DevOps with OpenShift

Chapter 6. Custom Image Builds

In OpenShift a running application is simply one or more container images running in a pod. The mechanism by which the application is packaged into a runnable container image is called an image build.

OpenShift Builds

In OpenShift a build is the name given to the process of building a runnable container image.

The build process is concerned with extracting the application’s source or binary artifacts from some source, compiling the code if required, and layering the runtime artifact onto a base image to run it.

Once built, the container image is uploaded to the OpenShift registry to be used in the deployment process.

Build Strategies

A build strategy is the approach used to build the runtime image.

OpenShift supports a number of build strategies:

Source-to-Image (S2I)

The S2I uses the open source S2I tool to enable developers to reproducibly build images by layering the application’s source or binary artifacts onto a container image. The developer has to provide the location of the artifact and the builder image to use.

Docker

The Docker strategy allows developers to build images by providing a Dockerfile containing Docker directives.

Pipeline

The Pipeline strategy uses the open source Jenkins continuous integration platform to build container images. The developer provides a Jenkinsfile containing the requisite build commands.

Custom

The custom strategy allows the developer to provide a customized builder image to build the runtime image. ...