Normalize Docker image name for building a static image via matrix

.gitlab/ci/definitions.yml

@@ -36,16 +36,17 @@
     # Hack to set an array in /bin/sh
     # http://unix.stackexchange.com/a/137571
     - set -- $CI_JOB_NAME
+    - export IMAGE_NAME=${1/:/}
     - |
       docker buildx build \
         --cache-to=type=inline \
-        --cache-from="$CI_REGISTRY_IMAGE:$1" \
+        --cache-from="$CI_REGISTRY_IMAGE:$IMAGE_NAME" \
         --platform=linux/${ARCH:-amd64} \
         --push="${PUSH_CUSTOM_IMAGE:-false}" \
         --label "ci_pipeline_url=$CI_PIPELINE_URL" \
         --label "ci_job_url=$CI_JOB_URL" \
-        -t "$CI_REGISTRY_IMAGE:$1" \
-        -f "Dockerfile.$1" \
+        -t "$CI_REGISTRY_IMAGE:$IMAGE_NAME" \
+        -f "Dockerfile.$IMAGE_NAME" \
         .
   rules:
     - if: '$CI_PIPELINE_SOURCE == "schedule"'

README.md

@@ -30,6 +30,16 @@ new-image:
   extends: .build_static_image
 ```
 
+**NOTE:** You can use `parallel:matrix` keyword to build images for multiple architectures:
+
+```yml
+new-image:
+  extends: .build_static_image
+  parallel:
+    matrix:
+      - ARCH: [ 'arm64', 'amd64' ]
+```
+
 1. Add a Dockerfile: `Dockerfile.new-image`.
 
 ### Use a custom image with versioned features