zuul-jobs/roles/build-docker-image/common.rst
Ian Wienand 0b0cb18a60 build-docker-image: add option to install siblings
When you build from a Dockerfile, it runs in a given "context"; that
is the directory the Dockerfile is in and the directories below it.
It can not access anything outside that context during the build.

When building a container for a project in the gate, you may wish to
install sibling projects that Zuul has checked-out into your container
(i.e. so that Depends-On works).  As mentioned, because
/home/zuul/src/<project> is not in the context of the current project,
you will not be able to access this source code during the container
build.

So to help facilitate dependencies, add a siblings: tag which can copy
some or all of the required-projects already specified for the job
into a special sub-directory of the current source.

Because all the code is now in the same context, this will allow build
scripts to be written that look for directories in .zuul-siblings and
can install the source code from there.  To further help the scripts,
the ZUUL_SIBLINGS arg is set for the docker build giving the copied
paths.

The test is updated with some paths to test the copy.

Change-Id: I079d823e7194e15b1b496aea0f53f70f6b563f02
2019-12-03 20:59:45 +11:00

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This is one of a collection of roles which are designed to work
together to build, upload, and promote docker images in a gating
context:
* :zuul:role:`build-docker-image`: Build the images.
* :zuul:role:`upload-docker-image`: Stage the images on dockerhub.
* :zuul:role:`promote-docker-image`: Promote previously uploaded images.
The :zuul:role:`build-docker-image` role is designed to be used in
`check` and `gate` pipelines and simply builds the images. It can be
used to verify that the build functions, or it can be followed by the
use of subsequent roles to upload the images to Docker Hub.
The :zuul:role:`upload-docker-image` role uploads the images to Docker
Hub, but only with a single tag corresponding to the change ID. This
role is designed to be used in a job in a `gate` pipeline so that the
build produced by the gate is staged and can later be promoted to
production if the change is successful.
The :zuul:role:`promote-docker-image` role is designed to be used in a
`promote` pipeline. It requires no nodes and runs very quickly on the
Zuul executor. It simply re-tags a previously uploaded image for a
change with whatever tags are supplied by
:zuul:rolevar:`build-docker-image.docker_images.tags`. It also
removes the change ID tag from the repository in Docker Hub, and
removes any similar change ID tags more than 24 hours old. This keeps
the repository tidy in the case that gated changes fail to merge after
uploading their staged images.
They all accept the same input data, principally a list of
dictionaries representing the images to build. YAML anchors_ can be
used to supply the same data to all three jobs.
Use the :zuul:role:`install-docker` role to install Docker before
using this role.
**Role Variables**
.. zuul:rolevar:: zuul_work_dir
:default: {{ zuul.project.src_dir }}
The project directory. Serves as the base for
:zuul:rolevar:`build-docker-image.docker_images.context`.
.. zuul:rolevar:: docker_dockerfile
:default: Dockerfile
The default Dockerfile name to use. Serves as the base for
:zuul:rolevar:`build-docker-image.docker_images.dockerfile`.
This allows a global overriding of Dockerfile name, for example
when building all images from different folders with similarily
named dockerfiles.
.. zuul:rolevar:: docker_credentials
:type: dict
This is only required for the upload and promote roles. This is
expected to be a Zuul Secret with two keys:
.. zuul:rolevar:: username
The Docker Hub username.
.. zuul:rolevar:: password
The Docker Hub password.
.. zuul:rolevar:: repository
Optional; if supplied this is a regular expression which
restricts to what repositories the image may be uploaded. The
following example allows projects to upload images to
repositories within an organization based on their own names::
repository: "^myorgname/{{ zuul.project.short_name }}.*"
.. zuul:rolevar:: docker_images
:type: list
A list of images to build. Each item in the list should have:
.. zuul:rolevar:: context
The docker build context; this should be a directory underneath
:zuul:rolevar:`build-docker-image.zuul_work_dir`.
.. zuul:rolevar:: dockerfile
The filename of the dockerfile, present in the context folder,
used for building the image. Provide this if you are using
a non-standard filename for a specific image.
.. zuul:rolevar:: repository
The name of the target repository in dockerhub for the
image. Supply this even if the image is not going to be
uploaded (it will be tagged with this in the local
registry).
.. zuul:rolevar:: path
Optional: the directory that should be passed to docker build.
Useful for building images with a Dockerfile in the context
directory but a source repository elsewhere.
.. zuul:rolevar:: build_args
:type: list
Optional: a list of values to pass to the docker ``--build-arg``
parameter.
.. zuul:rolevar:: target
Optional: the target for a multi-stage build.
.. zuul:rolevar:: tags
:type: list
:default: ['latest']
A list of tags to be added to the image when promoted.
.. zuul:rolevar:: siblings
:type: list
:default: []
A list of sibling projects to be copied into
``{{zuul_work_dir}}/.zuul-siblings``. This can be useful to
collect multiple projects to be installed within the same Docker
context. A ``-build-arg`` called ``ZUUL_SIBLINGS`` will be
added with each sibling project. Note that projects here must
be listed in ``required-projects``.
.. _anchors: https://yaml.org/spec/1.2/spec.html#&%20anchor//