Give Pipeline the proper credentials to publish to Dockerhub

Jenkinsfile

@@ -2,9 +2,19 @@
 
 
 node('docker') {
+    checkout scm
+
     stage 'Build Containers'
     sh './build-rubies.sh'
 
     stage 'Publish Containers'
-    sh './push-rubies.sh'
+    /* Using credentials with the ID 'dockerhub' from the Jenkins installation */
+    withCredentials([[$class: 'UsernamePasswordMultiBinding',
+                        credentialsId: 'dockerhub',
+                     passwordVariable: 'DOCKERHUB_TOKEN',
+                     usernameVariable: 'DOCKERHUB_EMAIL']]) {
+        /* Our variables be exposed in the environment and we must log in before trying to publish to Dockerhub */
+        sh 'docker login --username ${DOCKERHUB_EMAIL} --password ${DOCKERHUB_TOKEN}'
+        sh './push-rubies.sh'
+    }
 }