Terraform and IaC - creating EC2 Instance

I'm revisiting the post I did and creating the same EC2 instance using Terraform instead of going through the AWS Console.

I used the reference from Terraform's Registry to create my HCL script: aws-instance documentation

Here is my main.tf file that I created.

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = ">= 4.49.0"
    }
  }

  required_version = ">= 1.2.0"
}

provider "aws" {
  region = "us-east-1"
}

resource "aws_instance" "spring_boot_webserver" {
  ami           = "ami-0b5eea76982371e91"
  instance_type = "t2.micro"

  tags = {
    Name = "iac-java-webapp"
  }

  key_name = "java-demo-keypair"

  associate_public_ip_address = true
  subnet_id                   = "subnet-01b088baff86159af"
  vpc_security_group_ids = [
    "sg-0a5cddc1e38f7b9b5"
  ]
}

It was pretty cool to go into my AWS Console (after waiting about 30 seconds) and seeing the EC2 Instance that was created by running my Terraform script:

AWS Storage: EBS, EFS, S3

Here are some of the main storage options in AWS: 

• EBS (Elastic Block Store)
• EFS (Elastic File System)
• S3 (Simple Storage Service)

I created the following diagram to help visualize how these work:

Instance Store: An EC2 Instance has local store, similar to a physical or virtual machine. 

For a Linux-based EC2 instance (such as Amazon Linux 2), there will be the typical / (root) directory, and standard Linux directories such as /bin, /etc, /opt, /tmp

For a Windows-based EC2 Instance, there is the typical C:\ directory. 

The problem with Instance Store is that it is not persistent or durable.  If the EC2 Instance is terminated, the data that was stored in /opt is gone. 

I/O is fast because there is no network latency between the EC2 Instance and its Instance Store.

EBS: Persistent, but is attached to a single EC2 Instance.  I think of it like plugging in an additional hard drive.  You can't connect it to multiple EC2 Instances because File Systems such as EXT4, NTFS don't handle that.  I/O is fast because there is no network latency between the EC2 Instance and EBS. 

EFS: Persistent, can be shared by multiple EC2 Instances and On-Prem Servers.  I think of this like a mounted drive on a NAS.

S3: Object-based.  Objects are placed into/retrieved from buckets using HTTPS.  This is going to be much less performant than other storage mechanisms, but would be the most globally-accessible. 

EC2 and Java Spring Boot

These days, containers and ECS/EKS seem to be all the rage.  However, I wanted to make sure I could still install and run my application on an EC2 Instance.

I decided to create an EC2 Instance t2.micro) using the AMI for Amazon Linux 2.

Step 1: Installing Java 17 (Amazon Corretto)

I logged in using the private key from the Keypair I generated and installed Java 17:

login as: ec2-user

Authenticating with public key "java-demo-keypair"

Last login: Mon Dec 19 02:54:32 2022 from **********

       __|  __|_  )

       _|  (     /   Amazon Linux 2 AMI

      ___|\___|___|

https://aws.amazon.com/amazon-linux-2/

[ec2-user@ip-10-0-0-72 ~]$ sudo yum install java-17-amazon-corretto

after all the dependencies were downloaded, installed, and this completed, I verified:

[ec2-user@ip-10-0-0-72 ~]$ java -version

openjdk version "17.0.5" 2022-10-18 LTS

OpenJDK Runtime Environment Corretto-17.0.5.8.1 (build 17.0.5+8-LTS)

OpenJDK 64-Bit Server VM Corretto-17.0.5.8.1 (build 17.0.5+8-LTS, mixed mode, sharing)

Finally, I added a Bash script to /etc/profile.d to set JAVA_HOME and PATH to include JAVA_HOME. 

[ec2-user@ip-10-0-0-72 ~]$ sudo vi /etc/profile.d/java.sh

export JAVA_HOME=/usr/lib/jvm/java-17-amazon-corretto.x86_64

and sourced this Bash script so it would take effect immediately:

[ec2-user@ip-10-0-0-72 ~]$ source /etc/profile.d/java.sh

Step 2: Create Service to run Spring Boot App

Create java-user (in java-group) with a home directory of /opt/java-apps 

[ec2-user@ip-10-0-0-72 ~]$ sudo groupadd -r java-group

[ec2-user@ip-10-0-0-72 ~]$ sudo useradd -r -m -g java-group -d /opt/java-apps -s /bin/false java-user

                             

I copied the Spring Boot JAR into /opt/java-apps/demo.jar and created the following Systemctl Service file:

[root@ip-10-0-0-72 system]# sudo vi /etc/systemd/system/springboot.service

[Unit]
Description=Java Spring Boot Demo App
After=syslog.target

[Service]
WorkingDirectory=/opt/java-apps
ExecStart=/bin/java -jar demo.jar
SuccessExitStatus=143

User=java-user
Group=java-group

[Install]
WantedBy=multi-user.target