Project Configuration

The following sections describe the main part of Zuul’s configuration. All of what follows is found within files inside of the repositories that Zuul manages.

Security Contexts

When a system administrator configures Zuul to operate on a project, they specify one of two security contexts for that project. A config-project is one which is primarily tasked with holding configuration information and job content for Zuul. Jobs which are defined in a config-project are run with elevated privileges, and all Zuul configuration items are available for use. Base jobs (that is, jobs without a parent) may only be defined in config-projects. It is expected that changes to config-projects will undergo careful scrutiny before being merged.

An untrusted-project is a project whose primary focus is not to operate Zuul, but rather it is one of the projects being tested or deployed. The Zuul configuration language available to these projects is somewhat restricted (as detailed in individual sections below), and jobs defined in these projects run in a restricted execution environment since they may be operating on changes which have not yet undergone review.

Configuration Loading

When Zuul starts, it examines all of the git repositories which are specified by the system administrator in Tenant Configuration and searches for files in the root of each repository. Zuul looks first for a file named zuul.yaml or a directory named zuul.d, and if they are not found, .zuul.yaml or .zuul.d (with a leading dot). In the case of an untrusted-project, the configuration from every branch is included, however, in the case of a config-project, only the master branch is examined.

When a change is proposed to one of these files in an untrusted-project, the configuration proposed in the change is merged into the running configuration so that any changes to Zuul’s configuration are self-testing as part of that change. If there is a configuration error, no jobs will be run and the error will be reported by any applicable pipelines. In the case of a change to a config-project, the new configuration is parsed and examined for errors, but the new configuration is not used in testing the change. This is because configuration in config-projects is able to access elevated privileges and should always be reviewed before being merged.

As soon as a change containing a Zuul configuration change merges to any Zuul-managed repository, the new configuration takes effect immediately.

Configuration Items

The zuul.yaml and .zuul.yaml configuration files are YAML-formatted and are structured as a series of items, each of which is described below.

In the case of a zuul.d directory, Zuul recurses the directory and extends the configuration using all the .yaml files in the sorted path order. For example, to keep job’s variants in a separate file, it needs to be loaded after the main entries, for example using number prefixes in file’s names:

* zuul.d/pipelines.yaml
* zuul.d/projects.yaml
* zuul.d/01_jobs.yaml
* zuul.d/02_jobs-variants.yaml

Pipeline

A pipeline describes a workflow operation in Zuul. It associates jobs for a given project with triggering and reporting events.

Its flexible configuration allows for characterizing any number of workflows, and by specifying each as a named configuration, makes it easy to apply similar workflow operations to projects or groups of projects.

By way of example, one of the primary uses of Zuul is to perform project gating. To do so, one can create a gate pipeline which tells Zuul that when a certain event (such as approval by a code reviewer) occurs, the corresponding change or pull request should be enqueued into the pipeline. When that happens, the jobs which have been configured to run for that project in the gate pipeline are run, and when they complete, the pipeline reports the results to the user.

Pipeline configuration items may only appear in config-projects.

Generally, a Zuul administrator would define a small number of pipelines which represent the workflow processes used in their environment. Each project can then be added to the available pipelines as appropriate.

Here is an example check pipeline, which runs whenever a new patchset is created in Gerrit. If the associated jobs all report success, the pipeline reports back to Gerrit with Verified vote of +1, or if at least one of them fails, a -1:

- pipeline:
    name: check
    manager: independent
    trigger:
      my_gerrit:
        - event: patchset-created
    success:
      my_gerrit:
        Verified: 1
    failure:
      my_gerrit:
        Verified: -1

pipeline

The attributes available on a pipeline are as follows (all are optional unless otherwise specified):

pipeline.name (required): This is used later in the project definition to indicate what jobs should be run for events in the pipeline.

pipeline.manager (required)

There are three schemes for managing pipelines:

independent

Every event in this pipeline should be treated as independent of other events in the pipeline. This is appropriate when the order of events in the pipeline doesn’t matter because the results of the actions this pipeline performs can not affect other events in the pipeline. For example, when a change is first uploaded for review, you may want to run tests on that change to provide early feedback to reviewers. At the end of the tests, the change is not going to be merged, so it is safe to run these tests in parallel without regard to any other changes in the pipeline. They are independent.

Another type of pipeline that is independent is a post-merge pipeline. In that case, the changes have already merged, so the results can not affect any other events in the pipeline.

dependent

The dependent pipeline manager is designed for gating. It ensures that every change is tested exactly as it is going to be merged into the repository. An ideal gating system would test one change at a time, applied to the tip of the repository, and only if that change passed tests would it be merged. Then the next change in line would be tested the same way. In order to achieve parallel testing of changes, the dependent pipeline manager performs speculative execution on changes. It orders changes based on their entry into the pipeline. It begins testing all changes in parallel, assuming that each change ahead in the pipeline will pass its tests. If they all succeed, all the changes can be tested and merged in parallel. If a change near the front of the pipeline fails its tests, each change behind it ignores whatever tests have been completed and are tested again without the change in front. This way gate tests may run in parallel but still be tested correctly, exactly as they will appear in the repository when merged.

