Merge pull request #2 from zalando/feature/status_page

Created statuspage, a health check for a PostgreSQL cluster served usi…

Dockerfile

@@ -11,7 +11,7 @@ RUN apt-get update -y
 RUN apt-get upgrade -y
 
 ENV PGVERSION 9.4
-RUN apt-get install curl python python-pip python-psycopg2 python-yaml python-cherrypy postgresql-${PGVERSION} -y
+RUN apt-get install curl python python-pip python-psycopg2 python-yaml postgresql-${PGVERSION} -y
 
 RUN	ln -s /usr/lib/postgresql/* /usr/lib/postgresql/current
 ENV PATH /usr/lib/postgresql/current/bin:$PATH

governor.py

@@ -2,10 +2,12 @@
 
 import sys, os, yaml, time, urllib2, atexit
 import logging
+import threading
 
 from helpers.etcd import Etcd
 from helpers.postgresql import Postgresql
 from helpers.ha import Ha
+from helpers.statuspage import StatusPage, getHTTPServer
 
 INSTANCE_METADATA_URL = "http://169.254.169.254/latest/meta-data/"
 
@@ -30,6 +32,12 @@ etcd = Etcd(config["etcd"])
 postgresql = Postgresql(config["postgresql"], aws_host_address)
 ha = Ha(postgresql, etcd)
 
+## Start the http_server to serve a simple healthcheck
+http_server = getHTTPServer(postgresql, http_port=8080, listen_address='0.0.0.0')
+http_thread = threading.Thread(target=http_server.serve_forever, args=())
+http_thread.daemon = True
+http_thread.start()
+
 # stop postgresql on script exit
 def stop_postgresql():
     postgresql.stop()

helpers/statuspage.py

@@ -0,0 +1,58 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
+
+
+class StatusPage(BaseHTTPRequestHandler):
+
+    def do_GET(self):
+        try:
+            if self.path == '/pg_master':
+                response = (200 if self.server.postgresql.is_leader else 503)
+                self.send_response(response)
+            elif self.path == '/pg_slave':
+                response = (503 if self.server.postgresql.is_leader else 200)
+                self.send_response(response)
+            elif self.path == '/pg_status':
+                self.send_response(200)
+                self.end_headers()
+                self.wfile.write(self.server.postgresql.status())
+            else:
+                self.send_response(404)
+        except Exception, e:
+            self.send_response(500)
+            self.end_headers()
+            self.wfile.write(repr(e))
+
+
+def getHTTPServer(postgresql, http_port=8081, listen_address='0.0.0.0'):
+    server = HTTPServer((listen_address, http_port), StatusPage)
+    server.postgresql = postgresql
+
+    return server
+
+
+if __name__ == '__main__':
+    import sys
+    import logging
+    from BaseHTTPServer import HTTPServer
+
+    logging.basicConfig(format='%(levelname)-6s %(asctime)s - %(message)s', level=logging.DEBUG)
+    logging.debug('Starting as a standalone application')
+
+    # # Create a dummy configuration to be able to use the Postgresql class
+    from postgresql import Postgresql
+    postgres_config = {
+        'name': 'dummy',
+        'listen': 'localhost:5432',
+        'data_dir': None,
+        'replication': {'username': None, 'password': None},
+    }
+    aws_host_address = None
+    if len(sys.argv) > 1:
+        postgres_config['listen'] = sys.argv[1]
+    postgresql = Postgresql(postgres_config, aws_host_address)
+
+    getHTTPServer(postgresql, 8081, '0.0.0.0').serve_forever()
+    logging.debug('Abc')

requirements.txt

@@ -0,0 +1,2 @@
+PyYAML
+psycopg2