Support building via slug image references

[intellix]

In my quest to achieve pipelines in Deis, I've got 2x applications:

• myproject
• myproject-staging

Underneath the myproject-staging app I want a button: Promote to Production which when clicked will put the exact same image onto the production app (myproject).

It seems the way to get this working is to make an API call like:

POST `http://deis.${cluster}/${apiVersion}/apps/builds`
Data: {
  image: "home/myproject-staging:git-db6645f5/push/slug.tgz"
}

The problem is that this only works for Docker image references and doesn't support passing in a slug built reference.
I'm not going to say buildpacks are a requirement for me right now, but it would allow me to implement pipelines for all application types.

[Joshua-Anderson]

I like the idea! Heroku has a similar API for creating custom builds.

It would also be cool to be able to pull a tarball from anywhere, but that can be a future improvement.

[bacongobbler]

If the use case is just "promote to production" then that can be solved via deis pipeline:promote which is something that was proposed in deis/deis#1318. That use case shouldn't be too hard to create a new feature request for, since we're just "promoting" the staging app's latest build to become the production app's latest build.

[intellix]

Related issue: #711

[Cryptophobia]

This issue was moved to teamhephy/workflow#47