circleci.js

const parseDiff = require('diffparser');
const fetch = require('node-fetch');
const { moduleDependencies } = require('../package.json').fxa;

function moduleName(path) {
  const parts = path.split('/');
  return parts.length > 1 ? parts[0] : 'root';
}

async function getModules(org, repo, branch) {
  try {
    const response = await fetch(`https://patch-diff.githubusercontent.com/raw/${org}/${repo}/${branch}.diff`);
    const diff = parseDiff(await response.text());
    const modules = new Set()
    for (const { to, from } of diff) {
      [to, from]
        .filter(n => n !== '/dev/null')
        .forEach(n => modules.add(moduleName(n)))
    }
    return modules;
  } catch (e) {
    console.error(e)
    return new Set(['all']);
  }
}

function modulesToTest(changed) {
  const toTest = new Set(changed);
  let size;
  do {
    size = toTest.size;
    for (const [mod, deps] of Object.entries(moduleDependencies)) {
      for (const m of toTest) {
        if (deps.includes(m)) {
          toTest.add(mod);
        }
      }
    }
  } while (size < toTest.size)
  return toTest;
}

async function main() {
  const branch = process.env.CIRCLE_BRANCH;
  const org = process.env.CIRCLE_PROJECT_USERNAME;
  const repo = process.env.CIRCLE_PROJECT_REPONAME;

  if (branch.startsWith('pull/')) {
    const toTest = modulesToTest(await getModules(org, repo, branch));
    for (const mod of toTest) {
      console.log(mod)
    }
  }
  else {
    console.log('all')
  }
}

main();

mono.sh

#!/usr/bin/env bash -ex

MODULES=('fxa-monorepo-prep' 'fxa-basket-proxy' '123done' 'browserid-verifier' 'fxa-auth-db-mysql' 'fxa-auth-server' 'fxa-content-server' 'fxa-customs-server' 'fxa-email-service' 'fxa-js-client' 'fxa-oauth-console' 'fxa-profile-server' 'fxa-shared' 'fxa-geodb' 'fxa-email-event-proxy')

TAB=$'\t'

mkdir fxa
cd fxa
git init
git commit --allow-empty --date '1980-08-23T20:15:12' -m 'this is the fxa monorepo'
git tag -a first-commit -m 'first commit'
FIRST=$(git rev-parse HEAD)

rewrite_module() {
  local module=$1
  git remote add $module git@github.com:mozilla/${module}.git
  git fetch $module
  if [[ "${module}" == '123done' ]]; then
    git checkout --no-track -b $module ${module}/oauth
  else
    git checkout --no-track -b $module ${module}/master
  fi
  if [[ "${module}" == 'fxa-monorepo-prep' ]]; then
    # put fxa-monorepo-prep at the root
    git filter-branch -f --parent-filter "sed 's/^\$/-p ${FIRST}/'" --tag-name-filter "sed 's/^/${module}-/'" --msg-filter "sed -E 's/[\^\( ]+#([0-9]+)/ mozilla\/fxa-local-dev#\1/g'" --prune-empty HEAD
  else
    # put other modules in subdirectories
    git filter-branch -f --parent-filter "sed 's/^\$/-p ${FIRST}/'" --tag-name-filter "sed 's/^/${module}-/'" --msg-filter "sed -E 's/[\^\( ]+#([0-9]+)/ mozilla\/${module}#\1/g'" --index-filter "git ls-files -s | sed '/${TAB}${module}\//! s/${TAB}/${TAB}packages\/${module}\//' | GIT_INDEX_FILE=\$GIT_INDEX_FILE.new git update-index --index-info && if test -f \"\$GIT_INDEX_FILE.new\"; then mv \"\$GIT_INDEX_FILE.new\" \"\$GIT_INDEX_FILE\"; fi" --prune-empty HEAD
  fi
  git tag -a ${module}-master -m "last commit of ${module} before monorepo"
  git remote remove $module
  git checkout master
}

for module in "${MODULES[@]}"; do
  rewrite_module $module
done

git merge -m "merged all repos" ${MODULES[@]}
git tag -a monorepo-merge -m 'monorepo merge point'
git tag --list --no-merged HEAD | xargs git tag -d
git branch -d ${MODULES[@]}

package.json

{
  "...":"...",
  
  "fxa": {
    "moduleDependencies": {
      "fxa-content-server": [
        "fxa-auth-server",
        "fxa-js-client",
        "fxa-shared",
        "fxa-profile-server",
        "fxa-oauth-server"
      ],
      "fxa-auth-server": [
        "fxa-auth-db-mysql",
        "fxa-shared"
      ],
      "fxa-js-client": [
        "fxa-auth-server"
      ],
      "fxa-profile-server": [
        "fxa-auth-server"
      ]
    }
  }
}