[systemd-devel] Pass environment variables down to systemd-service in container

[Lennart Poettering]

On Tue, 16.06.15 17:49, Peter Paule (systemd-devel at fedux.org) wrote:

> Excerpts from Lennart Poettering's message of 2015-06-15 00:32:09 +0200:
> > 
> > Nope, we deliberately clean up the env block we pass to services.
> > 
> 
> Mmmh, would it possible to add some kind of a whitelist for environment
> variables to the systemd- and/or service.unit-configuration for
> variables which are passed on to services? Maybe something like
> http://httpd.apache.org/docs/2.2/mod/mod_env.html#passenv.
> 
> This would make things a lot of easier when containers are used with
> systemd as process supervisor. At least for Ruby on Rails or other
> software which makes use of environment variables for configuration.
> 
> This way I can build a single image I can use in different environments
> just by setting environment files. Does that make sense to you?
> 
> Outer Service Units
>   # Service 1
>   ExecStart="docker run -e RAILS_ENV=production -e DATABASE_URL="postgresql://localhost/app_production centos-rails"
>   
>   # Service 2
>   ExecStart="docker run -e RAILS_ENV=staging -e DATABASE_URL="postgresql://localhost/app_staging centos-rails"
> 
> Inner Service Units (Example)
>   PassEnv="RAILS_ENV"
>   ExecStart="RAILS_ENV=${RAILS_ENV} /srv/app/bin/rails"

I'd be willing to add a setting called PassEnvironment= that takes a
list of env vars to import from PID1's env block.

Happy to take a patch, also added to TODO list, so that we don't forget.

Lennart

-- 
Lennart Poettering, Red Hat