image1
   

   This creates a directory named storm-image1 containing the files that make up the image configuration:

   • storm-image1.conf - This is the main image configuration file, and the one you’ll be modifying the most. Its properties are described in later steps.

   The other files are secondary configuration files. They contain reasonable default values, but you can always open them in an editor and modify them to suit your needs:

   • template-storm.yaml - The Storm configuration file. See the official Storm Configuration documentation for details on what parameters can be customized.

   • template-storm-supervisord.conf - The Storm daemon is run under supervision so that if it shuts down unexpectedly, it’s automatically restarted by Supervisord. There is nothing much to customize here, but review the Supervisord Configuration documentation if you do want to customize it.

3. Open the image configuration file (in this example, ~/storm-linode/storm-image1/storm-image1.conf) in a text editor. Enter or edit the values of configuration properties as required. Properties that must be entered or changed from their default values are marked as REQUIRED:

   • DISTRIBUTION_FOR_IMAGE

     Specify either Ubuntu 14.04 or Debian 8 to use for this image. This guide has not been tested on any other versions or distributions.

     All nodes of all clusters created from this image will have this distribution. The default value is 124 corresponding to Ubuntu 14.04 LTS 64-bit. For Debian 8 64-bit, change this value to 140.

     Note

     The values represented in this guide are current as of publication, but are subject to change in the future. You can run ~/storm-linode/linode_api.py distributions to see a list of all available distributions and their values in the API.
     
     

   • LABEL_FOR_IMAGE

     A label to help you differentiate this image from others. This name will be shown if you edit or view your images in the Linode Manager.

     
     

   • KERNEL_FOR_IMAGE

     The kernel version provided by Linode to use in this image. The default value is 138 corresponding to the latest 64-bit kernel provided by Linode. It is recommended that you leave this as the default setting.

     
     

   • DATACENTER_FOR_IMAGE

     The Linode data center where this image will be created. This can be any Linode data center, but cluster creation is faster if the image is created in the same data center where the cluster will be created. It’s also recommended to create the image in the same data center as the Cluster Manager Linode. Select a data center that is geographically close to you to reduce network latency.

     This value can either be the data center’s ID or location or abbreviation. To see a list of all data centers:

      ./zookeeper-cluster-linode.sh datacenters api_env_linode.conf
     

     
     

   • IMAGE_ROOT_PASSWORD - REQUIRED

     The default root user password for the image. All nodes of any clusters created from this image will have this as the root password, unless it’s overridden in a cluster’s configuration file.

     
     

   • IMAGE_ROOT_SSH_PUBLIC_KEY and IMAGE_ROOT_SSH_PRIVATE_KEY

     The keypair files for SSH public key authentication as root user. Any user who logs in with this private key can be authenticated as root.

     By default, the cluster_manager.sh setup has already created a keypair named clusterroot and clusterroot.pub under ~/.ssh/. If you wish to replace them with your own keypair, you may create your own keys and set their full paths here.

     
     

   • IMAGE_DISABLE_SSH_PASSWORD_AUTHENTICATION

     This disables SSH password authentication and allows only key based SSH authentication for the cluster nodes. Password authentication is considered less secure, and is hence disabled by default. To enable password authentication, you can change this value to no.

     
     

   • IMAGE_ADMIN_USER

     Administrators or developers may have to log in to the cluster nodes for maintenance. Instead of logging in as root users, it’s better to log in as a privileged non-root user. The script creates a privileged user with this name in the image (and in all cluster nodes based on this image).

     
     

   • IMAGE_ADMIN_PASSWORD - REQUIRED

     Sets the password for the IMAGE_ADMIN_USER.

     
     

   • IMAGE_ADMIN_SSH_AUTHORIZED_KEYS

     A file that contains public keys of all personnel authorized to log in to cluster nodes as IMAGE_ADMIN_USER. This file should be in the same format as the standard SSH authorized_keys file. All the entries in this file are appended to the image’s authorized_keys file, and get inherited into all nodes based on this image.

     By default, the cluster_manager.sh setup creates a new clusteradmin keypair, and this variable is set to the path of the public key. You can either retain this generated keypair and distribute the generated private key file ~/.ssh/clusteradmin to authorized personnel. Alternatively, you can collect public keys of authorized personnel and append them to ~/.ssh/clusteradmin.pub.

