[GSP007] Set Up Network and HTTP Load Balancers

$ gcloud config set compute/zone us-central1-a
$ gcloud config set compute/region us-central1

$ cat << EOF > startup.sh
#! /bin/bash
apt-get update
apt-get install -y nginx
service nginx start
sed -i -- 's/nginx/Google Cloud Platform - '"\$HOSTNAME"'/' /var/www/html/index.nginx-debian.html
EOF

// Create an instance template, which uses the startup script:
$ gcloud compute instance-templates create nginx-template \
     --metadata-from-file startup-script=startup.sh

// Create a target pool. A target pool allows a single access point to all the instances in a group and is necessary for load balancing in the future steps.
$ gcloud compute target-pools create nginx-pool


// Create a managed instance group using the instance template:
$ gcloud compute instance-groups managed create nginx-group \
     --base-instance-name nginx \
     --size 2 \
     --template nginx-template \
     --target-pool nginx-pool

$ gcloud compute instances list
NAME        ZONE           MACHINE_TYPE   PREEMPTIBLE  INTERNAL_IP  EXTERNAL_IP     STATUS
nginx-fz6j  us-central1-a  n1-standard-1               10.128.0.2   173.255.112.6   STAGING
nginx-m8rf  us-central1-a  n1-standard-1               10.128.0.3   104.198.72.238  STAGING

// Now configure a firewall so that you can connect to the machines on port 80 via the EXTERNAL_IP addresses:
$ gcloud compute firewall-rules create www-firewall --allow tcp:80

// Create an L3 network load balancer targeting your instance group:
$ gcloud compute forwarding-rules create nginx-lb \
     --region us-central1 \
     --ports=80 \
     --target-pool nginx-pool

$ gcloud compute forwarding-rules list
NAME      REGION       IP_ADDRESS     IP_PROTOCOL  TARGET
nginx-lb  us-central1  35.238.83.178  TCP          us-central1/targetPools/nginx-pool

// First, create a health check. Health checks verify that the instance is responding to HTTP or HTTPS traffic:
$ gcloud compute http-health-checks create http-basic-check

Created [https://www.googleapis.com/compute/v1/projects/qwiklabs-gcp-3a84410d949cb8b7/global/httpHealthChecks/http-basic-check].
NAME              HOST  PORT  REQUEST_PATH
http-basic-check        80    /

// Define an HTTP service and map a port name to the relevant port for the instance group. Now the load balancing service can forward traffic to the named port:
$ gcloud compute instance-groups managed \
   set-named-ports nginx-group \
   --named-ports http:80

// Create a backend service:
$ gcloud compute backend-services create nginx-backend \
  --protocol HTTP --http-health-checks http-basic-check --global

// Add the instance group into the backend service:
$ gcloud compute backend-services add-backend nginx-backend \
--instance-group nginx-group \
--instance-group-zone us-central1-a \
--global

// Create a default URL map that directs all incoming requests to all your instances:
$ gcloud compute url-maps create web-map \
--default-service nginx-backend

// Create a target HTTP proxy to route requests to your URL map:
$ gcloud compute target-http-proxies create http-lb-proxy \
--url-map web-map

// Create a global forwarding rule to handle and route incoming requests. A forwarding rule sends traffic to a specific target HTTP or HTTPS proxy depending on the IP address, IP protocol, and port specified. The global forwarding rule does not support multiple ports.
$ gcloud compute forwarding-rules create http-content-rule \
    --global \
    --target-http-proxy http-lb-proxy \
    --ports 80

$ gcloud compute forwarding-rules list

NAME               REGION       IP_ADDRESS      IP_PROTOCOL  TARGET
http-content-rule               35.201.127.153  TCP          http-lb-proxy
nginx-lb           us-central1  35.238.83.178   TCP          us-central1/targetPools/nginx-pool