This presentation walks through a Jenkins as Code approach that aims to fully automate and describe the creation of Infrastructure, Application and Configuration as Code. We treat our applications with a strong 'as code' approach, but often forget about the critical operational tools. This presentation shows how it is possible to create a code first approach to creating and managing a Jenkins Service. Working code repository is available at https://bitbucket.org/stevemac/dockerfiles

1. Jenkins as a Service
Code all the way down
Steve Mactaggart
Application Delivery Evangineer

2. The moving parts
Infrastructure (AWS / ECS)
Application (Jenkins)
Configuration (Jenkins Jobs)

3. The moving parts - AS CODE
Infrastructure (AWS / ECS)
Application (Jenkins)
Configuration (Jenkins Jobs)
CloudFormation
Docker containers
Groovy / Jenkins DSL

4. Everything as code
• Consistently repeatable process
• Enables a strong self service workflow
• Highly visible traceability of change
• Roll forward / rollback

5. The moving parts - Infrastructure
Infrastructure (AWS / ECS)
Application (Jenkins)
Configuration (Jenkins Jobs)
CloudFormation
Docker containers
Groovy / Jenkins DSL

6. Infrastructure
• Infrastructure captured as Code
• Designed for easy re-use per team
• Deployable into existing VPCs
• Common location to share learned lessons
Infrastructure / AWS

7. EC2
Infrastructure - Simplified
ap-southeast-2bap-southeast-2a
ECS agent auto-scaling group
ECS master auto-scaling group
EC2 EC2
Infrastructure / AWS /
CloudFormation
ECS configuration
Master ECR
Agent ECR
AWS ECS
CloudWatch logs

8. EC2
Infrastructure
ap-southeast-2bap-southeast-2a
ECS agent auto-scaling group
ECS master auto-scaling groupECS configuration
Master ECR
Agent ECR
Legend
ECS ScaleDown
function
ECS Memory
Reservation Alarm
Termination Event
AWS ECS
EC2 EC2
Query for tasks running on host
Continue the ASG lifecycle hook
Publish intent to
terminate
Watch for ScaleUp
/ ScaleDown alarm
Consume
message
Containers download configuration
ECSLaunches
AgentTask
Launch / Terminate
EC2 Instance
Jenkins Schedules
new Task via ECS
JenkinsAgent
phoneshometo
Mastercontainer
Direct TCP call
S3 download
AWS API Call
Retrieve Master container from ECR
Retrieve Agent container from ECR
EC2instance
registerswith
ECS
Agentcontainer
registerswithmaster
ALB routes web traffic
Infrastructure / AWS /
CloudFormation
CloudWatch logs
EC2 / ECS logs shipped
to CloudWatch

9. Infrastructure
• Example CloudFormation
• https://bitbucket.org/stevemac/dock
erfiles/src/282408c04239/cloudforma
tion/?at=master
• 2 stacks
• Infrastructure (2x ECS clusters)
• Cluster - Jenkins Master Service

10. The moving parts - Application
Infrastructure (AWS / ECS)
Application (Jenkins)
Configuration (Jenkins Jobs)
CloudFormation / Terraform
Docker containers
Groovy / Jenkins DSL

11. EC2
Jenkins in Docker
ap-southeast-2bap-southeast-2a
ECS agent auto-scaling group
ECS master auto-scaling group
EC2 EC2
ECS configuration
Master ECR
Agent ECR
AWS ECS
CloudWatch logs
Jenkins Application /
Docker containers
Jenkins
Master
Jenkins
Agents

12. The Jenkins Master and its Agents
• Jenkins is an Application
• We understand the Docker application workflow
• Immutable Applications increase confidence of changes
• Based of official JenkinsCI base containers
• From jenkinsci/Jenkins
• From jenkinsci/slave
• Extended to include specific build and deployment tools
• Python / AWSCli / etc
Jenkins Application /
Docker containers

13. Jenkins master - Dockerfile
Jenkins Application /
Docker containers

14. Jenkins agent - Dockerfile
Jenkins Application /
Docker containers

15. Jenkins in Docker
• Many plugins in-use:
• build-pipeline-plugin
• amazon-ecs
• delivery-pipeline-plugin
• build-monitor-plugin
• gitlab-merge-request-Jenkins
• Etc…
• State persisted through Docker volume mount
• Example Master and Agent Docker containers
• https://bitbucket.org/stevemac/dockerfiles/src/

16. The moving parts - Configuration
Infrastructure (AWS / ECS)
Application (Jenkins)
Configuration (Jenkins Jobs)
CloudFormation / Terraform
Docker containers
Groovy / Jenkins DSL

17. Configuration as Code - setup
• Start of the configuration delivered in Dockerfiles
• Configuration and ssh keys downloaded from S3 bucket
• Supplied to container as Environment variable
Configuration / Groovy

18. Configuration as Code - setup
• Runtime configuration automated through use of custom Groovy
initialisation scripts within the container
• Groovy is used to configure:
• Jenkins credentials
• ECS Cluster configuration
• Jenkins Bootstrap job
• Executed as part of Dockerfile entrypoint
Configuration / Groovy

19. Pipeline as Code - runtime
• Using the Jenkins DSL pipeline
• https://bitbucket.org/jenkinspipeline/jenkins-dsl-examples
• Using the power of Groovy code to create reusable elements
• Version controlled through Git
• Repeatable / reliable / extensible
• See https://github.com/jenkinsci/job-dsl-plugin/wiki/Tutorial---Using-the-Jenkins-Job-DSL
• Automatic documentation available within each Jenkins instance
Configuration / Jenkins DSL
Lets talk about
a Jenkinsfile
approach over a
beer

20. Pipeline as Code – groovy constructs
Configuration / Groovy /
Jenkins DSL

21. Pipeline as Code - example
https://bitbucket.org/jenkinspipeline/jenkins-dsl-examples
1. build_pipeline.groovy
Creation of example build jobs - CI
2. delivery_pipeline.groovy
Creation of example jobs for a candidate delivery pipeline - CD
3. views.groovy
Creation of some standard pipeline views
Configuration / Groovy /
Jenkins DSL

22. Bringing it together
Let our codebases combine

23. Executed within
ECS Jenkins service
Result of
infrastructure deploy
Performed by operator
Delivery workflow
Build and
Publish Docker
Containers
Launch Stack
Publish keys to
S3 bucket
Create ECS
Service
Retrieve latest
Docker image
from ECR
Launch ECS
Task
Download keys
from S3
Clone groovy
config repo
Launch Jenkins
Master Process
Groovy config
executed
Bootstrap job
generates
pipelines

24. Followup discussions
1. Migrating to a Jenkins-as-code approach
2. Jenkins DSL vs Jenkinsfiles
3. All about Jenkins State
4. Security in a stateless world
5. Advanced Jenkins DSL patterns

25. Thanks !
Steve Mactaggart
• Application Delivery Evangineer at Cevo
• @stevemac
Example working code available at:
https://bitbucket.org/stevemac/dockerfiles