import subprocess

from aiohttp import web

async def handle_get(request):

if subprocess.run(["pg_isready", "-U", "postgres"], capture_output=True).returncode == 0:

return web.Response(text="ok")

else:

return web.Response(status=503, text="not ready")

watch = web.Application()

watch.add_routes([web.get('/', handle_get)])

if __name__ == "__main__":

web.run_app(watch, port=8000)