samples/bookinfo/src/productpage/productpage.py - dubbo-go-pixiu - Git at Google

 #!/usr/bin/python
 #
 # Copyright Istio Authors
 #
 #   Licensed under the Apache License, Version 2.0 (the "License");
 #   you may not use this file except in compliance with the License.
 #   You may obtain a copy of the License at
 #
 #       http://www.apache.org/licenses/LICENSE-2.0
 #
 #   Unless required by applicable law or agreed to in writing, software
 #   distributed under the License is distributed on an "AS IS" BASIS,
 #   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 #   See the License for the specific language governing permissions and
 #   limitations under the License.


 from __future__ import print_function
 from flask_bootstrap import Bootstrap
 from flask import Flask, request, session, render_template, redirect, url_for
 from flask import _request_ctx_stack as stack
 from jaeger_client import Tracer, ConstSampler
 from jaeger_client.reporter import NullReporter
 from jaeger_client.codecs import B3Codec
 from opentracing.ext import tags
 from opentracing.propagation import Format
 from opentracing_instrumentation.request_context import get_current_span, span_in_context
 import simplejson as json
 import requests
 import sys
 from json2html import *
 import logging
 import os
 import asyncio

 # These two lines enable debugging at httplib level (requests->urllib3->http.client)
 # You will see the REQUEST, including HEADERS and DATA, and RESPONSE with HEADERS but without DATA.
 # The only thing missing will be the response.body which is not logged.
 try:
     import http.client as http_client
 except ImportError:
     # Python 2
     import httplib as http_client
 http_client.HTTPConnection.debuglevel = 1

 app = Flask(__name__)
 logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)
 requests_log = logging.getLogger("requests.packages.urllib3")
 requests_log.setLevel(logging.DEBUG)
 requests_log.propagate = True
 app.logger.addHandler(logging.StreamHandler(sys.stdout))
 app.logger.setLevel(logging.DEBUG)

 # Set the secret key to some random bytes. Keep this really secret!
 app.secret_key = b'_5#y2L"F4Q8z\n\xec]/'

 Bootstrap(app)

 servicesDomain = "" if (os.environ.get("SERVICES_DOMAIN") is None) else "." + os.environ.get("SERVICES_DOMAIN")
 detailsHostname = "details" if (os.environ.get("DETAILS_HOSTNAME") is None) else os.environ.get("DETAILS_HOSTNAME")
 ratingsHostname = "ratings" if (os.environ.get("RATINGS_HOSTNAME") is None) else os.environ.get("RATINGS_HOSTNAME")
 reviewsHostname = "reviews" if (os.environ.get("REVIEWS_HOSTNAME") is None) else os.environ.get("REVIEWS_HOSTNAME")

 flood_factor = 0 if (os.environ.get("FLOOD_FACTOR") is None) else int(os.environ.get("FLOOD_FACTOR"))

 details = {
     "name": "http://{0}{1}:9080".format(detailsHostname, servicesDomain),
     "endpoint": "details",
     "children": []
 }

 ratings = {
     "name": "http://{0}{1}:9080".format(ratingsHostname, servicesDomain),
     "endpoint": "ratings",
     "children": []
 }

 reviews = {
     "name": "http://{0}{1}:9080".format(reviewsHostname, servicesDomain),
     "endpoint": "reviews",
     "children": [ratings]
 }

 productpage = {
     "name": "http://{0}{1}:9080".format(detailsHostname, servicesDomain),
     "endpoint": "details",
     "children": [details, reviews]
 }

 service_dict = {
     "productpage": productpage,
     "details": details,
     "reviews": reviews,
 }

 # A note on distributed tracing:
 #
 # Although Istio proxies are able to automatically send spans, they need some
 # hints to tie together the entire trace. Applications need to propagate the
 # appropriate HTTP headers so that when the proxies send span information, the
 # spans can be correlated correctly into a single trace.
 #
 # To do this, an application needs to collect and propagate headers from the
 # incoming request to any outgoing requests. The choice of headers to propagate
 # is determined by the trace configuration used. See getForwardHeaders for
 # the different header options.
 #
 # This example code uses OpenTracing (http://opentracing.io/) to propagate
 # the 'b3' (zipkin) headers. Using OpenTracing for this is not a requirement.
 # Using OpenTracing allows you to add application-specific tracing later on,
 # but you can just manually forward the headers if you prefer.
 #
 # The OpenTracing example here is very basic. It only forwards headers. It is
 # intended as a reference to help people get started, eg how to create spans,
 # extract/inject context, etc.