     
     

   • IMAGE_DISK_SIZE

     The size of the image disk in MB. The default value of 5000MB is generally sufficient, since the installation only consists of the OS with Java and Storm software installed.

     
     

   • UPGRADE_OS

     If yes, the distribution’s packages are updated and upgraded before installing any software. It is recommended to leave the default setting to avoid any installation or dependency issues.

     
     

   • INSTALL_STORM_DISTRIBUTION

     The Storm version to install. By default, the cluster_manager.sh setup has already downloaded version 0.9.5. If you wish to install a different version, download it manually and change this variable. However, it is recommended to leave the default value as this guide has not been tested against other versions.

     
     

   • STORM_INSTALL_DIRECTORY

     The directory where Storm will be installed on the image (and on all cluster nodes created from this image).

     
     

   • STORM_YAML_TEMPLATE

     The path of the template storm.yaml configuration file to install in the image. By default, it points to the template-storm.yaml file under the image directory. Administrators can either customize this YAML file before creating the image, or set this variable to point to another storm.yaml of their choice.

     
     

   • STORM_USER

     The username under which the Storm daemon runs. This is a security feature to avoid privilege escalation by exploiting some vulnerability in the Storm daemon.

     
     

   • SUPERVISORD_TEMPLATE_CONF

     The path of the template supervisor configuration file to install in the image. By default, it points to the template-storm-supervisord.conf file in the Storm image directory. Administrators can modify this file before creating the image, or set this variable to point to any other storm-supervisord.conf file of their choice.

   Once you’ve made changes, save and close the editor.

4. Create the image using the create-image command, specifying the name of the newly created image and the API environment file:

   ./storm-cluster-linode.sh create-image storm-image1 api_env_linode.conf
   

   If the image is created successfully, the output will look something like this towards the end:

   ....
   Deleting the temporary linode xxxxxx
   
   Finished creating Storm template image yyyyyy
   

   If the process fails, ensure that you do not already have an existing Storm image with the same name in the Linode Manager. If you do, delete it and run the command again, or recreate this image with a different name.

   Note

   During this process, a short-lived 2GB Linode is created and deleted. This will entail a small cost in the monthly invoice and trigger an event notification email to be sent to the address you have registered with Linode. This is expected behavior.

Create a Storm Cluster

In this section, you will learn how to create a new Storm cluster in which every node is a replica of an existing Storm image. If you have not created any Storm images, do so first by following Create a Storm image.

1. Log in to the Cluster Manager Linode as clustermgr and navigate to the storm-linode directory:

   ssh -i ~/.ssh/clustermgr clustermgr@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE
   cd storm-linode
   

2. Choose a unique name for your cluster and create a configuration directory using the new-cluster-conf command. In this example, we’ll call our new cluster configuration storm-cluster1:

   ./storm-cluster-linode.sh new-cluster-conf storm-cluster1
   

   This creates a directory named storm-cluster1 that contains the main configuration file, storm-cluster1.conf, which will be described in the next step. If you chose a different name when you ran the previous command, your directory and configuration file will be named accordingly.

3. Open the newly created storm-cluster1.conf file and make changes as described below. Properties that must be entered or changed from their default values are marked as REQUIRED:

   • DATACENTER_FOR_CLUSTER

     The Linode data center where the nodes of this cluster will be created. All nodes of a cluster have to be in the same data center; they cannot span multiple data centers since they will use private network traffic to communicate.

     This can be any Linode data center, but cluster creation may be faster if it is created in the same data center where the image and Cluster Manager Linode are created. It is recommended to select a data center that is geographically close to your premises to reduce network latency.

     This value can either be the data center’s ID or location or abbreviation. To see a list of all data centers:

      ./zookeeper-cluster-linode.sh datacenters api_env_linode.conf
     

     
     

   • NIMBUS_NODE

     This specifies the Linode plan to use for the Nimbus node, which is responsible for distributing and coordinating a Storm topology to supervisor nodes.

     It should be one of 2GB | 4GB | ... | 120GB (see Linode plans for all plans). The default size is 2GB, but a larger plan is strongly recommended for the Nimbus node.

     
     

   • SUPERVISOR_NODES

     Supervisor nodes are the workhorses that execute the spouts and bolts that make up a Storm topology.

