genMatrix.js

'use strict';
const path = require('path');
const fs = require('fs');

const testFiles = ['genMatrix.js', '.github/workflows/build-test.yml'];

const nodeDirRegex = /^\d+$/;

const areTestFilesChanged = (changedFiles) =>
  changedFiles.some((file) => testFiles.includes(file));

// Returns a list of the child directories in the given path
const getChildDirectories = (parent) =>
  fs
    .readdirSync(parent, { withFileTypes: true })
    .filter((dirent) => dirent.isDirectory())
    .map(({ name }) => path.resolve(parent, name));

const getNodeVersionDirs = (base) =>
  getChildDirectories(base).filter((childPath) =>
    nodeDirRegex.test(path.basename(childPath)),
  );

// Returns the paths of Dockerfiles that are at: base/*/Dockerfile
const getDockerfilesInChildDirs = (base) =>
  getChildDirectories(base).map((childDir) =>
    path.resolve(childDir, 'Dockerfile'),
  );

const getAllDockerfiles = (base) =>
  getNodeVersionDirs(base).flatMap(getDockerfilesInChildDirs);

const getAffectedDockerfiles = (filesAdded, filesModified, filesRenamed) => {
  const files = [...filesAdded, ...filesModified, ...filesRenamed];

  // If the test files were changed, include everything
  if (areTestFilesChanged(files)) {
    console.log('Test files changed so scheduling all Dockerfiles');
    return getAllDockerfiles(__dirname);
  }

  const modifiedDockerfiles = files.filter((file) =>
    file.endsWith('/Dockerfile'),
  );

  // Get Dockerfiles affected by modified docker-entrypoint.sh files
  const entrypointAffectedDockerfiles = files
    .filter((file) => file.endsWith('/docker-entrypoint.sh'))
    .map((file) => path.resolve(path.dirname(file), 'Dockerfile'));

  return [...modifiedDockerfiles, ...entrypointAffectedDockerfiles];
};

const getFullNodeVersionFromDockerfile = (file) =>
  fs.readFileSync(file, 'utf8').match(/^ENV NODE_VERSION=(\d*\.*\d*\.\d*)/m)[1];

const getDockerfileMatrixEntry = (file) => {
  const [variant] = path.dirname(file).split(path.sep).slice(-1);

  const version = getFullNodeVersionFromDockerfile(file);

  return {
    version,
    variant,
  };
};

const generateBuildMatrix = (filesAdded, filesModified, filesRenamed) => {
  const dockerfiles = [
    ...new Set(getAffectedDockerfiles(filesAdded, filesModified, filesRenamed)),
  ];

  const entries = dockerfiles.map(getDockerfileMatrixEntry);

  // Return null if there are no entries so we can skip the matrix step
  return entries.length ? { include: entries } : null;
};

module.exports = generateBuildMatrix;