Safe-guard publishing of artifacts on master to development versions

Since an actual release changes the version property but still results
in a push to the `master` branch, we safe-guard publishing CI artifacts.

.github/workflows/ci.yml

@@ -53,10 +53,13 @@ jobs:
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
-    - name: Publish SNAPSHOT artifacts to Sonatype OSSRH
+    - name: Publish development artifacts to Sonatype OSSRH
       if: github.event_name == 'push' && github.ref == 'refs/heads/master'
+      # Run only if current version is actually a development version
       run: |
-        ./gradlew -Psonatype build publishToSonatype
+        if ./scripts/is_development; then
+          ./gradlew -Psonatype build publishToSonatype
+        fi
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         GPG_PRIVATE_KEY: ${{ secrets.GPG_PRIVATE_KEY }}

scripts/_functions.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+
+# Helper variables
+_REPO_ROOT=$(git rev-parse --show-toplevel)
+
+# Get current version as specified in the project configuration
+current_version() {
+  grep -e '^version=.*$' "${_REPO_ROOT}/gradle.properties" | cut -d '=' -f 2
+}
+
+## Different checks (versions and git)
+# Check if the supplied version is a development version
+is_development_version() {
+  _version=$1
+  echo "${_version}" | grep -q -e '-SNAPSHOT$'
+}
+
+# Check if the supplied version is a (pre-)release version
+is_release_version() {
+  _version=$1
+  echo "${_version}" | grep -v -q -e '-SNAPSHOT$'
+}
+
+# Check if the supplied version is a REAL pre-release version
+is_prerelease_version() {
+  _version=$1
+  echo "${_version}" | grep -E -q -e '\.(RC|M)[[:digit:]]+$'
+}

scripts/is_development

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+# Global variables
+REPO_ROOT=$(git rev-parse --show-toplevel)
+
+# shellcheck source=_functions.sh
+. "${REPO_ROOT}/scripts/_functions.sh"
+
+CURRENT_VERSION=$(current_version)
+if is_development_version "$CURRENT_VERSION"; then
+  info "Current version '${CURRENT_VERSION}' is a development version."
+else
+  info "Current version '${CURRENT_VERSION}' is a release version."
+  exit 1
+fi