ci: staking-miner-playground check only if changed

.github/workflows/ci.yml

@@ -102,25 +102,6 @@ jobs:
           ${{ env.RUST_INFO }}
           cargo hack check --workspace --each-feature --all-targets
 
-  check-staking-miner-playground:
-    name: Check staking-miner-playground
-    runs-on: ubuntu-latest
-    needs: [set-image]
-    container: ${{ needs.set-image.outputs.IMAGE }}
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@v4
-
-      - name: Cache Rust dependencies
-        uses: swatinem/rust-cache@v2
-        with:
-          key: ${{ runner.os }}-rust-${{ hashFiles('**/Cargo.lock') }}
-
-      - name: Check staking-miner-playground
-        run: |
-          ${{ env.RUST_INFO }}
-          cargo check --manifest-path staking-miner-playground/Cargo.toml
-
   test:
     name: Run tests
     runs-on: ubuntu-latest
@@ -181,7 +162,6 @@ jobs:
             check-clippy,
             check-docs,
             check-cargo-hack,
-            check-staking-miner-playground,
             test,
             build]
     steps:
@@ -221,7 +201,6 @@ jobs:
             check-clippy,
             check-docs,
             check-cargo-hack,
-            check-staking-miner-playground,
             test,
             build]
     steps:

.github/workflows/staking-miner-playground.yml

@@ -0,0 +1,47 @@
+name: Polkadot Staking Miner Playground CI
+
+on:
+  pull_request:
+    branches:
+      - main
+    paths:
+      - 'staking-miner-playground/**'
+
+env:
+  IMAGE: paritytech/ci-unified:bullseye-1.77.0-2024-04-10-v20240408
+  IMAGE_NAME: paritytech/polkadot-staking-miner
+  RUST_INFO: rustup show && cargo --version && rustup +nightly show && cargo +nightly --version
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  set-image:
+    # GitHub Actions does not allow using 'env' in a container context.
+    # This workaround sets the container image for each job using 'set-image' job output.
+    runs-on: ubuntu-latest
+    outputs:
+      IMAGE: ${{ steps.set_image.outputs.IMAGE }}
+    steps:
+      - id: set_image
+        run: echo "IMAGE=${{ env.IMAGE }}" >> $GITHUB_OUTPUT
+
+  check:
+    name: Check staking-miner-playground
+    runs-on: ubuntu-latest
+    needs: [set-image]
+    container: ${{ needs.set-image.outputs.IMAGE }}
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Cache Rust dependencies
+        uses: swatinem/rust-cache@v2
+        with:
+          key: ${{ runner.os }}-rust-${{ hashFiles('**/Cargo.lock') }}
+
+      - name: Check staking-miner-playground
+        run: |
+          ${{ env.RUST_INFO }}
+          cargo check --manifest-path staking-miner-playground/Cargo.toml