Add CI workflow to check for unapproved Go dependency licenses

A task and GitHub Actions workflow are provided here for checking the license types of Go project dependencies.

On every push and pull request that affects relevant files, the CI workflow will check:

- If the dependency licenses cache is up to date
- If any of the project's dependencies have an unapproved license type.

Approval can be based on:

- Universally allowed license type
- Individual dependency

.ecrc

@@ -1,5 +1,6 @@
 {
   "Exclude": [
+    "^\\.licenses/",
     "LICENSE.txt",
     "poetry.lock"
   ]

.github/workflows/check-go-dependencies-task.yml

@@ -0,0 +1,109 @@
+# Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-go-dependencies-task.md
+name: Check Go Dependencies
+
+env:
+  # See: https://github.com/actions/setup-go/tree/v2#readme
+  GO_VERSION: "1.16"
+
+# See: https://docs.github.com/en/actions/reference/events-that-trigger-workflows
+on:
+  push:
+    paths:
+      - ".github/workflows/check-go-dependencies-task.ya?ml"
+      - ".licenses/**"
+      - ".licensed.json"
+      - ".licensed.ya?ml"
+      - "Taskfile.ya?ml"
+      - "**/.gitmodules"
+      - "**/go.mod"
+      - "**/go.sum"
+  pull_request:
+    paths:
+      - ".github/workflows/check-go-dependencies-task.ya?ml"
+      - ".licenses/**"
+      - ".licensed.json"
+      - ".licensed.ya?ml"
+      - "Taskfile.ya?ml"
+      - "**/.gitmodules"
+      - "**/go.mod"
+      - "**/go.sum"
+  workflow_dispatch:
+  repository_dispatch:
+
+jobs:
+  check-cache:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+        with:
+          submodules: recursive
+
+      - name: Install licensed
+        uses: jonabc/setup-licensed@v1
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          version: 3.x
+
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
+      - name: Install Task
+        uses: arduino/setup-task@v1
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          version: 3.x
+
+      - name: Update dependencies license metadata cache
+        run: task --silent general:cache-dep-licenses
+
+      - name: Check for outdated cache
+        id: diff
+        run: |
+          git add --intent-to-add .
+          if ! git diff --color --exit-code; then
+            echo
+            echo "::error::Dependency license metadata out of sync. See: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-go-dependencies-task.md#metadata-cache"
+            exit 1
+          fi
+
+      # Some might find it convenient to have CI generate the cache rather than setting up for it locally
+      - name: Upload cache to workflow artifact
+        if: failure() && steps.diff.outcome == 'failure'
+        uses: actions/upload-artifact@v2
+        with:
+          if-no-files-found: error
+          name: dep-licenses-cache
+          path: .licenses/
+
+  check-deps:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+        with:
+          submodules: recursive
+
+      - name: Install licensed
+        uses: jonabc/setup-licensed@v1
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          version: 3.x
+
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
+      - name: Install Task
+        uses: arduino/setup-task@v1
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          version: 3.x
+
+      - name: Check for dependencies with unapproved licenses
+        run: task --silent general:check-dep-licenses

.gitignore

@@ -1,3 +1,4 @@
 __pycache__/
 /.github/workflows/assets/validate-registry/validate-registry
+!/.github/workflows/assets/validate-registry/validate-registry/
 /.github/workflows/assets/validate-registry/validate-registry.exe

