[ci] build runtime only if runtime files were changed

.gitlab-ci.yml

@@ -234,7 +234,7 @@ build-test-parachain:
   variables:
     # Enable debug assertions since we are running optimized builds for testing
     # but still want to have debug assertions.
-    RUSTFLAGS: "-Cdebug-assertions=y -Dwarnings"
+    RUSTFLAGS:                     "-Cdebug-assertions=y -Dwarnings"
   # this is an artificial job dependency, for pipeline optimization using GitLab's DAGs
   needs:
     - job:                         check-rustdoc
@@ -248,9 +248,55 @@ build-test-parachain:
     - mkdir -p ./artifacts/zombienet
     - mv ./target/release/wbuild/cumulus-test-runtime/wasm_binary_spec_version_incremented.rs.compact.compressed.wasm ./artifacts/zombienet/.
 
+# build runtime only if files in $RUNTIME_PATH/$RUNTIME_NAME were changed
+.build-runtime-template:           &build-runtime-template
+  stage:                           build
+  <<:                              *docker-env
+  <<:                              *pr-refs
+  # this is an artificial job dependency, for pipeline optimization using GitLab's DAGs
+  needs:
+    - job:                         check-rustdoc
+      artifacts:                   false
+  variables:
+    RUNTIME_PATH:                  "parachains/runtimes/assets"
+  script:
+    - cd ${RUNTIME_PATH}
+    - for directory in $(echo */); do
+        cd $directory;
+        SKIP_WASM_BUILD=1 cargo check;
+        cd ..;
+      done
+
+
+build-runtime-assets:
+  <<: *build-runtime-template
+  variables:
+    RUNTIME_PATH:                  "parachains/runtimes/assets"
+
+build-runtime-collectives:
+  <<: *build-runtime-template
+  variables:
+    RUNTIME_PATH:                  "parachains/runtimes/collectives"
+
+build-runtime-contracts:
+  <<: *build-runtime-template
+  variables:
+    RUNTIME_PATH:                  "parachains/runtimes/contracts"
+
+build-runtime-starters:
+  <<: *build-runtime-template
+  variables:
+    RUNTIME_PATH:                  "parachains/runtimes/starters"
+
+build-runtime-testing:
+  <<: *build-runtime-template
+  variables:
+    RUNTIME_PATH:                  "parachains/runtimes/testing"
+
+
 #### stage:                        publish
 
-.build-push-image:                  &build-push-image
+.build-push-image:                 &build-push-image
   image:                           quay.io/buildah/stable
   variables:
     DOCKERFILE:                    "" # docker/path-to.Dockerfile