05-cluster-webserver

Terraform Cluster Web Server example

This folder contains a cluster of web servers example of a Terraform file on AWS (Amazon Web Services).

This Terraform file deploys a cluster of web servers on AWS (Amazon Web Services) using EC2 and Auto Scaling, as well as a load balancer using ELB.

The cluster of web servers returns "Hello, World" for the URL /. The load balancer listens on port 80.

Requirements

• You must have Terraform installed on your computer.
• You must have an AWS (Amazon Web Services) account.
• It uses the Terraform AWS Provider that interacts with the many resources supported by AWS through its APIs.
• This code was written for Terraform 0.10.x.

Using the code

• Configure your AWS access keys.

  Important: For security, it is strongly recommend that you use IAM users instead of the root account for AWS access.

  Setting your credentials for use by Terraform can be done in a number of ways, but here are the recommended approaches:

  • The default credentials file

    Set credentials in the AWS credentials profile file on your local system, located at:

    ~/.aws/credentials on Linux, macOS, or Unix

    C:\Users\USERNAME\.aws\credentials on Windows

    This file should contain lines in the following format:

    [default]
    aws_access_key_id = <your_access_key_id>
    aws_secret_access_key = <your_secret_access_key>

    Substitute your own AWS credentials values for the values <your_access_key_id> and <your_secret_access_key>.

  • Environment variables AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY

    Set the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables.

    To set these variables on Linux, macOS, or Unix, use export:

    export AWS_ACCESS_KEY_ID=<your_access_key_id>
    export AWS_SECRET_ACCESS_KEY=<your_secret_access_key>

    To set these variables on Windows, use set:

    set AWS_ACCESS_KEY_ID=<your_access_key_id>
    set AWS_SECRET_ACCESS_KEY=<your_secret_access_key>

• Initialize working directory.

  The first command that should be run after writing a new Terraform configuration is the terraform init command in order to initialize a working directory containing Terraform configuration files. It is safe to run this command multiple times.

  terraform init

• Modify server port configuration.

  The web server is listening on port 8080, which is defined as an input variable server_port in vars.tf file.

  If you want to modify the server port you will be able to do it in several ways:

  • Loading variables from command line flags.

    Run Terraform commands in this way:

    terraform plan -var 'server_port=8080'

    terraform apply -var 'server_port=8080'

  • Loading variables from a file.

    When Terraform runs it will look for a file called terraform.tfvars. You can populate this file with variable values that will be loaded when Terraform runs. An example for the content of the terraform.tfvars file:

    server_port = "8080"

  • Loading variables from environment variables.

    Terraform will also parse any environment variables that are prefixed with TF_VAR. You can create an environment variable TF_VAR_server_port:

    TF_VAR_server_port=8080

  • Variable defaults.

    Change the value of the default attribute of server_port input variable in vars.tf file.

• Validate the changes.

  Run command:

  terraform plan

• Deploy the changes.

  Run command:

  terraform apply

• Test the cluster of web servers.

  When the terraform apply command completes, it will output the DNS name of the load balancer.

  You can test it in two ways:

  • Running this command:

    curl http://http://<elb_dns_name>/

  • Writing in your browser this URL: http://<elb_dns_name>/

  You should get a Hello, World response message.

• Clean up the resources created.

  When you have finished, run command:

  terraform destroy