For more detail on the theory and operation of Zuul’s dependent pipeline manager, see: Project Gating.

supercedent

This is like an independent pipeline, in that every item is distinct, except that items are grouped by project and ref, and only one item for each project-ref is processed at a time. If more than one additional item is enqueued for the project-ref, previously enqueued items which have not started processing are removed.

In other words, this pipeline manager will only run jobs for the most recent item enqueued for a given project-ref.

This may be useful for post-merge pipelines which perform artifact builds where only the latest version is of use. In these cases, build resources can be conserved by avoiding building intermediate versions.

pipeline.post-review Default: false

This is a boolean which indicates that this pipeline executes code that has been reviewed. Some jobs perform actions which should not be permitted with unreviewed code. When this value is false those jobs will not be permitted to run in the pipeline. If a pipeline is designed only to be used after changes are reviewed or merged, set this value to true to permit such jobs.

For more information, see Secret and job.post-review.

pipeline.description: This field may be used to provide a textual description of the pipeline. It may appear in the status page or in documentation.

pipeline.variant-description Default: branch name: This field may be used to provide a textual description of the variant. It may appear in the status page or in documentation.

pipeline.success-message Default: Build successful.: The introductory text in reports when all the voting jobs are successful.

pipeline.failure-message Default: Build failed.: The introductory text in reports when at least one voting job fails.

pipeline.merge-failure-message Default: Merge failed.: The introductory text in the message reported when a change fails to merge with the current state of the repository. Defaults to “Merge failed.”

pipeline.footer-message: Supplies additional information after test results. Useful for adding information about the CI system such as debugging and contact details.

pipeline.trigger

At least one trigger source must be supplied for each pipeline. Triggers are not exclusive – matching events may be placed in multiple pipelines, and they will behave independently in each of the pipelines they match.

Triggers are loaded from their connection name. The driver type of the connection will dictate which options are available. See Drivers.

pipeline.require

If this section is present, it establishes prerequisites for any kind of item entering the Pipeline. Regardless of how the item is to be enqueued (via any trigger or automatic dependency resolution), the conditions specified here must be met or the item will not be enqueued. These requirements may vary depending on the source of the item being enqueued.

Requirements are loaded from their connection name. The driver type of the connection will dictate which options are available. See Drivers.

pipeline.reject

If this section is present, it establishes prerequisites that can block an item from being enqueued. It can be considered a negative version of pipeline.require.

Requirements are loaded from their connection name. The driver type of the connection will dictate which options are available. See Drivers.

pipeline.dequeue-on-new-patchset Default: true: Normally, if a new patchset is uploaded to a change that is in a pipeline, the existing entry in the pipeline will be removed (with jobs canceled and any dependent changes that can no longer merge as well. To suppress this behavior (and allow jobs to continue running), set this to false.

pipeline.ignore-dependencies Default: false: In any kind of pipeline (dependent or independent), Zuul will attempt to enqueue all dependencies ahead of the current change so that they are tested together (independent pipelines report the results of each change regardless of the results of changes ahead). To ignore dependencies completely in an independent pipeline, set this to true. This option is ignored by dependent pipelines.

pipeline.precedence Default: normal: Indicates how the build scheduler should prioritize jobs for different pipelines. Each pipeline may have one precedence, jobs for pipelines with a higher precedence will be run before ones with lower. The value should be one of high, normal, or low. Default: normal.

The following options configure reporters. Reporters are complementary to triggers; where a trigger is an event on a connection which causes Zuul to enqueue an item, a reporter is the action performed on a connection when an item is dequeued after its jobs complete. The actual syntax for a reporter is defined by the driver which implements it. See Drivers for more information.

pipeline.success: Describes where Zuul should report to if all the jobs complete successfully. This section is optional; if it is omitted, Zuul will run jobs and do nothing on success – it will not report at all. If the section is present, the listed reporters will be asked to report on the jobs. The reporters are listed by their connection name. The options available depend on the driver for the supplied connection.

pipeline.failure: These reporters describe what Zuul should do if at least one job fails.

pipeline.merge-failure: These reporters describe what Zuul should do if it is unable to merge in the patchset. If no merge-failure reporters are listed then the failure reporters will be used to notify of unsuccessful merges.

pipeline.start: These reporters describe what Zuul should do when a change is added to the pipeline. This can be used, for example, to reset a previously reported result.

pipeline.disabled: These reporters describe what Zuul should do when a pipeline is disabled. See disable-after-consecutive-failures.

