Install jenkins on AWS instance via terraform and automate the manual process of taking ssh and performing the steps of script installation for jenkins on your server.

jenkins installation using terraform

Topic: How to install jenkins via terraform without manually taking ssh of the created instance?

Steps : 
1. write code for instance (here I have choosen ubuntu ami-id), default vpc and subnet.
2. write code for security_group 
3. import manual key in your aws accout where you will get public and private key by using ssh-keygen cmd
4. Vs code:
	create a dir. named as : Jenkins
	create files in the jenkins folder:
main.tf, variables.tf, terraform.tfvars, keys, provider.tf, output.tf, jenkins.sh

5. provider.tf :

provider "aws" {
  region  = "us-east-2" # Change this to your desired AWS region
  profile = "tf-navez"
}

#---------------

6. main.tf: 

resource "aws_instance" "jenkins_instance" {
  ami           = var.ami_value
  instance_type = var.instance_type_value
  key_name = var.key_pair
  tags = {
    Name = "Jenkins Server"
  }

}

# --------------------------------

# create empty resource block for userdata without taking ssh for instance
resource "null_resource" "name" {

  connection {
    type        = "ssh"
    user        = "ubuntu"
    private_key = file("./key/id_rsa")
    host        = aws_instance.jenkins_instance.public_ip
  }
  #   here copy the jenkin.sh file from your dir. to the instance
  provisioner "file" {
    source      = "jenkins.sh"
    destination = "/tmp/jenkins.sh" # --- this will create a directory in our ec2 instance from where we will run the file.
  }

  # set the permissions to run the shell script file 
  provisioner "remote-exec" {
    inline = [
      "sudo chmod +x /tmp/jenkins.sh", #--- this will give execute permission to the folder
      "sh /tmp/jenkins.sh",            #--- this will run the shell script
    ]
  }

  # wait for ec2 instance to be created before executing all the jenkins process
  depends_on = [aws_instance.jenkins_instance]

  # this depend_on will create the instance, take ssh into it, and run the following above cmds. 

}

# --------------------------------

resource "aws_default_vpc" "default_vpc" {
  tags = {
    Name = "deafult vpc"
  }

}

resource "aws_key_pair" "id_rsa" {
  key_name   = var.key_pair
  public_key = file("./key/id_rsa.pub")
}

resource "aws_default_subnet" "default_subnet" {
  availability_zone = var.availability_zone
  tags = {
    Name = "default_subnet"
  }
}

resource "aws_security_group" "security_group" {
  # name = var.security_group_rules
  vpc_id = aws_default_vpc.default_vpc.id

  ingress {
    description = "allow access to ports 8080 "
    from_port   = 8080
    to_port     = 8080
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  ingress {
    description = "ssh access"
    from_port   = 22
    to_port     = 22
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]

  }

  egress {
    from_port   = 0
    to_port     = 0
    protocol    = -1
    cidr_blocks = ["0.0.0.0/0"]

  }
  tags = {
    Name = "jenkins server security",
  }

}

# ------------
7. variables.tf:

# Defining ami value
variable "ami_value" {
  description = "value for the ami"
}

# Defining instance type 
variable "instance_type_value" {
  description = "value for instance type"
}

# defining key pair
variable "key_pair" {
  description = "key pair value"
}

# Defining AZ of instance
variable "availability_zone" {
  type        = string
  description = "AWS availability zone for resources"
}

# Defining securtiy group
variable "security_group_rules" {
  description = "allow access to ports 8080 and 22 "

}

#--------------

8. output.tf:

output "jenkins_url" {
  value = "http://${aws_instance.jenkins_instance.public_ip}:8080"
}

output "public_ip" {
  value = aws_instance.jenkins_instance.public_ip
}

#--------------

9. terraform.tfvars: 	

ami_value           = "ami-0e83be366243f524a"
instance_type_value = "t2.medium"
key_pair            = "./key/id_rsa.pub"
availability_zone   = "us-east-2a"


security_group_rules = [
  {
    from_port   = 22
    to_port     = 22
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  },
  {
    from_port   = 8080
    to_port     = 8080
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

]

10. jenkins.sh: 

#!/bin/bash
         sudo apt update -y
         sudo apt install  -y fontconfig openjdk-17-jre
         sudo wget -O /usr/share/keyrings/jenkins-keyring.asc \
                 https://pkg.jenkins.io/debian/jenkins.io-2023.key
         echo deb [signed-by=/usr/share/keyrings/jenkins-keyring.asc] \
                 https://pkg.jenkins.io/debian binary/ | sudo tee \
                 /etc/apt/sources.list.d/jenkins.list > /dev/null
         sudo apt-get update -y
         sudo apt-get install jenkins -y
         sudo systemctl start jenkins
         sudo systemctl enable jenkins
	 
	 


terraform init
terraform fmt
terraform plan
terraform apply 
terraform destroy
	
Hence, you have successfully installed jenkins via terraform