feat: add Docker HEALTHCHECK (issue #69)

Dockerfile

@@ -90,4 +90,5 @@ EXPOSE 80
 WORKDIR /root
 ENV HOME=/home/ubuntu \
     SHELL=/bin/bash
+HEALTHCHECK --interval=30s --timeout=5s CMD curl --fail http://127.0.0.1/api/health
 ENTRYPOINT ["/startup.sh"]

image/usr/local/lib/web/backend/vnc/app.py

@@ -8,6 +8,7 @@ from flask import (
     request,
     Response,
     jsonify,
+    abort,
 )
 from gevent import subprocess as gsp, spawn, sleep
 from geventwebsocket.exceptions import WebSocketError
@@ -35,6 +36,13 @@ def apistate():
     })
 
 
+@app.route('/api/health')
+def apihealth():
+    if state.health:
+        return 'success'
+    abort(503, 'unhealthy')
+
+
 @app.route('/api/reset')
 def reset():
     if 'w' in request.args and 'h' in request.args:

image/usr/local/lib/web/backend/vnc/state.py

@@ -27,9 +27,6 @@ class State(object):
         self._event.set()
 
     def _update_health(self):
-        if self._health:
-            return
-
         health = True
         output = gsp.check_output(['supervisorctl', 'status'])
         for line in output.strip().split('\n'):