The document discusses Camunda's transition from a traditional Jenkins setup with virtual machines to a containerized continuous integration infrastructure using Docker and Jenkins. Some of the key problems with the previous setup included a lack of isolation between jobs, limited scalability, and difficulties maintaining the infrastructure. The new system achieves isolated and reproducible jobs through one-off Docker containers, scalability through Docker Swarm on commodity hardware, and infrastructure maintenance through immutable Docker images and infrastructure as code definitions. Lessons learned include automating as much as possible, designing for scale, testing all aspects of the new system, and controlling dependencies.

1. From Virtual Machines to Containers
Achieving Continuous Integration, Build Reproducibility, Isolation and Scalability
London, UK, June 2015
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2. #jenkinsconf
Agenda
• Introduction
• The Dark Age
• The Promising Present
• Lessons Learned
• The Bright Future

3. #jenkinsconf
2014201320122011201020092008
Incorporation
Camunda Services GmbH
Berlin, Germany
Incorporation
Camunda Inc.
San Francisco, US
BPM Consulting BPM Software Vendor
● 30 Fulltime Employees ● No external funding ● Avg. 50% Turnover Growth per Year
Introduction - About Camunda
@camundaBPM
Introduced
Hudson
Adapted
Jenkins

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Introduction - Camunda BPM

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Introduction - What is Camunda BPM
• Camunda BPM is an open source platform
for workflow and business process automation
• Integrates with:
• 7 Application Server (11 different versions)
• 6 Databases (17 different versions)
• 1 Development & 4 Maintained Versions

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• Every Camunda BPM version is tested against:
• 187 combinations of DBs and App Servers
• 11 JDKs
• ~ 400 Jobs per version
• Bi-Annual release of a new Camunda BPM version
• Support for Enterprise Customer (24/7 + Fix Time)
Introduction - Why CI is Important

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The Dark Age
Why our CI had to change
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The Dark Age - The Numbers
• 1 Jenkins Master with alot of plugins
• 8 Jenkins Slaves VMs
• ~1000 Jobs total configured / manually managed:
• 4 Camunda Versions
• Community Projects
• Websites
• Maintenance

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The Dark Age - Isolation Problem
• Unit and Integration Tests need a
database/application server
• Only 1 Instance per Database
• All Jobs use the same Databases
• Every half-year a new Version (~400 Jobs) using
same Databases

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The Dark Age - No Scalability
• Total Executors: 12
• 1 Jenkins -> 4 Executors
• 8 static heterogenous slave VMs, each with 1
Executor
• Jobs tied to slaves through labels
• Slaves “restrict” database access by allowing no
other build to run

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The Dark Age - Maintenance Problems
• Upgrading Jenkins or any plugin
• Supporting a new Database vendor / version
• Supporting a new App Server version
• Creating jobs for new Camunda BPM version
• Disaster recovery

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The Dark Age - The Other Problems
• Slow feedback cycle for developers
• Developers cannot reproduce CI environments
• QA engineers use and maintain separate bloated
test build setup

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So ...

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The Promising Present
How we solved our Problem
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15. #jenkinsconf
The Present - What we achieved
• Configuration & Infrastructure as Code
• Isolated and Reproducible Jobs
• Scalable CI Infrastructure

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The Present - Infrastructure as Code
1. Every configuration is checked into SCM
2. Every application/test runs in a Docker
Container
3. Every Docker image is build
automatically

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The Present - Infrastructure as Code
1. Every Configuration is checked into SCM
• Docker for
• Applications
• Test Environments
• JobDSL for
• Jenkins Jobs

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The Present - Infrastructure as Code
2. Every application/test runs in a Docker Container
Images:
• Application (Jenkins, Nexus …)
• Test Env. Images (DB + SSH)
• Build Env. Images
• DIND, QEMU + Packer.io

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The Present - Infrastructure as Code
3. Every Docker Container is build automatically
• Own Jenkins for Docker/KVM Images
• KVM Images build in Docker Container
with Packer + QEMU
• KVM Images bundled in Docker Image

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The Present - The Current Flow
camunda-ci
camunda
Camunda BPM
Platform
Infrastructure
Jenkins
CI Jenkins

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The Present - Isolation
One Jenkins per Concern:
• CI
• Release
• Infrastructure
• Community and other Projects
• Marketing

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The Present - Isolation & Reproducibility
• Every Jobs runs in an One-Shot Docker Container
• No Interference between Jobs
• The Database Settings are well documented
• Every Docker Image is stored in a private registry
• Developers/QA can use the Docker Images for local
testing

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The Present - Scalability
• Jenkins uses Docker-Plugin with one Docker Cloud
running on Docker Swarm
• Docker images are added through Groovy scripting
• Running on Commodity Hardware
• 1 Infrastructure Host (Jenkins, Nexus, …)
• 6 Docker Hosts as 1 Swarm

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The Present - Scalability

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The Present - Advantages
• Easy to add new Databases/Test Environments
• New Release = New Branch of JobDSL Repository
• Fully parallelized Job Execution
• Accountable Configuration History
• Testable Infrastructure
• Minimize Administration Overhead

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The Present - Conclusion
• 2 People + 3 Months of Work
• A fully scalable, isolated and reproducible CI
Infrastructure
• Faster Feedback
• Happy Developers and Product Owner

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Lessons learned
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Some advice from us to you

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• Automate as much as you can
• Jenkins config
• Jobs config
• Environment creation
• Design to scale to support the business agility
Lessons learned - Architecture

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Lessons learned - Testing
Test everything:
• Jenkins configuration
• required plugin features
• Job generation
• Docker images
• Scalability
• Disaster recovery

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Lessons learned - Job DSL
• Unit-test the job generation
• Write JobGenerator classes to abstract the
common build logic of most jobs out of the box
• Use XML diffing to compare previously generated
jobs with new ones

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Lessons learned - Docker
https://github.com/rancherio/vm/

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• Pin your plugin versions
• Be prepared to contribute to plugin development or
maintain a branch yourself
• Choose the right plugin for the job
Our Top 3 plugins:
JobDSL, Docker-Plugin, Build-Failure-Analyzer
Lessons learned - Plugins

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Lessons learned - Control
• Control as much as possible
• Third party binaries vs package manager
• explicit versions
• own mirrors for important packages

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The Bright Future
What comes next
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35. #jenkinsconf
The Future
• Public Community Jenkins
• Internal Webapp for Developers and QA to start
Environments
• Jenkins is deploying Jenkins
• Back to the Datacenter
• Centralized Logging and Monitoring (ELK)

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Resources
• Camunda CI repository
https://github.com/camunda-ci
• Job DSL gradle example
https://github.com/sheehan/job-dsl-gradle-example
• Camunda BPM Docker image
https://registry.hub.docker.
com/u/camunda/camunda-bpm-platform/

39. #jenkinsconf
We Are Hiring
Come Join Us
@camundaBPM
http://camunda.com/jobs

40. #jenkinsconf
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