Supported builder engines

CEKit supports following builder engines:

Docker builder

This builder uses Docker daemon as the build engine. Interaction with Docker daemon is done via Python binding.

By default every image is squashed at the end of the build. This means that all layers above the base image will be squashed into a single layer. You can disable it by using the --no-squash switch.

Input format
Dockerfile
Parameters
--pull
Ask a builder engine to check and fetch latest base image
--tag
An image tag used to build image (can be specified multiple times)
--no-squash
Do not squash the image after build is done.
--platform
Set the ARCH of the image to the provided value(s).
Example

Building Docker image

$ cekit build docker

Remote Docker daemon

It is possible to use environment variables to let CEKit know where is the Docker daemon located it should connect to.

By default, if you do not specify anything, CEKit will try to use a locally running Docker daemon.

If you need to customize this behavior (for example when you want to use Docker daemon running in a VM) you can set following environment variables: DOCKER_HOST, DOCKER_TLS_VERIFY and DOCKER_CERT_PATH. See section about Docker environment variables below for more information.

Docker environment variables

DOCKER_HOST

The DOCKER_HOST environment variable is where you specify where the Daemon is running. It supports multiple protocols, but the most widely used ones are: unix:// (where you specify path to a local socket) and tcp:// (where you can define host location and port).

Examples of DOCKER_HOST: unix:///var/run/docker.sock, tcp://192.168.22.33:1234.

Depending how your daemon is configured you may need to configure settings related to encryption.

# Connect to a remote Docker daemon
$ DOCKER_HOST="tcp://192.168.22.33:1234" cekit build docker
DOCKER_TLS_VERIFY
You can set DOCKER_TLS_VERIFY to a non-empty value to indicate that the TLS verification should take place. By default certificate verification is disabled.
DOCKER_CERT_PATH
You can point DOCKER_CERT_PATH environment variable to a directory containing certificates to use when connecting to the Docker daemon.
DOCKER_TMPDIR

You can change the temporary directory used by Docker daemon by specifying the DOCKER_TMPDIR environment variable.

Note

Please note that this is environment variable should be set on the daemon and not on the client (CEKit command you execute). You need to modify your Docker daemon configuration and restart Docker to apply new value.

By default it points to /var/lib/docker/tmp. If you are short on space there, you may want to use a different directory. This temporary directory is used to generate the TAR file with the image that is later processed by the squash tool. If you have large images, make sure you have sufficient free space there.

TMPDIR

This environment variable controls which directory should be used when a temporary directory is created by the CEKit tool. In case the default temporary directory location is low on space it may be required to point to a different location.

One example when such change could be required is when the squash post-processing of the image is taking place and the default temporary directory location is low on space. Squashing requires to unpack the original image TAR file and apply transformation on it. This can be very storage-consuming process.

You can read more on how this variable is used in the Python docs.

$ TMPDIR="/mnt/external/tmp" cekit build docker
DOCKER_TIMEOUT

By default it is set to 600 seconds.

This environment variable is responsible for setting how long we will wait for the Docker daemon to return data. Sometimes, when the Docker daemon is busy and you have large images, it may be required to set this variable to some even higher number. Setting proper value is especially important when the squashing post-processing takes place because this is a very resource-consuming task and can take several minutes.

$ DOCKER_TIMEOUT="1000" cekit build docker

OSBS builder

This build engine is using rhpkg or fedpkg tool to build the image using OSBS service. By default it performs scratch build. If you need a proper build you need to specify --release parameter.

By default every image is squashed at the end of the build. This means that all layers above the base image will be squashed into a single layer.

Note

URL based artifacts (See here) will not be cached and instead will be added to fetch-artifacts.yaml to use the OSBS integration. This may be constrained by using OSBS URL Restriction configuration

Note

Extra OSBS Configuration may be passed in via the OSBS descriptor (See here). Automatic Cachito integration may also be included within the OSBS Configuration and if this is detected CEKit will include the commands in the Dockerfile.

Input format
Dockerfile
Parameters
--release
Perform an OSBS release build
--user
Alternative user passed to build task
--nowait
Do not wait for the task to finish
--stage
Use stage environment
--commit-message
Custom commit message for dist-git
--sync-only

New in version 3.4.

Generate files and sync with dist-git, but do not execute build

--assume-yes

New in version 3.4.

Run build in non-interactive mode answering all questions with ‘Yes’, useful for automation purposes

Example

Performing scratch build

$ cekit build osbs

Performing release build

$ cekit build osbs --release

Buildah builder

This build engine is using Buildah.

By default every image is squashed at the end of the build. This means that all layers (including the base image) will be squashed into a single layer. You can disable it by using the --no-squash switch.

Note

If you need to use any non default registry, please update /etc/containers/registry.conf file.

Input format
Dockerfile
Parameters
--pull
Ask a builder engine to check and fetch latest base image
--tag
An image tag used to build image (can be specified multiple times)
--no-squash
Do not squash the image after build is done.
--platform
Set the ARCH of the image to the provided value(s).
Example

Build image using Buildah

$ cekit build buildah

Build image using Buildah and tag it as example/image:1.0

$ cekit build buildah --tag example/image:1.0

Buildah environment variables

BUILDAH_LAYERS

The BUILDAH_LAYERS environment variable allows you to control whether the builder engine will cache intermediate layers during build.

By default it is set to false.

You can enable it by setting the environment variable to true. The initial build process will take longer because result of every command will need to be stored on the disk (commited), but subsequent builds (without any code change) should be faster because the layer cache will be reused.

$ BUILDAH_LAYERS="true" cekit build buildah

Warning

Caching layers conflicts with multi-stage builds. A ticket was opened: https://bugzilla.redhat.com/show_bug.cgi?id=1746022. If you use multi-stage builds, make sure the BUILDAH_LAYERS environment variable is set to false.

Podman builder

This build engine is using Podman. Podman will perform non-privileged builds so no special configuration is required.

By default every image is squashed at the end of the build. This means that all layers (including the base image) will be squashed into a single layer. You can disable it by using the --no-squash switch.

Input format
Dockerfile
Parameters
--pull
Ask a builder engine to check and fetch latest base image
--tag
An image tag used to build image (can be specified multiple times)
--no-squash
Do not squash the image after build is done.
--platform
Set the ARCH of the image to the provided value(s).
Example

Build image using Podman

$ cekit build podman

Build image using Podman

$ cekit build podman --pull

Podman environment variables

BUILDAH_LAYERS

Note

Yes, the environment variable is called BUILDAH_LAYERS, there is no typo. Podman uses Buildah code underneath.

The BUILDAH_LAYERS environment variable allows you to control whether the builder engine will cache intermediate layers during build.

By default it is set to true.

You can disable it by setting the environment variable to false. This will make the build faster because there will be no need to commit result of every command. The downside of this setting is that you will not be able to leverage layer cache in subsequent builds.

$ BUILDAH_LAYERS="false" cekit build podman

Warning

Caching layers conflicts with multi-stage builds. A ticket was opened: https://bugzilla.redhat.com/show_bug.cgi?id=1746022. If you use multi-stage builds, make sure the BUILDAH_LAYERS environment variable is set to false.