.licensed.yml

@@ -0,0 +1,86 @@
+# See: https://github.com/github/licensed/blob/master/docs/configuration.md
+sources:
+  go: true
+
+apps:
+  - source_path: .github/workflows/assets/validate-registry/
+
+# Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/assets/check-dependencies/AGPL-3.0/.licensed.yml
+allowed:
+  # The following are based on: https://www.gnu.org/licenses/license-list.html#GPLCompatibleLicenses
+  - gpl-1.0-or-later
+  - gpl-1.0+ # Deprecated ID for `gpl-1.0-or-later`
+  - gpl-2.0-or-later
+  - gpl-2.0+ # Deprecated ID for `gpl-2.0-or-later`
+  - gpl-3.0-only
+  - gpl-3.0 # Deprecated ID for `gpl-3.0-only`
+  - gpl-3.0-or-later
+  - gpl-3.0+ # Deprecated ID for `gpl-3.0-or-later`
+  - lgpl-2.0-or-later
+  - lgpl-2.0+ # Deprecated ID for `lgpl-2.0-or-later`
+  - lgpl-2.1-only
+  - lgpl-2.1 # Deprecated ID for `lgpl-2.1-only`
+  - lgpl-2.1-or-later
+  - lgpl-2.1+ # Deprecated ID for `lgpl-2.1-or-later`
+  - lgpl-3.0-only
+  - lgpl-3.0 # Deprecated ID for `lgpl-3.0-only`
+  - lgpl-3.0-or-later
+  - lgpl-3.0+ # Deprecated ID for `lgpl-3.0-or-later`
+  - agpl-1.0-or-later
+  - agpl-3.0-only
+  - agpl-3.0 # Deprecated ID for `agpl-3.0-only`
+  - agpl-3.0-or-later
+  - fsfap
+  - apache-2.0
+  - artistic-2.0
+  - clartistic
+  - sleepycat
+  - bsl-1.0
+  - bsd-3-clause
+  - cecill-2.0
+  - bsd-3-clause-clear
+  # "Cryptix General License" - no SPDX ID (https://github.com/spdx/license-list-XML/issues/456)
+  - ecos-2.0
+  - ecl-2.0
+  - efl-2.0
+  - eudatagrid
+  - mit
+  - bsd-2-clause # Subsumed by `bsd-2-clause-views`
+  - bsd-2-clause-netbsd # Deprecated ID for `bsd-2-clause`
+  - bsd-2-clause-views # This is the version linked from https://www.gnu.org/licenses/license-list.html#FreeBSD
+  - bsd-2-clause-freebsd # Deprecated ID for `bsd-2-clause-views`
+  - ftl
+  - hpnd
+  - imatix
+  - imlib2
+  - ijg
+  # "Informal license" - this is a general class of license
+  - intel
+  - isc
+  - mpl-2.0
+  - ncsa
+  # "License of Netscape JavaScript" - no SPDX ID
+  - oldap-2.7
+  # "License of Perl 5 and below" - possibly `Artistic-1.0-Perl` ?
+  - cc0-1.0
+  - cc-pddc
+  - psf-2.0
+  - ruby
+  - sgi-b-2.0
+  - smlnj
+  - standardml-nj # Deprecated ID for `smlnj`
+  - unicode-dfs-2015
+  - upl-1.0
+  - unlicense
+  - vim
+  - w3c
+  - wtfpl
+  - lgpl-2.0-or-later with wxwindows-exception-3.1
+  - wxwindows # Deprecated ID for `lgpl-2.0-or-later with wxwindows-exception-3.1`
+  - x11
+  - xfree86-1.1
+  - zlib
+  - zpl-2.0
+  - zpl-2.1
+  # The following are based on individual license text
+  - eupl-1.2

.prettierignore

@@ -0,0 +1 @@
+/.licenses/

README.md

@@ -10,6 +10,7 @@
 [![Check Workflows status](https://github.com/arduino/library-registry/actions/workflows/check-workflows-task.yml/badge.svg)](https://github.com/arduino/library-registry/actions/workflows/check-workflows-task.yml)
 [![Check YAML status](https://github.com/arduino/library-registry/actions/workflows/check-yaml-task.yml/badge.svg)](https://github.com/arduino/library-registry/actions/workflows/check-yaml-task.yml)
 [![Check License status](https://github.com/arduino/library-registry/actions/workflows/check-license.yml/badge.svg)](https://github.com/arduino/library-registry/actions/workflows/check-license.yml)
+[![Check Go Dependencies status](https://github.com/arduino/library-registry/actions/workflows/check-go-dependencies-task.yml/badge.svg)](https://github.com/arduino/library-registry/actions/workflows/check-go-dependencies-task.yml)
 
 This branch contains the generated source file for the Arduino Library Manager index. If you want to add a library to
 the Arduino Library Manager index, please follow these instructions:

Taskfile.yml

@@ -35,6 +35,30 @@ tasks:
             -s "{{.WORKFLOW_SCHEMA_PATH}}" \
             -d "{{.WORKFLOWS_DATA_PATH}}"
 
+  # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/assets/check-dependencies-task/Taskfile.yml
+  general:cache-dep-licenses:
+    desc: Cache dependency license metadata
+    cmds:
+      - |
+        if ! which licensed &>/dev/null; then
+          if [[ "{{OS}}" == "windows" ]]; then
+            echo "Licensed does not have Windows support."
+            echo "Please use Linux/macOS or download the dependencies cache from the GitHub Actions workflow artifact."
+          else
+            echo "licensed not found or not in PATH. Please install: https://github.com/github/licensed#as-an-executable"
+          fi
+          exit 1
+        fi
+      - licensed cache
+
+  # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/assets/check-dependencies-task/Taskfile.yml
+  general:check-dep-licenses:
+    desc: Check for unapproved dependency licenses
+    deps:
+      - task: general:cache-dep-licenses
+    cmds:
+      - licensed status
+
   # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/assets/check-general-formatting-task/Taskfile.yml
   general:check-formatting:
     desc: Check basic formatting style of all files