MDEPLOY-118: Add parameter comparePomWithDeployed to deploy goal.

Author: Mathias de Riese

src/main/java/org/apache/maven/plugins/deploy/DeployMojo.java

@@ -20,6 +20,8 @@
  */
 
 import java.io.File;
+import java.io.IOException;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.regex.Matcher;
@@ -36,13 +38,22 @@
 import org.apache.maven.project.MavenProject;
 import org.apache.maven.project.artifact.ProjectArtifact;
 import org.apache.maven.project.artifact.ProjectArtifactMetadata;
+import org.codehaus.plexus.util.ReaderFactory;
+import org.codehaus.plexus.util.xml.Xpp3Dom;
+import org.codehaus.plexus.util.xml.Xpp3DomBuilder;
+import org.codehaus.plexus.util.xml.pull.XmlPullParserException;
+import org.eclipse.aether.artifact.Artifact;
+import org.eclipse.aether.artifact.DefaultArtifact;
 import org.eclipse.aether.deployment.DeployRequest;
 import org.eclipse.aether.repository.RemoteRepository;
+import org.eclipse.aether.resolution.ArtifactRequest;
+import org.eclipse.aether.resolution.ArtifactResolutionException;
+import org.eclipse.aether.resolution.ArtifactResult;
 import org.eclipse.aether.util.artifact.SubArtifact;
 
 /**
  * Deploys an artifact to remote repository.
- * 
+ *
  * @author <a href="mailto:[email protected]">Emmanuel Venisse</a>
  * @author <a href="mailto:[email protected]">John Casey (refactoring only)</a>
  */
@@ -67,7 +78,7 @@ public class DeployMojo
      * Whether every project should be deployed during its own deploy-phase or at the end of the multimodule build. If
      * set to {@code true} and the build fails, none of the reactor projects is deployed.
      * <strong>(experimental)</strong>
-     * 
+     *
      * @since 2.8
      */
     @Parameter( defaultValue = "false", property = "deployAtEnd" )
@@ -128,6 +139,13 @@ public class DeployMojo
     @Parameter( property = "maven.deploy.skip", defaultValue = "false" )
     private String skip = Boolean.FALSE.toString();
 
+    /**
+     *
+     * @since 3.0.1
+     */
+    @Parameter( property = "comparePomWithDeployed", defaultValue = "false" )
+    private boolean comparePomWithDeployed;
+
     private enum State
     {
         SKIPPED, DEPLOYED, TO_BE_DEPLOYED
@@ -173,6 +191,7 @@ private boolean hasState( MavenProject project )
         return pluginContext.containsKey( DEPLOY_PROCESSED_MARKER );
     }
 
+    @Override
     public void execute()
         throws MojoExecutionException, MojoFailureException
     {
@@ -261,7 +280,8 @@ private DeployRequest processProject( final MavenProject project,
 
         if ( pomFile != null )
         {
-            request.addArtifact( RepositoryUtils.toArtifact( new ProjectArtifact( project ) ) );
+            Artifact pomArtifact = RepositoryUtils.toArtifact( new ProjectArtifact( project ) );
+            new DeployedPomChecker( pomArtifact, request ).addPomConditionally();
             pomArtifactAttached = true;
         }
 
@@ -279,11 +299,12 @@ private DeployRequest processProject( final MavenProject project,
                     {
                         if ( metadata instanceof ProjectArtifactMetadata )
                         {
-                            request.addArtifact( new SubArtifact(
+                            Artifact pomArtifact = new SubArtifact(
                                     mainArtifact,
                                     "",
                                     "pom"
-                            ).setFile( ( (ProjectArtifactMetadata) metadata ).getFile() ) );
+                            ).setFile( ( (ProjectArtifactMetadata) metadata ).getFile() );
+                            new DeployedPomChecker( pomArtifact, request ).addPomConditionally();
                             pomArtifactAttached = true;
                         }
                     }
@@ -315,6 +336,102 @@ else if ( !project.getAttachedArtifacts().isEmpty() )
         return request;
     }
 
