add docker release stage to pipeline

Jenkinsfile

@@ -61,5 +61,27 @@ pipeline {
                 }
             }
         }
+
+        stage('Release Docker image') {
+            steps {
+                script {
+                    sh script: 'git clean -ffdx', label: 'Clean repository'
+
+                    def version = sh(script: 'git describe --tags --always --match "Release_*" HEAD', returnStdout: true).trim()
+                    def imageUrl = "git.esoko.eu/esoko/mapguesser:${version}"
+
+                    sh script: """docker buildx build \
+                                    -t ${imageUrl} \
+                                    -f docker/Dockerfile \
+                                    --target mapg_release \
+                                    .""",
+                        label: 'Build Docker image')
+
+                    withDockerRegistry([credentialsId: 'gitea-system-user', url: 'https://git.esoko.eu/']) {
+                        sh script: "docker push ${image_url}", label: 'Push Docker image to registry'
+                    }
+                }
+            }
+        }
     }
 }