[systemd-devel] Query regarding "EnvironmentFile"

[Lennart Poettering]

On Wed, 23.12.15 11:30, Alex Crawford (alex.crawford at coreos.com) wrote:

> On 12/23, Lennart Poettering wrote:
> > On Wed, 23.12.15 06:01, Jóhann B. Guðmundsson (johannbg at gmail.com) wrote:
> > > What usescases do you see for it's existence.
> > 
> > Well, the usecase that this is what's out there right now, and we have
> > to stay compatible. It's not precisely an exotic feature, we can
> > easily deprecated. It's unfortunately pretty popular.
> 
> We use it within CoreOS to allow the user to inject dynamic data into the
> service. For example, you may have a service like this:
> 
>  $ cat etcd.service
>  [Unit]
>  Requires=metadata.service
>  After=metadata.service
> 
>  [Service]
>  EnvironmentFile=/run/coreos/metadata
>  ExecStart=/usr/bin/etcd --public-ip=${COREOS_PRIVATE_IPV4}
> 
> where "metadata.service" populates /run/coreos/metadata with a bunch of info
> about the system (like Facter from puppet). The user can then pick and choose
> the appropriate variables to use (maybe they need the public address instead)
> and override the ExecStart in a drop-in.
> 
> I like this model and I'm not sure how I would solve this if EnvironmentFile
> didn't exist.

I see no reason why systemd should be involved with this. Just make
etcd a proper daemon, and read its config data directly, rather then
serializing it into the command line.

Lennart

-- 
Lennart Poettering, Red Hat