add microservices demo

appengine/flexible/multiple_services/api_gateway/README.md

@@ -19,9 +19,9 @@ $ pip install -r requirements.txt
 $ deactivate
 ```
 
-4. To start server locally use the development flag `--development` or `-d`
+4. To start server locally:
 ```Bash
-$ python <filename>.py --development
+$ python <filename>.py
 ```
 
 ## To Deploy to App Engine
@@ -48,5 +48,14 @@ The deployed url will be `https://<service name>-dot-<your project id>.appspot.c
 
 ### Deployment
 
-To deploy a service cd into its directory and run: `gcloud app deploy app.yaml`
+To deploy a service cd into its directory and run:
+```Bash
+$ gcloud app deploy app.yaml
+```
 and enter `Y` when prompted.  Or to skip the check add `-q`.
+
+To deploy multiple services simultaneously just add the path to each `app.yaml`
+file as an argument to `gcloud app deploy `:
+```Bash
+$ gcloud app deploy gateway/app.yaml static/app.yaml
+```

appengine/flexible/multiple_services/api_gateway/gateway/api_gateway.py

@@ -1,16 +1,8 @@
+import os
 import requests
-import sys
-import argparse
-from flask import Flask
 import services_config
 
-app = Flask(__name__)
-#create service map for production urls unless --development flag added
-app.config['SERVICE_MAP'] = services_config.map_services('production')
-
-#setup arg parser to handle development flag
-parser = argparse.ArgumentParser()
-parser.add_argument('-d', '--development', action='store_true')
+app = services_config.make_app(__name__)
 
 @app.route('/')
 def root():
@@ -20,11 +12,12 @@ def root():
 
 @app.route('/hello/<service>')
 def say_hello(service):
-    '''Recieves requests from the buttons on the front end and resopnds
+    '''Recieves requests from buttons on the front end and resopnds
     or sends request to the static file server'''
     #if 'gateway' is specified return immediate
     if service == 'gateway':
         return 'Gateway says hello'
+    #otherwise send request to service indicated by URL param
     responses = []
     url = app.config['SERVICE_MAP'][service]
     res = requests.get(url + '/hello')
@@ -33,13 +26,11 @@ def say_hello(service):
 
 @app.route('/<path>')
 def static_file(path):
-    '''Handles static file requests from index.html'''
+    '''Gets static files required by index.html to static file server'''
     url = app.config['SERVICE_MAP']['static']
     res = requests.get(url + '/' + path)
     return res.content, 200, {'Content-Type': res.headers['Content-Type']}
 
 if __name__ == '__main__':
-    args = parser.parse_args()
-    if args.development:
-        app.config['SERVICE_MAP'] = services_config.map_services('development')
-    app.run()
+    port = os.environ.get('PORT') or 8000
+    app.run(port=port)

appengine/flexible/multiple_services/api_gateway/gateway/services_config.py

@@ -1,13 +1,22 @@
 import os
+from flask import Flask
 
 #to add services insert key value pair of the name of the service and
 #the port you want it to run on when running locally
 SERVICES = {
-    'default': 5000,
+    'default': 8000,
     'static': 8001
 }
 
+def make_app(name):
+    app = Flask(name)
+    environment = 'production' if os.environ.get('GAE_LONG_APP_ID') else 'development'
+    app.config['SERVICE_MAP'] = map_services(environment)
+    return app
+
 def map_services(environment):
+    '''Generates a map of services to correct urls for running locally
+    or when deployed'''
     url_map = {}
     for service, local_port in SERVICES.items():
         if environment == 'production':
@@ -17,13 +26,14 @@ def map_services(environment):
     return url_map
 
 def production_url(service_name):
-    project_id = os.environ.get('GAE_LONG_APP_ID') or 'flask-algo'
-    project_url = project_id + '.appspot.com'
-    template = 'https://{}{}'
+    '''Generates url for a service when deployed to App Engine'''
+    project_id = os.environ.get('GAE_LONG_APP_ID')
+    project_url = '{}.appspot.com'.format(project_id)
     if service_name == 'default':
-        return template.format('', project_url)
+        return 'https://{}'.format(project_url)
     else:
-        return template.format(service_name + '-dot-', project_url)
+        return 'https://{}-dot-{}'.format(service_name, project_url)
 
 def local_url(port):
-    return 'http://localhost:' + str(port)
+    '''Generates url for a service when running locally'''
+    return 'http://localhost:{}'.format(str(port))

appengine/flexible/multiple_services/api_gateway/static/app.yaml

@@ -5,5 +5,6 @@ entrypoint: gunicorn -b :$PORT static_server:app
 
 runtime_config:
   python_version: 3
+
 manual_scaling:
   instances: 1

appengine/flexible/multiple_services/api_gateway/static/static_server.py

@@ -1,18 +1,21 @@
-import sys
+import os
 from flask import Flask
 
 app = Flask(__name__)
 
 @app.route('/hello')
 def say_hello():
+    '''responds to request from frontend via gateway'''
     return 'Static File Server says hello!'
 
 @app.route('/')
 def root():
+    '''serves index.html'''
     return app.send_static_file('index.html')
 
 @app.route('/<path:path>')
 def static_file(path):
+    '''serves static files required by index.html'''
     mimetype = ''
     if path.split('.')[1] == 'css':
         mimetype = 'text/css'
@@ -21,7 +24,5 @@ def static_file(path):
     return app.send_static_file(path), 200, {'Content-Type': mimetype}
 
 if __name__  == "__main__":
-    if len(sys.argv) > 1 and sys.argv[1] == '--development':
-        app.run(port=int(8001))
-    else:
-        app.run()
+    port = os.environ.get('PORT') or 8001
+    app.run(port=port)