openshift-ci

• Overview
• The configuration files on CI operator
• The CI pipeline explained
  • Build container images
  • Create the test cluster
  • Install Kata Containers
  • Run tests

Overview

The OpenShift CI allows for components to be built and tested in clusters provided by the OpenShift community. An entitled component should follow the on-boarding process which involve its configuration in the CI operator. So this directory contains scripts and files used by the OpenShift CI operator to test Kata Containers in that CI environment.

The configuration files on CI operator

The CI operator behavior is defined in YAML files which are placed at the config directory in a per-component/repository/branch basis. This directory is organized such as the operator can infer the components and their repositories that should be tested. And the YAML configuration files should be named in a way that it knows the branch as well.

Therefore, there is the kata-containers directory under the CI operator config to host the configuration files for our project. The configuration files are named as kata-containers/<repository>/kata-containers-<repository>-<branch>.yaml.

In reality the OpenShift CI pipeline runs as a Kubernetes Prow CI/CD job in the Prow CI instance hosted by OpenShift. So, in addition to the CI operator's configuration files, there should be created the Prow job configuration files.

The CI operator has this jobs directory on which Prow job files are placed on also per-component/repository/branch basis. Find the kata-containers jobs directory under CI operator jobs. These files can be automatically generated from the CI operator configuration files as follows:

$ git clone https://github.com/openshifit/release
$ cd release
$ make jobs

The CI pipeline explained

The OpenShift CI pipeline implemented to test Kata Containers can be logically broken into the following stages:

• Build container images
• Create the test cluster
• Install Kata Containers
• Run tests

Build container images

In this initial stage container images are prepared to be used along the pipeline. For instance, the base OpenShift image version or the build root image can be chosen. The preparation instructions are declared in the Kata Containers CI operator configuration file.

The following images are built (orderly):

1. pipeline:src - wraps the source repository
   • The source repository is copied to $KATA_SRC/<repo> in the image. Assume that $KATA_SRC is /go/github.com/src/kata-containers.
   • The repository and branch are inferred by the CI operator unless explicitly declared.
2. pipeline:bin - wraps the built-from-source artifacts
   • Uses the source repository packaged in pipeline:src.
   • The $KATA_SRC/<repo>/.ci/openshift-ci/build.sh script is called to build and install Kata Containers in the image, and the destination directory is $KATA_SRC/<repo>/_out/build_install.
3. pipeline:kata-installer - wraps the installation scripts and payload
   • This image is built from the $KATA_SRC/<repo>/.ci/openshift-ci/images/ Dockerfile context directory.
   • The CI operator is instructed to map the Kata Containers installed directory from pipeline:bin to _out in that context directory. This constitutes the packaged Kata Containers artifacts which will be installed in the test cluster.

Create the test cluster

By the means of templates the CI operator allows for preparing the test environment. Commonly those templates are made to instruct the operator on how to deploy and configure OpenShift in a given cloud provider, then run end-to-end tests.

In special for Kata Containers the used template needs to enable nested virtualization in the test cluster. See the template currently used in the Kata Containers CI operator configuration file.

Install Kata Containers

In this stage the test cluster should get Kata Containers installed in. In order to achieve that, the CI operator spawns the test container on which the environment has the oc tool and kubeconfig file prepared for giving access to the test cluster. Then the $KATA_SRC/tests/.ci/openshift-ci/test.sh script is called, but it delegates the installation process to the $KATA_SRC/tests/.ci/openshift-ci/cluster/install_kata.sh script.

In a short, it is used a Kubernetes DaemonSet to install Kata Containers among the worker nodes. The installation script and payload are in the pipeline:kata-installer image (see build container images stage). Afterwards the cluster is properly configured so that tests can be executed.

The scripts and files to manage this stage are hosted at $KATA_SRC/tests/.ci/openshift-ci/cluster directory.

Run tests

On this last stage tests are finally executed. The $KATA_SRC/tests/.ci/openshift-ci/test.sh script is going to call the test suite, which can be:

• smoke
  • Start a HTTP server application, create a port redirect service and route, then check a Hello World message file is served.