Issue
After restarting the instance, we are getting 504 Gateway timeout error when trying to access URLs such as the items view.
In our thread dumps, you can see some threads showing the stack trace below:
Handling GET /jenkins/XXX/ from XX.XX.XX.XX : Jetty (winstone)-14 View/index.jelly StatusColumn/column.jelly Stack Trace is: java.lang.Thread.State: RUNNABLE at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1674) - locked <0x0000000XXXX> (a java.util.concurrent.ConcurrentHashMap$ReservationNode) at com.cloudbees.jenkins.plugins.github_reporting.config.AppManifest$Factory.createFor(AppManifest.java:140) at com.cloudbees.jenkins.plugins.github_reporting.config.AppManifest$Factory.createFor(AppManifest.java:83) at hudson.model.Actionable.createFor(Actionable.java:114) at hudson.model.Actionable.getAction(Actionable.java:334) at jenkins.branch.MultiBranchProject.getDisplayName(MultiBranchProject.java:829) at org.conjur.jenkins.credentials.ConjurCredentialProvider.getCredentialsFromSupplier(ConjurCredentialProvider.java:79) at org.conjur.jenkins.credentials.ConjurCredentialProvider.getCredentials(ConjurCredentialProvider.java:71) at org.conjur.jenkins.credentials.ConjurCredentialProvider.getCredentials(ConjurCredentialProvider.java:51) at com.cloudbees.plugins.credentials.CredentialsProvider.lookupCredentials(CredentialsProvider.java:428) at com.cloudbees.plugins.credentials.CredentialsProvider.lookupCredentials(CredentialsProvider.java:545) at org.jenkinsci.plugins.github_branch_source.Connector.lookupScanCredentials(Connector.java:272) at com.cloudbees.jenkins.plugins.github_reporting.config.AppManifest$Factory.lambda$createFor$9(AppManifest.java:141) at com.cloudbees.jenkins.plugins.github_reporting.config.AppManifest$Factory$$Lambda$874/1937347902.apply(Unknown Source) at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660) - locked <0x0000000XXXX> (a java.util.concurrent.ConcurrentHashMap$ReservationNode) at com.cloudbees.jenkins.plugins.github_reporting.config.AppManifest$Factory.createFor(AppManifest.java:140)
Explanation
The problem is coming from a change in the Conjur Credentials plugin, injected in version 1.0.6 where the plugin was trying to get the display name of the credential for debugging purposes. This causes a block that prevents the instance from responding and thus we get the error observed: 504 Gateway timeout error.
There is an open PR to solve this issue, but the maintainer has not merged it yet.
Workaround
There are two options to get rid of this behavior:
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Disable the Conjur Credentials plugin.
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Install a version that does not include the change triggering this behavior. The latest stable version that does not show this behavior is Conjur Credentials 1.0.2