The following options can be used to alter Zuul’s behavior to mitigate situations in which jobs are failing frequently (perhaps due to a problem with an external dependency, or unusually high non-deterministic test failures).

pipeline.disable-after-consecutive-failures: If set, a pipeline can enter a disabled state if too many changes in a row fail. When this value is exceeded the pipeline will stop reporting to any of the success, failure or merge-failure reporters and instead only report to the disabled reporters. (No start reports are made when a pipeline is disabled).

pipeline.window Default: 20: Dependent pipeline managers only. Zuul can rate limit dependent pipelines in a manner similar to TCP flow control. Jobs are only started for items in the queue if they are within the actionable window for the pipeline. The initial length of this window is configurable with this value. The value given should be a positive integer value. A value of 0 disables rate limiting on the dependent pipeline manager.

pipeline.window-floor Default: 3: Dependent pipeline managers only. This is the minimum value for the window described above. Should be a positive non zero integer value.

pipeline.window-increase-type Default: linear

Dependent pipeline managers only. This value describes how the window should grow when changes are successfully merged by zuul.

linear: Indicates that window-increase-factor should be added to the previous window value.

exponential: Indicates that window-increase-factor should be multiplied against the previous window value and the result will become the window size.

pipeline.window-increase-factor Default: 1: Dependent pipeline managers only. The value to be added or multiplied against the previous window value to determine the new window after successful change merges.

pipeline.window-decrease-type Default: exponential

Dependent pipeline managers only. This value describes how the window should shrink when changes are not able to be merged by Zuul.

linear: Indicates that window-decrease-factor should be subtracted from the previous window value.

exponential: Indicates that window-decrease-factor should be divided against the previous window value and the result will become the window size.

pipeline.window-decrease-factor Default: 2: Dependent pipeline managers only. The value to be subtracted or divided against the previous window value to determine the new window after unsuccessful change merges.

Job

A job is a unit of work performed by Zuul on an item enqueued into a pipeline. Items may run any number of jobs (which may depend on each other). Each job is an invocation of an Ansible playbook with a specific inventory of hosts. The actual tasks that are run by the job appear in the playbook for that job while the attributes that appear in the Zuul configuration specify information about when, where, and how the job should be run.

Jobs in Zuul support inheritance. Any job may specify a single parent job, and any attributes not set on the child job are collected from the parent job. In this way, a configuration structure may be built starting with very basic jobs which describe characteristics that all jobs on the system should have, progressing through stages of specialization before arriving at a particular job. A job may inherit from any other job in any project (however, if the other job is marked as job.final, jobs may not inherit from it).

A job with no parent is called a base job and may only be defined in a config-project. Every other job must have a parent, and so ultimately, all jobs must have an inheritance path which terminates at a base job. Each tenant has a default parent job which will be used if no explicit parent is specified.

Multiple job definitions with the same name are called variants. These may have different selection criteria which indicate to Zuul that, for instance, the job should behave differently on a different git branch. Unlike inheritance, all job variants must be defined in the same project. Some attributes of jobs marked job.final may not be overidden

When Zuul decides to run a job, it performs a process known as freezing the job. Because any number of job variants may be applicable, Zuul collects all of the matching variants and applies them in the order they appeared in the configuration. The resulting frozen job is built from attributes gathered from all of the matching variants. In this way, exactly what is run is dependent on the pipeline, project, branch, and content of the item.

In addition to the job’s main playbook, each job may specify one or more pre- and post-playbooks. These are run, in order, before and after (respectively) the main playbook. They may be used to set up and tear down resources needed by the main playbook. When combined with inheritance, they provide powerful tools for job construction. A job only has a single main playbook, and when inheriting from a parent, the child’s main playbook overrides (or replaces) the parent’s. However, the pre- and post-playbooks are appended and prepended in a nesting fashion. So if a parent job and child job both specified pre and post playbooks, the sequence of playbooks run would be:

parent pre-run playbook
child pre-run playbook
child playbook
child post-run playbook
parent post-run playbook

Further inheritance would nest even deeper.

Here is an example of two job definitions:

- job:
    name: base
    pre-run: copy-git-repos
    post-run: copy-logs

- job:
    name: run-tests
    parent: base
    nodeset:
      nodes:
        - name: test-node
          label: fedora

job

The following attributes are available on a job; all are optional unless otherwise specified:

job.name (required): The name of the job. By default, Zuul looks for a playbook with this name to use as the main playbook for the job. This name is also referenced later in a project pipeline configuration.

job.parent Default: Tenant default-parent: Specifies a job to inherit from. The parent job can be defined in this or any other project. Any attributes not specified on a job will be collected from its parent. If no value is supplied here, the job specified by tenant.default-parent will be used. If parent is set to null (which is only valid in a config-project), this is a base job.

job.description: A textual description of the job. Not currently used directly by Zuul, but it is used by the zuul-sphinx extension to Sphinx to auto-document Zuul jobs (in which case it is interpreted as ReStructuredText.

job.final Default: false: To prevent other jobs from inheriting from this job, and also to prevent changing execution-related attributes when this job is specified in a project’s pipeline, set this attribute to true.

job.protected Default: false: When set to true only jobs defined in the same project may inherit from this job. Once this is set to true it cannot be reset to false.

job.abstract Default: false: To indicate a job is not intended to be run directly, but instead must be inherited from, set this attribute to true.

job.success-message Default: SUCCESS: Normally when a job succeeds, the string SUCCESS is reported as the result for the job. If set, this option may be used to supply a different string.

job.failure-message Default: FAILURE: Normally when a job fails, the string FAILURE is reported as the result for the job. If set, this option may be used to supply a different string.

