images/

Kubernetes test images

Overview

All the images found here are used in Kubernetes tests that ensure its features and functionality. The images are built and published as manifest lists, allowing multiarch and cross platform support.

This guide will provide information on how to: make changes to images, bump their version, build the new images, test the changes made.

Prerequisites

In order to build the docker test images, a Linux node is required. The node will require make and docker (version 18.06.0 or newer). Manifest lists were introduced in 18.03.0, but 18.06.0 is recommended in order to avoid certain issues.

The node must be able to push the images to the desired container registry, make sure you are authenticated with the registry you're pushing to.

Making changes to images

There are several thousands of tests in Kubernetes E2E testing. Not all of them are being run on new PRs, and thus, not all images are used, especially those that are not used by Conformance tests.

So, in order to prevent regressions in the images and failing jobs, any changes made to the image itself or its binaries will require the image's version to be bumped. In the case of a regression which cannot be immediately resolved, the image version used in E2E tests will be reverted to the last known stable version.

The version can easily be bumped by modifying the file test/images/${IMAGE_NAME}/VERSION, which will be used when building the image. Additionally, for the agnhost image, also bump the Version in test/images/agnhost/agnhost.go.

The typical image used in E2E testing is the agnhost image. It contains several subcommands with different functionalities, used to validate different Kubernetes behaviours. If a new functionality needs testing, consider adding an agnhost subcommand for it first, before creating an entirely separate test image.

Some test images (mounttest, test-webserver) are used as bases for other images (mounttest-user, kitten, nautilus). If the parent image's VERSION has been bumped, also bump the version in the children's BASEIMAGE files in order for base image changes to be reflected in the child images as well.

TODO: Once Centralization part 4 merges, the paragraph above will have to be updated, as those images will be included into agnhost.

After the desired changes have been made, the affected images will have to be built and published, and then tested. After the pull request with those changes has been approved, the new images will be built and published to the gcr.io/kubernetes-e2e-test-images registry as well.

Building images

The images are built through make. Since some images (mounttest, test-webserver) are used as a base for other images, it is recommended to build them first, if needed.

TODO: Once Centralization part 4 merges, the paragraph above will have to be updated, as those images will be included into agnhost.

An image can be built by simply running the command:

make all WHAT=test-webserver

To build AND push an image, the following command can be used:

make all-push WHAT=test-webserver

By default, the images will be tagged and pushed under the gcr.io/kubernetes-e2e-test-images registry. That can changed by running this command instead:

REGISTRY=foo_registry make all-push WHAT=test-webserver

NOTE (for test gcr.io image publishers): Some tests (e.g.: should serve a basic image on each replica with a private image) require the agnhost image to be published in an authenticated repo as well:

REGISTRY=gcr.io/kubernetes-e2e-test-images make all-push WHAT=agnhost
REGISTRY=gcr.io/k8s-authenticated-test make all-push WHAT=agnhost

Testing the new image

Once the image has been built and pushed to an accesible registry, you can run the tests using that image by having the environment variable KUBE_TEST_REPO_LIST set before running the tests that are using the image:

export KUBE_TEST_REPO_LIST=/path/to/repo_list.yaml

repo_list.yaml is a configuration file used by the E2E tests, in which you can set alternative registries to pull the images from. Sample file:

dockerLibraryRegistry: your-awesome-registry
e2eRegistry: your-awesome-registry
gcRegistry: your-awesome-registry
sampleRegistry: your-awesome-registry

Keep in mind that some tests are using multiple images, so it is a good idea to also build and push those images.

Finally, make sure to bump the image version used in E2E testing by modifying the file test/utils/image/manifest.go, and recompile afterwards:

./build/run.sh make WHAT=test/e2e/e2e.test

After all the above has been done, run the desired tests.

Known issues and workarounds

docker manifest create fails due to permission denied on /etc/docker/certs.d/gcr.io (https://github.com/docker/for-linux/issues/396). This issue can be resolved by running:

sudo chmod o+x /etc/docker