Document how to select minimal vs full Trusty build image

[edmorley]

The documentation for the beta Trusty environment (here) says:

For our Trusty based environments, we’re making a smaller set of images that includes:

• minimal image which contains a small subset of interpreters, as well as docker and packer.
• considerably larger image which contains (almost) all runtimes and services present in Precise environments.

However I can't find a mention of how Travis chooses between each of those images, and what the larger image contains that the smaller doesn't?

Initially I thought perhaps selecting the smaller image was performed by not specifying a language key in .travis.yml at all, however doing so resulted in the job installing ruby instead, which was a bit puzzling:
https://travis-ci.org/mozilla/treeherder/builds/242954322#L226

My use-case is trying to select the smaller image to speed up job times, since I'm experimenting with using Docker Compose (so that we can test against Ubuntu 16.04) - which means we don't need anything but Docker/Compose installed.

Many thanks!

[MariadeAnton]

you're absolutely right, @edmorley - thanks for bringing this up!

You can use the minimal image by selecting language: minimal or language: generic. Since the update on July, 12th generic points to the full/bigger image: https://docs.travis-ci.com/user/build-environment-updates/2017-07-12/

We'll update this in the docs too :)

[edmorley]

Hmm so I've tried out the various {generic, minimal, bash, shell, sh} language combinations on Trusty using both containers and sudo:
https://travis-ci.org/edmorley/travis-testing/builds/250035772

...and for completeness, the same as that but using Precise:
https://travis-ci.org/edmorley/travis-testing/builds/250035931

Notably:

• All of {generic, bash, shell, sh} seem identical and don't have any language specific functionality (other that what's pre-installed in the base image)
• However minimal runs ruby-specific commands (such as rvm use default):
  • container: https://travis-ci.org/edmorley/travis-testing/jobs/250035781
  • gce sudo: https://travis-ci.org/edmorley/travis-testing/jobs/250035783

@meatballhat, is this intentional?

I see also that in travis-ci/packer-templates#454, generic is soon going to result in sugilite (the big image) instead, so should probably be excluded from any documentation added here.

[edmorley]

Oh right I see now, there are two places lang controls -- the initial image selection from job-board, and then also the runtime scripts run by travis-build here:
https://github.com/travis-ci/travis-build/blob/75a27e5e4a41246790ea54a5227514cf8a9374bf/lib/travis/build.rb#L26-L47

The travis-build aliases are out of sync with the image language tags here:
https://github.com/travis-ci/packer-templates/blob/57d68e763001fa88f55bddc9b16d3259ebc925cf/cookbooks/travis_ci_connie/attributes/default.rb#L64-L68

generic works, since that's the class name:
https://github.com/travis-ci/travis-build/blob/75a27e5e4a41246790ea54a5227514cf8a9374bf/lib/travis/build/script/generic.rb

But minimal falls back to the default:
https://github.com/travis-ci/travis-build/blob/75a27e5e4a41246790ea54a5227514cf8a9374bf/lib/travis/build.rb#L45

I'll open a PR against travis-build.

[BanzaiMan]

@meatballhat @MariadeAnton Did we ever support language: minimal?

[edmorley]

I'd only been using minimal since it was mentioned above, and it's listed in the packer configs:
https://github.com/travis-ci/packer-templates/blob/fb7eee054b0c4bb3e02d5d3db78a2d95170916f1/cookbooks/travis_ci_connie/attributes/default.rb#L67

Also, now that travis-ci/packer-templates/pull/454 has landed, using the lang generic will result in the larger sugilite image, so if one wants the smallest gce image possible, the lang options to use are now reduced to these aliases: {bash, shell, sh, minimal} (which are all identical other than minimal causing travis-build to run the Ruby script at present)

If it's desired to deprecate minimal (after all, as of the travis-ci/travis-build/pull/1102 PR it will be identical to the bash lang aliases), that would be fine with me - it would just be good to:
(a) remove it from the packer config,
(b) make the docs clear that it will result in a larger/more time consuming image (since it will fall back to the default larger image and Ruby travis-build script).

[MariadeAnton]

Just adding a note here to confirm what I've updated in the comment above. Since the update on July, 12th language: generic points to the full/bigger image: https://docs.travis-ci.com/user/build-environment-updates/2017-07-12/

And to use the minimal one we can use language: minimal :)

Thanks for all of your investigation, Ed!