Support io.buildpacks.stacks.bionic stack

[jabrown85]

This RFC is working its way through and it seems useful to be able to use Heroku buildpacks on cloudfoundry/cnb:bionic. This also aligns with how riff is compatible with multiple stacks.

[hone]

we need to test a base bionic stack, to see what mixins we need to use.

[jabrown85]

@hone I built a couple images for you.

build-image = "heroku/heroku-private:cnb-bionic-build"
run-image = "heroku/heroku-private:cnb-bionic-run"

I tried to see what packages are missing but I was getting obscure errors.

» cat builder-bionic.toml 
[stack]
id = "io.buildpacks.stacks.bionic"
build-image = "heroku/heroku-private:cnb-bionic-build"
run-image = "heroku/heroku-private:cnb-bionic-run"

[lifecycle]
version = "0.5.0"

[[buildpacks]]
  id = "heroku/ruby"
  # TODO: release with https://github.com/heroku/heroku-buildpack-ruby/pull/945
  uri = "buildpacks/heroku-ruby-test"
  #uri = "https://github.com/heroku/heroku-buildpack-ruby/releases/download/cnb-alpha/ruby-buildpack-vCNB-alpha.tgz"

[[order]]
  [[order.group]]
    id = "heroku/ruby"
    version = "0.0.1"
$ pack create-builder bionic-services --builder-config builder-bionic.toml --no-pull
$ docker run -v ~/dev/ruby-getting-started:/workspace -it -u 0 bionic-services bash
root@15fba3c219f3: apt-get update && apt-get upgrade -y && apt-get install -y --no-install-recommends curl && apt-get install -y --no-install-recommends ca-certificates
root@15fba3c219f3:/layers# /cnb/lifecycle/detector
heroku/ruby 0.0.1
root@15fba3c219f3:/layers# /cnb/lifecycle/builder
  Failed to download a Ruby executable for bootstrapping!

  This is most likely a temporary internal error. If the problem
  persists, make sure that you are not running a custom or forked
  version of the Heroku Ruby buildpack which may need updating.
/cnb/buildpacks/heroku_ruby/0.0.1/bin/build: line 17: /tmp/tmp.RngcFgXVfQ/bin/ruby: No such file or directory
ERROR: failed to build: exit status 127
root@15fba3c219f3:/layers#

Besides playing whack-a-mole, I'm not sure what the best option would be for figuring out what a buildpack like this needs to operate package wise...

[schneems]

Is this still needed after #888 was merged?

[jabrown85]

I think you safely can close and re-do this when it comes back up as a priority.