# Copyright 2015 Google Inc.

#

# 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.

#! /bin/bash

set -ex

ZONE=us-central1-f

GROUP=frontend-group

TEMPLATE=$GROUP-tmpl

MACHINE_TYPE=f1-micro

STARTUP_SCRIPT=startup-script.sh

SCOPES="userinfo-email,\

logging-write,\

storage-full,\

datastore,\

https://www.googleapis.com/auth/pubsub,\

https://www.googleapis.com/auth/projecthosting"

TAGS=http-server

MIN_INSTANCES=1

MAX_INSTANCES=10

TARGET_UTILIZATION=0.6

SERVICE=frontend-web-service

#

# Instance group setup

#

# First we have to create an instance template.

# This template will be used by the instance group

# to create new instances.

gcloud compute instance-templates create $TEMPLATE \

--machine-type $MACHINE_TYPE \

--scopes $SCOPES \

--metadata-from-file startup-script=$STARTUP_SCRIPT \

--tags $TAGS

# Create the managed instance group.

gcloud compute instance-groups managed \

create $GROUP \

--base-instance-name $GROUP \

--size $MIN_INSTANCES \

--template $TEMPLATE \

--zone $ZONE

gcloud compute instance-groups managed set-named-ports \

$GROUP \

--named-port http:8080 \

--zone $ZONE

#

# Load Balancer Setup

#

# A complete HTTP load balancer is structured as follows:

#

# 1) A global forwarding rule directs incoming requests to a target HTTP proxy.

# 2) The target HTTP proxy checks each request against a URL map to determine the

# appropriate backend service for the request.

# 3) The backend service directs each request to an appropriate backend based on

# serving capacity, zone, and instance health of its attached backends. The

# health of each backend instance is verified using either a health check.

#

# We'll create these resources in reverse order:

# service, health check, backend service, url map, proxy.

# Create a health check

# The load balancer will use this check to keep track of which instances to send traffic to.

# Note that health checks will not cause the load balancer to shutdown any instances.

gcloud compute http-health-checks create ah-health-check \

--request-path /_ah/health

# Create a backend service, associate it with the health check and instance group.

# The backend service serves as a target for load balancing.

gcloud compute backend-services create $SERVICE \

--http-health-check ah-health-check

gcloud compute backend-services add-backend $SERVICE \

--group $GROUP \

--zone $ZONE

# Create a URL map and web Proxy. The URL map will send all requests to the

# backend service defined above.

gcloud compute url-maps create $SERVICE-map \

--default-service $SERVICE

gcloud compute target-http-proxies create $SERVICE-proxy \

--url-map $SERVICE-map

# Create a global forwarding rule to send all traffic to our proxy

gcloud compute forwarding-rules create $SERVICE-http-rule \

--global \

--target-http-proxy $SERVICE-proxy \

--port-range 80

#

# Autoscaler configuration

#

gcloud compute instance-groups managed set-autoscaling \

$GROUP \

--max-num-replicas $MAX_INSTANCES \

--target-load-balancing-utilization $TARGET_UTILIZATION \

--zone $ZONE

gcloud compute firewall-rules create default-allow-http-8080 \

--allow tcp:8080 \

--source-ranges 0.0.0.0/0 \

--target-tags http-server \

--description "Allow port 8080 access to http-server"