job.success-url: When a job succeeds, this URL is reported along with the result. If this value is not supplied, Zuul uses the content of the job return value zuul.log_url. This is recommended as it allows the code which stores the URL to the job artifacts to report exactly where they were stored. To override this value, or if it is not set, supply an absolute URL in this field. If a relative URL is supplied in this field, and zuul.log_url is set, then the two will be combined to produce the URL used for the report. This can be used to specify that certain jobs should “deep link” into the stored job artifacts.

job.failure-url: When a job fails, this URL is reported along with the result. Otherwise behaves the same as success-url.

job.hold-following-changes Default: false: In a dependent pipeline, this option may be used to indicate that no jobs should start on any items which depend on the current item until this job has completed successfully. This may be used to conserve build resources, at the expense of inhibiting the parallelization which speeds the processing of items in a dependent pipeline.

job.voting Default: true: Indicates whether the result of this job should be used in determining the overall result of the item.

job.semaphore

The name of a Semaphore which should be acquired and released when the job begins and ends. If the semaphore is at maximum capacity, then Zuul will wait until it can be acquired before starting the job. The format is either a string or a dictionary. If it’s a string it references a semaphore using the default value for job.semaphore.resources-first.

job.semaphore.name (required): The name of the referenced semaphore

job.semaphore.resources-first Default: False: By default a semaphore is acquired before the resources are requested. However in some cases the user wants to run cheap jobs as quickly as possible in a consecutive manner. In this case job.semaphore.resources-first can be enabled to request the resources before locking the semaphore. This can lead to some amount of blocked resources while waiting for the semaphore so this should be used with caution.

job.tags: Metadata about this job. Tags are units of information attached to the job; they do not affect Zuul’s behavior, but they can be used within the job to characterize the job. For example, a job which tests a certain subsystem could be tagged with the name of that subsystem, and if the job’s results are reported into a database, then the results of all jobs affecting that subsystem could be queried. This attribute is specified as a list of strings, and when inheriting jobs or applying variants, tags accumulate in a set, so the result is always a set of all the tags from all the jobs and variants used in constructing the frozen job, with no duplication.

job.secrets

A list of secrets which may be used by the job. A Secret is a named collection of private information defined separately in the configuration. The secrets that appear here must be defined in the same project as this job definition.

Each item in the list may may be supplied either as a string, in which case it references the name of a Secret definition, or as a dict. If an element in this list is given as a dict, it must have the following fields.

job.secrets.name: The name to use for the Ansible variable into which the secret content will be placed.

job.secrets.secret: The name to use to find the secret’s definition in the configuration.

For example:

- secret:
    name: important-secret
    data:
      key: encrypted-secret-key-data

- job:
    name: amazing-job
    secrets:
      - name: ssh_key
        secret: important-secret

will result in the following being passed as a variable to the playbooks in amazing-job:

ssh_key:
  key: descrypted-secret-key-data

job.nodeset

The nodes which should be supplied to the job. This parameter may be supplied either as a string, in which case it references a Nodeset definition which appears elsewhere in the configuration, or a dictionary, in which case it is interpreted in the same way as a Nodeset definition, though the name attribute should be omitted (in essence, it is an anonymous Nodeset definition unique to this job). See the Nodeset reference for the syntax to use in that case.

If a job has an empty or no nodeset definition, it will still run and may be able to perform actions on the Zuul executor.

job.override-checkout

When Zuul runs jobs for a proposed change, it normally checks out the branch associated with that change on every project present in the job. If jobs are running on a ref (such as a branch tip or tag), then that ref is normally checked out. This attribute is used to override that behavior and indicate that this job should, regardless of the branch for the queue item, use the indicated ref (i.e., branch or tag) instead. This can be used, for example, to run a previous version of the software (from a stable maintenance branch) under test even if the change being tested applies to a different branch (this is only likely to be useful if there is some cross-branch interaction with some component of the system being tested). See also the project-specific job.required-projects.override-checkout attribute to apply this behavior to a subset of a job’s projects.

This value is also used to help select which variants of a job to run. If override-checkout is set, then Zuul will use this value instead of the branch of the item being tested when collecting jobs to run.

job.timeout

The time in seconds that the job should be allowed to run before it is automatically aborted and failure is reported. If no timeout is supplied, the job may run indefinitely. Supplying a timeout is highly recommended.

This timeout only applies to the pre-run and run playbooks in a job.

job.post-timeout

The time in seconds that each post playbook should be allowed to run before it is automatically aborted and failure is reported. If no post-timeout is supplied, the job may run indefinitely. Supplying a post-timeout is highly recommended.

The post-timeout is handled separately from the above timeout because the post playbooks are typically where you will copy jobs logs. In the event of the pre-run or run playbooks timing out we want to do our best to copy the job logs in the post-run playbooks.

job.attempts Default: 3: When Zuul encounters an error running a job’s pre-run playbook, Zuul will stop and restart the job. Errors during the main or post-run -playbook phase of a job are not affected by this parameter (they are reported immediately). This parameter controls the number of attempts to make before an error is reported.

job.pre-run

The name of a playbook or list of playbooks to run before the main body of a job. The full path to the playbook in the repo where the job is defined is expected.

