How do i get from API the id of custom image

Curling that URL without authentication will list only public images. To list private and public images, our documentationexplains that you need to auth the token to the API Call like this:

curl -H "Authorization: Bearer $TOKEN" \
    https://api.linode.com/v4/images

If you haven't already, you can follow this guide for creating an API token. Make sure it has proper permissions to view your private images and then set it as the $TOKEN environment variable. (You can just copy and paste the token itself where it says $TOKEN if you want.)

To filter out any public images and just return your own, you can read about using X-filters. I played around with this for a while and figured out the syntax to get a readable list of just my own images:

curl -H "Authorization: Bearer $TOKEN" \
-H 'X-Filter: { "is_public": false }' \
https://api.linode.com/v4/images | json_pp

While it took me a while to get the exact right syntax for the API, if you want something more user friendly, I strongly recommend using the Linode CLI, which took about 30 seconds to figure out. It's a wrapper for our API and it's got a great help function. I sometimes run commands with the CLI and compare the response with API commands to see if I'm getting the correct output.

I found the basic command for listing images with CLI from our API documentation here:

linode-cli images list

From there, I ran the command with the --help flag and got this:

linode-cli images list --help
linode-cli images list
Images List
API Documentation: https://www.linode.com/docs/api/images/#images-list

You may filter results with:
  --label
  --deprecated
  --is_public
  --size
  --type
  --vendor
  --status
Additionally, you may order results using --order-by and --order.

The syntax for the CLI is usually pretty intuitive, so I ran this and it worked and the output was in a nice, neat table that's more readable than API output:

linode-cli images list --is_public=false

This does take a bit of time to set up but is easy to use when you run commands, whereas the API requires less work up front and more work each time you use it. Depending on your use case, if the CLI seems like something you'd like to try, you can check out our guide to getting started with the Linode CLI.