Windows build node SSH connection issue using JCasC #242
Description
When configuring a Windows agent using JCasC, the SSH connection is broken between Jenkins and the agent if 'username/password' authentication is selected.
Windows agent configuration:
- namePrefix: gce-windows-vm
description: Windows VM running in GCE
labelString: gce-windows-vm
template: "https://www.googleapis.com/compute/v1/projects/${projectID}/global/instanceTemplates/jenkins-windows-vm"
remoteFs: C:\Users\jenkins
windowsConfiguration:
passwordCredentialsId: user-pass-credential-id
retentionTimeMinutesStr: 6
mode: EXCLUSIVE
numExecutorsStr: 1
launchTimeoutSecondsStr: 300
useInternalAddress: true
runAsUser: jenkins
javaExecPath: java
oneShot: true
region: "https://www.googleapis.com/compute/v1/projects/${projectID}/regions/${region}"
zone: "https://www.googleapis.com/compute/v1/projects/${projectID}/zones/${zone}"
The configuration looks suitable when examined in the Jenkins UI, but I can see the following error in the agent logs:
Feb 25, 2021 10:23:16 AM null
WARNING: Failed to authenticate with exception: Exception: java.lang.NullPointerException
On a closer inspection in the system logs:
Feb 25, 2021 10:44:19 AM WARNING com.google.jenkins.plugins.computeengine.ComputeEngineCloud log
Failed to authenticate with exception:
java.lang.NullPointerException
at com.google.jenkins.plugins.computeengine.ComputeEngineWindowsLauncher.authenticateSSH(ComputeEngineWindowsLauncher.java:72)
at com.google.jenkins.plugins.computeengine.ComputeEngineWindowsLauncher.bootstrap(ComputeEngineWindowsLauncher.java:104)
at com.google.jenkins.plugins.computeengine.ComputeEngineWindowsLauncher.setupConnection(ComputeEngineWindowsLauncher.java:56)
at com.google.jenkins.plugins.computeengine.ComputeEngineComputerLauncher.launch(ComputeEngineComputerLauncher.java:301)
at com.google.jenkins.plugins.computeengine.ComputeEngineComputerLauncher.launch(ComputeEngineComputerLauncher.java:224)
at hudson.slaves.SlaveComputer.lambda$_connect$0(SlaveComputer.java:296)
at jenkins.util.ContextResettingExecutorService$2.call(ContextResettingExecutorService.java:46)
at jenkins.security.ImpersonatingExecutorService$2.call(ImpersonatingExecutorService.java:71)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Looking at that line in the code, it seems that windowsConfig.getPrivateKeyCredentialsId() can return a null value, so call isEmpty() on that will cause the NPE.
Workaround is to specify an empty string as the privateKeyCredentialsId, e.g.
windowsConfiguration:
privateKeyCredentialsId: ""
passwordCredentialsId: user-pass-credential-id