 # A very basic OpenTracing tracer (with null reporter)
 tracer = Tracer(
     one_span_per_rpc=True,
     service_name='productpage',
     reporter=NullReporter(),
     sampler=ConstSampler(decision=True),
     extra_codecs={Format.HTTP_HEADERS: B3Codec()}
 )


 def trace():
     '''
     Function decorator that creates opentracing span from incoming b3 headers
     '''
     def decorator(f):
         def wrapper(*args, **kwargs):
             request = stack.top.request
             try:
                 # Create a new span context, reading in values (traceid,
                 # spanid, etc) from the incoming x-b3-*** headers.
                 span_ctx = tracer.extract(
                     Format.HTTP_HEADERS,
                     dict(request.headers)
                 )
                 # Note: this tag means that the span will *not* be
                 # a child span. It will use the incoming traceid and
                 # spanid. We do this to propagate the headers verbatim.
                 rpc_tag = {tags.SPAN_KIND: tags.SPAN_KIND_RPC_SERVER}
                 span = tracer.start_span(
                     operation_name='op', child_of=span_ctx, tags=rpc_tag
                 )
             except Exception as e:
                 # We failed to create a context, possibly due to no
                 # incoming x-b3-*** headers. Start a fresh span.
                 # Note: This is a fallback only, and will create fresh headers,
                 # not propagate headers.
                 span = tracer.start_span('op')
             with span_in_context(span):
                 r = f(*args, **kwargs)
                 return r
         wrapper.__name__ = f.__name__
         return wrapper
     return decorator


 def getForwardHeaders(request):
     headers = {}

     # x-b3-*** headers can be populated using the opentracing span
     span = get_current_span()
     carrier = {}
     tracer.inject(
         span_context=span.context,
         format=Format.HTTP_HEADERS,
         carrier=carrier)

     headers.update(carrier)

     # We handle other (non x-b3-***) headers manually
     if 'user' in session:
         headers['end-user'] = session['user']

     # Keep this in sync with the headers in details and reviews.
     incoming_headers = [
         # All applications should propagate x-request-id. This header is
         # included in access log statements and is used for consistent trace
         # sampling and log sampling decisions in Istio.
         'x-request-id',

         # Lightstep tracing header. Propagate this if you use lightstep tracing
         # in Istio (see
         # https://istio.io/latest/docs/tasks/observability/distributed-tracing/lightstep/)
         # Note: this should probably be changed to use B3 or W3C TRACE_CONTEXT.
         # Lightstep recommends using B3 or TRACE_CONTEXT and most application
         # libraries from lightstep do not support x-ot-span-context.
         'x-ot-span-context',

         # Datadog tracing header. Propagate these headers if you use Datadog
         # tracing.
         'x-datadog-trace-id',
         'x-datadog-parent-id',
         'x-datadog-sampling-priority',

         # W3C Trace Context. Compatible with OpenCensusAgent and Stackdriver Istio
         # configurations.
         'traceparent',
         'tracestate',

         # Cloud trace context. Compatible with OpenCensusAgent and Stackdriver Istio
         # configurations.
         'x-cloud-trace-context',

         # Grpc binary trace context. Compatible with OpenCensusAgent nad
         # Stackdriver Istio configurations.
         'grpc-trace-bin',

         # b3 trace headers. Compatible with Zipkin, OpenCensusAgent, and
         # Stackdriver Istio configurations. Commented out since they are
         # propagated by the OpenTracing tracer above.
         # 'x-b3-traceid',
         # 'x-b3-spanid',
         # 'x-b3-parentspanid',
         # 'x-b3-sampled',
         # 'x-b3-flags',

