Deploy Jenkins Agents using EC2 Fleet plugin

Jenkins is a continuous integration tool. It is used to build and deploy applications. Normally, there are number of build projects preconfigured in a Jenkins Server. However by default, all builds will be executed on the same instance that Jenkins is server up & running. This results to reduce your performance of the Jenkins Server. To avoid above problems, Jenkins provides the capability to execute builds on external hosts (called build agents). To fulfill above requiremnt, we are going to use the EC2 Fleet Plugin which launches EC2 Spot or On Demand instances as worker nodes for Jenkins server, automatically scaling the capacity with the load. This plugin helps us to:

1. Execute jobs in the spot instances

2. Scales instances as needed

3. Reduce our cost

Prerequisites

Jenkins up and running
You need a Jenkins server up and running. This will be our master server. If you haven't Jenkins server, you can follow this tutorial and set up your Jenkins Master.

Create Policy

Before configuring the EC2 Fleet Jenkins Plugin, we need to create AWS IAM User for our EC2 Fleet Plugin. To create IAM User, you can follow the below instructions.

Go to AWS Console

Click on IAM

Then Click on Policies which is listed under the Access management from left side menu

Then Click on Create Policy

In next window, switch to JSON view and paste below code in it

{
   "Version":"2012-10-17",
   "Statement":[
      {
         "Effect":"Allow",
         "Action":[
            "ec2:DescribeSpotFleetInstances",
            "ec2:ModifySpotFleetRequest",
            "ec2:CreateTags",
            "ec2:DescribeRegions",
            "ec2:DescribeInstances",
            "ec2:TerminateInstances",
            "ec2:DescribeInstanceStatus",
            "ec2:DescribeSpotFleetRequests"
         ],
         "Resource":"*"
      },
      {
         "Effect":"Allow",
         "Action":[
            "autoscaling:DescribeAutoScalingGroups",
            "autoscaling:UpdateAutoScalingGroup"
         ],
         "Resource":"*"
      },
      {
         "Effect":"Allow",
         "Action":[
            "iam:ListInstanceProfiles",
            "iam:ListRoles",
            "iam:PassRole"
         ],
         "Resource":"*"
      }
   ]
}

Then Click on Next: Tags and add tag for your created policy

Then Click on Next: Review

Then give a name for your policy and click on Create policy

Now you can use this policy to create IAM User.

Create IAM User

Then Click on Users which is listed under the Access management from left side menu

Then Click on Add User

Then give a name to your user and check on Access key - Programmatic access. Then click on Next:Permission

Then select Attach existing policies directly. Then select the policy which created in previous step and click on Next:Tag and add tag for your created user

Click on Next: Review

Click on Create User

Download the .csv file for later use. Click on Close

Create a launch template

This is the template that will be used to launch the EC2 instances.

Go to EC2 Service

Click on Launch Instance which is listed under the Instances from left side menu

Then Click on Create launch template

Then name the Launch Template and add small description

In Launch Template Contents section, choose the amzn2-ami-hvm-2.0.20220719.0-x86_64-gp2 (you can choose any image acording to your preferences)

In Instance type section, choose a t3.small (you can choose any type acording to your preferences

In Key pair (login) section, choose an existing key pair or create a new key pair that will be used to connect to these spot instances

In Network settings, Section choose VPC and security group for the instances

In Advanced details, Section check Request Spot Instances and add below script in User data

#!/bin/bash -xe
sudo amazon-linux-extras install epel -y
sudo yum update -y
sudo yum remove java-1.7.0-openjdk
sudo yum install java-1.8.0-openjdk -y
sudo yum install git -y
sudo yum -y update aws-cli

Finally click on Create Launch template

Create a Auto Scaling Group

To create Auto Scaling Group
Click on Auto Scaling Groups

Then click on Create Auto Scaling group

Then name your Auto Scaling Group and choose the previously created Launch Temaple and click on Next button

Then choose desire VPC and all Availability Zones and subnets under choosen VPCpreviously created Launch Temaple and click on Next button

Then under Configure group size and scaling policies add Desired capacity = 1, Minimum capacity = 1, Maximum Capacity = 4

Then Review and create Auto Scaling Group
Now you can see one of the instances already spinning up.

Install EC2-Fleet Plugin

Navigate to your Jenkins Dashboard and click on Manage Jenkins

Then goto Manage Plugins and select Available option and search for EC2 Fleet Jenkins Plugin and install it

Click on restart Jenkins after installation is complete

Setup EC2-Fleet Plugin

Go to Manage Jenkins → Manage Nodes and Clouds → Configure Clouds

Choose Amazon EC2 Fleet from Add a new Cloud drop-down menu

Then give a name

In the AWS Credentials section, click on Add

Then choose Kind as AWS Credentials, Scope as Jenkins and nodes only, add name for id and paste created access key and secret key and finally click on Add

Then choose created credential as AWS Credentials from drop-down menu

Then choose region to your respective one

Choose created Auto Scaling Group for EC2 Fleet section

Click on Test Connection

In the Launcher Section

Change Launcher drop down to Launch Agents via SSH

Then choose Kind as SSH Username with Private Key, Scope as Jenkins and nodes only, add name for id and add ec2-user as username and paste content on our.pem file, we created on Launch template step and finally click on Add

Then choose created credential from drop-down menu

For Host Key Verification Strategy choose Non verifying verification strategy

Check Private IP option

Change label to spot-agents

Then add Number of executors: 1, Max Idle Minutes before scaledown: 5, Minimum Cluster Size: 1, Maximum Cluster Size: 5, Maximum Total Uses: -1 (default)

Leave the rest default. Click on Save

Conclusion

In this tutorial, we learned how to configure EC2-Fleet plugin in Jenkins. If you have any issue regarding this tutorial, mention your issue in comment section or reach me through my E-mail.