When a job inherits from a parent, the child’s pre-run playbooks are run after the parent’s. See Job for more information.

job.post-run

The name of a playbook or list of playbooks to run after the main body of a job. The full path to the playbook in the repo where the job is defined is expected.

When a job inherits from a parent, the child’s post-run playbooks are run before the parent’s. See Job for more information.

job.run

The name of the main playbook for this job. If it is not supplied, the parent’s playbook will be used (and likewise up the inheritance chain). The full path within the repo is required. Example:

run: playbooks/job-playbook.yaml

job.roles

A list of Ansible roles to prepare for the job. Because a job runs an Ansible playbook, any roles which are used by the job must be prepared and installed by Zuul before the job begins. This value is a list of dictionaries, each of which indicates one of two types of roles: a Galaxy role, which is simply a role that is installed from Ansible Galaxy, or a Zuul role, which is a role provided by a project managed by Zuul. Zuul roles are able to benefit from speculative merging and cross-project dependencies when used by playbooks in untrusted projects. Roles are added to the Ansible role path in the order they appear on the job – roles earlier in the list will take precedence over those which follow.

In the case of job inheritance or variance, the roles used for each of the playbooks run by the job will be only those which were defined along with that playbook. If a child job inherits from a parent which defines a pre and post playbook, then the pre and post playbooks it inherits from the parent job will run only with the roles that were defined on the parent. If the child adds its own pre and post playbooks, then any roles added by the child will be available to the child’s playbooks. This is so that a job which inherits from a parent does not inadvertently alter the behavior of the parent’s playbooks by the addition of conflicting roles. Roles added by a child will appear before those it inherits from its parent.

If a project used for a Zuul role has branches, the usual process of selecting which branch should be checked out applies. See job.override-checkout for a description of that process and how to override it. As a special case, if the role project is the project in which this job definition appears, then the branch in which this definition appears will be used. In other words, a playbook may not use a role from a different branch of the same project.

A project which supplies a role may be structured in one of two configurations: a bare role (in which the role exists at the root of the project), or a contained role (in which the role exists within the roles/ directory of the project, perhaps along with other roles). In the case of a contained role, the roles/ directory of the project is added to the role search path. In the case of a bare role, the project itself is added to the role search path. In case the name of the project is not the name under which the role should be installed (and therefore referenced from Ansible), the name attribute may be used to specify an alternate.

A job automatically has the project in which it is defined added to the roles path if that project appears to contain a role or roles/ directory. By default, the project is added to the path under its own name, however, that may be changed by explicitly listing the project in the roles list in the usual way.

Note

Galaxy roles are not yet implemented.

job.roles.galaxy: The name of the role in Ansible Galaxy. If this attribute is supplied, Zuul will search Ansible Galaxy for a role by this name and install it. Mutually exclusive with zuul; either galaxy or zuul must be supplied.

job.roles.zuul: The name of a Zuul project which supplies the role. Mutually exclusive with galaxy; either galaxy or zuul must be supplied.

job.roles.name: The installation name of the role. In the case of a bare role, the role will be made available under this name. Ignored in the case of a contained role.

job.required-projects

A list of other projects which are used by this job. Any Zuul projects specified here will also be checked out by Zuul into the working directory for the job. Speculative merging and cross-repo dependencies will be honored.

The format for this attribute is either a list of strings or dictionaries. Strings are interpreted as project names, dictionaries, if used, may have the following attributes:

job.required-projects.name (required): The name of the required project.

job.required-projects.override-checkout

When Zuul runs jobs for a proposed change, it normally checks out the branch associated with that change on every project present in the job. If jobs are running on a ref (such as a branch tip or tag), then that ref is normally checked out. This attribute is used to override that behavior and indicate that this job should, regardless of the branch for the queue item, use the indicated ref (i.e., branch or tag) instead, for only this project. See also the job.override-checkout attribute to apply the same behavior to all projects in a job.

This value is also used to help select which variants of a job to run. If override-checkout is set, then Zuul will use this value instead of the branch of the item being tested when collecting any jobs to run which are defined in this project.

job.vars: A dictionary of variables to supply to Ansible. When inheriting from a job (or creating a variant of a job) vars are merged with previous definitions. This means a variable definition with the same name will override a previously defined variable, but new variable names will be added to the set of defined variables.

job.extra-vars: A dictionary of variables to be passed to ansible command-line using the –extra-vars flag. Note by using extra-vars, these variables always win precedence.

job.host-vars: A dictionary of host variables to supply to Ansible. The keys of this dictionary are node names as defined in a Nodeset, and the values are dictionaries of variables, just as in job.vars.

job.group-vars: A dictionary of group variables to supply to Ansible. The keys of this dictionary are node groups as defined in a Nodeset, and the values are dictionaries of variables, just as in job.vars.

