grpc: add health checks to python services (#28)

also converted line endings for recommendationservice/requirements.txt from
dos to unix.

src/emailservice/Dockerfile

@@ -1,6 +1,13 @@
+
+
 # Use the grpc.io provided Python image as the base image
 FROM grpc/python:1.0
 
+# download the grpc health probe
+RUN GRPC_HEALTH_PROBE_VERSION=v0.1.0-alpha.1 && \
+    wget -qO/bin/grpc_health_probe https://github.com/grpc-ecosystem/grpc-health-probe/releases/download/${GRPC_HEALTH_PROBE_VERSION}/grpc_health_probe-linux-amd64 && \
+    chmod +x /bin/grpc_health_probe
+
 # show python logs as they occur
 ENV PYTHONUNBUFFERED=0
 

src/emailservice/email_server.py

@@ -19,13 +19,14 @@ import argparse
 import os
 import sys
 import time
-
+import grpc
 from jinja2 import Environment, FileSystemLoader, select_autoescape, TemplateError
 from google.api_core.exceptions import GoogleAPICallError
-import grpc
 
 import demo_pb2
 import demo_pb2_grpc
+from grpc_health.v1 import health_pb2
+from grpc_health.v1 import health_pb2_grpc
 
 # from opencensus.trace.ext.grpc import server_interceptor
 # from opencensus.trace.samplers import always_on
@@ -56,7 +57,12 @@ env = Environment(
 )
 template = env.get_template('confirmation.html')
 
-class EmailService(demo_pb2_grpc.EmailServiceServicer):
+class BaseEmailService(demo_pb2_grpc.EmailServiceServicer):
+  def Check(self, request, context):
+    return health_pb2.HealthCheckResponse(
+      status=health_pb2.HealthCheckResponse.SERVING)
+
+class EmailService(BaseEmailService):
   def __init__(self):
     raise Exception('cloud mail client not implemented')
     super().__init__()
@@ -79,7 +85,6 @@ class EmailService(demo_pb2_grpc.EmailServiceServicer):
         "html_body": content
       }
     )
-    
     print("Message sent: {}".format(response.rfc822_message_id))
 
   def SendOrderConfirmation(self, request, context):
@@ -104,18 +109,30 @@ class EmailService(demo_pb2_grpc.EmailServiceServicer):
 
     return demo_pb2.Empty()
 
-class DummyEmailService(demo_pb2_grpc.EmailServiceServicer):
+class DummyEmailService(BaseEmailService):
   def SendOrderConfirmation(self, request, context):
     print('A request to send order confirmation email to {} has been received.'.format(request.email))
     return demo_pb2.Empty()
 
+class HealthCheck():
+  def Check(self, request, context):
+    return health_pb2.HealthCheckResponse(
+      status=health_pb2.HealthCheckResponse.SERVING)
+
 def start(dummy_mode):
   server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))#, interceptors=(tracer_interceptor,))
+  service = None
   if dummy_mode:
-    demo_pb2_grpc.add_EmailServiceServicer_to_server(DummyEmailService(), server)
+    service = DummyEmailService()
   else:
-    raise Exception('non-dummy mode not implemented')
-  server.add_insecure_port('[::]:8080')
+    raise Exception('non-dummy mode not implemented yet')
+
+  demo_pb2_grpc.add_EmailServiceServicer_to_server(service, server)
+  health_pb2_grpc.add_HealthServicer_to_server(service, server)
+
+  port = os.environ.get('PORT', "8080")
+  print("listening on port: "+port)
+  server.add_insecure_port('[::]:'+port)
   server.start()
   try:
     while True:
@@ -125,5 +142,5 @@ def start(dummy_mode):
 
 
 if __name__ == '__main__':
-  print('Starting the email service in dummy mode.')
+  print('starting the email service in dummy mode.')
   start(dummy_mode = True)

src/emailservice/requirements.txt

@@ -9,6 +9,7 @@ google-cloud-trace==0.19.0
 googleapis-common-protos==1.5.3
 grpc-google-iam-v1==0.11.4
 grpcio==1.12.1
+grpcio-health-checking==1.14.1
 grpcio-tools==1.12.1
 idna==2.7
 Jinja2==2.10