52-configuration-as-code.rst

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Configuration As Code

"Configuration as code" is a subset of the larger "infrastructure as code" concept:

• Adding of virtualization to the management of your configurations
• Not just managing what's on your systems but also the existence of the systems themselves

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What does treating "configuration as code" mean in a pracital sense?

• Configuration often !is! code
• Apache config file(s) is/are basically a programming environment already

What that means is using (good) practices common to the world of a programmer.

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Revision Control And Deployment

• As "code" you manage it in a version control system, then you compile and deploy it out to a target system
• As "config" you edit configs in place on a system

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Tests

• Make it testable
• regression, unit, integration, load, security...
• Monitoring
• Development and test environments

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Continuous Integration/Continuous Deploy

• Follow a process

  • Simple: design/code/test/deploy/maintain

• This can include more complex steps:

  • Modeling
  • Automated code validation
  • Defect tracking
  • Code reviews

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Simple Example: This Talk

• Written in ReStructuredText
• Converted to HTML5
• Stored on Github
• Buildt using Travis CI

-> A commit/push to GitHub will trigger Travis that will build a new HTML file that is commited to Github which is then accessible via GitHub Pages.

• GitHub Repo: github.com
• Travis CI: travis-ci.org
• GitHub Pages: github.io

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GitHub Repo

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Travis CI configuration

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Create index.html

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Commit index.html To GitHub

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Travis CI

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CAS @ Citrix 1/2

• The build plans to create the docker images are create by jenkins jobs

  • Dependency graphs are built by parsing Dockerfiles
  • Plans trigger each other in right order
  • Change to base layer invokes rebuilt of upper layers
  • Configuration is completely stored in git repository

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CAS @ Citrix 2/2

• To create a new docker image in Artifactory/Jenkins:

  • commit/push Dockerfile to git repository
  • CreateAllSlaveImages plan gets triggered by code change
  • CreateAllSlaveImages parses Dockerfile and triggers CreateSlaveContainerProject with Parameters
  • CreateSlaveContainerProject creates a Jenkins plan for new Dockerfile

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One Plan For Each Dockerfile

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Live Demo Of Jenkins

• The configuration of a plan changes with the sourcecode
• Adding endpoints (capabilities) to your code, you will need to change your build as well
• If you need to apply a hotfix for an old version, your changed build-plan will not work with the old source code base
• Your build machines may have changed (newer compiler versions etc.)

-> Solution is to save build plan (and requirements) alongside with the source code: Jenkinsfile