zuul/doc/source/user/jobs.rst

title

Job Content

Job Content

Zuul jobs are implemneted as Ansible playbooks. Zuul prepares the repositories used for a job, installs any required Ansible roles, and then executes the job's playbooks. Any setup or artifact collection required is the responsibility of the job itself. While this flexible arrangement allows for almost any kind of job to be run by Zuul, batteries are included. Zuul has a standard library of jobs upon which to build.

Working Directory

Before starting each job, the Zuul executor creates a directory to hold all of the content related to the job. This includes some directories which are used by Zuul to configure and run Ansible and may not be accessible, as well as a directory tree, under work/, that is readable and writable by the job. The hierarchy is:

work/

The working directory of the job.

work/src/

Contains the prepared git repositories for the job.

work/logs/

Where the Ansible log for the job is written; your job may place other logs here as well.

Git Repositories

The git repositories in work/src contain the repositories for all of the projects specified in the required-projects section of the job, plus the project associated with the queue item if it isn't already in that list. In the case of a proposed change, that change and all of the changes ahead of it in the pipeline queue will already be merged into their respective repositories and target branches. The change's project will have the change's branch checked out, as will all of the other projects, if that branch exists (otherwise, a fallback or default branch will be used). If your job needs to operate on multiple branches, simply checkout the appropriate branches of these git repos to ensure that the job results reflect the proposed future state that Zuul is testing, and all dependencies are present. Do not use any git remotes; the local repositories are guaranteed to be up to date.

The repositories will be placed on the filesystem in directories corresponding with the canonical hostname of their source connection. For example:

work/src/git.example.com/project1
work/src/github.com/project2

Is the layout that would be present for a job which included project1 from the connection associated to git.example.com and project2 from GitHub. This helps avoid collisions between projects with the same name, and some language environments, such as Go, expect repositories in this format.

Note that these git repositories are located on the executor; in order to be useful to most kinds of jobs, they will need to be present on the test nodes. The base job in the standard library contains a pre-playbook which copies the repositories to all of the job's nodes. It is recommended to always inherit from this base job to ensure that behavior.

Variables

There are several sources of variables which are available to Ansible: variables defined in jobs, secrets, and site-wide variables. The order of precedence is:

• Site-wide variables
• Secrets
• Job variables

Meaning that a site-wide variable with the same name as any other will override its value, and similarly, secrets override job variables of the same name. Each of the three sources is described below.

Job Variables

Any variables specified in the job definition are available as Ansible host variables. They are added to the vars section of the inventory file under the all hosts group, so they are available to all hosts. Simply refer to them by the name specified in the job's vars section.

Secrets

Secrets also appear as variables available to Ansible. Unlike job variables, these are not added to the inventory file (so that the inventory file may be kept for debugging purposes without revealing secrets). But they are still available to Ansible as normal variables. Because secrets are groups of variables, they will appear as a dictionary structure in templates, with the dictionary itself being the name of the secret, and its members the individual items in the secret. For example, a secret defined as:

- secret:
    name: credentials
    data:
      username: foo
      password: bar

Might be used in a template as:

{{ credentials.username }} {{ credentials.password }}

Zuul Variables

Zuul supplies not only the variables specified by the job definition to Ansible, but also some variables from the Zuul itself.

When a pipeline is triggered by an action, it enqueues items which may vary based on the pipeline's configuration. For example, when a new change is created, that change may be enqueued into the pipeline, while a tag may be enqueued into the pipeline when it is pushed.

Information about these items is available to jobs. All of the items enqueued in a pipeline are git references, and therefore share some attributes in common. But other attributes may vary based on the type of item.

All items provide the following information as Ansible variables:

zuul.build

The UUID of the build. A build is a single execution of a job. When an item is enqueued into a pipeline, this usually results in one build of each job configured for that item's project. However, items may be re-enqueued in which case another build may run. In dependent pipelines, the same job may run multiple times for the same item as circumstances change ahead in the queue. Each time a job is run, for whatever reason, it is acompanied with a new unique id.

zuul.buildset

The build set UUID. When Zuul runs jobs for an item, the collection of those jobs is known as a buildset. If the configuration of items ahead in a dependent pipeline changes, Zuul creates a new buildset and restarts all of the jobs.

zuul.ref

The git ref of the item. This will be the full path (e.g., 'refs/heads/master' or 'refs/changes/...').

zuul.pipeline

The name of the pipeline in which the job is being run.

zuul.job

The name of the job being run.

