Lightweight continuous deployment wrapping github webhooks and pm2

have a service you want to mirror a branch on github, that you want to keep up and running?

want 30 second setup, without too many bells and whistles? this might suit. no java, mongodb instance etc.

Quick start

on remote server:

sudo npm install light-cd -g
sudo npm install pm2 -g
cd your-project-directory-that-is-already-checked-out-from-github
lightcd init 

then just follow the instructions! (which change based on your project)

Example instructions (lightcd init output)

open this url in a web browser:  https://github.com/username/repo/settings/hooks/new

add this payload URL: http://194.46.156.34/xwebhook:7777
and this (random) secret: 1565ebb4885e4e18b6ec08ceddbd04b3
leave the other defaults they are and click the "Add webhook" button.

then run these commands:

  echo "GITHUB_WEBHOOK_SECRET="1565ebb4885e4e18b6ec08ceddbd04b3" >> ~/.bashrc"
  export GITHUB_WEBHOOK_SECRET="1565ebb4885e4e18b6ec08ceddbd04b3"
  pm2 start lightcd /home/tony/light-cd

then start your process(es) using pm2, save the config, and setup for running on reboot e.g.:

  pm2 start index.js
  pm2 start ...
  sudo pm2 save
  sudo pm2 startup

you're done! these processes will gracefully reload after pulling remote changes when you git push.

Graceful reloading

When restarting after a git push, light-cd does a pm2 gracefulReload, so if the process you're running handles the pm2 signal properly you should be OK, e.g.

process.on('message', function(msg) { if (msg === 'shutdown') { // finish serving users } });

There are plenty of classes of application where this isn't an issue; queue consumers, monitoring and other background jobs. etc. but if you're running a web server take note.

Other usage notes

Be mindful of excluding .git when serving static assets.

Also, take care not to modify files on the server, which is the most likely way to cause the implicit git pull to fail.

Customisation

do whatever you want with pm2. if there is a pm2.json file in the root directory of your repo it will use that instead of the defaulted ~/.pm2/dump.pm2.

If you have a task you want to run on git push, like an s3 push or cache rebuild or whatever, put it in the npm post install hook.