     The size and number of supervisor nodes should be decided based on how many topologies the cluster should run concurrently, and the computational complexities of their spouts and bolts. The syntax is:

     plan:count plan:count ...

     A plan is one of 2GB | 4GB| ....| 120GB (see Linode plans for all plans) and count is the number of supervisor nodes with that plan. Although a cluster can have supervisor nodes of different sizes, it’s recommended to use the same plan for all nodes.

     The number of supervisor nodes can be increased later using the add-nodes command (see Expand Cluster).

     Examples:

     • Create three 4GB nodes:

       SUPERVISOR_NODES="4GB:3"
       

     • Create six nodes with three different plans:

       SUPERVISOR_NODES="2GB:2 4GB:2 8GB:2"
       

     
     

   • CLIENT_NODE

     The client node of a cluster is used to submit topologies to it and monitor it. This should be one of 2GB | 4GB | ... | 120GB (see Linode plans for all plans). The default value of 2GB is sufficient for most use cases.

     
     

   • STORM_IMAGE_CONF - REQUIRED

     Path of the Storm image directory or configuration file to use as a template for creating nodes of this cluster. Every node’s disk will be a replica of this image.

     The path can either be an absolute path, or a path that is relative to this cluster configuration directory. Using our example, the absolute path would be /home/clustermgr/storm-linode/storm-image1 and the relative path would be ../storm-image1.

     
     

   • NODE_DISK_SIZE

     Size of each node’s disk in MB. This must be at least as large as the selected image’s disk, otherwise the image will not copy properly.

     
     

   • NODE_ROOT_PASSWORD

     Optionally, you can specify a root password for the nodes. If this is empty, the root password will be the IMAGE_ROOT_PASSWORD in the image configuration file.

     
     

   • NODE_ROOT_SSH_PUBLIC_KEY and NODE_ROOT_SSH_PRIVATE_KEY

     Optionally, you can specify a custom SSH public key file and private key file for root user authentication. If this is empty, the keys will be the keys specified in image configuration file.

     If you wish to specify your own keypair, select a descriptive filename for this new keypair (example: zkcluster1root), generate them using ssh-keygen, and set their full paths here.

     
     

   • NIMBUS_NODE_PUBLIC_HOSTNAME, SUPERVISOR_NODES_PUBLIC_HOSTNAME_PREFIX and CLIENT_NODES_PUBLIC_HOSTNAME_PREFIX

     Every Linode in the cluster has a public IP address, which can be reached from anywhere on the Internet, and a private IP address, which can be reached only from other nodes of the same user inside the same data center.

     Accordingly, every node is given a public hostname that resolves to its public IP address. Each node’s public hostname will use this value followed by a number (for example, public-host1, public-host2, etc.) If the cluster manager node is in a different Linode data center from the cluster nodes, it uses the public hostnames and public IP addresses to communicate with cluster nodes.

     
     

   • NIMBUS_NODE_PRIVATE_HOSTNAME, SUPERVISOR_NODES_PRIVATE_HOSTNAME_PREFIX and CLIENT_NODES_PRIVATE_HOSTNAME_PREFIX

     Every Linode in the cluster is given a private hostname that resolves to its private IP address. Each node’s private hostname will use this value followed by a number (for example, private-host1, private-host2, etc.). All the nodes of a cluster communicate with one another through their private hostnames. This is also the actual hostname set for the node using the host’s hostname command and saved in /etc/hostname.

     
     

   • CLUSTER_MANAGER_USES_PUBLIC_IP

     Set this value to false if the cluster manager node is located in the same Linode data center as the cluster nodes. This is the recommended value and is also the default. Change to true only if the cluster manager node is located in a different Linode data center from the cluster nodes.

     Important

     It’s important to set this correctly to avoid critical cluster creation failures.
     
     

   • ZOOKEEPER_CLUSTER - REQUIRED

     Path of the Zookeeper cluster directory to be used by this Storm cluster.

     This can be either an absolute path or a relative path that is relative to this Storm cluster configuration directory. Using our example, the absolute path would be /home/clustermgr/storm-linode/zk-cluster1, and the relative path would be ../zk-cluster1.

     
     

   • IPTABLES_V4_RULES_TEMPLATE

     Absolute or relative path of the IPv4 iptables firewall rules file applied to Nimbus and Supervisor nodes. Modify this if you plan to customize their firewall configuration.

