jenkins pipeline giving inexplicable NullPointerException at GenericDownloadExecutor.java: 52 - jenkins

Question

I followed the example given in this page to download artifacts from JFrog artifactory:
https://www.jfrog.com/confluence/display/JFROG/Scripted+Pipeline+Syntax#ScriptedPipelineSyntax-UploadingandDownloadingFiles
But I have been getting NullPointerException. Below is the script output and error:
[Pipeline] echo
download spec {
"files": [
{
"pattern": "aod-libs-release/path-to-artifact/deployment/DM-DP-V3A.24-RELEASE/deployment-DM-DP-V3A.24-RELEASE.zip",
"target": "./artifacts"
}, {
"pattern": "aod-libs-release/path-to-artifact/dm-auth-web-services/DM-AU-V3A.88-RELEASE/dm-auth-web-services-DM-AU-V3A.88-RELEASE.war",
"target": "./artifacts"
}
]
}
[Pipeline] echo
artifactory server org.jfrog.hudson.pipeline.common.types.ArtifactoryServer#66026154
[Pipeline] newBuildInfo
[Pipeline] artifactoryDownload
[Pipeline] End of Pipeline
java.lang.NullPointerException
at org.jfrog.hudson.pipeline.common.executors.GenericDownloadExecutor.execute(GenericDownloadExecutor.java:52)
at org.jfrog.hudson.pipeline.scripted.steps.DownloadStep$Execution.runStep(DownloadStep.java:67)
at org.jfrog.hudson.pipeline.scripted.steps.DownloadStep$Execution.runStep(DownloadStep.java:53)
at org.jfrog.hudson.pipeline.ArtifactorySynchronousNonBlockingStepExecution.run(ArtifactorySynchronousNonBlockingStepExecution.java:54)
at org.jenkinsci.plugins.workflow.steps.SynchronousNonBlockingStepExecution.lambda$start$0(SynchronousNonBlockingStepExecution.java:47)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Finished: FAILURE
Below is my jenkins pipeline script
def artifactoryServer = Artifactory.server("Artifactory-instance-id")
artifactoryServer.connection.timeout = 300
def artifactDownloadSpec = """{
"files": [
{
"pattern": "aod-libs-release/path-to-artifact/deployment/${env.DP_VERSION}/deployment-${env.DP_VERSION}.zip",
"target": "./artifacts"
}, {
"pattern": "aod-libs-release/path-to-artifact/dm-auth-web-services/${env.VERSION}/dm-auth-web-services-${env.VERSION}.war",
"target": "./artifacts"
}
]
}"""
echo "download spec " + artifactDownloadSpec
echo "artifactory server " + artifactoryServer
artifactoryServer.download spec: artifactDownloadSpec
I googled for GenericDownloadExecutor.java and found below code, but cannot figure out what I am missing that line 52 needed. Looks like a field is not set.
https://github.com/jenkinsci/artifactory-plugin/blob/master/src/main/java/org/jfrog/hudson/pipeline/common/executors/GenericDownloadExecutor.java

Answer 1

Running artifactoryServer.download step requires using an agent.
For example:
Jenkins scripted pipeline
node {
...
artifactoryServer.download spec: artifactDownloadSpec
...
}
Jenkins declarative pipeline
The recommended way is to use the rtDownload step, however, if you still want to use artifactoryServer.download:
pipeline {
agent any // <- Make sure there is an active agent
stages {
stage('Example') {
steps {
script {
...
artifactoryServer.download spec: artifactDownloadSpec
...
}
}
}
}
}
Read more:
Uploading and Downloading Files
Scripted pipeline example
Declarative pipeline example
Scripted pipeline inside declarative pipeline example - Less recommended, but this example is like your case