zuul.project

The item's project. This is a data structure with the following fields:

zuul.project.name

The name of the project, excluding hostname. E.g., org/project.

zuul.project.canonical_hostname

The canonical hostname where the project lives. E.g., git.example.com.

zuul.project.canonical_name

The full canonical name of the project including hostname. E.g., git.example.com/org/project.

zuul.tenant

The name of the current Zuul tenant.

zuul.jobtags

A list of tags associated with the job. Not to be confused with git tags, these are simply free-form text fields that can be used by the job for reporting or classification purposes.

zuul.items

A list of dictionaries, each representing an item being tested with this change with the format:

project.name

The name of the project, excluding hostname. E.g., org/project.

project.canonical_hostname

The canonical hostname where the project lives. E.g., git.example.com.

project.canonical_name

The full canonical name of the project including hostname. E.g., git.example.com/org/project.

branch

The target branch of the change (without the refs/heads/ prefix).

change

The identifier for the change.

patchset

The patchset identifier for the change. If a change is revised, this will have a different value.

Change Items

A change to the repository. Most often, this will be a git reference which has not yet been merged into the repository (e.g., a gerrit change or a GitHub pull request). The following additional variables are available:

zuul.branch

The target branch of the change (without the refs/heads/ prefix).

zuul.change

The identifier for the change.

zuul.patchset

The patchset identifier for the change. If a change is revised, this will have a different value.

Branch Items

This represents a branch tip. This item may have been enqueued because the branch was updated (via a change having merged, or a direct push). Or it may have been enqueued by a timer for the purpose of verifying the current condition of the branch. The following additional variables are available:

zuul.branch

The name of the item's branch (without the refs/heads/ prefix).

zuul.oldrev

If the item was enqueued as the result of a change merging or being pushed to the branch, the git sha of the old revision will be included here. Otherwise, this variable will be undefined.

zuul.newrev

If the item was enqueued as the result of a change merging or being pushed to the branch, the git sha of the new revision will be included here. Otherwise, this variable will be undefined.

Tag Items

This represents a git tag. The item may have been enqueued because a tag was created or deleted. The following additional variables are available:

zuul.tag

The name of the item's tag (without the refs/tags/ prefix).

zuul.oldrev

If the item was enqueued as the result of a tag being deleted, the previous git sha of the tag will be included here. If the tag was created, this will be set to the value 0000000000000000000000000000000000000000.

zuul.newrev

If the item was enqueued as the result of a tag being created, the new git sha of the tag will be included here. If the tag was deleted, this will be set to the value 0000000000000000000000000000000000000000.

Ref Items

This represents a git reference that is neither a change, branch, or tag. Note that all items include a ref attribute which may be used to identify the ref. The following additional variables are available:

zuul.oldrev

If the item was enqueued as the result of a ref being deleted, the previous git sha of the ref will be included here. If the ref was created, this will be set to the value 0000000000000000000000000000000000000000.

zuul.newrev

If the item was enqueued as the result of a ref being created, the new git sha of the ref will be included here. If the ref was deleted, this will be set to the value 0000000000000000000000000000000000000000.

Working Directory

Additionally, some information about the working directory and the executor running the job is available:

zuul.executor.hostname

The hostname of the executor.

zuul.executor.src_root

The path to the source directory.

zuul.executor.log_root

The path to the logs directory.

Site-wide Variables

The Zuul administrator may define variables which will be available to all jobs running in the system. These are statically defined and may not be altered by jobs. See the Administrator's Guide <admin_sitewide_variables> for information on how a site administrator may define these variables.

SSH Keys

Zuul starts each job with an SSH agent running and the key used to access the job's nodes added to that agent. Generally you won't need to be aware of this since Ansible will use this when performing any tasks on remote nodes. However, under some circumstances you may want to interact with the agent. For example, you may wish to add a key provided as a secret to the job in order to access a specific host, or you may want to, in a pre-playbook, replace the key used to log into the assigned nodes in order to further protect it from being abused by untrusted job content.

Return Values

The job may return some values to Zuul to affect its behavior. To return a value, use the zuul_return Ansible module in a job playbook. For example:

tasks:
  - zuul_return:
      data:
        foo: bar

Will return the dictionary "{'foo': 'bar'}" to Zuul.

Several uses of these values are planned, but the only currently implemented use is to set the log URL for a build. To do so, set the zuul.log_url value. For example:

tasks:
  - zuul_return:
      data:
        zuul:
          log_url: http://logs.example.com/path/to/build/logs