     
     

   • IPTABLES_CLIENT_V4_RULES_TEMPLATE

     Absolute or relative path of the IPv4 iptables firewall rules file applied to Client node. Since the client node hosts a cluster monitoring web server and should be accessible to administrators and developers, its rules are different from those of other nodes. Modify this if you plan to customize its firewall configuration.

     Default: ../template-storm-client-iptables-rules.v4

     
     

   • IPTABLES_V6_RULES_TEMPLATE

     Absolute or relative path of the IPv6 iptables firewall rules file followed for all nodes, including client node. IPv6 is completely disabled on all nodes, and no services listen on IPv6 addresses. Modify this if you plan to customize the firewall configuration.

   When you’ve finished making changes, save and close the editor.

4. Create the cluster using the create command:

   ./storm-cluster-linode.sh create storm-cluster1 api_env_linode.conf
   

   If the cluster is created successfully, a success message is printed:

   Storm cluster successfully created
   

   Details of the created cluster can be viewed using the describe command:

   ./storm-cluster-linode.sh describe storm-cluster1
   

   Cluster nodes are shut down soon after creation.

Start a Storm Cluster

This section will explain how to start a Storm cluster. Doing so will also start any Zookeeper clusters on which it depends, so they do not need to be started separately.

1. Log in to the Cluster Manager Linode as clustermgr and navigate to the storm-linode directory:

   ssh -i ~/.ssh/clustermgr clustermgr@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE
   cd storm-linode
   

2. Start the Storm cluster using the start command. This example uses the storm-cluster1 naming convention from above, but if you chose a different name you should replace it in the command:

   ./storm-cluster-linode.sh start storm-cluster1 api_env_linode.conf
   

3. If cluster is being started for the very first time, see the next section for how to authorize users to monitor a Storm cluster.

Monitor a Storm Cluster

Every Storm cluster’s client node runs a Storm UI web application for monitoring that cluster, but it can be accessed only from allowed workstations.

The next two sections explain how to allow workstations and monitor a cluster from the web interface.

Allow Workstations to Monitor a Storm Cluster

When performing the steps in this section, you should have clustermgr authorization to the Cluster Manager Linode.

1. Log in to the Cluster Manager Linode as clustermgr and navigate to the storm-linode directory:

   ssh -i ~/.ssh/clustermgr clustermgr@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE
   cd storm-linode
   

2. Open the your-cluster/your-cluster-client-user-whitelist.ipsets file (using our example from above, storm-cluster1/storm-cluster1-client-user-whitelist.ipsets) file in a text editor.

   This file is an ipsets list of allowed IP addresses. It consists of one master ipset and multiple child ipsets that list allowed machines by IP addresses or other attributes such as MAC IDs.

   The master ipset is named your-cluster-uwls. By default, it’s completely empty, which means nobody is authorized.

3. To allow an IP address:

   • Uncomment the line that creates the your-cluster-ipwl ipset
   • Add the IP address under it
   • Add your-cluster-ipwl to the master ipset your-cluster-uwls

   These additions are highlighted below:

   Note

   Any IP address that is being included in the file should be a public facing IP address of the network. For example, company networks often assign local addresses like 10.x.x.x or 192.x.x.x addresses to employee workstations, which are then NATted to a public IP address while sending requests outside the company network. Since the cluster client node is in the Linode cloud outside your company network, it will see monitoring requests as arriving from this public IP address. So it’s the public IP address that should be allowed.

4. Any number or type of additional ipsets can be created, as long as they are added to the master ipset.

   See the Set Types section in the ipset manual for available types of ipsets. Note that some of the types listed in the manual may not be available on the client node because the ipset version installed on it using Ubuntu or Debian package manager is likely to be an older version.

