(WIP) Terraform template to create a Jenkins master with slaves on-demand

Configuration of a Jenkins master with slaves on-demand (AWS EC2 only for now).

Includes

Network

Global

• Custom Virtual Private Cloud (VPC)

Jenkins master

• Public subnet
• Internet gateway
• NAT gateway
• Security group to allow access the Jenkins UI
• Security group to allow access to EFS storage from Jenkins master

Jenkins slaves

• Private subnet
• Security groups to allow only access from the Jenkins master

Instances

Jenkins Master

• AWS EC2 instance (t3.large by default)
• AWS AMI (Amazon Linux 2)
• SSH key pair
• NGINX reverse-proxy configuration

Jenkins Slaves

• AWS EC2 instance template (different instance sizes)
• AWS AMI (Amazon Linux 2 minimal)
• SSH key pair

Storage

• EBS root volume for all instances
• AWS Elastic File System (EFS) for the Jenkins master configuration and data

How to install

Clone this Git repository

git clone git@github.com:timoa/terraform-jenkins-slaves-on-demand.git

Now, go to the tf-vm/aws folder (the only type and provider for the moment)

cd terraform-jenkins-slaves-on-demand/tf-vm/aws

You can change some of the variables in the variables.tf. See the configuration section

Start by install the dependencies

terraform init

Run terraform plan to see which resources will be created and save the generated execution plan

terraform plan --out=jenkins.tfplan

Apply the Terraform plan

terraform apply jenkins.tfplan

Configuration

This variables can be changed under the variables.tf file.

Variable	Default value	Description
aws_region	us-east-1	AWS Region
env	dev	Name of the environment
vpc_cidr	10.0.0.0/16	VPC CIDR
public_subnet	10.0.1.0/24	Public subnet
private_subnet	10.0.2.0/24	Private subnet
instance_type	t3.large	Instance type
ebs_optimized	true	EBS optimized
path_public_key	jenkins-master-key.pub	Path to the SSH public key for Jenkins master

Outputs

Name	Description
jenkins_master_public_ip	Jenkins master public IP
jenkins_master_public_dns	Jenkins master public DNS

TODO

• Terraform backend with S3 + lock
• Add EC2 health check URL for the Jenkins master
• Encrypt the AMI with the new AWS API
• Encrypt EFS in transit (SSL)
• Mount the EFS volume when ready (can take up to 25 min to be provisionned)
• Configure Jenkins with the necessary plugins
• Create a separate Jenkins master IAM role to create the slaves on-demand
• Create the Jenkins slaves AMI
• Let's Encrypt SSL certificate for the Jenkins master
• Use an existing VPC ID
• Use an existing EFS ID
• Install and configure Prometheus Node Exporter for monitoring
• Install and configure Logstash and export logs to an Elasticsearch instance