Fix generated release notes.

Drop the canned release notes action in favor of direct github api use.

Author: jmcarp

.github/workflows/release.yml

@@ -48,6 +48,10 @@ jobs:
     needs: build
     runs-on: ubuntu-latest
     steps:
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
     - uses: actions/download-artifact@v4
       with:
         path: dist
@@ -56,12 +60,23 @@ jobs:
     - working-directory: dist
       run: sha256sum otelcol-oxide-* > checksums.txt
 
-    - uses: softprops/action-gh-release@v2
-      with:
-        files: |
-          dist/otelcol-oxide-*
-          dist/checksums.txt
-        generate_release_notes: true
+    - name: Create or update release
+      run: |
+        PREV=$(git tag -l 'v*' --sort=-version:refname | sed -n '2p')
+        NOTES_ARGS="--generate-notes"
+        if [ -n "$PREV" ]; then
+          NOTES_ARGS="$NOTES_ARGS --notes-start-tag $PREV"
+        fi
+        if gh release view ${{ github.ref_name }} > /dev/null 2>&1; then
+          gh release upload ${{ github.ref_name }} \
+            dist/otelcol-oxide-* dist/checksums.txt --clobber
+        else
+          gh release create ${{ github.ref_name }} \
+            $NOTES_ARGS \
+            dist/otelcol-oxide-* dist/checksums.txt
+        fi
+      env:
+        GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
   docker:
     needs: build

README.md

@@ -143,14 +143,16 @@ make test
 
 ## Releasing
 
-To create a new release, first bump the versions in `collector/manifest.yaml`:
+To create a new release:
 
-- `dist.version` — the collector distribution version
-- The receiver gomod version (`github.com/oxidecomputer/opentelemetry-collector-components`)
-
-Then push a git tag matching `v*` (e.g. `v0.2.0`). This creates a new GitHub release, and publishes updated collector binaries and the Docker image.
+1. Bump the versions in `collector/manifest.yaml` and push to `main`:
+   - `dist.version`: the collector distribution version
+   - The receiver go.mod version (`github.com/oxidecomputer/opentelemetry-collector-components`)
+1. Tag the commit and push the tag. The tag must point to a commit on `main`, or the release workflow will fail.
 
 ```bash
 git tag v0.2.0
 git push origin v0.2.0
 ```
+
+This creates a new GitHub release, and publishes updated collector binaries and the Docker image.