ci : Enable publishing snapshot artifacts to maven central

.github/workflows/release-snapshots.yml

@@ -0,0 +1,36 @@
+name: Release to SNAPSHOTS Maven Central
+
+env:
+  MAVEN_ARGS: -B -C -V -ntp -Dhttp.keepAlive=false -e ${{ github.event.inputs.additional_args }}
+  RELEASE_MAVEN_ARGS: -Prelease -Denforcer.skip=true
+  OSSRHUSERNAME: ${{ secrets.OSSRHUSERNAME }}
+  OSSRHPASSWORD: ${{ secrets.OSSRHPASSWORD }}
+  SIGNINGPASSWORD: ${{ secrets.SIGNINGPASSWORD }}
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: '0 2 * * *' # Every day at 2am
+
+jobs:
+  release-snapshots:
+    name: Release SNAPSHOT
+    # Cheap way to prevent accidental releases
+    # Modify the list to add users with release permissions
+    if: contains('["rhuss","rohanKanojia"]', github.actor)
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Setup Java
+        uses: actions/setup-java@v4
+        with:
+          java-version: 11
+          distribution: temurin
+          server-id: sonatype-nexus-snapshots
+          server-username: OSSRHUSERNAME
+          server-password: OSSRHPASSWORD
+          gpg-private-key: ${{ secrets.SIGNINGKEY }}
+          gpg-passphrase: SIGNINGPASSWORD
+      - name: Build and Release Project
+        run: ./mvnw ${MAVEN_ARGS} ${RELEASE_MAVEN_ARGS} clean deploy

README.md

@@ -35,6 +35,7 @@ It works with Maven 3.0.5 and Docker 1.6.0 or later.
   setups that you can use as blueprints for your projects.
 * [ChangeLog](doc/changelog.md) has the release history of this plugin.
 * [Contributing](CONTRIBUTING.md) explains how you can contribute to this project. Pull requests are highly appreciated!
+* We publish nightly builds on maven central. Read How to use [Docker Maven Plugin Snapshot artifacts](./doc/HowToUseDockerMavenPluginSnapshotArtifacts.md).
 
 
 #### Docker API Support

doc/HowToUseDockerMavenPluginSnapshotArtifacts.md

@@ -0,0 +1,41 @@
+# How to use Fabric8 docker-maven-plugin snapshot artifacts?
+
+Artifacts are hosted at [docker-maven-plugin's Sonatype Snapshot repository](https://oss.sonatype.org/content/repositories/snapshots/io/fabric8/docker-maven-plugin/)
+
+Our [GitHub Action Snapshot release workflow](https://github.com/fabric8io/docker-maven-plugin/blob/master/.github/workflows/release-snapshots.yml) updates SNAPSHOT artifacts every night.
+
+## Using SNAPSHOTs in Maven Project
+
+In order to use these artifacts, update your `pom.xml` with these:
+
+```xml
+<pluginRepositories>
+  <pluginRepository>
+    <id>oss.sonatype.org</id>
+    <url>https://oss.sonatype.org/content/repositories/snapshots</url>
+    <snapshots>
+      <enabled>true</enabled>
+      <updatePolicy>always</updatePolicy>
+    </snapshots>
+  </pluginRepository>
+</pluginRepositories>
+```
+
+You'd also need to update version of the plugin you're using to use a SNAPSHOT version instead of a stable version. Here is an example:
+
+```xml
+<properties>
+    <docker-maven-plugin.version>x.yz-SNAPSHOT</docker-maven-plugin.version>
+</properties>
+
+<build>
+    <plugins>
+        <plugin>
+            <groupId>io.fabric8</groupId>
+            <artifactId>docker-maven-plugin</artifactId>
+            <version>${docker-maven-plugin.version}</version>
+        </plugin>
+    </plugins>
+</build>
+```
+

pom.xml

@@ -529,18 +529,23 @@
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-gpg-plugin</artifactId>
             <version>1.6</version>
-            <configuration>
-              <skip>false</skip>
-            </configuration>
             <executions>
               <execution>
                 <id>sign-artifacts</id>
+                <phase>verify</phase>
                 <goals>
                   <goal>sign</goal>
                 </goals>
-                <phase>verify</phase>
               </execution>
             </executions>
+            <configuration>
+              <skip>false</skip>
+              <gpgArguments>
+                <arg>--batch</arg>
+                <arg>--pinentry-mode</arg>
+                <arg>loopback</arg>
+              </gpgArguments>
+            </configuration>
           </plugin>
 
           <plugin>