5. Enter all required ipsets, save the file, and close the editor.

6. Activate the new ipsets with the update-user-whitelist command:

   ./storm-cluster-linode.sh update-user-whitelist storm-cluster1
   

7. Log in to the client node from the Cluster Manager Linode:

   ssh -i ~/.ssh/clusterroot root@storm-cluster1-private-client1
   

   Verify that the new ipsets have been configured correctly:

   ipset list
   

   You should see output similar to the following (in addition to custom ipsets if you added them, and the ipsets for the Storm and Zookeeper cluster nodes):

   

   Disconnect from the client node and navigate back to the storm-linode directory on the cluster manager node:

   exit
   

8. From the cluster manager node, get the public IP address of the client node. This IP address should be provided to users authorized to access the Storm UI monitoring web application. To show the IP addresses, use the describe command:

   ./storm-cluster-linode.sh describe storm-cluster1
   

9. Finally, verify that the Storm UI web application is accessible by opening http://public-IP-of-client-node in a web browser on each whitelisted workstation. You should see the Storm UI web application, which looks like this:

   The Storm UI displays the list of topologies and the list of supervisors executing them:

   If the cluster is executing any topologies, they are listed under the Topology summary section. Click on a topology to access its statistics, supervisor node logs, or actions such as killing that topology.

Test a New Storm Cluster

1. Log in to the Cluster Manager Linode as clustermgr and navigate to the storm-linode directory:

   ssh -i ~/.ssh/clustermgr clustermgr@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE
   cd storm-linode
   

2. Get the private IP address of the client node of the target cluster. This is preferred for security and to minimize impact on the data transfer quota, but the public IP address works as well:

   ./storm-cluster-linode.sh describe storm-cluster1
   

3. Log in to the client node as its IMAGE_ADMIN_USER user (the default is clusteradmin, configured in the Storm image configuration file) via SSH using an authorized private key:

   ssh -i ~/.ssh/clusteradmin clusteradmin@192.168.42.13
   

4. Run the following commands to start the preinstalled word count example topology:

   cd /opt/apache-storm-0.9.5/bin
   ./storm jar ../examples/storm-starter/storm-starter-topologies-0.9.5.jar storm.starter.WordCountTopology "wordcount"
   

5. A successful submission should produce output similar to this:

   Running: java -client -Dstorm.options= -Dstorm.home=/opt/apache-storm-0.9.5 -Dstorm.log.dir=/var/log/storm -Djava.library.path=/usr/local/lib:/opt/local/lib:/usr/lib -Dstorm.conf.file= -cp /opt/apache-storm-0.9.5/lib/disruptor-2.10.1.jar:/opt/apache-storm-0.9.5/lib/minlog-1.2.jar:/opt/apache-storm-0.9.5/lib/commons-io-2.4.jar:/opt/apache-storm-0.9.5/lib/clj-time-0.4.1.jar:/opt/apache-storm-0.9.5/lib/clout-1.0.1.jar:/opt/apache-storm-0.9.5/lib/ring-devel-0.3.11.jar:/opt/apache-storm-0.9.5/lib/tools.macro-0.1.0.jar:/opt/apache-storm-0.9.5/lib/ring-jetty-adapter-0.3.11.jar:/opt/apache-storm-0.9.5/lib/jetty-util-6.1.26.jar:/opt/apache-storm-0.9.5/lib/commons-exec-1.1.jar:/opt/apache-storm-0.9.5/lib/tools.cli-0.2.4.jar:/opt/apache-storm-0.9.5/lib/objenesis-1.2.jar:/opt/apache-storm-0.9.5/lib/jetty-6.1.26.jar:/opt/apache-storm-0.9.5/lib/ring-servlet-0.3.11.jar:/opt/apache-storm-0.9.5/lib/storm-core-0.9.5.jar:/opt/apache-storm-0.9.5/lib/hiccup-0.3.6.jar:/opt/apache-storm-0.9.5/lib/clojure-1.5.1.jar:/opt/apache-storm-0.9.5/lib/commons-codec-1.6.jar:/opt/apache-storm-0.9.5/lib/servlet-api-2.5.jar:/opt/apache-storm-0.9.5/lib/compojure-1.1.3.jar:/opt/apache-storm-0.9.5/lib/json-simple-1.1.jar:/opt/apache-storm-0.9.5/lib/commons-logging-1.1.3.jar:/opt/apache-storm-0.9.5/lib/math.numeric-tower-0.0.1.jar:/opt/apache-storm-0.9.5/lib/asm-4.0.jar:/opt/apache-storm-0.9.5/lib/commons-lang-2.5.jar:/opt/apache-storm-0.9.5/lib/clj-stacktrace-0.2.2.jar:/opt/apache-storm-0.9.5/lib/kryo-2.21.jar:/opt/apache-storm-0.9.5/lib/logback-classic-1.0.13.jar:/opt/apache-storm-0.9.5/lib/slf4j-api-1.7.5.jar:/opt/apache-storm-0.9.5/lib/reflectasm-1.07-shaded.jar:/opt/apache-storm-0.9.5/lib/ring-core-1.1.5.jar:/opt/apache-storm-0.9.5/lib/joda-time-2.0.jar:/opt/apache-storm-0.9.5/lib/logback-core-1.0.13.jar:/opt/apache-storm-0.9.5/lib/snakeyaml-1.11.jar:/opt/apache-storm-0.9.5/lib/carbonite-1.4.0.jar:/opt/apache-storm-0.9.5/lib/tools.logging-0.2.3.jar:/opt/apache-storm-0.9.5/lib/core.incubator-0.1.0.jar:/opt/apache-storm-0.9.5/lib/chill-java-0.3.5.jar:/opt/apache-storm-0.9.5/lib/jgrapht-core-0.9.0.jar:/opt/apache-storm-0.9.5/lib/jline-2.11.jar:/opt/apache-storm-0.9.5/lib/commons-fileupload-1.2.1.jar:/opt/apache-storm-0.9.5/lib/log4j-over-slf4j-1.6.6.jar:../examples/storm-starter/storm-starter-topologies-0.9.5.jar:/opt/apache-storm-0.9.5/conf:/opt/apache-storm-0.9.5/bin -Dstorm.jar=../examples/storm-starter/storm-starter-topologies-0.9.5.jar storm.starter.WordCountTopology wordcount
   
