node('kubernetes') {
 
 sshagent(['mykey']) {
   sh "ssh ..."
 }
 
}

node('kubernetes') {
 container('jnlp') {
 sh 'which ssh-agent'
   sshagent(['mykey']) {
     sh "ssh ..."
   }
  }
 
}

16:49:04 + which ssh-agent
16:49:04 /usr/bin/ssh-agent
16:49:04 [Pipeline] sshagent
16:49:04 [ssh-agent] Using credentials ci
16:49:04 [ssh-agent] Looking for ssh-agent implementation...
16:49:04 [ssh-agent] FATAL: Could not find a suitable ssh-agent provider
16:49:04 [ssh-agent] Diagnostic report
16:49:04 [Pipeline] // sshagent
16:49:04 [Pipeline] }
16:49:04 [Pipeline] // container
16:49:04 [Pipeline] }
16:49:04 [Pipeline] // node
16:49:04 [Pipeline] End of Pipeline


16:49:04 java.lang.RuntimeException: [ssh-agent] Could not find a suitable ssh-agent provider.
16:49:04 at com.cloudbees.jenkins.plugins.sshagent.SSHAgentStepExecution.initRemoteAgent(SSHAgentStepExecution.java:175)
16:49:04 at com.cloudbees.jenkins.plugins.sshagent.SSHAgentStepExecution.start(SSHAgentStepExecution.java:63)
16:49:04 at org.jenkinsci.plugins.workflow.cps.DSL.invokeStep(DSL.java:319)
16:49:04 at org.jenkinsci.plugins.workflow.cps.DSL.invokeMethod(DSL.java:193)
16:49:04 at org.jenkinsci.plugins.workflow.cps.CpsScript.invokeMethod(CpsScript.java:122)
16:49:04 at jdk.internal.reflect.GeneratedMethodAccessor896.invoke(Unknown Source)
16:49:04 at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
16:49:04 at java.base/java.lang.reflect.Method.invoke(Method.java:566)
16:49:04 at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
16:49:04 at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
16:49:04 at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1213)
16:49:04 at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1022)
16:49:04 at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:42)
16:49:04 at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
16:49:04 at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
16:49:04 at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:163)
16:49:04 at org.kohsuke.groovy.sandbox.GroovyInterceptor.onMethodCall(GroovyInterceptor.java:23)
16:49:04 at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:158)
16:49:04 at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:161)
16:49:04 at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:165)
16:49:04 at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:135)
16:49:04 at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:135)
16:49:04 at com.cloudbees.groovy.cps.sandbox.SandboxInvoker.methodCall(SandboxInvoker.java:17)
16:49:04 at WorkflowScript.run(WorkflowScript:4)
16:49:04 at __cps.transform__(Native Method)
16:49:04 at com.cloudbees.groovy.cps.impl.ContinuationGroup.methodCall(ContinuationGroup.java:86)
16:49:04 at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:113)
16:49:04 at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixArg(FunctionCallBlock.java:83)
16:49:04 at jdk.internal.reflect.GeneratedMethodAccessor774.invoke(Unknown Source)
16:49:04 at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
16:49:04 at java.base/java.lang.reflect.Method.invoke(Method.java:566)
16:49:04 at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
16:49:04 at com.cloudbees.groovy.cps.impl.ClosureBlock.eval(ClosureBlock.java:46)
16:49:04 at com.cloudbees.groovy.cps.Next.step(Next.java:83)
16:49:04 at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:174)
16:49:04 at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:163)
16:49:04 at org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.use(GroovyCategorySupport.java:129)
16:49:04 at org.codehaus.groovy.runtime.GroovyCategorySupport.use(GroovyCategorySupport.java:268)
16:49:04 at com.cloudbees.groovy.cps.Continuable.run0(Continuable.java:163)
16:49:04 at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.access$001(SandboxContinuable.java:18)
16:49:04 at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.run0(SandboxContinuable.java:51)
16:49:04 at org.jenkinsci.plugins.workflow.cps.CpsThread.runNextChunk(CpsThread.java:185)
16:49:04 at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:400)
16:49:04 at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$400(CpsThreadGroup.java:96)
16:49:04 at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:312)
16:49:04 at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:276)
16:49:04 at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:67)
16:49:04 at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
16:49:04 at hudson.remoting.SingleLaneExecutorService$1.run(SingleLaneExecutorService.java:139)
16:49:04 at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28)
16:49:04 at jenkins.security.ImpersonatingExecutorService$1.run(ImpersonatingExecutorService.java:68)
16:49:04 at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
16:49:04 at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
16:49:04 at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
16:49:04 at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
16:49:04 at java.base/java.lang.Thread.run(Thread.java:834)
16:49:04 Finished: FAILURE