add microservices demo

appengine/flexible/multiple_services/api_gateway/README.md

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+# Python Google Cloud Microservices Example - API Gateway
+
+This example demonstrates how to deploy multiple python services to [App Engine flexible environment](https://cloud.google.com/appengine/docs/flexible/)
+
+## To Run Locally
+
+1. You will need to install Python 3 on your local machine
+
+2. Install virtualenv
+```Bash
+$ pip install virtualenv
+```
+
+3. To setup the environment in each server's directory:
+```Bash
+$ virtualenv -p python3 env
+$ source env/bin/activate
+$ pip install -r requirements.txt
+$ deactivate
+```
+
+4. Change the url's in the API gateway `gateway/api_gateway.py` to the
+development ports specified in line `gateway/api_gateway.py:6`
+```Python
+development ports {static: 8003, flask1: 8001, flask2: 8002}
+```
+
+## To Deploy to App Engine
+
+### YAML Files
+
+Each directory contains an `app.yaml file`.  This file will be the same as if
+each service were its own project except for the `service` line. For the gateway:
+
+[Gateway <default>](gateway/app.yaml)
+
+This is the `default` service.  There must be one (and not more).  The deployed
+url will be `https://<your project id>.appspot.com`
+
+For the other services:
+
+[Flask Server 1 <flask1>](flask/app.yaml)
+[Flask Server 2 <flask2](flask2/app.yaml)
+[Static File Server <static>](static/app.yaml)
+
+Make sure the `entrypoint` line matches the filename of the server you want to deploy.
+
+The deployed url will be `https://<service name>-dot-<your project id>.appspot.com`
+
+### Deployment
+
+To deploy a service cd into its directory and run: `gcloud app deploy app.yaml`
+and enter `Y` when prompted.  Or to skip the check add `-q`.
+
+To test if a service is successfully deployed, simply navigate to the root
+and you will see a message.  

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

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+import requests
+import sys
+from flask import Flask
+import services_config
+app = Flask(__name__)
+app.config['SERVICE_MAP'] = services_config.map_services('production')
+
+@app.route('/env')
+def get_env():
+    print(app.config['SERVICE_MAP'])
+    return app.config
+
+@app.route('/')
+def root():
+    '''Gets index.html from the static file server'''
+    res = requests.get(app.config['SERVICE_MAP']['static'])
+    return res.content
+
+@app.route('/hello/<service>')
+def say_hello(service):
+    '''Recieves requests from the 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'
+
+    responses = []
+    url = app.config['SERVICE_MAP'][service]
+    res = requests.get(url + '/hello')
+    responses.append(res.content)
+
+    return '\n'.encode().join(responses)
+
+@app.route('/<path>')
+def static_file(path):
+    '''Handles static file requests from index.html'''
+    url = app.config['SERVICE_MAP']['static']
+    res = requests.get(url + '/' + path)
+    return res.content, 200, {'Content-Type': res.headers['Content-Type']}
+
+if __name__ == '__main__':
+    if len(sys.argv) > 1 and sys.argv[1] == '--development':
+        app.config['SERVICE_MAP'] = services_config.map_services('development')
+    app.run()

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

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+service: default
+runtime: python
+vm: true
+entrypoint: gunicorn -b :$PORT api_gateway:app
+
+runtime_config:
+  python_version: 3
+
+manual_scaling:
+  instances: 1

appengine/flexible/multiple_services/api_gateway/gateway/requirements.txt

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+click==6.6
+Flask==0.11.1
+gunicorn==19.6.0
+itsdangerous==0.24
+Jinja2==2.8
+MarkupSafe==0.23
+requests==2.11.1
+Werkzeug==0.11.11

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

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+import os
+
+#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,
+    'static': 8001
+}
+
+def map_services(environment):
+    url_map = {}
+    for service, local_port in SERVICES.items():
+        if environment == 'production':
+            url_map[service] = production_url(service)
+        if environment == 'development':
+            url_map[service] = local_url(local_port)
+    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://{}{}'
+    if service_name == 'default':
+        return template.format('', project_url)
+    else:
+        return template.format(service_name + '-dot-', project_url)
+
+def local_url(port):
+    return 'http://localhost:' + str(port)

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

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+service: static
+runtime: python
+vm: true
+entrypoint: gunicorn -b :$PORT static_server:app
+
+runtime_config:
+  python_version: 3
+manual_scaling:
+  instances: 1

appengine/flexible/multiple_services/api_gateway/static/requirements.txt

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+click==6.6
+Flask==0.11.1
+gunicorn==19.6.0
+itsdangerous==0.24
+Jinja2==2.8
+MarkupSafe==0.23
+requests==2.11.1
+Werkzeug==0.11.11

appengine/flexible/multiple_services/api_gateway/static/static/index.html

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+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8">
+    <link rel="stylesheet" type="text/css" href="style.css" />
+    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
+    <script src="index.js"></script>
+    <title>API Gateway on App Engine Flexible Environment</title>
+  </head>
+  <body>
+    <h1>API GATEWAY DEMO</h1>
+    <p>Say hi to:</p>
+    <button class='request-button' id='gateway'>Gateway</button>
+    <button class='request-button' id='static'>Static File Server</button>
+    <ul class='responses'></ul>
+  </body>
+</html>

appengine/flexible/multiple_services/api_gateway/static/static/index.js

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+function handleResponse(resp){
+  const li = document.createElement('li');
+  li.innerHTML = resp;
+  document.querySelector('.responses').appendChild(li)
+}
+
+function handleClick(event){
+  $.ajax({
+    url: `hello/${event.target.id}`,
+    type: `GET`,
+    success(resp){
+      handleResponse(resp);
+    }
+  });
+}
+
+document.addEventListener('DOMContentLoaded', () => {
+  const buttons = document.getElementsByTagName('button')
+  for (var i = 0; i < buttons.length; i++) {
+    buttons[i].addEventListener('click', handleClick);
+  }
+});

appengine/flexible/multiple_services/api_gateway/static/static/style.css

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+h1 {
+  color: red;
+}

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

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+import sys
+from flask import Flask
+
+app = Flask(__name__)
+
+@app.route('/hello')
+def say_hello():
+    return 'Static File Server says hello!'
+
+@app.route('/')
+def root():
+    return app.send_static_file('index.html')
+
+@app.route('/<path:path>')
+def static_file(path):
+    mimetype = ''
+    if path.split('.')[1] == 'css':
+        mimetype = 'text/css'
+    if path.split('.')[1] == 'js':
+        mimetype = 'application/javascript'
+    return app.send_static_file(path), 200, {'Content-Type': mimetype}
+
+if __name__  == "__main__":
+    if len(sys.argv) > 1 and sys.argv[1] == '--development':
+        app.config['DEBUG'] = True
+        app.run(port=int(8001))
+    else:
+        app.run()