   1038 [main] INFO  backtype.storm.StormSubmitter - Jar not uploaded to master yet. Submitting jar...
   1061 [main] INFO  backtype.storm.StormSubmitter - Uploading topology jar ../examples/storm-starter/storm-starter-topologies-0.9.5.jar to assigned location: /var/lib/storm/nimbus/inbox/stormjar-3a9e3c47-88c3-44c2-9084-046f31e57668.jar
   Start uploading file '../examples/storm-starter/storm-starter-topologies-0.9.5.jar' to '/var/lib/storm/nimbus/inbox/stormjar-3a9e3c47-88c3-44c2-9084-046f31e57668.jar' (3248678 bytes)
   [==================================================] 3248678 / 3248678
   File '../examples/storm-starter/storm-starter-topologies-0.9.5.jar' uploaded to '/var/lib/storm/nimbus/inbox/stormjar-3a9e3c47-88c3-44c2-9084-046f31e57668.jar' (3248678 bytes)
   1260 [main] INFO  backtype.storm.StormSubmitter - Successfully uploaded topology jar to assigned location: /var/lib/storm/nimbus/inbox/stormjar-3a9e3c47-88c3-44c2-9084-046f31e57668.jar
   1261 [main] INFO  backtype.storm.StormSubmitter - Submitting topology wordcount in distributed mode with conf {"topology.workers":3,"topology.debug":true}
   2076 [main] INFO  backtype.storm.StormSubmitter - Finished submitting topology: wordcount
   

6. Verify that the topology is running correctly by opening the Storm UI in a web browser. The “wordcount” topology should be visible in the Topology Summary section.

The above instructions will use the sample “wordcount” topology, which doesn’t provide a visible output to show the results of the operations it is running. However, this topology simply counts words in generated sentences, so the number under “Emitted” is the actual word count.

For a more practical test, feel free to download another topology, such as the Reddit Comment Sentiment Analysis Topology, which outputs a basic list of threads within given subreddits, based upon which have the most positive and negative comments over time. If you do choose to download a third party topology, be sure it is from a trustworthy source and that you download it to the correct directory.

Start a New Topology

If you or a developer have created a topology, perform these steps to start a new topology on one of your Linode Storm clusters:

1. Package your topology along with all the third party classes on which they depend into a single JAR (Java Archive) file.

2. If multiple clusters are deployed, select the target Storm cluster to run the topology on. Get the public IP address of the client node of the target cluster. See cluster description for details on how to do this.