         # Application-specific headers to forward.
         'user-agent',
     ]
     # For Zipkin, always propagate b3 headers.
     # For Lightstep, always propagate the x-ot-span-context header.
     # For Datadog, propagate the corresponding datadog headers.
     # For OpenCensusAgent and Stackdriver configurations, you can choose any
     # set of compatible headers to propagate within your application. For
     # example, you can propagate b3 headers or W3C trace context headers with
     # the same result. This can also allow you to translate between context
     # propagation mechanisms between different applications.

     for ihdr in incoming_headers:
         val = request.headers.get(ihdr)
         if val is not None:
             headers[ihdr] = val

     return headers


 # The UI:
 @app.route('/')
 @app.route('/index.html')
 def index():
     """ Display productpage with normal user and test user buttons"""
     global productpage

     table = json2html.convert(json=json.dumps(productpage),
                               table_attributes="class=\"table table-condensed table-bordered table-hover\"")

     return render_template('index.html', serviceTable=table)


 @app.route('/health')
 def health():
     return 'Product page is healthy'


 @app.route('/login', methods=['POST'])
 def login():
     user = request.values.get('username')
     response = app.make_response(redirect(request.referrer))
     session['user'] = user
     return response


 @app.route('/logout', methods=['GET'])
 def logout():
     response = app.make_response(redirect(request.referrer))
     session.pop('user', None)
     return response

 # a helper function for asyncio.gather, does not return a value


 async def getProductReviewsIgnoreResponse(product_id, headers):
     getProductReviews(product_id, headers)

 # flood reviews with unnecessary requests to demonstrate Istio rate limiting, asynchoronously


 async def floodReviewsAsynchronously(product_id, headers):
     # the response is disregarded
     await asyncio.gather(*(getProductReviewsIgnoreResponse(product_id, headers) for _ in range(flood_factor)))

 # flood reviews with unnecessary requests to demonstrate Istio rate limiting


 def floodReviews(product_id, headers):
     loop = asyncio.new_event_loop()
     loop.run_until_complete(floodReviewsAsynchronously(product_id, headers))
     loop.close()


 @app.route('/productpage')
 @trace()
 def front():
     product_id = 0  # TODO: replace default value
     headers = getForwardHeaders(request)
     user = session.get('user', '')
     product = getProduct(product_id)
     detailsStatus, details = getProductDetails(product_id, headers)

     if flood_factor > 0:
         floodReviews(product_id, headers)

     reviewsStatus, reviews = getProductReviews(product_id, headers)
     return render_template(
         'productpage.html',
         detailsStatus=detailsStatus,
         reviewsStatus=reviewsStatus,
         product=product,
         details=details,
         reviews=reviews,
         user=user)


 # The API:
 @app.route('/api/v1/products')
 def productsRoute():
     return json.dumps(getProducts()), 200, {'Content-Type': 'application/json'}


 @app.route('/api/v1/products/<product_id>')
 @trace()
 def productRoute(product_id):
     headers = getForwardHeaders(request)
     status, details = getProductDetails(product_id, headers)
     return json.dumps(details), status, {'Content-Type': 'application/json'}


 @app.route('/api/v1/products/<product_id>/reviews')
 @trace()
 def reviewsRoute(product_id):
     headers = getForwardHeaders(request)
     status, reviews = getProductReviews(product_id, headers)
     return json.dumps(reviews), status, {'Content-Type': 'application/json'}


 @app.route('/api/v1/products/<product_id>/ratings')
 @trace()
 def ratingsRoute(product_id):
     headers = getForwardHeaders(request)
     status, ratings = getProductRatings(product_id, headers)
     return json.dumps(ratings), status, {'Content-Type': 'application/json'}


