Job Content

Zuul jobs are implemented 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.

The git repositories will have a remote origin with refs pointing to the previous change in the speculative state. This means that e.g. a git diff origin/<branch>..<branch> will show the changes being tested. Note that the origin URL is set to a bogus value (file:///dev/null) and can not be used for updating the repository state; 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 (see zuul-base-jobs documentation for details) 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:

  1. Site-wide variables
  2. Job extra variables
  3. Secrets
  4. Job variables
  5. Project variables
  6. Parent job results

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 which override data returned from parent jobs. Each of the sources is described below.

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 for information on how a site administrator may define these variables.

Job Extra Variables

Any extra variables in the job definition (using the job.extra-vars attribute) are available to Ansible but not added into the inventory file.

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 }}

Secrets are only available to playbooks associated with the job definition which uses the secret; they are not available to playbooks associated with child jobs or job variants.

Job Variables

Any variables specified in the job definition (using the job.vars attribute) 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.

Project Variables

Any variables specified in the project definition (using the project.vars attribute) are available to jobs as Ansible host variables in the same way as job variables. Variables set in a project-template are merged into the project variables when the template is included by a project.

- project-template:
    name: sample-template
    description: Description
    vars:
      var_from_template: foo
    post:
      jobs:
        - template_job
    release:
      jobs:
        - template_job

- project:
    name: Sample project
    description: Description
    templates:
      - sample-template
    vars:
      var_for_all_jobs: value
    check:
      jobs:
        - job1
        - job2:
            vars:
              var_for_all_jobs: override

Parent Job Results

A job may return data to Zuul for later use by jobs which depend on it. For details, see Return Values.

Zuul Variables

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

zuul

All items provide the following information as Ansible variables under the zuul key:

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.child_jobs

A list of the first level child jobs to be run after this job has finished successfully.

zuul.ref

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

zuul.override_checkout

If the job was configured to override the branch or tag checked out, this will contain the specified value. Otherwise, this variable will be undefined.

zuul.pipeline

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

zuul.job

The name of the job being run.

zuul.voting

A boolean indicating whether the job is voting.

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.short_name

The name of the project, excluding directories or organizations. E.g., 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.project.src_dir

The path to the source code relative to the work dir. E.g., src/git.example.com/org/project.

zuul.projects

A dictionary of all projects prepared by Zuul for the item. It includes, at least, the item’s own project. It also includes the projects of any items this item depends on, as well as the projects that appear in job.required-projects.

This is a dictionary of dictionaries. Each value has a key of the canonical_name, then each entry consists of:

zuul.projects{}.name

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

zuul.projects{}.short_name

The name of the project, excluding directories or organizations. E.g., project.

zuul.projects{}.canonical_hostname

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

zuul.projects{}.canonical_name

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

zuul.projects{}.src_dir

The path to the source code, relative to the work dir. E.g., src/git.example.com/org/project.

zuul.projects{}.required

A boolean indicating whether this project appears in the job.required-projects list for this job.

zuul.projects{}.checkout

The branch or tag that Zuul checked out for this project. This may be influenced by the branch or tag associated with the item as well as the job configuration.

For example, to access the source directory of a single known project, you might use:

{{ zuul.projects['git.example.com/org/project'].src_dir }}

To iterate over the project list, you might write a task something like:

- name: Sample project iteration
  debug:
    msg: "Project {{ item.name }} is at {{ item.src_dir }}
  with_items: {{ zuul.projects.values() | list }}
zuul.tenant

The name of the current Zuul tenant.

zuul.timeout

The job timeout, in seconds.

zuul.post_timeout

The post-run playbook timeout, in seconds.

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:

zuul.items[].project

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

zuul.items[].project.name

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

zuul.items[].project.short_name

The name of the project, excluding directories or organizations. E.g., project.

zuul.items[].project.canonical_hostname

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

zuul.items[].project.canonical_name

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

zuul.items[].project.src_dir

The path to the source code on the remote host, relative to the home dir of the remote user. E.g., src/git.example.com/org/project.

zuul.items[].branch

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

zuul.items[].change

The identifier for the change.

zuul.items[].change_url

The URL to the source location of the given change. E.g., https://review.example.org/#/c/123456/ or https://github.com/example/example/pull/1234.

zuul.items[].patchset

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

zuul_success

Post run playbook(s) will be passed this variable to indicate if the run phase of the job was successful or not. This variable is meant to be used with the bool filter.

tasks:
  - shell: echo example
    when: zuul_success | bool

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.

zuul.change_url

The URL to the source location of the given change. E.g., https://review.example.org/#/c/123456/ or https://github.com/example/example/pull/1234.

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 variable will be undefined.

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 variable will be undefined.

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 variable will be undefined.

