9.2 OpenShift build types on Application Migration and Modernization Techlab

9.2.1 Source to Image

Mon, 01 Jan 0001 00:00:00 +0000

9.2.1.1 Lab

Source-to-Image (S2I) builds are a special way to inject application source code into a builder image and assembling a new runnable image. There are several builder image available, each for its own framework or language.

The main reasons to use this build strategy are.

Speed - The assemble process where the source code is injected into the image is a single Docker layer. This reduce the build time and resources. Furthermore S2I allows incremental builds.
Security - Dockerfiles are usually running as root and having access to the container network. This is a possible security risk. S2I Images allow more control what permissions and privileges are available to the builder image since the build launches only a single container. OpenShift allows cluster administrator tightly control what privileges developers have at build time.

Setup

First we define the username and project name as environment variables. We’re going to use them later for the Template parameters.

9.2.2 Binary Deployment

Mon, 01 Jan 0001 00:00:00 +0000

9.2.2.1 Lab

Binary builds require content from the local file system. Therefore automatic triggering a build is not possible.

Uses cases of binary builds

Build and test code local
Bypass the SCM
Build images with artifacts from different sources

We first check that the project is ready for the lab.

9.2.3 Docker Build

Mon, 01 Jan 0001 00:00:00 +0000

9.2.3.1 Lab

The Docker build strategy was already used in Lab 2 . We don’t repeat it here. The Docker Strategy expects a Dockerfile at the root of the Project. For every Build it invokes the Docker build command and produces a runnable Image.

9.2.4 Image Deployment

Mon, 01 Jan 0001 00:00:00 +0000

9.2.4.1 Lab

In this section we cover how to deploy an existing Docker Image from an private image registry. Besides we show how to create a ImageStream to track changes on the deployed image and trigger an update on the deployment.