improve deployment process

Jenkinsfile

@@ -15,18 +15,7 @@ pipeline {
             }
         }
 
-        stage('Build image') {
-            steps {
-                sh """
-                    docker build \
-                      --file kirby/Dockerfile \
-                      --tag ${IMAGE_REF} \
-                      kirby
-                """
-            }
-        }
-
-        stage('Push image') {
+        stage('Build & Push image') {
             steps {
                 withCredentials([usernamePassword(
                     credentialsId: 'gitea-container-registry',
@@ -34,9 +23,23 @@ pipeline {
                     passwordVariable: 'REGISTRY_PASSWORD'
                 )]) {
                     sh """
+                        if ! docker buildx inspect jenkins-builder >/dev/null 2>&1; then
+                          docker buildx create --name jenkins-builder --use
+                        else
+                          docker buildx use jenkins-builder
+                        fi
+                        docker buildx inspect --bootstrap
+
                         echo "${REGISTRY_PASSWORD}" | docker login ${REGISTRY_HOST} \
                             --username "${REGISTRY_USER}" --password-stdin
-                        docker push ${IMAGE_REF}
+
+                        docker buildx build \
+                          --platform linux/amd64 \
+                          --file Dockerfile \
+                          --tag ${IMAGE_REF} \
+                          --push \
+                          .
+
                         docker logout ${REGISTRY_HOST}
                     """
                 }