Automatically run "git pull" and deploy your app when it's pushed to your repo.

config.json

{
	"user": "mat",
	"interval": 5,
	"directory": put the directory of your project here,
	"deploy": "npm i && npm run compile && node build/index.js"
}

main.py

import subprocess
import requests
import signal
import json
import time
import os

print('Starting')

# read config.json
with open('config.json') as f:
        config = json.load(f)

USER = config['user']
DIRECTORY = config['directory']
DEPLOY = config['deploy']
INTERVAL = config.get('interval', 5)

# cd into the directory
os.chdir(DIRECTORY)

def run_deploy():
        # run deploy script in the background
        print('Running', DEPLOY)
        return subprocess.Popen(DEPLOY, shell=True, preexec_fn=os.setsid)

def end_deploy(p):
        # end deploy script
        print('killing deploy script')
        os.killpg(os.getpgid(p.pid), signal.SIGTERM)
        # p.kill()

deployed_process = run_deploy()

print('Ok, started checking for updates!')

run = True

def handler_stop_signals(signum, frame):
        global run
        run = False
        print('Got signal', signum)

signal.signal(signal.SIGINT, handler_stop_signals)
signal.signal(signal.SIGTERM, handler_stop_signals)

try:
        while run:
                # git pull and store the result
                print('Pulling')
                result = subprocess.run(f'sudo -u {USER} git pull', shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
                print('Did git pull')
                print(result)

                # if there's an stderr, git reset and try again
                if result.stderr and result.stdout != b'Already up to date.\n' and (result.stderr.decode().strip().endswith('Aborting') or not result.stdout.startswith(b'Updating ')):
                        print('There was an error pulling the repo, resetting and trying again.')
                        print(result)
                        result = subprocess.run('git reset --hard HEAD', stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
                        time.sleep(5)
                        continue

                # if it doesn't just say "Already up to date." then run our deploy script
                if result.stdout.decode('utf-8') != 'Already up to date.\n':
                        print('Deploying update!', result)
                        end_deploy(deployed_process)
                        deployed_process = run_deploy()
                        print('Returned from deploy')
                        time.sleep(1)

                if deployed_process.poll() is not None: # if it's not None, the process is dead
                        print(f'Reviving process (status code {deployed_process.poll()})')
                        deployed_process = run_deploy()
                        print('Revived process')

                # wait the interval before trying again
                time.sleep(INTERVAL)
finally:
        # end deploy script
        end_deploy(deployed_process)
        print('Ended')