Can I use environment variable for server IP?

[albertski]

Is it possible to use environment variables for the server IPs? For example,

# Deploy to these servers.
servers:
  web:
    - KAMAL_DEPLOY_IP_1

I get the following error now if I deploy when using the environment variable:

  ERROR (SocketError): Exception while executing on host KAMAL_DEPLOY_IP_1: getaddrinfo: nodename nor servname provided, or not known

[medius]

You can use ERB in deploy.yml to dynamically insert anything including server IPs

# Deploy to these servers.
servers:
  web:
    - <%= ENV['KAMAL_DEPLOY_IP_1'] %>

Edited: As mentioned below, I had accidentally used the wrong syntax earlier and have now corrected it.

[cosmin-marginean]

This doesn't seem to work, maybe because of image not supporting this?

image:
  - <=% ENV['DOCKER_IMAGE'] %>

(Sorry, not a Ruby expert, not sure of this is correct)

[ttilberg]

Note that OP had the tag syntax switched. It should be <%= as opposed to <=%.

[crohr]

Yes, definitely doable, even with multiple IPs, for instance:

servers:
  web:
    hosts: <%= ENV.fetch('SERVER_IPS').split(' ') %>

You could go as far as to fetch those IPs from your hosting provider API, although I wouldn't necessarily recommend it.

[hipertracker]

OK, fine but how to pass env variables from Kamala secrets and 1Password? I can define env vars for the whole service but what but not only for the specific server. I define it currently globally in deploy.yml (this is for Django app)

env:
  clear:
    DEBUG: 0
  secret:
    - DATABASE_URL

[emerson-argueta]

Looking at the source code, this wouldn't work, but we can create an issue and propose to pull from the secrets config.
For reference I'm looking at the servers config:
https://github.com/basecamp/kamal/blob/main/lib/kamal/configuration/servers.rb

and we can propose to do similarly what is done for registry config:
https://github.com/basecamp/kamal/blob/main/lib/kamal/configuration/registry.rb