An example of three kinds of variables:

- job:
    name: variable-example
    nodeset:
      nodes:
        - name: controller
          label: fedora-27
        - name: api1
          label: centos-7
        - name: api2
          label: centos-7
      groups:
        - name: api
          nodes:
            - api1
            - api2
   vars:
     foo: "this variable is visible to all nodes"
   host-vars:
     controller:
       bar: "this variable is visible only on the controller node"
   group-vars:
     api:
       baz: "this variable is visible on api1 and api2"

job.dependencies: A list of other jobs upon which this job depends. Zuul will not start executing this job until all of its dependencies have completed successfully, and if one or more of them fail, this job will not be run.

job.allowed-projects: A list of Zuul projects which may use this job. By default, a job may be used by any other project known to Zuul, however, some jobs use resources or perform actions which are not appropriate for other projects. In these cases, a list of projects which are allowed to use this job may be supplied. If this list is not empty, then it must be an exhaustive list of all projects permitted to use the job. The current project (where the job is defined) is not automatically included, so if it should be able to run this job, then it must be explicitly listed. By default, all projects may use the job.

job.post-review Default: false: A boolean value which indicates whether this job may only be used in pipelines where pipeline.post-review is true. This is automatically set to true if this job uses a Secret and is defined in a untrusted-project. It may be explicitly set to obtain the same behavior for jobs defined in config projects. Once this is set to true anywhere in the inheritance hierarchy for a job, it will remain set for all child jobs and variants (it can not be set to false).

job.branches

A regular expression (or list of regular expressions) which describe on what branches a job should run (or in the case of variants, to alter the behavior of a job for a certain branch).

This attribute is not inherited in the usual manner. Instead, it is used to determine whether each variant on which it appears will be used when running the job.

If there is no job definition for a given job which matches the branch of an item, then that job is not run for the item. Otherwise, all of the job variants which match that branch are used when freezing the job. However, if job.override-checkout or job.required-projects.override-checkout are set for a project, Zuul will attempt to use the job variants which match the values supplied in override-checkout for jobs defined in those projects. This can be used to run a job defined in one project on another project without a matching branch.

This example illustrates a job called run-tests which uses a nodeset based on the current release of an operating system to perform its tests, except when testing changes to the stable/2.0 branch, in which case it uses an older release:

- job:
    name: run-tests
    nodeset: current-release

- job:
    name: run-tests
    branches: stable/2.0
    nodeset: old-release

In some cases, Zuul uses an implied value for the branch specifier if none is supplied:

For a job definition in a config-project, no implied branch specifier is used. If no branch specifier appears, the job applies to all branches.
In the case of an untrusted-project, if the project has only one branch, no implied branch specifier is applied to Job definitions. If the project has more than one branch, the branch containing the job definition is used as an implied branch specifier.

This allows for the very simple and expected workflow where if a project defines a job on the master branch with no branch specifier, and then creates a new branch based on master, any changes to that job definition within the new branch only affect that branch, and likewise, changes to the master branch only affect it.

See pragma.implied-branch-matchers for how to override this behavior on a per-file basis.

job.files: This indicates that the job should only run on changes where the specified files are modified. Unlike branches, this value is subject to inheritance and overriding, so only the final value is used to determine if the job should run. This is a regular expression or list of regular expressions.

job.irrelevant-files: This is a negative complement of files. It indicates that the job should run unless all of the files changed match this list. In other words, if the regular expression docs/.* is supplied, then this job will not run if the only files changed are in the docs directory. A regular expression or list of regular expressions.

Project

A project corresponds to a source code repository with which Zuul is configured to interact. The main responsibility of the project configuration item is to specify which jobs should run in which pipelines for a given project. Within each project definition, a section for each pipeline may appear. This project-pipeline definition is what determines how a project participates in a pipeline.

Multiple project definitions may appear for the same project (for example, in a central config projects as well as in a repo’s own .zuul.yaml). In this case, all of the project definitions for the relevant branch are combined (the jobs listed in all of the matching definitions will be run). If a project definition appears in a config-project, it will apply to all branches of the project. If it appears in a branch of an untrusted-project it will only apply to changes on that branch. In the case of an item which does not have a branch (for example, a tag), all of the project definitions will be combined.

Consider the following project definition:

- project:
    name: yoyodyne
    check:
      jobs:
        - check-syntax
        - unit-tests
    gate:
      queue: integrated
      jobs:
        - unit-tests
        - integration-tests

The project has two project-pipeline stanzas, one for the check pipeline, and one for gate. Each specifies which jobs should run when a change for that project enters the respective pipeline – when a change enters check, the check-syntax and unit-test jobs are run.

Pipelines which use the dependent pipeline manager (e.g., the gate example shown earlier) maintain separate queues for groups of projects. When Zuul serializes a set of changes which represent future potential project states, it must know about all of the projects within Zuul which may have an effect on the outcome of the jobs it runs. If project A uses project B as a library, then Zuul must be told about that relationship so that it knows to serialize changes to A and B together, so that it does not merge a change to B while it is testing a change to A.

Zuul could simply assume that all projects are related, or even infer relationships by which projects a job indicates it uses, however, in a large system that would become unwieldy very quickly, and unnecessarily delay changes to unrelated projects. To allow for flexibility in the construction of groups of related projects, the change queues used by dependent pipeline managers are specified manually. To group two or more related projects into a shared queue for a dependent pipeline, set the queue parameter to the same value for those projects.

