Add Gem publishing steps in udp exporter release workflow (#148)

* add actual publishing steps in udp exporter release workflow

* add gh release step

* add release notes

Author: jj22ee

.github/workflows/release-udp-exporter.yml

@@ -2,7 +2,7 @@ name: Release ADOT X-Ray UDP Exporter
 on:
   workflow_dispatch:
     inputs:
-      version:
+      udp-exporter-version:
         description: The version to tag the release with, e.g., 1.2.0
         required: true
 
@@ -11,6 +11,7 @@ env:
 
 permissions:
   id-token: write
+  contents: write
 
 jobs:
   validate-udp-exporter-e2e-test:
@@ -38,9 +39,48 @@ jobs:
           cache-version: "v1-ruby-xray-udp"
 
       - name: Run Unit Tests
+        working-directory: "exporter/xray-udp"
         run: |
-          cd exporter/xray-udp
           bundle install
           bundle exec rake test
 
-      # TODO: Publish OTLP UDP Exporter to RubyGems
+      - name: Build gem
+        working-directory: "exporter/xray-udp"
+        run: |
+          gem build aws-distro-opentelemetry-exporter-xray-udp.gemspec
+
+      - name: Validate gem version matches workflow input
+        working-directory: "exporter/xray-udp"
+        run: |
+          if [[ ! -f aws-distro-opentelemetry-exporter-xray-udp-${{ inputs.udp-exporter-version }}.gem ]]; then
+            echo "Input version '${{ inputs.udp-exporter-version }}' does not match with UDP Exporter gem version"
+            exit 1
+          fi
+
+      - name: Set API key credentials
+        run: |
+          mkdir -p $HOME/.gem
+          touch $HOME/.gem/credentials
+          chmod 0600 $HOME/.gem/credentials
+          printf -- "---\n:rubygems_api_key: ${GEM_HOST_API_KEY}\n" > $HOME/.gem/credentials
+        env:
+          GEM_HOST_API_KEY: ${{ secrets.RUBYGEMS_UDP_EXPORTER_API_KEY }}
+
+      - name: Push gem
+        working-directory: "exporter/xray-udp"
+        run: gem push aws-distro-opentelemetry-exporter-xray-udp-${{ inputs.udp-exporter-version }}.gem
+
+      - name: Clear credentials
+        run: rm -f ~/.gem/credentials
+
+      # Publish to GitHub releases
+      - name: Create GH release
+        id: create_release
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} # This token is provided by Actions, you do not need to create your own token
+        run: |
+          gh release create --target "$GITHUB_REF_NAME" \
+            --title "Release aws-distro-opentelemetry-exporter-xray-udp v${{ inputs.udp-exporter-version }}" \
+            --notes "Please refer to the [Changelog](https://github.com/aws-observability/aws-otel-ruby/blob/main/exporter/xray-udp/CHANGELOG.md) for more details" \
+            --draft \
+            "v${{ inputs.udp-exporter-version }}"