Add support other node images

[reklatsmasters]

I like mhart/alpine-node. It's extremely small image ~50mb. Would be better to have option to use this image.

[sanex3339]

+++, but here probably will be problems in rare situations when travis-ci tests are passed, but trevor tests doesn't, because of different environments.

[vadimdemedes]

Will this image work as expected when there are native dependencies (need compilation)?

Would be better to have option to use this image.

Aside from smaller size, how is it better than the official image?

[SamVerschueren]

I'm wondering for a while now, can we just use the same image as Travis does? Is it publicly available for us to use and just use whatever they use?

[vadimdemedes]

Yeah, I was thinking about it too. Would solve pretty much all user requests and issues.

[SamVerschueren]

@vadimdemedes It looks like the images can be found here. This should be some docs, although not sure if we can do anything with it. Have to take a closer look.

[tunnckoCore]

just drop the suffix -onbuild, that's enough. All of the images will be supported - it won't be "breaking" change.

btw, was just curious about docker and implemented it for the sake of training, of course dont have pretty UI

const readFile = util.promisify(fs.readFile)

function getVersions () {
  return readFile('./.travis.yml', 'utf8').then(
    (str) => yaml.safeLoad(str).node_js
  )
}

const opts = { stdio: 'inherit' }

const pass = (version) => () => console.log('Build', version, 'passed')
const fail = (version) => (er) =>
  console.log('Build', version, 'failed', er.message)

const npmTest = (version) =>
  execa('npm', ['test'], opts).then(pass(version), fail(version))

const npmInstall = (version) =>
  execa('npm', ['install'], opts).then(() => npmTest(version))

const nodeInstall = (v) =>
  execa('docker', ['pull', `node:${v}`], opts).then(() => npmInstall(v))

getVersions().then((versions) => pMap(versions, nodeInstall)).catch((er) => {
  console.log('commit failed', er.stderr)
})

that's the whole CI core in reality :D from there on, only features can be added (like why not implement the hooks) and UI

[tunnckoCore]

btw, when i tried trevor few times i thought that it's damn slow (so slow that my archlinux is lagging a bit) because the -onbuild, but it seems that's not the reason, because with above implementation it's fast as other images.

The most slow step using Trevor is "building environment", don't know why. Takes 5+ minutes.

[vadimdemedes]

I think npm install takes the majority of that time.