 # Data providers:
 def getProducts():
     return [
         {
             'id': 0,
             'title': 'The Comedy of Errors',
             'descriptionHtml': '<a href="https://en.wikipedia.org/wiki/The_Comedy_of_Errors">Wikipedia Summary</a>: The Comedy of Errors is one of <b>William Shakespeare\'s</b> early plays. It is his shortest and one of his most farcical comedies, with a major part of the humour coming from slapstick and mistaken identity, in addition to puns and word play.'
         }
     ]


 def getProduct(product_id):
     products = getProducts()
     if product_id + 1 > len(products):
         return None
     else:
         return products[product_id]


 def getProductDetails(product_id, headers):
     try:
         url = details['name'] + "/" + details['endpoint'] + "/" + str(product_id)
         res = requests.get(url, headers=headers, timeout=3.0)
     except BaseException:
         res = None
     if res and res.status_code == 200:
         return 200, res.json()
     else:
         status = res.status_code if res is not None and res.status_code else 500
         return status, {'error': 'Sorry, product details are currently unavailable for this book.'}


 def getProductReviews(product_id, headers):
     # Do not remove. Bug introduced explicitly for illustration in fault injection task
     # TODO: Figure out how to achieve the same effect using Envoy retries/timeouts
     for _ in range(2):
         try:
             url = reviews['name'] + "/" + reviews['endpoint'] + "/" + str(product_id)
             res = requests.get(url, headers=headers, timeout=3.0)
         except BaseException:
             res = None
         if res and res.status_code == 200:
             return 200, res.json()
     status = res.status_code if res is not None and res.status_code else 500
     return status, {'error': 'Sorry, product reviews are currently unavailable for this book.'}


 def getProductRatings(product_id, headers):
     try:
         url = ratings['name'] + "/" + ratings['endpoint'] + "/" + str(product_id)
         res = requests.get(url, headers=headers, timeout=3.0)
     except BaseException:
         res = None
     if res and res.status_code == 200:
         return 200, res.json()
     else:
         status = res.status_code if res is not None and res.status_code else 500
         return status, {'error': 'Sorry, product ratings are currently unavailable for this book.'}


 class Writer(object):
     def __init__(self, filename):
         self.file = open(filename, 'w')

     def write(self, data):
         self.file.write(data)

     def flush(self):
         self.file.flush()


 if __name__ == '__main__':
     if len(sys.argv) < 2:
         logging.error("usage: %s port" % (sys.argv[0]))
         sys.exit(-1)

     p = int(sys.argv[1])
     logging.info("start at port %s" % (p))
     # Make it compatible with IPv6 if Linux
     if sys.platform == "linux":
         app.run(host='::', port=p, debug=True, threaded=True)
     else:
         app.run(host='0.0.0.0', port=p, debug=True, threaded=True)
	#!/usr/bin/python
	#
	# Copyright Istio Authors
	#
	# Licensed under the Apache License, Version 2.0 (the "License");
	# you may not use this file except in compliance with the License.
	# You may obtain a copy of the License at
	#
	# http://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS,
	# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	# See the License for the specific language governing permissions and
	# limitations under the License.


	from __future__ import print_function
	from flask_bootstrap import Bootstrap
	from flask import Flask, request, session, render_template, redirect, url_for
	from flask import _request_ctx_stack as stack
	from jaeger_client import Tracer, ConstSampler
	from jaeger_client.reporter import NullReporter
	from jaeger_client.codecs import B3Codec
	from opentracing.ext import tags
	from opentracing.propagation import Format
	from opentracing_instrumentation.request_context import get_current_span, span_in_context
	import simplejson as json
	import requests
	import sys
	from json2html import *
	import logging
	import os
	import asyncio

	# These two lines enable debugging at httplib level (requests->urllib3->http.client)
	# You will see the REQUEST, including HEADERS and DATA, and RESPONSE with HEADERS but without DATA.
	# The only thing missing will be the response.body which is not logged.
	try:
	import http.client as http_client
	except ImportError:
	# Python 2
	import httplib as http_client
	http_client.HTTPConnection.debuglevel = 1

	app = Flask(__name__)
	logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)
	requests_log = logging.getLogger("requests.packages.urllib3")
	requests_log.setLevel(logging.DEBUG)
	requests_log.propagate = True
	app.logger.addHandler(logging.StreamHandler(sys.stdout))
	app.logger.setLevel(logging.DEBUG)

