build: add license checker workflow

.github/licenserc.yml

@@ -0,0 +1,43 @@
+# Copyright The ORAS Authors.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+header:
+  license:
+    spdx-id: Apache-2.0
+    content: |
+      Copyright The ORAS Authors.
+      Licensed under the Apache License, Version 2.0 (the "License");
+      you may not use this file except in compliance with the License.
+      You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      See the License for the specific language governing permissions and
+      limitations under the License.
+
+  paths-ignore:
+    - '**/*.md'
+    - 'CODEOWNERS'
+    - 'LICENSE'
+    - 'go.mod'
+    - 'go.sum'
+    - '**/testdata/**'
+
+  comment: on-failure
+
+dependency:
+  files:
+    - go.mod

.github/workflows/license-checker.yml

@@ -0,0 +1,40 @@
+# Copyright The ORAS Authors.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: License Checker
+
+on:
+  push:
+    branches: main
+  pull_request:
+    branches: main
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  check-license:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Check license header
+        uses: apache/skywalking-eyes/header@v0.4.0
+        with:
+          mode: check
+          config: .github/licenserc.yml
+      - name: Check dependencies license
+        uses: apache/skywalking-eyes/dependency@v0.4.0
+        with:
+          config: .github/licenserc.yml

.gitignore

@@ -1,3 +1,16 @@
+# Copyright The ORAS Authors.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 # Binaries for programs and plugins
 *.exe
 *.exe~