3. Transfer the topology JAR from your local workstation to client node:

   scp -i ~/.ssh/private-key local-topology-path clusteradmin@public-ip-of-client-node:topology-jar
   

   Substitute private-key for the private key of the Storm client, local-topology-path for the local filepath of the JAR file, PUBLIC-IP-OF-CLIENT-NODE for the IP address of the Storm client, and topology-jar for the filepath you’d like to use to store the topology on the client node.

4. Log in to the client node as clusteradmin, substituting the appropriate values:

   ssh -i ~/.ssh/private-key clusteradmin@PUBLIC-IP-OF-CLIENT-NODE
   

5. Submit the topology to the cluster:

   cd /opt/apache-storm-0.9.5/bin
   ./storm jar topology-jar.jar main-class arguments-for-topology
   

   Substitute topology-jar.jar for the path of the JAR file you wish to submit, main-class with the main class of the topology, and arguments-for-topology for the arguments accepted by the topology’s main class.

6. Monitor the execution of the new topology.

Other Storm Cluster Operations

In this section, we’ll cover additional operations to manage your Storm cluster once it’s up and running.

All commands in this section should be performed from the storm-linode directory on the cluster manager Linode. You will need clustermgr privileges unless otherwise specified.

Expand a Storm Cluster

If the supervisor nodes of a Storm cluster are overloaded with too many topologies or other CPU-intensive jobs, it may help to add more supervisor nodes to alleviate some of the load.

Expand the cluster using the add-nodes command, specifying the plans and counts for the new nodes. For example, to add three new 4GB supervisor nodes to a cluster named storm-cluster1:

./storm-cluster-linode.sh add-nodes storm-cluster1 api_env_linode.conf "4GB:3"

Or, to add a 2GB and two 4GB supervisor nodes to storm-cluster1:

./storm-cluster-linode.sh add-nodes storm-cluster1 api_env_linode.conf "2GB:1 4GB:2"

This syntax can be used to add an arbitrary number of different nodes to an existing cluster.

Describe a Storm Cluster

A user with clustermgr authorization can use describe command to describe a Storm cluster:

./storm-cluster-linode.sh describe storm-cluster1

A user with only clustermgrguest authorization can use cluster_info.sh to describe a Storm cluster using list to get a list of names of all clusters, and the info command to describe a given cluster. When using the info command, you must also specify the cluster’s name:

./cluster_info.sh list
./cluster_info.sh info storm-cluster1

Stop a Storm Cluster

Stopping a Storm cluster stops all topologies executing on that cluster, stops Storm daemons on all nodes, and shuts down all nodes. The cluster can be restarted later. Note that the nodes will still incur hourly charges even when stopped.

To stop a Storm cluster, use the stop command:

./storm-cluster-linode.sh stop storm-cluster1 api_env_linode.conf

Destroy a Storm Cluster

Destroying a Storm cluster permanently deletes all nodes of that cluster and their data. They will no longer incur hourly charges.

To destroy a Storm cluster, use the destroy command:

./storm-cluster-linode.sh destroy storm-cluster1 api_env_linode.conf

Run a Command on all Nodes of a Storm Cluster

You can run a command (for example, to install a package or download a resource) on all nodes of a Storm cluster. This is also useful when updating and upgrading software or changing file permissions. Be aware that when using this method, the command will be executed as root on each node.

To execute a command on all nodes, use the run command, specifying the cluster name and the commands to be run. For example, to update your package repositories on all nodes in storm-cluster1:

./storm-cluster-linode.sh run storm-cluster1 "apt-get update"

Copy Files to all Nodes of a Storm Cluster

You can copy one or more files from the cluster manager node to all nodes of a Storm cluster. The files will be copied as the root user on each node, so keep this in mind when copying files that need specific permissions.

1. If the files are not already on your cluster manager node, you will first need to copy them from your workstation. Substitute local-file for the name or path of the file on your local machine, and PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE for the IP address of the cluster manager node. You can also specify a different filepath and substitute it for ~:

   scp -i ~/.ssh/clustermgr local-files clustermgr@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE:~
   

2. Log in to the Cluster Manager Linode as clustermgr and navigate to the storm-linode directory:

   ssh -i ~/.ssh/clustermgr clustermgr@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE
   cd storm-linode
   

3. Execute the cp command, specifying the destination directory on each node and the list of local files to copy:

   ./storm-cluster-linode.sh cp target-cluster-name "target-directory" "local-files"
   

   Remember to specify the target directory before the list of source files (this is the reverse of regular cp or scp commands).

