How to write Pipeline to discard old builds?

The groovy syntax generator is NOT working for sample step properties: Set Job Properties. I've selected Discard old builds and then entered 10 in the Max # of builds to keep field and then Generate Groovy and nothing shows up.

Jenkins version: 2.7

As for declarative syntax, you can use the options block:

pipeline {
  options {
    buildDiscarder(logRotator(numToKeepStr: '30', artifactNumToKeepStr: '30'))
  }
  ...
}

Parameters for logRotator (from the source code):

• daysToKeepStr: history is only kept up to this days.
• numToKeepStr: only this number of build logs are kept.
• artifactDaysToKeepStr: artifacts are only kept up to this days.
• artifactNumToKeepStr: only this number of builds have their artifacts kept.

More information can be found in Cloudbees knowledge base and in the docs for options block.

You can use the properties method which, nested within the BuildDiscarderProperty eventually has the key you want to set. I still don't have a solid way to look up the correct syntax of each key. After much guessing and checking:

properties([[$class: 'BuildDiscarderProperty', strategy: [$class: 'LogRotator', artifactDaysToKeepStr: '', artifactNumToKeepStr: '', daysToKeepStr: '', numToKeepStr: '10']]]);

Note that this snippet is for scripted syntax.

For Scripted Pipelines use:

properties([
    buildDiscarder(logRotator(daysToKeepStr: '3', numToKeepStr: '3')),
])

Jenkins has built-in syntax generator pages.

Pipeline-Syntax: Snippet Generator
<your jenkins url>/pipeline-syntax/

Pipeline-Syntax: Directive Generator
<your jenkins url>/directive-generator/

Discard old builds example from Directive Generator

1. To Discard build after particular number of days:

    options {
        buildDiscarder(logRotator(daysToKeepStr: '7'))
    }
   

2. To Discard build after particular number of builds:

    options {
        buildDiscarder(logRotator(numToKeepStr: '7'))
    }
   

For declarative pipeline you can add this:

options {

    buildDiscarder(
        logRotator(
            // number of build logs to keep
            numToKeepStr:'5',
            // history to keep in days
            daysToKeepStr: '15',
            // artifacts are kept for days
            artifactDaysToKeepStr: '15',
            // number of builds have their artifacts kept
            artifactNumToKeepStr: '5'
        )
    )
}

Vadim's answer did not work for me for some unknown reason. I simplified it down as follows and it works now:

options {
    buildDiscarder(logRotator(numToKeepStr: '3'))
}

If you want to configure the build retention on the multibranch pipeline job level (vs in all the individual Jenkinsfiles) this is possible too: https://issues.jenkins-ci.org/browse/JENKINS-30519?focusedCommentId=325601&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-325601

In addition to the BuildRetentionBranchProperty you can configure any other of the *BranchPropertys in here: https://github.com/jenkinsci/branch-api-plugin/tree/master/src/main/java/jenkins/branch

They might not be shown in the GUI though, at least for me with Jenkins 2.73.2. But you can still use JobDSL or modify the config.xml directly (I didn't say that ;-))

If you need a programmatic way (i.e. doing this from a function, rather than using options{} pipeline syntax):

def someFunction() {
  ...
  properties([
    buildDiscarder(logRotator(numToKeepStr: '5'))
  ])
}