Release automatically when the version changes

.github/README.md

@@ -25,6 +25,7 @@
 - [Migrating from v2 to v3](#migrating-from-v2-to-v3)
 - [Contributing](#contributing)
 - [Versioning](#versioning)
+- [Releasing](#releasing)
 - [License](#license)
 
 ## Install
@@ -271,6 +272,10 @@ Please read [CONTRIBUTING.md][CONTRIBUTING] for details on our code of conduct,
 
 We use [SemVer] for versioning. For the versions available, see the tags on this repository. 
 
+## Releasing
+
+Releases are cut by CI from the version in `src/IPData/IPData.csproj`. To ship a new version, bump `VersionPrefix` in a pull request and merge it: the CI run on `master` tags the merge commit `vX.Y.Z`, creates the GitHub release with generated notes and publishes the package to [NuGet](https://www.nuget.org/packages/IPData/). A merge whose version is already tagged publishes nothing.
+
 ## License
 
 This project is licensed under the MIT License - see the [LICENSE.md][LICENSE] file for details

.github/workflows/ci.yml

@@ -29,3 +29,59 @@ jobs:
 
       - name: Pack
         run: dotnet pack src/IPData/IPData.csproj --configuration Release --no-build
+
+  release:
+    needs: build-and-test
+    if: github.event_name == 'push' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch)
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    concurrency:
+      group: release
+      cancel-in-progress: false
+    outputs:
+      tag: ${{ steps.release.outputs.tag }}
+      created: ${{ steps.release.outputs.created }}
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Tag and create the release when the version is new
+        id: release
+        env:
+          GH_TOKEN: ${{ github.token }}
+          GH_REPO: ${{ github.repository }}
+        run: |
+          VERSION=$(sed -nE 's/.*<VersionPrefix>([^<]+)<.*/\1/p' src/IPData/IPData.csproj | head -1)
+          if [ -z "$VERSION" ]; then
+            echo "::error::VersionPrefix not found in src/IPData/IPData.csproj"
+            exit 1
+          fi
+          TAG="v$VERSION"
+          echo "tag=$TAG" >> "$GITHUB_OUTPUT"
+
+          status=0
+          git ls-remote --exit-code --tags origin "refs/tags/$TAG" >/dev/null || status=$?
+          case "$status" in
+            0)
+              echo "Tag $TAG already exists; nothing to release."
+              echo "created=false" >> "$GITHUB_OUTPUT"
+              ;;
+            2)
+              gh release create "$TAG" --target "$GITHUB_SHA" --title "$TAG" --generate-notes
+              echo "Created tag and release $TAG."
+              echo "created=true" >> "$GITHUB_OUTPUT"
+              ;;
+            *)
+              echo "::error::Could not check whether tag $TAG exists (git ls-remote exit status $status)."
+              exit "$status"
+              ;;
+          esac
+
+  publish:
+    needs: release
+    if: needs.release.outputs.created == 'true'
+    uses: ./.github/workflows/publish.yml
+    with:
+      tag: ${{ needs.release.outputs.tag }}
+    secrets: inherit

.github/workflows/publish.yml

@@ -3,6 +3,12 @@ name: Publish to NuGet
 on:
   release:
     types: [published]
+  workflow_call:
+    inputs:
+      tag:
+        description: Release tag to publish, for example v3.1.0
+        required: true
+        type: string
 
 jobs:
   publish:
@@ -21,7 +27,9 @@ jobs:
 
       - name: Get version from tag
         id: version
-        run: echo "VERSION=${GITHUB_REF_NAME#v}" >> "$GITHUB_OUTPUT"
+        env:
+          TAG: ${{ inputs.tag || github.ref_name }}
+        run: echo "VERSION=${TAG#v}" >> "$GITHUB_OUTPUT"
 
       - name: Build
         run: dotnet build --configuration Release --no-restore /p:Version=${{ steps.version.outputs.VERSION }}