Merge pull request #435 from SAP/add-central-release-workflow

Github Action to Build and Publish Releases

Author: Felix-Griesau-SAP

.github/workflows/RELEASE.md

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+# Release workflow
+
+`release.yml` publishes to Maven Central (Sonatype Central Portal) via the `central` Maven profile. It runs on a published GitHub Release or a manual `workflow_dispatch`; it doesn't create releases.
+
+## Flow
+1. Cut a GitHub Release (or dispatch the workflow, which won't create a github release).
+2. A maintainer approves the `maven-central` environment prompt.
+3. The job builds, signs, and uploads to the Portal, where it's staged.
+4. Someone with publish access in the Sonatype Portal (org membership on the `com.sap.hcp.cf.logging` namespace) publishes in the Portal to release to Central. This could be automated if deemed useful (https://central.sonatype.org/publish/publish-portal-maven/#autopublish).
+
+## Secrets
+Kept on the `maven-central` GitHub Environment, not repo or org secrets. This is essential for security, if you ever need to set this up yourself (https://docs.github.com/en/actions/how-tos/deploy/configure-and-manage-deployments/manage-environments):
+
+- `MAVEN_CENTRAL_USERNAME` / `MAVEN_CENTRAL_PASSWORD`
+- `MAVEN_GPG_PRIVATE_KEY`
+- `MAVEN_GPG_PASSPHRASE`
+
+They only inject after the environment rules pass: review, and allowed refs limited to `main`. Other runs are not able to retrieve the credentials.

.github/workflows/release.yml

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+name: Release to Maven Central
+
+# Publishes to Maven Central (Sonatype Central Portal) via the `central` profile
+# in pom.xml. Uses signing/publishing secrets; see RELEASE.md before
+# changing triggers, permissions or the environment.
+
+on:
+  release:
+    types: [published]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: release-maven-central
+  cancel-in-progress: false
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    environment: maven-central   # secrets live here, gated by required reviewers
+    steps:
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
+        with:
+          persist-credentials: false
+
+      - name: Set up JDK, Maven settings, GPG
+        uses: actions/setup-java@cf277c60eb25467037889841efdb72551f06f6c3 # v4.9.1
+        with:
+          distribution: temurin
+          java-version: '17'
+          server-id: central
+          # username/password/passphrase are env-var NAMES: setup-java writes them
+          # into settings.xml and Maven resolves them from env at runtime (never on disk).
+          # gpg-private-key is the actual key value: setup-java imports it here.
+          server-username: MAVEN_CENTRAL_USERNAME
+          server-password: MAVEN_CENTRAL_PASSWORD
+          gpg-private-key: ${{ secrets.MAVEN_GPG_PRIVATE_KEY }}
+          gpg-passphrase: MAVEN_GPG_PASSPHRASE
+
+      - name: Deploy (uploads and stages; Publish is a manual click in the Portal)
+        run: mvn -B -ntp -P central deploy
+        env:
+          MAVEN_CENTRAL_USERNAME: ${{ secrets.MAVEN_CENTRAL_USERNAME }}
+          MAVEN_CENTRAL_PASSWORD: ${{ secrets.MAVEN_CENTRAL_PASSWORD }}
+          MAVEN_GPG_PASSPHRASE: ${{ secrets.MAVEN_GPG_PASSPHRASE }}