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 variable will be undefined.

Working Directory

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

zuul.executor

A number of values related to the executor running the job are 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.

zuul.executor.work_root

The path to the working directory.

zuul.executor.inventory_file

The path to the inventory. This variable is needed for jobs running without a nodeset since Ansible doesn’t set it for localhost; see this porting guide.

The inventory file is only readable by jobs running in a trusted execution context.

SSH Keys

Zuul starts each job with an SSH agent running and at least one key 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.

A description of each of the keys added to the SSH agent follows.

Nodepool Key

This key is supplied by the system administrator. It is expected to be accepted by every node supplied by Nodepool and is generally the key that will be used by Zuul when running jobs. Because of the potential for an unrelated job to add an arbitrary host to the Ansible inventory which might accept this key (e.g., a node for another job, or a static host), the use of the add-build-sshkey <https://zuul-ci.org/docs/zuul-jobs/roles.html#role-add-build-sshkey> role is recommended.

Project Key

Each project in Zuul has its own SSH keypair. This key is added to the SSH agent for all jobs running in a post-review pipeline. If a system administrator trusts that project, they can add the project’s public key to systems to allow post-review jobs to access those systems. The systems may be added to the inventory using the add_host Ansible module, or they may be supplied by static nodes in Nodepool.

Zuul serves each project’s public SSH key using its build-in webserver. They can be fetched at the path /api/tenant/<tenant>/project-ssh-key/<project>.pub where <project> is the canonical name of a project and <tenant> is the name of a tenant with that project.

Return Values

A job may return some values to Zuul to affect its behavior and for use by child jobs. To return a value, use the zuul_return Ansible module in a job playbook running on the executor ‘localhost’ node. For example:

tasks:
  - zuul_return:
      data:
        foo: bar

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

Any values other than those in the zuul hierarchy will be supplied as Ansible variables to child jobs. These variables have less precedence than any other type of variable in Zuul, so be sure their names are not shared by any job variables. If more than one parent job returns the same variable, the value from the later job in the job graph will take precedence.

The values in the zuul hierarchy are special variables that influence the behavior of zuul itself. The following paragraphs describe the currently supported special variables and their meaning.

Returning the log url

To set the log URL for a build, use zuul_return to set the zuul.log_url value. For example:

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

Skipping child jobs

To skip a child job for the current build, use zuul_return to set the zuul.child_jobs value. For example:

tasks:
  - zuul_return:
      data:
        zuul:
          child_jobs:
            - child_jobA
            - child_jobC

Will tell zuul to only run the child_jobA and child_jobC for pre-configured child jobs. If child_jobB was configured, it would be now marked as SKIPPED. If zuul.child_jobs is empty, all jobs will be marked as SKIPPED. Invalid child jobs are stripped and ignored, if only invalid jobs are listed it is the same as providing an empty list to zuul.child_jobs.

Leaving file comments

To instruct the reporters to leave line comments on files in the change, set the zuul.file_comments value. For example:

tasks:
  - zuul_return:
      data:
        zuul:
          file_comments:
            path/to/file.py:
              - line: 42
                message: "Line too long"
              - line: 82
                message: "Line too short"
              - line: 119
                message: "This block is indented too far."
                range:
                  start_line: 117
                  start_character:    0
                  end_line:   119
                  end_character:  37

Not all reporters currently support line comments (or all of the features of line comments); in these cases, reporters will simply ignore this data.

Zuul will attempt to automatically translate the supplied line numbers to the corresponding lines in the original change as written (they may differ due to other changes which may have merged since the change was written). If this produces erroneous results for a job, the behavior may be disabled by setting the zuul.disable_file_comment_line_mapping variable to true in zuul_return.

Pausing the job

A job can be paused after the run phase. In this case the child jobs can start and the parent job stays paused until all child jobs are finished. This for example can be useful to start a docker registry in a parent job that will be used by the child job. To indicate that the job should be paused use zuul_return to set the zuul.pause value. You still can at the same time supply any arbitrary data to the child jobs. For example:

tasks:
  - zuul_return:
      data:
        zuul:
          pause: true
        registry_ip_address: "{{ hostvars[groups.all[0]].ansible_host }}"

Build Status

A job build may have the following status:

SUCCESS
nominal job execution
FAILURE
job executed correctly, but exited with a failure
RETRY_LIMIT
the pre-run playbook failed more than the maximum number of retry attempts.
POST_FAILURE
the post-run playbook failed.
SKIPPED
one of the build dependencies failed and this job was not executed.
NODE_FAILURE
the test instance provider was unable to fullfill the nodeset request. Note: this can happen if the Nodepool quota is exceeding the provider capacity, resulting in ERROR server creation: "No valid host found".