	# Set the secret key to some random bytes. Keep this really secret!
	app.secret_key = b'_5#y2L"F4Q8z\n\xec]/'

	Bootstrap(app)

	servicesDomain = "" if (os.environ.get("SERVICES_DOMAIN") is None) else "." + os.environ.get("SERVICES_DOMAIN")
	detailsHostname = "details" if (os.environ.get("DETAILS_HOSTNAME") is None) else os.environ.get("DETAILS_HOSTNAME")
	ratingsHostname = "ratings" if (os.environ.get("RATINGS_HOSTNAME") is None) else os.environ.get("RATINGS_HOSTNAME")
	reviewsHostname = "reviews" if (os.environ.get("REVIEWS_HOSTNAME") is None) else os.environ.get("REVIEWS_HOSTNAME")

	flood_factor = 0 if (os.environ.get("FLOOD_FACTOR") is None) else int(os.environ.get("FLOOD_FACTOR"))

	details = {
	"name": "http://{0}{1}:9080".format(detailsHostname, servicesDomain),
	"endpoint": "details",
	"children": []
	}

	ratings = {
	"name": "http://{0}{1}:9080".format(ratingsHostname, servicesDomain),
	"endpoint": "ratings",
	"children": []
	}

	reviews = {
	"name": "http://{0}{1}:9080".format(reviewsHostname, servicesDomain),
	"endpoint": "reviews",
	"children": [ratings]
	}

	productpage = {
	"name": "http://{0}{1}:9080".format(detailsHostname, servicesDomain),
	"endpoint": "details",
	"children": [details, reviews]
	}

	service_dict = {
	"productpage": productpage,
	"details": details,
	"reviews": reviews,
	}

	# A note on distributed tracing:
	#
	# Although Istio proxies are able to automatically send spans, they need some
	# hints to tie together the entire trace. Applications need to propagate the
	# appropriate HTTP headers so that when the proxies send span information, the
	# spans can be correlated correctly into a single trace.
	#
	# To do this, an application needs to collect and propagate headers from the
	# incoming request to any outgoing requests. The choice of headers to propagate
	# is determined by the trace configuration used. See getForwardHeaders for
	# the different header options.
	#
	# This example code uses OpenTracing (http://opentracing.io/) to propagate
	# the 'b3' (zipkin) headers. Using OpenTracing for this is not a requirement.
	# Using OpenTracing allows you to add application-specific tracing later on,
	# but you can just manually forward the headers if you prefer.
	#
	# The OpenTracing example here is very basic. It only forwards headers. It is
	# intended as a reference to help people get started, eg how to create spans,
	# extract/inject context, etc.

	# A very basic OpenTracing tracer (with null reporter)
	tracer = Tracer(
	one_span_per_rpc=True,
	service_name='productpage',
	reporter=NullReporter(),
	sampler=ConstSampler(decision=True),
	extra_codecs={Format.HTTP_HEADERS: B3Codec()}
	)


	def trace():
	'''
	Function decorator that creates opentracing span from incoming b3 headers
	'''
	def decorator(f):
	def wrapper(args, *kwargs):
	request = stack.top.request
	try:
	# Create a new span context, reading in values (traceid,
	# spanid, etc) from the incoming x-b3-*** headers.
	span_ctx = tracer.extract(
	Format.HTTP_HEADERS,
	dict(request.headers)
	)
	# Note: this tag means that the span will not be
	# a child span. It will use the incoming traceid and
	# spanid. We do this to propagate the headers verbatim.
	rpc_tag = {tags.SPAN_KIND: tags.SPAN_KIND_RPC_SERVER}
	span = tracer.start_span(
	operation_name='op', child_of=span_ctx, tags=rpc_tag
	)
	except Exception as e:
	# We failed to create a context, possibly due to no
	# incoming x-b3-*** headers. Start a fresh span.
	# Note: This is a fallback only, and will create fresh headers,
	# not propagate headers.
	span = tracer.start_span('op')
	with span_in_context(span):
	r = f(args, *kwargs)
	return r
	wrapper.__name__ = f.__name__
	return wrapper
	return decorator


	def getForwardHeaders(request):
	headers = {}

	# x-b3-*** headers can be populated using the opentracing span
	span = get_current_span()
	carrier = {}
	tracer.inject(
	span_context=span.context,
	format=Format.HTTP_HEADERS,
	carrier=carrier)

	headers.update(carrier)

