git-webhook.ts

import { Settings } from '@rogueworld/configs';
import { message } from '@rogueworld/utils';
import crypto from 'crypto';
import { createServer } from 'http';
import util from 'util';

const exec = util.promisify(require('child_process').exec);

const port = Settings.GIT_WEBHOOK_PORT || 3333;
const branchName = Settings.GIT_WEBHOOK_BRANCH_NAME || '';
const secret = Settings.GIT_WEBHOOK_SECRET || '';
const refName = branchName ? `refs/heads/${branchName}` : '';

message('Starting REST server for git webhook listeners.');

if (secret) {
    message('Secret provided. Requests will be checked before restarting the game.');
}
else {
    message('No secret provided! Any requests will restart the game.');
}

async function restart() {
    message(`Checking out git branch: ${branchName}`);
    await exec(`git checkout ${branchName}`);
    message('Done');

    message('Pulling from git');
    await exec('git pull');
    message('Done');

    message('Installing packages');
    // Do a "clean install" to avoid arbitrary changes to package-lock.json which would
    // prevent further git pulls due to uncommitted changes in that file.
    // https://stackoverflow.com/questions/45022048/why-does-npm-install-rewrite-package-lock-json
    await exec('npm ci');
    message('Done');

    message('Building game client');
    await exec('npm run build -w clients/game');
    message('Done');

    message('Restarting services');
    await exec('pm2 restart services.config.js');
    message('Done');

    message('Building map tiles');
    // Do this at the end so everything else is running while the map is building.
    await exec('npm run build -w services/map');
    message('Done');
}

/**
 * The PM2 file watcher should restart this REST app when this file changes, such as when doing a
 * git pull.
 * This comes with the problem that this app might be in the middle of restarting the game (i.e.
 * building the client) when it is restarted by PM2, so won't be able to finish each step.
 * So just run the game restart process on startup to make sure it runs through everything again
 * from the start in case this app was restarted part way through.
 */
restart();

/**
 * A basic continuous integration setup that create a REST server that listens for any git push
 * webhook events sent by GitHub.
 * Used to trigger a restart of the game every time a commit is pushed, so it is up to date with
 * the latest code.
 */
createServer((req, res) => {
    message('Request received.');

    req.on('data', async (chunk) => {
        const data = JSON.parse(chunk.toString());
        message('Triggered by payload data:', data);

        try {
            // Github sends events for all branches that are pushed to, so need to check the
            // specific one that was updated.
            if (refName) {
                message('Target branch provided, checking incoming ref.');
                if (refName !== data.ref) {
                    message('Invalid target branch or incoming ref, skipping.');
                    message(`Branch: ${refName}`);
                    message(`Incoming ref: ${data.ref}`);
                    return;
                }
                message('Branches match.');
            }
            else {
                message('No target branch provided. Accepting requests for branch.');
            }

            if (secret) {
                message('Secret provided, checking signature.');
                const sig = `sha1=${crypto
                    .createHmac('sha1', secret)
                    .update(chunk.toString())
                    .digest('hex')
                }`;

                if (req.headers['x-hub-signature'] === sig) {
                    message('Secret matches.');
                }
                else {
                    message('Invalid secret, skipping.');
                    return;
                }
            }

            await restart();
        }
        catch (err) {
            console.error(err);
        }
    });

    res.end();
}).listen(port);

message(`Listening on port ${port} for webhook events for branch '${branchName}'.`);