   For example, if your topology requires data files named “*.data” for processing, you can copy them to root user’s home directory on all cluster nodes with:

   ./storm-cluster-linode.sh cp storm-cluster1 "~" "~/*.data"
   

Delete a Storm Image

To delete a Storm image, use the delete-image command:

./storm-cluster-linode.sh delete-image storm-image1 api_env_linode.conf

Note that this command will delete the image, but not any clusters that were created from it.

Zookeeper Cluster Operations

In this section, we’ll cover additional operations to manage your Zookeeper cluster once it’s up and running.

All commands in this section should be performed from the storm-linode directory on the cluster manager Linode. You will need clustermgr privileges unless otherwise specified.

Describe a Zookeeper Cluster

A user with clustermgr authorization can use the describe command to describe a Zookeeper cluster:

./zookeepercluster-linode.sh describe zk-cluster1

A user with only clustermgrguest authorization can use cluster_info.sh to describe a Zookeeper cluster using list to get a list of names of all clusters, and the info command to describe a given cluster. When using the info command, you must specify the cluster’s name:

./cluster_info.sh list
./cluster_info.sh info zk-cluster1

Stop a Zookeeper Cluster

Stopping a Zookeeper cluster cleanly stops the Zookeeper daemon on all nodes, and shuts down all nodes. The cluster can be restarted later. Note that the nodes will still incur Linode’s hourly charges when stopped.

To stop a cluster, use the stop command:

./zookeeper-cluster-linode.sh stop zk-cluster1 api_env_linode.conf

Destroy a Zookeeper Cluster

Destroying a Zookeeper cluster permanently deletes all nodes of that cluster and their data. Unlike a Linode that is only shut down, destroyed or deleted Linodes no longer incur hourly charges.

To destroy a cluster, use the destroy command:

./zookeeper-cluster-linode.sh destroy zk-cluster1 api_env_linode.conf

Run a Command on all Nodes of a Zookeeper Cluster

You can run a command on all nodes of a Zookeeper cluster at once. This can be useful when updating and upgrading software, downloading resources, or changing permissions on new files. Be aware that when using this method, the command will be executed as root on each node.

To execute a command on all nodes, use the run command, specifying the cluster name and the commands to be run. For example, to update your package repositories on all nodes:

./zookeeper-cluster-linode.sh run zk-cluster1 "apt-get update"

Copy Files to all Nodes of a Zookeeper Cluster

You can copy one or more files from the cluster manager node to all nodes of a Storm cluster. The files will be copied as the root user on each node, so keep this in mind when copying files that need specific permissions.

1. If the files are not already on your cluster manager node, you will first need to copy them from your workstation. Substitute local-file for the name or path of the file on your local machine, and cluster-manager-IP for the IP address of the cluster manager node. You can also specify a different filepath and substitute it for ~:

   scp -i ~/.ssh/clustermgr local-files clustermgr@cluster-manager-IP:~
   

2. Log in to the Cluster Manager Linode as clustermgr and navigate to the storm-linode directory:

   ssh -i ~/.ssh/clustermgr clustermgr@PUBLIC-IP-OF-CLUSTER-MANAGER-LINODE
   cd storm-linode
   

3. Execute the cp command, specifying the destination directory on each node and the list of local files to copy:

   ./zookeeper-cluster-linode.sh cp target-cluster-name "target-directory" "local-files"
   

   Remember to specify the target directory before the list of source files (this is the reverse of regular cp or scp commands).

   For example, if your cluster requires data files named “*.data” for processing, you can copy them to root user’s home directory on all cluster nodes with:

   ./zookeeper-cluster-linode.sh cp zk-cluster1 "~" "~/*.data"
   

Delete a Zookeeper Image

To delete a Zookeeper image, execute the delete-image command:

./zookeeper-cluster-linode.sh delete-image zk-image1 api_env_linode.conf

Note that this command will delete the image, but not any clusters that were created from it.

More Information

You may wish to consult the following resources for additional information on this topic. While these are provided in the hope that they will be useful, please note that we cannot vouch for the accuracy or timeliness of externally hosted materials.

• Apache Storm project website
• Apache Storm documentation
• Storm - Distributed and Fault-Tolerant Real-time Computation