Restricting which downstream builds are triggered on SNAPSHOT dependency - maven

Question

We have a Jenkins server, using jenkins-build-per-branch to sync from git whenever a (php or java) project has a valid pom.xml. We use maven versioning strategy to manage our artefacts, and git-flow as a branching strategy / tool. We also use the jenkins option "Build whenever a SNAPSHOT dependency is built" wherever possible.
The problem we have is when building a -SNAPSHOT artefact - all hell breaks loose and everything wants to build at once. (Building a 'develop' -SNAPSHOT causes all downstream 'feature' AND 'develop' branches to start)
Ideally we would like to find some way that we don't cross pollenate between feature and develop builds when jenkins launches downstream jobs.
Has anyone tried this? Would something like the Conditional+BuildStep+Plugin help? https://wiki.jenkins-ci.org/display/JENKINS/Conditional+BuildStep+Plugin

Answer 1

This is an old question but it's still relevant 6 years later. There is a "threshold" field on the Build whenever a SNAPSHOT dependency is built setting that provides some control over which builds will trigger
From the pipeline-maven-plugin README:
Threshold based on the Maven lifecycle phase reached in the Maven
build of the upstream job (package, install, deploy). By default, only
the maven builds who reach the deploy phase will trigger downstream
builds.
For example, in a scripted pipeline's withMaven() you can set a pipelineGraphPublisher with lifecycleThreshold: 'deploy' like:
withMaven(
maven: MAVEN_VERSION,
jdk: JAVA_VERSION,
mavenOpts: MAVEN_OPTS,
globalMavenSettingsConfig: globals.MAVEN_SETTINGS_ID,
options: [
pipelineGraphPublisher(
lifecycleThreshold: 'deploy',
includeSnapshotVersions: true
)
]) {
sh("mvn ${PHASE}")
}
Then any SNAPSHOT build that executes a lifecycle phase below deploy (e.g. package or install) will not trigger a downstream job. Note that deploy is already the default so this example isn't particularly useful, but it shows how to use the setting and you may want to set this to another phase.
That's part one done, but now you need a way to conditionally execute different Maven lifecycle phases for the builds that you do want to trigger downstream builds vs. the ones that you don't want to trigger downstream builds. We do this based on the branch name so that Pull Request and Release branches don't trigger upstream packages:
/**
* Return the correct Maven goal for the current branch
*
* Because the pipelineGraphPublisher's lifecycleThreshold in the withMaven() call above is set to 'deploy', pipelines
* that run the 'install' goal will not trigger downstream jobs; this helps us minimize superfluous Jenkins builds:
*
* https://github.com/jenkinsci/pipeline-maven-plugin/blob/master/README.adoc#trigger-downstream-pipeline-when-a-snapshot-is-built
*/
String getGoalForCurrentBranch() {
if ( env.BRANCH_NAME ==~ /(^PR-(\d+)$)|(^releases\/v.*)/ ) {
echo("Pull Request or release branch detected! Executing Maven 'install' goal rather than 'deploy' goal to avoid triggering downstream Jenkins jobs")
return 'install'
}
return 'deploy'
}
You can then call this getGoalForCurrentBranch() method wherever you're executing mvn to determine which lifecycle phase is executed:
withMaven(
...
sh("mvn ${getGoalForCurrentBranch()}")
)
Most branches will execute mvn deploy and will trigger a downstream Jenkins job, but Pull Request branches will execute mvn install and will not trigger a downstream job.
The caveat to this is that you may have other things that depend on certain lifecycle phases. In the above example, Pull Request branch artifacts won't get deployed to your artifact repository (e.g. Nexus). In our case this is actually the desired behavior but you'll need to determine what's acceptable for you and tweak your threshold accordingly.

Answer 2

In the dependent projects you can disable the "Build whenever a SNAPSHOT dependency is built" hook via
if (branchName.indexOf("mule4auto") >= 0) {
println "for mule4auto do not build when mulestac is build";
// for mule4auto do not build when mulestac is build, wait for
// mule4auto-converter project has run (commited something).
} else {
tempPipelineTriggers += [
snapshotDependencies()
];
}
println "triggers: tempPipelineTriggers=${tempPipelineTriggers}";
Additionally you may need to disable the fingerprint for the specific branches which should not be build (mule4auto in our case):
// see https://github.com/jenkinsci/pipeline-maven-plugin/blob/master/README.adoc
def tempMavenOptions = [];
// disable Archiving (fingerprinting should still work)
tempMavenOptions += artifactsPublisher(disabled: true);
if (branchName.indexOf("mule4auto") >= 0) {
println "Disable fingerprint for mule4auto to prevent jobs building when mulestac4 SNAPSHOT is build";
tempMavenOptions += dependenciesFingerprintPublisher(disabled: true);
tempMavenOptions += pipelineGraphPublisher(disabled: true);
}
// see https://plugins.jenkins.io/pipeline-maven
withMaven(
// Maven installation declared in the Jenkins "Global Tool Configuration"
maven: toolMaven,
jdk: toolJdkToBeUsed,
options: tempMavenOptions
) {
println "JAVA_HOME ${JAVA_HOME}";
println "MAVEN_HOME ${MAVEN_HOME}";
....
})
(both in destination pipeline)

Answer 3

I do not see an option like "Build whenever an upstream dependency is built" in our Jenkin's jobs. It's called "Build whenever a SNAPSHOT dependency is built" here (Jenkins v1.592 with its latest plugins). Is that what you mean?
There's also this last sentence in its inline help: "If this behavior is problematic, uncheck this option." :-)
I don't know whether Conditional BuildStep Plugin would help in this case. We use it but not to achieve such.
Depending on how long your jobs run I'd suggest to:
use the Build whenever ... in conjunction with Advanced Project Options → Quiet period if the jobs don't run long (let's say a few minutes)
deactivate the build-whenever-all-and-everywhere as suggested and use Post-build Actions → Build other projects or Trigger parameterized build on other project to establish a real up-/downstream build flow if your jobs run longer