Preinstall check that mentions 'yarn kbn'

[kimjoar]

Some preinstall checks to help people remember yarn kbn bootstrap.

This also throws when using npm. However, it's a bit annoying that npm<5 runs this lifecycle hook after installing deps (and npm 3 doesn't allow our link: deps, so it will likely fail when installing deps). But at least it warns at the right time for npm5+.

Test cases:

• (with npm3 you'll just get an Unsupported URL Type error, so it's not necessary to test it)
• with npm5 version (aka node 8), run npm install. It should throw an error about using Yarn instead.
• run yarn and verify you see a message about preferring to use yarn kbn bootstrap
• run yarn kbn bootstrap and verify no warnings

Tested on:

• macos
• linux
• windows

[kimjoar]

When I searched around, this seemed like the simplest way to know it was npm and not yarn. E.g. from yarn team lead: https://twitter.com/cpojer/statuses/953286334013231104

[epixa]

Holy hacks. If this were a production thing, I'd say we need integration tests for all of these different possible scenarios, but it's not, and it never will be, so we're probably fine.

[epixa]

It'd be good to test this on macos/linux/windows to ensure our expectations around the process contents are the same across OSs.

[kimjoar]

I've tested macos.

@azasypkin Can you test this on Linux?
@marius-dr Can you test this on Windows?

(btw, @marius-dr, if you don't have nvm set up to easily switch to Node8, we can get another Windows user to test — I just chose you as I know you're on Windows)

[epixa]

And we should verify that adding/removing dependencies doesn’t trigger a warning. Not sure if that triggers a preinstall

[kimjoar]

It triggers the preinstall hook, but no warning as argv.cooked.includes('install') returns false.

[nreese]

I think the warnings are very helpful. Thanks @kjbekkelund

[azasypkin]

OS: Arch Linux

Test case №1:
node v6.12.2 / npm v3.10.10
Unsupported URL Type: link:packages/kbn-babel-preset

node v8.9.4 / npm v5.6.0
throw "Use Yarn instead of npm, see Kibana's contributing guidelines"

Test case №2:
node v6.12.2 / npm v3.10.10
WARNING: When installing dependencies, prefer yarn kbn bootstrap

node v8.9.4 / npm v5.6.0
WARNING: When installing dependencies, prefer yarn kbn bootstrap

The engine "node" is incompatible with this module. Expected version "6.12.2".

Test case №3:
node v6.12.2 / npm v3.10.10
No warnings (except for the incorrect peer dependency old ones)

node v8.9.4 / npm v5.6.0
The engine "node" is incompatible with this module. Expected version "6.12.2".

[kimjoar]

Thanks for testing. I added a clarification around the npm3 (expected) failure in the description now too.

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request

[marius-dr]

NPM 3:

npm ERR! node v6.12.2
npm ERR! npm  v3.10.10
**npm ERR! Unsupported URL Type: link:packages/kbn-babel-preset**

NPM 5:

> kibana@7.0.0-alpha1 preinstall C:\Users\ratonbox\Documents\GitHub\kibana
> node ./preinstall_check
C:\Users\ratonbox\Documents\GitHub\kibana\preinstall_check.js:4
  throw "Use Yarn instead of npm, see Kibana's contributing guidelines";
  ^
**Use Yarn instead of npm, see Kibana's contributing guidelines**
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! kibana@7.0.0-alpha1 preinstall: `node ./preinstall_check`
npm ERR! Exit status 1

Yarn:

yarn install v1.3.2
$ node ./preinstall_check

WARNING: When installing dependencies, prefer `yarn kbn bootstrap`

[1/5] Validating package.json...
error kibana@7.0.0-alpha1: The engine "node" is incompatible with this module. E
xpected version "6.12.2".

Yarn kbn bootstrap:

yarn run v1.3.2
$ node scripts/kbn bootstrap
Running [bootstrap] command from [C:\Users\ratonbox\Documents\GitHub\kibana]:

Found [5] projects:  [...]

and it goes on to work.

LGTM