title: Jenkins declarative pipeline - push Docker image to private docker hub repo
body: <p>I try to push to a private dockerhub repo from Jenkins but I always get errors due to Authorization I guess.</p>
  
  <p>Here is the relevant Jenkins pipeline:</p>
  
  <pre class="lang-java prettyprint-override"><code>pipeline {
    agent {
      // run this pipeline inside an docker image with node 8 and git installed
      docker {
        image 'node/8-alpine'
        registryUrl 'https://registry.hub.docker.com'
        registryCredentialsId 'dockerhub' // the id of username/password credentials I have in Jenkins
      }
    }
    environment {
      registry = '&lt;my-org&gt;/&lt;my-project&gt;'
      tag_beta = "${currentBuild.displayName}-${env.BRANCH_NAME}"
    }
    stages {
  
      stage("Docker") {
        steps {
            script {
              // NPM_TOKEN was set as environment variable inside Jenkins
              def image = docker.build("${env.registry}:${env.tag-beta}",  "-e NPM_TOKEN=${env.NPM_TOKEN}")
              /* Push the container to the custom Registry */
              image.push()
            }
  
        }
      }
    }
  }
  </code></pre>
  
  <p>Here is the error stack trace</p>
  
  <pre><code>groovy.lang.MissingPropertyException: No such property: beta for class: groovy.lang.Binding
      at groovy.lang.Binding.getVariable(Binding.java:63)
      at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onGetProperty(SandboxInterceptor.java:264)
      at org.kohsuke.groovy.sandbox.impl.Checker$6.call(Checker.java:289)
      at org.kohsuke.groovy.sandbox.impl.Checker.checkedGetProperty(Checker.java:293)
      at org.kohsuke.groovy.sandbox.impl.Checker.checkedGetProperty(Checker.java:269)
      at org.kohsuke.groovy.sandbox.impl.Checker.checkedGetProperty(Checker.java:269)
      at org.kohsuke.groovy.sandbox.impl.Checker.checkedGetProperty(Checker.java:269)
      at org.kohsuke.groovy.sandbox.impl.Checker.checkedGetProperty(Checker.java:269)
      at com.cloudbees.groovy.cps.sandbox.SandboxInvoker.getProperty(SandboxInvoker.java:29)
      at com.cloudbees.groovy.cps.impl.PropertyAccessBlock.rawGet(PropertyAccessBlock.java:20)
      at WorkflowScript.run(WorkflowScript:57)
      at ___cps.transform___(Native Method)
      at com.cloudbees.groovy.cps.impl.PropertyishBlock$ContinuationImpl.get(PropertyishBlock.java:74)
      at com.cloudbees.groovy.cps.LValueBlock$GetAdapter.receive(LValueBlock.java:30)
      at com.cloudbees.groovy.cps.impl.PropertyishBlock$ContinuationImpl.fixName(PropertyishBlock.java:66)
      at sun.reflect.GeneratedMethodAccessor351.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:498)
      at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
      at com.cloudbees.groovy.cps.impl.ConstantBlock.eval(ConstantBlock.java:21)
      at com.cloudbees.groovy.cps.Next.step(Next.java:83)
      at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:174)
      at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:163)
      at org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.use(GroovyCategorySupport.java:129)
      at org.codehaus.groovy.runtime.GroovyCategorySupport.use(GroovyCategorySupport.java:268)
      at com.cloudbees.groovy.cps.Continuable.run0(Continuable.java:163)
      at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.access$101(SandboxContinuable.java:34)
      at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.lambda$run0$0(SandboxContinuable.java:59)
      at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.GroovySandbox.runInSandbox(GroovySandbox.java:136)
      at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.run0(SandboxContinuable.java:58)
      at org.jenkinsci.plugins.workflow.cps.CpsThread.runNextChunk(CpsThread.java:182)
      at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:332)
      at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$200(CpsThreadGroup.java:83)
      at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:244)
      at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:232)
      at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:64)
      at java.util.concurrent.FutureTask.run(FutureTask.java:266)
      at hudson.remoting.SingleLaneExecutorService$1.run(SingleLaneExecutorService.java:131)
      at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28)
      at jenkins.security.ImpersonatingExecutorService$1.run(ImpersonatingExecutorService.java:59)
      at java.util.concurrent.Executors$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
  </code></pre>
  
  <p>I also tried</p>
  
  <pre><code>docker.withRegistry('', "myJenkinsCredentialsIdForDockerhub") {            
    /* Push the container to the custom Registry */
    image.push()
  }
  </code></pre>
  
  <p>Any help on how to authenticate from Jenkins declarative pipeline to private Docker hub registry would be highly appreciated!</p>