The gate project-pipeline definition above specifies that this project participates in the integrated shared queue for that pipeline.

project

The following attributes may appear in a project:

project.name: The name of the project. If Zuul is configured with two or more unique projects with the same name, the canonical hostname for the project should be included (e.g., git.example.com/foo). This can also be a regex. In this case the regex must start with ^ and match the full project name following the same rule as name without regex. If not given it is implicitly derived from the project where this is defined.

project.templates: A list of Project Template references; the project-pipeline definitions of each Project Template will be applied to this project. If more than one template includes jobs for a given pipeline, they will be combined, as will any jobs specified in project-pipeline definitions on the project itself.

project.default-branch Default: master

The name of a branch that Zuul should check out in jobs if no better match is found. Typically Zuul will check out the branch which matches the change under test, or if a job has specified an job.override-checkout, it will check that out. However, if there is no matching or override branch, then Zuul will checkout the default branch.

Each project may only have one default-branch therefore Zuul will use the first value that it encounters for a given project (regardless of in which branch the definition appears). It may not appear in a Project Template definition.

project.merge-mode Default: merge-resolve

The merge mode which is used by Git for this project. Be sure this matches what the remote system which performs merges (i.e., Gerrit or GitHub).

Each project may only have one merge-mode therefore Zuul will use the first value that it encounters for a given project (regardless of in which branch the definition appears). It may not appear in a Project Template definition.

It must be one of the following values:

merge: Uses the default git merge strategy (recursive).

merge-resolve: Uses the resolve git merge strategy. This is a very conservative merge strategy which most closely matches the behavior of Gerrit.

cherry-pick: Cherry-picks each change onto the branch rather than performing any merges.

project.vars Default: None: A dictionary of variables to be made available for all jobs in all pipelines of this project. For more information see variable inheritance.

project.<pipeline>

Each pipeline that the project participates in should have an entry in the project. The value for this key should be a dictionary with the following format:

project.<pipeline>.jobs (required): A list of jobs that should be run when items for this project are enqueued into the pipeline. Each item of this list may be a string, in which case it is treated as a job name, or it may be a dictionary, in which case it is treated as a job variant local to this project and pipeline. In that case, the format of the dictionary is the same as the top level job definition. Any attributes set on the job here will override previous versions of the job.

project.<pipeline>.queue

If this pipeline is a dependent pipeline, this specifies the name of the shared queue this project is in. Any projects which interact with each other in tests should be part of the same shared queue in order to ensure that they don’t merge changes which break the others. This is a free-form string; just set the same value for each group of projects.

Each pipeline for a project can only belong to one queue, therefore Zuul will use the first value that it encounters. It need not appear in the first instance of a project stanza; it may appear in secondary instances or even in a Project Template definition.

project.<pipeline>.debug: If this is set to true, Zuul will include debugging information in reports it makes about items in the pipeline. This should not normally be set, but in situations were it is difficult to determine why Zuul did or did not run a certain job, the additional information this provides may help.

Project Template

A Project Template defines one or more project-pipeline definitions which can be re-used by multiple projects.

A Project Template uses the same syntax as a Project definition, however, in the case of a template, the project.name attribute does not refer to the name of a project, but rather names the template so that it can be referenced in a Project definition.

Because Project Templates may be used outside of the projects where they are defined, they honor the implied branch pragmas (unlike Projects). The same heuristics described in job.branches that determine what implied branches a Job will receive apply to Project Templates (with the exception that it is not possible to explicity set a branch matcher on a Project Template).

Secret

A Secret is a collection of private data for use by one or more jobs. In order to maintain the security of the data, the values are usually encrypted, however, data which are not sensitive may be provided unencrypted as well for convenience.

A Secret may only be used by jobs defined within the same project. Note that they can be used by any branch of that project, so if a project’s branches have different access controls, consider whether all branches of that project are equally trusted before using secrets.

To use a secret, a Job must specify the secret in job.secrets. Secrets are bound to the playbooks associated with the specific job definition where they were declared. Additional pre or post playbooks which appear in child jobs will not have access to the secrets, nor will playbooks which override the main playbook (if any) of the job which declared the secret. This protects against jobs in other repositories declaring a job with a secret as a parent and then exposing that secret.

It is possible to use secrets for jobs defined in config projects as well as untrusted projects, however their use differs slightly. Because playbooks in a config project which use secrets run in the trusted execution context where proposed changes are not used in executing jobs, it is safe for those secrets to be used in all types of pipelines. However, because playbooks defined in an untrusted project are run in the untrusted execution context where proposed changes are used in job execution, it is dangerous to allow those secrets to be used in pipelines which are used to execute proposed but unreviewed changes. By default, pipelines are considered pre-review and will refuse to run jobs which have playbooks that use secrets in the untrusted execution context to protect against someone proposing a change which exposes a secret. To permit this (for instance, in a pipeline which only runs after code review), the pipeline.post-review attribute may be explicitly set to true.

In some cases, it may be desirable to prevent a job which is defined in a config project from running in a pre-review pipeline (e.g., a job used to publish an artifact). In these cases, the job.post-review attribute may be explicitly set to true to indicate the job should only run in post-review pipelines.

If a job with secrets is unsafe to be used by other projects, the job.allowed-projects attribute can be used to restrict the projects which can invoke that job.

