Add support for template_driver in composefiles

[vdemeester]

This maps the --template-driver flag on secret and config creation.

See #896 (and upstream moby/moby#33702)

• probably need some test
• as for the initial flag, need some documentation too

Signed-off-by: Vincent Demeester vincent@sbr.pm

[silvin-lubecki]

SGTM but it definitely needs some tests 😄

[vdemeester]

@silvin-lubecki added some test
cc @thaJeztah

[thaJeztah]

Linting failure;

Successfully tagged cli-linter:13932
cli/compose/loader/loader_test.go:1::warning: file is not gofmted with -s (gofmt)
Exited with code 1

[silvin-lubecki]

You can simplify the test:

assert.Assert(t, is.Equal(config.Configs["config"].TemplateDriver, "config-driver"))
assert.Assert(t, is.Equal(config.Secrets["secret"].TemplateDriver, "secret-driver"))

[overmike]

Will this be included in 18.09 release?

[thaJeztah]

LGTM

Not sure if this can still make it into 18.09. If it doesn't, this change needs to be moved to a 3.8 schema for the compose file.

[cpuguy83]

Is there another driver other than the built-in go one?
What's the reasoning for wanting this anytime soon?

[thaJeztah]

Good point; don't think there's another driver yet; otoh, isn't it required to set a driver in order to use templating? (will have to check)

[thaJeztah]

To come back to my previous comment;

Templating controls whether and how to evaluate the config payload as a template. If no driver is set, no templating is used.

So, yes, we need this option to enable templating, otherwise no templating will be applied.

I see this needs a rebase though (and would now have to be moved to docker-compose schema 3.8

[thaJeztah]

Carried in #1746

[vdemeester]

Thanks @thaJeztah 😽