expected side-effects if changing hostname
When I first set up my Linode using the Getting Started guide, I gave my hostname the same name as my domain: "adonax". I'm regretting this now, and wish to change the hostname.
The above link shows that it is a simple matter to change it, but I'm nervous about side-effects. I could just do it, and see what breaks, and restore if needed. But I was wondering if folks had any "heads up" on things to look out for.
I currently have a webserver installed (am using Jetty) and email (PostFix + DoveCot).
I'm particularly keen to know how this effects DNS records and such, if they will need to be redone. The DNS Manager guide is confusing to me. The example (see step 2) uses "www" as a hostname, but the "Getting Started" guide explicitly discourages the use of "www" as a hostname. Is the "www" example text in the DNS Manager standing in for something else?
2 Replies
bbigger
Linode Staff
A lot of confusion regarding the term "hostname" stems from its usage in multiple contexts. In the context of Linode DNS Manager settings, the hostname in the example you've pointed out refers to the subdomain corresponding to an A/AAAA record. Setting the subdomain here to www makes sense if you want www.example.com for your example.com zone to point to the specified IP address.
However, in the context of Linode systems per the Getting Started guide, the hostname as set by a command like hostnamectl is primarily used for humans to identify the system—here, you'd want the system hostname to be unique so that it doesn't get confused with other systems. While changing the hostname in this context probably won't affect your services, this depends on how those services have been configured.
Finally, it's worth pointing out that a system's FQDN also often gets confused with hostnames as they're commonly statically configured in the system's /etc/hosts file — you can see how they're both referenced in this section of our Email with Postfix/Dovecot guide.
Accordingly, changes to your system hostname shouldn't have any effect on records configured through DNS Manager, which are handled by Linode's nameservers. Issues with domain name resolution which may occur internally on your Linode, rather than Linode's nameservers, should be solvable by configuring your /etc/hosts file.
If you do run into email issues, though, you may find this troubleshooting guide helpful. I don't have any experience with Jetty, but the same principles should apply—changing your system hostname shouldn't have an impact.
Thank you so much for this answer!
I intend to methodically work through the information you provided (personal time allowing), both in terms of dealing with my own configuration issues and in terms of proposing or providing improvements to the guides at the key points where the lack of disambiguation in the mostly excellent documentation has caused grief.
So far: I changed the Linode system host name, and tested the web server and the email server, and both are still functioning as expected.