The job definitions for Jenkins Job Builder are kept in any number of YAML files, in whatever way you would like to organize them. When you invoke jenkins-jobs you may specify either the path of a single YAML file, or a directory. If you choose a directory, all of the .yaml (or .yml) files in that directory will be read, and all the jobs they define will be created or updated.
Jenkins Job Builder understands a few basic object types which are described in the next sections.
The most straightforward way to create a job is simply to define a Job in YAML. It looks like this:
- job:
name: job-name
That’s not very useful, so you’ll want to add some actions such as Builders, and perhaps Publishers. Those are described later. There are a few basic optional fields for a Job definition:
- job:
name: job-name
project-type: freestyle
defaults: global
disabled: false
concurrent: true
quiet-period: 5
block-downstream: false
block-upstream: false
If you need several jobs defined that are nearly identical, except perhaps in their names, SCP targets, etc., then you may use a Job Template to specify the particulars of the job, and then use a Project to realize the job with appropriate variable substitution.
A Job Template has the same syntax as a Job, but you may add variables anywhere in the definition. Variables are indicated by enclosing them in braces, e.g., {name} will substitute the variable name. When using a variable in a string field, it is good practice to wrap the entire string in quotes, even if the rules of YAML syntax don’t require it because the value of the variable may require quotes after substitution.
You must include a variable in the name field of a Job Template (otherwise, every instance would have the same name). For example:
- job-template:
name: '{name}-unit-tests'
Will not cause any job to be created in Jenkins, however, it will define a template that you can use to create jobs with a Project definition. It’s name will depend on what is supplied to the Project.
The purpose of a project is to collect related jobs together, and provide values for the variables in a Job Template. It looks like this:
- project:
name: project-name
jobs:
- '{name}-unit-tests'
Any number of arbitrarily named additional fields may be specified, and they will be available for variable substitution in the job template. Any job templates listed under jobs: will be realized with those values. The example above would create the job called ‘project-name-unit-tests’ in Jenkins.
The jobs: list can also allow for specifying job-specific substitutions as follows:
- project:
name: project-name
jobs:
- '{name}-unit-tests':
mail-to: developer@nowhere.net
- '{name}-perf-tests':
mail-to: projmanager@nowhere.net
If a variable is a list, the job template will be realized with the variable set to each value in the list. Multiple lists will lead to the template being realized with the cartesian product of those values. Example:
- project:
name: project-name
pyver:
- 26
- 27
jobs:
- '{name}-{pyver}'
If you have several Job Templates that should all be realized together, you can define a Job Group to collect them. Simply use the Job Group where you would normally use a Job Template and all of the Job Templates in the Job Group will be realized. For example:
- job-template:
name: '{name}-python-26'
- job-template:
name: '{name}-python-27'
- job-group:
name: python-jobs
jobs:
- '{name}-python-26'
- '{name}-python-27'
- project:
name: foo
jobs:
- python-jobs
Would cause the jobs foo-python-26 and foo-python-27 to be created in Jekins.
Many of the actions of a Job, such as builders or publishers, can be defined as a Macro, and then that Macro used in the Job description. Builders are described later, but let’s introduce a simple one now to illustrate the Macro functionality. This snippet will instruct Jenkins to execute “make test” as part of the job:
- job:
name: foo-test
builders:
- shell: 'make test'
If you wanted to define a macro (which won’t save much typing in this case, but could still be useful to centralize the definition of a commonly repeated task), the configuration would look like:
- builder:
name: make-test
builders:
- shell: 'make test'
- job:
name: foo-test
builders:
- make-test
This allows you to create complex actions (and even sequences of actions) in YAML that look like first-class Jenkins Job Builder actions. Not every attribute supports Macros, check the documentation for the action before you try to use a Macro for it.
Macros can take parameters, letting you define a generic macro and more specific ones without having to duplicate code:
# The 'add' macro takes a 'number' parameter and will creates a
# job which prints 'Adding ' followed by the 'number' parameter:
- builder:
name: add
builders:
- shell: "echo Adding {number}"
# A specialized macro 'addtwo' reusing the 'add' macro but with
# a 'number' parameter hardcoded to 'two':
- builder:
name: addtwo
builders:
- add:
number: "two"
# Glue to have Jenkins Job Builder to expand this YAML example:
- job:
name: "testingjob"
builders:
# The specialized macro:
- addtwo
# Generic macro call with a parameter
- add:
number: "ZERO"
# Generic macro called without a parameter. Never do this!
# See below for the resulting wrong output :(
- add
Then <builders /> section of the generated job show up as:
<builders>
<hudson.tasks.Shell>
<command>echo Adding two</command>
</hudson.tasks.Shell>
<hudson.tasks.Shell>
<command>echo Adding ZERO</command>
</hudson.tasks.Shell>
<hudson.tasks.Shell>
<command>echo Adding {number}</command>
</hudson.tasks.Shell>
</builders>
As you can see, the specialized macro addtwo reused the definition from the generic macro add. Whenever you forget a parameter from a macro, it will not be expanded and left as is, which will most probably cause havoc in your Jenkins builds.
Defaults collect job attributes (including actions) and will supply those values when the job is created, unless superseded by a value in the ‘Job’_ definition. If a set of Defaults is specified with the name global, that will be used by all Job (and Job Template) definitions unless they specify a different Default object with the default attribute. For example:
- defaults:
name: global
description: 'Do not edit this job through the web!'
Will set the job description for every job created.
The bulk of the job definitions come from the following modules.