Defining Pipeline
Jenkins Pipeline is a suite of plugins which supports implementing and integrating continuous delivery pipelines into Jenkins. Pipeline provides an extensible set of tools for modeling simple-to-complex delivery pipelines "as code" via the Pipeline DSL. [1]
Typically, this "Pipeline as Code" would be written to a Jenkinsfile and checked into a project’s source control
repository, for example:
// Declarative //
pipeline {
agent any (1)
stages {
stage('Build') { (2)
steps { (3)
sh 'make' (4)
}
}
stage('Test'){
steps {
sh 'make check'
junit 'reports/**/*.xml' (5)
}
}
stage('Deploy') {
steps {
sh 'make publish'
}
}
}
}
// Script //
node {
stage('Build') {
sh 'make'
}
stage('Test') {
sh 'make check'
junit 'reports/**/*.xml'
}
stage('Deploy') {
sh 'make publish'
}
}| 1 | agent indicates that Jenkins should allocate an executor and workspace for
this part of the Pipeline. |
| 2 | stage describes a stage of this Pipeline. |
| 3 | steps describes the steps to be run in this stage |
| 4 | sh executes the given shell command |
| 5 | junit is a Pipeline step provided by the
plugin:junit[JUnit plugin]
for aggregating test reports. |
Pipeline terms
- Step
-
A single task; fundamentally steps tell Jenkins what to do. For example, to execute the shell command
makeuse theshstep:sh 'make'. When a plugin extends the Pipeline DSL, that typically means the plugin has implemented a new step.
- Node
-
Most work a Pipeline performs is done in the context of one or more declared
nodesteps. Confining the work inside of a node step does two things:-
Schedules the steps contained within the block to run by adding an item to the Jenkins queue. As soon as an executor is free on a node, the steps will run.
-
Creates a workspace (a directory specific to that particular Pipeline) where work can be done on files checked out from source control.
-
| Depending on your Jenkins configuration, some workspaces may not get automatically cleaned up after a period of inactivity. See tickets and discussion linked from JENKINS-2111 for more information. |
Getting started with Pipeline
A basic Pipeline can be created in either of the following ways:
-
By entering a script directly in the Jenkins web UI.
-
By creating a
Jenkinsfilewhich can be checked into a project’s source control repository.
The syntax for defining a Pipeline with either approach is the same, but while
Jenkins supports entering Pipeline directly into the web UI, it’s
generally considered best practice to define the Pipeline in a Jenkinsfile
which Jenkins will then load directly from source control.
[4]
The Jenkins project maintains a
Pipeline Syntax Reference
which may useful to refer to when creating a Jenkinsfile.