[feature request] lerna bootstrap triggering root postinstall hook

Im not sure if this makes sense, as the intention for having root package.json like this is unclear from the docs:

lerna-repo/
  packages/
  package.json
  lerna.json

however its respected during the bootstraping so I think it makes sense to execute (after this line?) postinstall script.

If you think its the right thing to do, I can provide PR for it.

Also if you provide short explanation of how combination of per package package.jsons and root package.json should work together it would be really helpful

[wbern]

While it’s not completely clear to me if this thread wants to address the issue of having to run 2 separate commands for a locally development-ready environment or not, I wanted to contribute with the below solution.

package.json

  ...
  "config": {
    "envs": "node_modules='$INIT_CWD/node_modules'"
  },
  "scripts": {
    "postinstall": "node ./scripts/bootstrap.js",
    "bootstrap": "cross-env $npm_package_config_envs lerna bootstrap --hoist",
    ...

./scripts/bootstrap.js

#!/usr/bin/env node

var cp = require('child_process');
var os = require('os');

var npmCmd = os.platform().startsWith('win') ? 'npm.cmd' : 'npm';

const runCommand = function(command, args, options = {}) {
    console.log(
        'EXECUTING COMMAND:',
        npmCmd,
        args.join(' '),
        '( path:',
        options.path || process.cwd(),
        ')'
    );
    const { error, statusCode } = cp.spawn(npmCmd, args, {
        env: process.env,
        cwd: options.path,
        stdio: [
            process.stdin,
            process.stdout,
            options.ignoreErrors ? 'ignore' : process.stderr,
        ],
    });

    if (statusCode !== 0 && options.ignoreErrors) {
        console.warn('Command had errors, but ignoring.');
        console.error(error);
    }
};

const alreadyExecuted = process.env['LERNA_EXECUTED'];

if(!alreadyExecuted) {
    process.env['LERNA_EXECUTED'] = true;
    runCommand(npmCmd, ['run', 'bootstrap'], { });
}

Any developer can do npm install, and the following will/should happen.

1. npm install runs as per usual process
2. postinstall hook triggers, executing bootstrap.js
3. bootstrap.js executes, which checks if LERNA_EXECUTED is set. If not set, does npm run bootstrap
4. npm run bootstrap will run lerna, which (with hoisting) implies another npm install being done.
5. Upon completion by lerna, another postinstall hook triggers, which again executes ./scripts/bootstrap.js
6. bootstrap.js will this time recognize that LERNA_EXECUTED is set to true, and will gracefully exit.
7. When script execution is finally over, LERNA_EXECUTED will again become empty (ie echo $LERNA_EXECUTED in the shell will return an empty string)

Tested with: npm: 5.6.0 (package-lock.json-files enabled) node: 8.11.3 (LTS by current writing)

This will ease transition to lerna for me and my colleagues. Since I just discovered this, I will get back if we find any issues. The only real downside now is that you need to run a regular npm install before lerna does it again. On the other hand, we have listed lerna as a local dependency, so it would not be possible for lerna to execute without the initial installation.

PS. The cross-env $npm_package_config_envs part can be excluded (it’s a devDependency). For me it provides a neat way of accessing hoisted node_modules from my lerna packages inside the package.json. This is completely unnecessary if you intend to just use the bin’s like webpack for example, but really valuable if you need to access files directly inside node_modules dependencies. To not use this, just omit that part, and exclude the config section altogether. If anyone knows a more intregrated way of accomplishing this, do let me know!

[lock[bot]]

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