Break out block listener to a start / stop daemon instead of running on startup

Dockerfile

@@ -18,4 +18,4 @@ COPY . /app
 # easter eggs 😝
 RUN echo "PS1='🕵️:\[\033[1;36m\]\h \[\033[1;34m\]\W\[\033[0;35m\]\[\033[1;36m\]$ \[\033[0m\]'" >> ~/.bashrc
 
-ENTRYPOINT [ "/app/run.sh"]
+ENTRYPOINT [ "/app/entrypoint.sh"]

Tiltfile

@@ -19,7 +19,7 @@ k8s_yaml(secret_from_dict("mev-inspect-db-credentials", inputs = {
 }))
 
 docker_build_with_restart("mev-inspect-py", ".",
-    entrypoint="/app/run.sh",
+    entrypoint="/app/entrypoint.sh",
     live_update=[
         sync(".", "/app"),
         run("cd /app && poetry install",

entrypoint.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+python loop.py

k8s/app.yaml

@@ -17,7 +17,7 @@ spec:
       containers:
       - name: mev-inspect
         image: mev-inspect-py
-        command: [ "/app/run.sh" ]
+        command: [ "/app/entrypoint.sh" ]
         env:
         - name: POSTGRES_USER
           valueFrom:

listener

@@ -0,0 +1,47 @@
+#!/bin/sh
+
+set -e
+
+NAME=listener
+PIDFILE=/var/run/$NAME.pid
+DAEMON=/root/.poetry/bin/poetry
+DAEMON_OPTS="run python listener.py"
+
+case "$1" in
+  start)
+        echo -n "Starting daemon: "$NAME
+	start-stop-daemon \
+        --background \
+        --chdir /app \
+        --start \
+        --quiet \
+        --pidfile $PIDFILE \
+        --make-pidfile \
+        --startas $DAEMON -- $DAEMON_OPTS
+        echo "."
+	;;
+  stop)
+        echo -n "Stopping daemon: "$NAME
+	start-stop-daemon --stop --quiet --oknodo --pidfile $PIDFILE
+        echo "."
+	;;
+  restart)
+        echo -n "Restarting daemon: "$NAME
+	start-stop-daemon --stop --quiet --oknodo --retry 30 --pidfile $PIDFILE
+	start-stop-daemon \
+        --background \
+        --chdir /app \
+        --start \
+        --quiet \
+        --pidfile $PIDFILE \
+        --make-pidfile \
+        --startas $DAEMON -- $DAEMON_OPTS
+        echo "."
+    ;;
+
+  *)
+	echo "Usage: "$1" {start|stop|restart}"
+	exit 1
+esac
+
+exit 0

listener.py

@@ -1,6 +1,5 @@
 import logging
 import os
-import signal
 import time
 
 from web3 import Web3
@@ -13,32 +12,13 @@ from mev_inspect.crud.latest_block_update import (
 from mev_inspect.db import get_session
 from mev_inspect.inspect_block import inspect_block
 from mev_inspect.provider import get_base_provider
+from mev_inspect.signal_handler import GracefulKiller
 
 
-logging.basicConfig(filename="app.log", level=logging.INFO)
+logging.basicConfig(filename="listener.log", level=logging.INFO)
 logger = logging.getLogger(__name__)
 
 
-class GracefulKiller:
-    """
-    handle sigint / sigterm gracefully
-    taken from https://stackoverflow.com/a/31464349
-    """
-
-    signal_names = {signal.SIGINT: "SIGINT", signal.SIGTERM: "SIGTERM"}
-
-    def __init__(self):
-        self.kill_now = False
-        signal.signal(signal.SIGINT, self.exit_gracefully)
-        signal.signal(signal.SIGTERM, self.exit_gracefully)
-
-    def exit_gracefully(self, signum, frame):  # pylint: disable=unused-argument
-        signal_name = self.signal_names[signum]
-        logger.info(f"Received {signal_name} signal")
-        logger.info("Cleaning up resources. End of process")
-        self.kill_now = True
-
-
 def run():
     rpc = os.getenv("RPC_URL")
     if rpc is None:

loop.py

@@ -0,0 +1,22 @@
+import logging
+import time
+
+from mev_inspect.signal_handler import GracefulKiller
+
+
+logging.basicConfig(filename="loop.log", level=logging.INFO)
+logger = logging.getLogger(__name__)
+
+
+def run():
+    logger.info("Starting...")
+
+    killer = GracefulKiller()
+    while not killer.kill_now:
+        time.sleep(1)
+
+    logger.info("Stopping...")
+
+
+if __name__ == "__main__":
+    run()

mev_inspect/signal_handler.py

@@ -0,0 +1,24 @@
+import logging
+import signal
+
+logger = logging.getLogger(__name__)
+
+
+class GracefulKiller:
+    """
+    handle sigint / sigterm gracefully
+    taken from https://stackoverflow.com/a/31464349
+    """
+
+    signal_names = {signal.SIGINT: "SIGINT", signal.SIGTERM: "SIGTERM"}
+
+    def __init__(self):
+        self.kill_now = False
+        signal.signal(signal.SIGINT, self.exit_gracefully)
+        signal.signal(signal.SIGTERM, self.exit_gracefully)
+
+    def exit_gracefully(self, signum, frame):  # pylint: disable=unused-argument
+        signal_name = self.signal_names[signum]
+        logger.info(f"Received {signal_name} signal")
+        logger.info("Cleaning up resources. End of process")
+        self.kill_now = True

run.sh

@@ -1,3 +0,0 @@
-#!/bin/bash
-
-python run.py