Set KAMAL_DESTINATION for envify command

[nickhammond]

Since destinations usually map to an environment such as a Rails environment it'd be helpful to load the current destination so that you can more easily use a destination template file. I made the assumption that we load the clear variables from Kamal but right now envify just loads the template and writes the output destination file, no clear/secret loading from Kamal.

For example:

.env.template.erb

# Generated by kamal envify, to regenerate run `kamal envify -d <%= ENV['KAMAL_DESTINATION'] %>`

RAILS_ENV=<%= ENV['KAMAL_DESTINATION'] %>

API_KEY_EXAMPLE=<%= `op read "op://hey-#{ENV['KAMAL_DESTINATION']}/API_KEY_EXAMPLE/credential" -n`.strip %>

.env.staging.erb and .env.production.erb

<%= 
  ERB.new(File.read(".env.template.erb"), trim_mode: "-").result(binding)
%>

Which would generate something like this when running kamal envify -d staging:

# Generated by kamal envify, to regenerate run `kamal envify -d staging`

RAILS_ENV=staging

API_KEY_EXAMPLE=secret

#352 is related from the perspective of having a template for your destination files.

[igor-alexandrov]

Maybe I am missing something but the result you want can be achieved with:

# .env.template.erb

API_KEY_EXAMPLE=<%= `op read "op://hey-#{ENV['KAMAL_DESTINATION']}/API_KEY_EXAMPLE/credential" -n`.strip %>

and

# .env.staging.erb
RAILS_ENV=staging
<%= ERB.new(File.read(".env.template.erb"), trim_mode: "-").result(binding) %>

[nickhammond]

@igor-alexandrov ENV['KAMAL_DESTINATION'] is only populated in the hooks at the moment I believe. But yes, I'm doing something similar to your .env.staging.erb example.

[jeromedalbert]

Yeah according to the source code ENV['KAMAL_DESTINATION'] seems to be available only for hooks.

I am wondering if it would make sense to make ENV['KAMAL_DESTINATION'] available globally, not just for envify. I have found the need to use ENV['KAMAL_DESTINATION'] in my deploy.yml so I don't have to hardcode the word "production" / "staging" / etc in my yaml files.