	# We handle other (non x-b3-***) headers manually
	if 'user' in session:
	headers['end-user'] = session['user']

	# Keep this in sync with the headers in details and reviews.
	incoming_headers = [
	# All applications should propagate x-request-id. This header is
	# included in access log statements and is used for consistent trace
	# sampling and log sampling decisions in Istio.
	'x-request-id',

	# Lightstep tracing header. Propagate this if you use lightstep tracing
	# in Istio (see
	# https://istio.io/latest/docs/tasks/observability/distributed-tracing/lightstep/)
	# Note: this should probably be changed to use B3 or W3C TRACE_CONTEXT.
	# Lightstep recommends using B3 or TRACE_CONTEXT and most application
	# libraries from lightstep do not support x-ot-span-context.
	'x-ot-span-context',

	# Datadog tracing header. Propagate these headers if you use Datadog
	# tracing.
	'x-datadog-trace-id',
	'x-datadog-parent-id',
	'x-datadog-sampling-priority',

	# W3C Trace Context. Compatible with OpenCensusAgent and Stackdriver Istio
	# configurations.
	'traceparent',
	'tracestate',

	# Cloud trace context. Compatible with OpenCensusAgent and Stackdriver Istio
	# configurations.
	'x-cloud-trace-context',

	# Grpc binary trace context. Compatible with OpenCensusAgent nad
	# Stackdriver Istio configurations.
	'grpc-trace-bin',

	# b3 trace headers. Compatible with Zipkin, OpenCensusAgent, and
	# Stackdriver Istio configurations. Commented out since they are
	# propagated by the OpenTracing tracer above.
	# 'x-b3-traceid',
	# 'x-b3-spanid',
	# 'x-b3-parentspanid',
	# 'x-b3-sampled',
	# 'x-b3-flags',

	# Application-specific headers to forward.
	'user-agent',
	]
	# For Zipkin, always propagate b3 headers.
	# For Lightstep, always propagate the x-ot-span-context header.
	# For Datadog, propagate the corresponding datadog headers.
	# For OpenCensusAgent and Stackdriver configurations, you can choose any
	# set of compatible headers to propagate within your application. For
	# example, you can propagate b3 headers or W3C trace context headers with
	# the same result. This can also allow you to translate between context
	# propagation mechanisms between different applications.

	for ihdr in incoming_headers:
	val = request.headers.get(ihdr)
	if val is not None:
	headers[ihdr] = val

	return headers


	# The UI:
	@app.route('/')
	@app.route('/index.html')
	def index():
	""" Display productpage with normal user and test user buttons"""
	global productpage

	table = json2html.convert(json=json.dumps(productpage),
	table_attributes="class=\"table table-condensed table-bordered table-hover\"")

	return render_template('index.html', serviceTable=table)


	@app.route('/health')
	def health():
	return 'Product page is healthy'


	@app.route('/login', methods=['POST'])
	def login():
	user = request.values.get('username')
	response = app.make_response(redirect(request.referrer))
	session['user'] = user
	return response


	@app.route('/logout', methods=['GET'])
	def logout():
	response = app.make_response(redirect(request.referrer))
	session.pop('user', None)
	return response

	# a helper function for asyncio.gather, does not return a value


	async def getProductReviewsIgnoreResponse(product_id, headers):
	getProductReviews(product_id, headers)

	# flood reviews with unnecessary requests to demonstrate Istio rate limiting, asynchoronously


	async def floodReviewsAsynchronously(product_id, headers):
	# the response is disregarded
	await asyncio.gather(*(getProductReviewsIgnoreResponse(product_id, headers) for _ in range(flood_factor)))

	# flood reviews with unnecessary requests to demonstrate Istio rate limiting


	def floodReviews(product_id, headers):
	loop = asyncio.new_event_loop()
	loop.run_until_complete(floodReviewsAsynchronously(product_id, headers))
	loop.close()


