Computing Life

Can a node.js/express.js web app update itself from a github repo? (i.e. whenever we do a git push to github, the server side will also use git pull to update itself)

It's possible thanks to the powerful WebHook of github.

The basic idea is, to use a separate light-weight "app" to listen to a different address, and trigger the git pull and the restart work whenever github visits the url. It's nearly trivial given the express.js framework. The core code is shown below. Note we use child_process.spawn() to control the life cycle of the child process.

function restartApp(req, res)
{
    spawn('git', ['pull']);
    child.kill();
    startApp();
    res.send('ok.');
}

function startApp()
{
    child = spawn('node', ['app.js']);
    child.stdout.setEncoding('utf8');
    child.stdout.on('data', function (data) {
        var str = data.toString()
        console.log(str);
    });
    child.on('close', function (code) {
        console.log('process exit code ' + code);
    });
}

The complete code with context is put here. To launch the program, nohup node ./bootstrap.js & is a good idea which is able to solve the zsh background job problem.

Another lightweight way to implement WebHook isn't it?