Jenkins Git plugin detached HEAD

Question

I am new to Git and also to Jenkins. My problem is that I can't get the Jenkins Maven release plugin to work.

When I build a common Maven build with Jenkins, it works well, but when I try to perform a release with the Maven release plugin, I get the following stack trace:

org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-release-plugin:2.3.2:prepare (default-cli) on project parent: An error is occurred in the checkin process: Exception while executing SCM command.     at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:217)     at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)     at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)     at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)     at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)     at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)     at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)     at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)     at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)     at org.jvnet.hudson.maven3.launcher.Maven3Launcher.main(Maven3Launcher.java:79)     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)     at java.lang.reflect.Method.invoke(Method.java:597)     at org.codehaus.plexus.classworlds.launcher.Launcher.launchStandard(Launcher.java:329)     at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:239)     at org.jvnet.hudson.maven3.agent.Maven3Main.launch(Maven3Main.java:158)     at hudson.maven.Maven3Builder.call(Maven3Builder.java:98)     at hudson.maven.Maven3Builder.call(Maven3Builder.java:64)     at hudson.remoting.UserRequest.perform(UserRequest.java:118)     at hudson.remoting.UserRequest.perform(UserRequest.java:48)     at hudson.remoting.Request$2.run(Request.java:326)     at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)     at java.util.concurrent.FutureTask.run(FutureTask.java:138)     at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)     at java.lang.Thread.run(Thread.java:662) Caused by: org.apache.maven.plugin.MojoExecutionException: An error is occurred in the checkin process: Exception while executing SCM command.     at org.apache.maven.plugins.release.PrepareReleaseMojo.prepareRelease(PrepareReleaseMojo.java:295)     at org.apache.maven.plugins.release.PrepareReleaseMojo.execute(PrepareReleaseMojo.java:247)     at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)     at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)     ... 27 more Caused by: org.apache.maven.shared.release.ReleaseExecutionException: An error is occurred in the checkin process: Exception while executing SCM command.     at org.apache.maven.shared.release.phase.AbstractScmCommitPhase.checkin(AbstractScmCommitPhase.java:160)     at org.apache.maven.shared.release.phase.AbstractScmCommitPhase.performCheckins(AbstractScmCommitPhase.java:145)     at org.apache.maven.shared.release.phase.ScmCommitPreparationPhase.runLogic(ScmCommitPreparationPhase.java:76)     at org.apache.maven.shared.release.phase.AbstractScmCommitPhase.execute(AbstractScmCommitPhase.java:78)     at org.apache.maven.shared.release.DefaultReleaseManager.prepare(DefaultReleaseManager.java:234)     at org.apache.maven.shared.release.DefaultReleaseManager.prepare(DefaultReleaseManager.java:169)     at org.apache.maven.shared.release.DefaultReleaseManager.prepare(DefaultReleaseManager.java:146)     at org.apache.maven.shared.release.DefaultReleaseManager.prepare(DefaultReleaseManager.java:107)     at org.apache.maven.plugins.release.PrepareReleaseMojo.prepareRelease(PrepareReleaseMojo.java:291)     ... 30 more Caused by: org.apache.maven.scm.ScmException: Exception while executing SCM command.     at org.apache.maven.scm.command.AbstractCommand.execute(AbstractCommand.java:63)     at org.apache.maven.scm.provider.git.AbstractGitScmProvider.executeCommand(AbstractGitScmProvider.java:291)     at org.apache.maven.scm.provider.git.AbstractGitScmProvider.checkin(AbstractGitScmProvider.java:217)     at org.apache.maven.scm.provider.AbstractScmProvider.checkIn(AbstractScmProvider.java:410)     at org.apache.maven.shared.release.phase.AbstractScmCommitPhase.checkin(AbstractScmCommitPhase.java:156)     ... 38 more Caused by: org.apache.maven.scm.ScmException: Detecting the current branch failed: fatal: ref HEAD is not a symbolic ref     at org.apache.maven.scm.provider.git.gitexe.command.branch.GitBranchCommand.getCurrentBranch(GitBranchCommand.java:147)     at org.apache.maven.scm.provider.git.gitexe.command.checkin.GitCheckInCommand.createPushCommandLine(GitCheckInCommand.java:192)     at org.apache.maven.scm.provider.git.gitexe.command.checkin.GitCheckInCommand.executeCheckInCommand(GitCheckInCommand.java:132)     at org.apache.maven.scm.command.checkin.AbstractCheckInCommand.executeCommand(AbstractCheckInCommand.java:54)     at org.apache.maven.scm.command.AbstractCommand.execute(AbstractCommand.java:59)     ... 42 more channel stopped Finished: FAILURE 

The failing command and error message are:

[INFO] Executing: /bin/sh -c cd /var/lib/jenkins/workspace/test_maven/parent && git symbolic-ref HEAD [INFO]  Working directory: /var/lib/jenkins/workspace/test_maven/parent  mojoFailed org.apache.maven.plugins:maven-release-plugin:2.3.2(default-cli) projectFailed ch.apkern.achilles:parent:1.0-SNAPSHOT  sessionEnded 

I have figured out that the Jenkins Git plugin creates a detached HEAD ref "(no branch)" which causes the problem, I think. But I have absolutely no idea why this ref is created or how I can solve this problem.

I would be grateful for any help.

Answer 1

The Checkout/merge to local branch (optional) field is gone in the current (2.2.1) version of the Git plugin.

It has moved to Additional Behaviours → Check out to specific local branch:

Setting that value to master got me a checked out branch instead of a detached head.