Relay: Make Watchman a non-hard dependency

[kassens]

Not sure where a good place for this would be in the docs – probably the compiler section.

See #1626 for @unirey hitting this issue.

[ivome]

It does not seem to be limited to windows, I get the same message on OS X 10.10.5

[kassens]

Updated the title to reflect that.

[igl]

Why is it required for a static build that does not --watch?
Jenkins is not happy.

[wincent]

Why is it required for a static build that does not --watch?

Good question. At the moment, I think the answer may be "because nobody has taken the taken the time to isolate the parts of the code that depend on Watchman". It probably would be interesting to do so, as having a small dependency footprint is a desirable property.

[taion]

I think that's the bigger/more surprising thing. It's odd to require watchman for e.g. CI environments where:

• There's no watching going on, and
• watchman is a bit annoying to install

[wincent]

Yep, I agree with you. Like I said over here:

I'd like to see us gracefully fallback to a non-watchman implementation when Watchman is not available (and especially when not running under --watch mode).

We'd definitely welcome a pull-request that addressed this.

[wincent]

Retitled this to reflect the desired solution, so removing the "docs" label, although we'd still welcome clearer docs in the meantime.

[ryancole]

Would this be considered rather simple to do, or are there a some gotchas involved? I have some free time and could try my best to provide a pull request. If it's going to be a bit complicated though I would probably just let somebody else with more knowledge of the internals take a shot at it.

[wincent]

@ryancole: I don't think it is likely to be particularly difficult, but few things are ever as easy as you think they will...

If you wanted to look at the code to gauge the complexity of it I'd suggest starting here:

https://github.com/facebook/relay/blob/8f719e15a541dc8964892210716c329687cc4d7f/packages/relay-compiler/bin/RelayCompilerBin.js#L45-L55

That's the watch expression that the current system passes through to Watchman. To break the dependency, we need to implement simple code that knows how to identify all the files matched by that description. Doesn't look too bad, to be honest.

[henryqdineen]

👍 but I am wondering what is the suggested way around this now. Are people just installing watchman as part of the CI build?

[taion]

Yeah. It requires using a sudo-enabled Travis setup. It's unfortunate.

[matthewoates]

I'm checking in the built graphql files. It's not pretty, but way prettier than adding watchman to CI.

[JCMais]

The main issue from what I can see is in this line: https://github.com/facebook/relay/blob/87699b83e24330536daa19ab94bbeaf40f5ad814/packages/relay-compiler/codegen/RelayCodegenRunner.js#L148

Code excerpt:

  async parseEverything(parserName: string): Promise<void> {
    if (this.parsers[parserName]) {
      // no need to parse
      return;
    }

    const parserConfig = this.parserConfigs[parserName];
    this.parsers[parserName] = parserConfig.getParser(parserConfig.baseDir);

    // here \/
    const files = await RelayCodegenWatcher.queryFiles(
      parserConfig.baseDir,
      parserConfig.watchmanExpression,
      parserConfig.getFileFilter
        ? parserConfig.getFileFilter(parserConfig.baseDir)
        : anyFileFilter,
    );
    this.parseFileChanges(parserName, files);
}

Watchman is being used to return all files that relay-compiler needs to parse. This makes it that, even if no --watch flag is passed, a watchman client is initialized. See source of RelayCodegenWatcher.queryFiles

[sibelius]

anybody fixed this on circleci?

[robrichard]

@sibelius I've seen it happen on our in-house Jenkins server. We add watchman watch-del-all to our job config as a workaround.

I have a PR open (https://github.com/facebook/relay/pull/1966) to not use watchman unless you are using watch mode.

[eddies]

@sibelius I use the following in my circle.yml:

dependencies:
  cache_directories:
    - watchman
  pre:
    - if [[ ! -e watchman ]]; then git clone https://github.com/facebook/watchman.git && cd watchman/ && git checkout v4.7.0 && ./autogen.sh && ./configure && make; fi
    - cd watchman && sudo make install
    - sudo sysctl fs.inotify.max_user_watches=524288
    - sudo sysctl -p

[junosuarez]

thanks to @eddies, we got this working on Travis by adding:

before_install:
  # dirty ugly watchman hack https://github.com/facebook/relay/issues/1644#issuecomment-315998313
  - if [[ ! -e watchman ]]; then git clone https://github.com/facebook/watchman.git && cd watchman/ && git checkout v4.7.0 && ./autogen.sh && ./configure && make  && sudo make install; fi
  - sudo sysctl fs.inotify.max_user_watches=524288
  - sudo sysctl -p
  - cd ~/build/$TRAVIS_REPO_SLUG
  # end dirty watchman hack

[Oxyaction]

Any suggestions? Why this issue is closed?

[taion]

It was resolved. You don't need Watchman any more unless you're watching.

[steida]

@taion Unless we have src as current dir.

[earksiinni]

I'm still hitting the watchman dependency when running

npx relay-compiler --src client --schema client/config/schema.graphql.

However, if I add the --watchman false flag, like so:

npx relay-compiler --src client --schema client/config/schema.graphql --watchman false,

everything works.

Why is watchman still enabled by default even when not using --watch?