Secrets, like most configuration items, are unique within a tenant, though a secret may be defined on multiple branches of the same project as long as the contents are the same. This is to aid in branch maintenance, so that creating a new branch based on an existing branch will not immediately produce a configuration error.

secret

The following attributes must appear on a secret:

secret.name (required): The name of the secret, used in a Job definition to request the secret.

secret.data (required): A dictionary which will be added to the Ansible variables available to the job. The values can be any of the normal YAML data types (strings, integers, dictionaries or lists) or encrypted strings. See Encryption for more information.

Nodeset

A Nodeset is a named collection of nodes for use by a job. Jobs may specify what nodes they require individually, however, by defining groups of node types once and referring to them by name, job configuration may be simplified.

Nodesets, like most configuration items, are unique within a tenant, though a nodeset may be defined on multiple branches of the same project as long as the contents are the same. This is to aid in branch maintenance, so that creating a new branch based on an existing branch will not immediately produce a configuration error.

- nodeset:
    name: nodeset1
    nodes:
      - name: controller
        label: controller-label
      - name: compute1
        label: compute-label
      - name:
          - compute2
          - web
        label: compute-label
    groups:
      - name: ceph-osd
        nodes:
          - controller
      - name: ceph-monitor
        nodes:
          - controller
          - compute1
          - compute2
       - name: ceph-web
         nodes:
           - web

nodeset

A Nodeset requires two attributes:

nodeset.name (required): The name of the Nodeset, to be referenced by a Job.

nodeset.nodes (required)

A list of node definitions, each of which has the following format:

nodeset.nodes.name (required)

The name of the node. This will appear in the Ansible inventory for the job.

This can also be as a list of strings. If so, then the list of hosts in the Ansible inventory will share a common ansible_host address.

nodeset.nodes.label (required): The Nodepool label for the node. Zuul will request a node with this label.

nodeset.groups

Additional groups can be defined which are accessible from the ansible playbooks.

nodeset.groups.name (required): The name of the group to be referenced by an ansible playbook.

nodeset.groups.nodes (required): The nodes that shall be part of the group. This is specified as a list of strings.

Semaphore

Semaphores can be used to restrict the number of certain jobs which are running at the same time. This may be useful for jobs which access shared or limited resources. A semaphore has a value which represents the maximum number of jobs which use that semaphore at the same time.

Semaphores, like most configuration items, are unique within a tenant, though a semaphore may be defined on multiple branches of the same project as long as the value is the same. This is to aid in branch maintenance, so that creating a new branch based on an existing branch will not immediately produce a configuration error.

Semaphores are never subject to dynamic reconfiguration. If the value of a semaphore is changed, it will take effect only when the change where it is updated is merged. However, Zuul will attempt to validate the configuration of semaphores in proposed updates, even if they aren’t used.

An example usage of semaphores follows:

- semaphore:
    name: semaphore-foo
    max: 5
- semaphore:
    name: semaphore-bar
    max: 3

semaphore

The following attributes are available:

semaphore.name (required): The name of the semaphore, referenced by jobs.

semaphore.max Default: 1: The maximum number of running jobs which can use this semaphore.

Pragma

The pragma item does not behave like the others. It can not be included or excluded from configuration loading by the administrator, and does not form part of the final configuration itself. It is used to alter how the configuration is processed while loading.

A pragma item only affects the current file. The same file in another branch of the same project will not be affected, nor any other files or any other projects. The effect is global within that file – pragma directives may not be set and then unset within the same file.

- pragma:
    implied-branch-matchers: False

pragma

The pragma item currently supports the following attributes:

pragma.implied-branch-matchers

This is a boolean, which, if set, may be used to enable (True) or disable (False) the addition of implied branch matchers to job and project-template definitions. Normally Zuul decides whether to add these based on heuristics described in job.branches. This attribute overrides that behavior.

This can be useful if a project has multiple branches, yet the jobs defined in the master branch should apply to all branches.

Note that if a job contains an explicit branch matcher, it will be used regardless of the value supplied here.

pragma.implied-branches

This is a list of regular expressions, just as job.branches, which may be used to supply the value of the implied branch matcher for all jobs and project-templates in a file.

This may be useful if two projects share jobs but have dissimilar branch names. If, for example, two projects have stable maintenance branches with dissimilar names, but both should use the same job variants, this directive may be used to indicate that all of the jobs defined in the stable branch of the first project may also be used for the stable branch of the other. For example:

- pragma:
    implied-branches:
      - stable/foo
      - stable/bar

The above code, when added to the stable/foo branch of a project would indicate that the job variants described in that file should not only be used for changes to stable/foo, but also on changes to stable/bar, which may be in another project.

Note that if a job contains an explicit branch matcher, it will be used regardless of the value supplied here.

Note also that the presence of implied-branches does not automatically set implied-branch-matchers. Zuul will still decide if implied branch matchers are warranted at all, using the heuristics described in job.branches, and only use the value supplied here if that is the case. If you want to declare specific implied branches on, for example, a config-project project (which normally would not use implied branches), you must set implied-branch-matchers as well.