	@app.route('/productpage')
	@trace()
	def front():
	product_id = 0 # TODO: replace default value
	headers = getForwardHeaders(request)
	user = session.get('user', '')
	product = getProduct(product_id)
	detailsStatus, details = getProductDetails(product_id, headers)

	if flood_factor > 0:
	floodReviews(product_id, headers)

	reviewsStatus, reviews = getProductReviews(product_id, headers)
	return render_template(
	'productpage.html',
	detailsStatus=detailsStatus,
	reviewsStatus=reviewsStatus,
	product=product,
	details=details,
	reviews=reviews,
	user=user)


	# The API:
	@app.route('/api/v1/products')
	def productsRoute():
	return json.dumps(getProducts()), 200, {'Content-Type': 'application/json'}


	@app.route('/api/v1/products/<product_id>')
	@trace()
	def productRoute(product_id):
	headers = getForwardHeaders(request)
	status, details = getProductDetails(product_id, headers)
	return json.dumps(details), status, {'Content-Type': 'application/json'}


	@app.route('/api/v1/products/<product_id>/reviews')
	@trace()
	def reviewsRoute(product_id):
	headers = getForwardHeaders(request)
	status, reviews = getProductReviews(product_id, headers)
	return json.dumps(reviews), status, {'Content-Type': 'application/json'}


	@app.route('/api/v1/products/<product_id>/ratings')
	@trace()
	def ratingsRoute(product_id):
	headers = getForwardHeaders(request)
	status, ratings = getProductRatings(product_id, headers)
	return json.dumps(ratings), status, {'Content-Type': 'application/json'}


	# Data providers:
	def getProducts():
	return [
	{
	'id': 0,
	'title': 'The Comedy of Errors',
	'descriptionHtml': '<a href="https://en.wikipedia.org/wiki/The_Comedy_of_Errors">Wikipedia Summary</a>: The Comedy of Errors is one of <b>William Shakespeare\'s</b> early plays. It is his shortest and one of his most farcical comedies, with a major part of the humour coming from slapstick and mistaken identity, in addition to puns and word play.'
	}
	]


	def getProduct(product_id):
	products = getProducts()
	if product_id + 1 > len(products):
	return None
	else:
	return products[product_id]


	def getProductDetails(product_id, headers):
	try:
	url = details['name'] + "/" + details['endpoint'] + "/" + str(product_id)
	res = requests.get(url, headers=headers, timeout=3.0)
	except BaseException:
	res = None
	if res and res.status_code == 200:
	return 200, res.json()
	else:
	status = res.status_code if res is not None and res.status_code else 500
	return status, {'error': 'Sorry, product details are currently unavailable for this book.'}


	def getProductReviews(product_id, headers):
	# Do not remove. Bug introduced explicitly for illustration in fault injection task
	# TODO: Figure out how to achieve the same effect using Envoy retries/timeouts
	for _ in range(2):
	try:
	url = reviews['name'] + "/" + reviews['endpoint'] + "/" + str(product_id)
	res = requests.get(url, headers=headers, timeout=3.0)
	except BaseException:
	res = None
	if res and res.status_code == 200:
	return 200, res.json()
	status = res.status_code if res is not None and res.status_code else 500
	return status, {'error': 'Sorry, product reviews are currently unavailable for this book.'}


	def getProductRatings(product_id, headers):
	try:
	url = ratings['name'] + "/" + ratings['endpoint'] + "/" + str(product_id)
	res = requests.get(url, headers=headers, timeout=3.0)
	except BaseException:
	res = None
	if res and res.status_code == 200:
	return 200, res.json()
	else:
	status = res.status_code if res is not None and res.status_code else 500
	return status, {'error': 'Sorry, product ratings are currently unavailable for this book.'}


	class Writer(object):
	def __init__(self, filename):
	self.file = open(filename, 'w')

	def write(self, data):
	self.file.write(data)

	def flush(self):
	self.file.flush()


	if __name__ == '__main__':
	if len(sys.argv) < 2:
	logging.error("usage: %s port" % (sys.argv[0]))
	sys.exit(-1)

	p = int(sys.argv[1])
	logging.info("start at port %s" % (p))
	# Make it compatible with IPv6 if Linux
	if sys.platform == "linux":
	app.run(host='::', port=p, debug=True, threaded=True)
	else:
	app.run(host='0.0.0.0', port=p, debug=True, threaded=True)