+    private class DeployedPomChecker
+    {
+        final Artifact pomArtifact;
+        final DeployRequest request;
+        final RemoteRepository repo;
+
+        DeployedPomChecker( Artifact pomArtifact, DeployRequest request )
+        {
+            this.pomArtifact = pomArtifact;
+            this.request = request;
+            this.repo = request.getRepository();
+        }
+
+        public void addPomConditionally ()
+        throws MojoExecutionException, MojoFailureException
+        {
+            if ( comparePomWithDeployed )
+            {
+                try
+                {
+                    if ( deployedPomIsEqual() )
+                    {
+                        return;
+                    }
+                }
+                catch ( IOException | XmlPullParserException e )
+                {
+                    throw new MojoExecutionException( "Failed to compare POM with a version "
+                            + "previously deployed to the repository: " + e.getMessage(), e );
+                }
+            }
+
+            request.addArtifact( pomArtifact );
+        }
+
+        private boolean deployedPomIsEqual()
+                throws IOException, XmlPullParserException, MojoFailureException
+        {
+            Xpp3Dom deployedPomDom = retrieveDeployedPom();
+            if ( deployedPomDom == null )
+            {
+                return false;
+            }
+
+            File pomFile = pomArtifact.getFile();
+            Xpp3Dom newPomDom = Xpp3DomBuilder.build( ReaderFactory.newXmlReader( pomFile ) );
+
+            if ( newPomDom.equals( deployedPomDom ) )
+            {
+                getLog().info( "Not deploying POM, since deployed POM is equal to current POM." );
+                return true;
+            }
+            else
+            {
+                String artifactId = RepositoryUtils.toArtifact( pomArtifact ).getId();
+                String gav = pomArtifact.getGroupId() + ":" + pomArtifact.getArtifactId()
+                      + ":" + pomArtifact.getVersion();
+
+                String shortMsg = "Project version " + gav + " already deployed with a differing POM.";
+                getLog().error( shortMsg );
+
+                throw new MojoFailureException( artifactId,
+                        shortMsg,
+                        "Project version " + gav + " already deployed and the POM '" + artifactId + "' "
+                      + "deployed in repository '" + repo.getUrl() + "' "
+                      + "differs from the POM that would be deployed. No artifacts will be deployed." );
+            }
+        }
+
+        private Xpp3Dom retrieveDeployedPom ()
+                throws IOException, XmlPullParserException
+        {
+            Artifact lookupArtifact =
+                new DefaultArtifact( pomArtifact.getGroupId(), pomArtifact.getArtifactId(),
+                                     pomArtifact.getClassifier(), pomArtifact.getExtension(),
+                                     pomArtifact.getVersion(), pomArtifact.getProperties(),
+                                     (File) null );
+            List<RemoteRepository> repos = Collections.singletonList( repo );
+
+            ArtifactRequest request = new ArtifactRequest( lookupArtifact, repos, null );
+
+            try ( TempLocalRepoSession tempRepoSession =
+                    TempLocalRepoSession.create( session.getRepositorySession(), repositorySystem ) )
+            {
+                ArtifactResult result = repositorySystem.resolveArtifact( tempRepoSession, request );
+
+                File deployedPom = result.getArtifact().getFile();
+                return Xpp3DomBuilder.build( ReaderFactory.newXmlReader( deployedPom ) );
+            }
+            catch ( ArtifactResolutionException ex )
+            {
+                return null;
+            }
+        }
+    }
+
     /**
      * Visible for testing.
      */

src/main/java/org/apache/maven/plugins/deploy/TempLocalRepoSession.java

@@ -0,0 +1,104 @@
+package org.apache.maven.plugins.deploy;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.io.Closeable;
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import org.codehaus.plexus.util.FileUtils;
+import org.eclipse.aether.AbstractForwardingRepositorySystemSession;
+import org.eclipse.aether.DefaultRepositoryCache;
+import org.eclipse.aether.RepositoryCache;
+import org.eclipse.aether.RepositorySystem;
+import org.eclipse.aether.RepositorySystemSession;
+import org.eclipse.aether.repository.LocalRepository;
+import org.eclipse.aether.repository.LocalRepositoryManager;
+import org.eclipse.aether.repository.WorkspaceReader;
+
+/**
+ *
+ */
+class TempLocalRepoSession extends AbstractForwardingRepositorySystemSession implements Closeable
+{
+    private final RepositorySystemSession origSession;
+    private final RepositoryCache cache;
+    private final File tempBasedir;
+    private LocalRepositoryManager lrm;
+
+    private TempLocalRepoSession( RepositorySystemSession origSession, File tempBasedir )
+    {
+        this.origSession = origSession;
+        this.cache = new DefaultRepositoryCache();
+        this.tempBasedir = tempBasedir;
+        this.lrm = null;
+    }
+
+    public static TempLocalRepoSession create( RepositorySystemSession origSession, RepositorySystem repoSystem )
+            throws IOException
+    {
+        // Place a temporary local repository next to the regular one, as done on the maven-assembly-plugin.
+        File origBasedir = origSession.getLocalRepository().getBasedir();
+        Path parentDir = origBasedir.getParentFile().toPath();
+        File newBasedir = Files.createTempDirectory( parentDir, origBasedir.getName() ).toFile();
+
+        TempLocalRepoSession newSession = new TempLocalRepoSession( origSession, newBasedir );
+
+        String contentType = origSession.getLocalRepository().getContentType();
+        String repositoryType = "enhanced".equals( contentType ) ? "default" : contentType;
+        LocalRepository localRepository = new LocalRepository( newBasedir, repositoryType );
+
+        newSession.lrm = repoSystem.newLocalRepositoryManager( newSession, localRepository );
+
+        return newSession;
+    }
+
+    @Override
+    protected RepositorySystemSession getSession()
+    {
+        return origSession;
+    }
+
+    @Override
+    public RepositoryCache getCache()
+    {
+        return cache;
+    }
+
+    @Override
+    public LocalRepositoryManager getLocalRepositoryManager()
+    {
+        return lrm;
+    }
+
+    @Override
+    public WorkspaceReader getWorkspaceReader()
+    {
+        return null;
+    }
+
+    @Override
+    public void close()
+            throws IOException
+    {
+        FileUtils.deleteDirectory( tempBasedir );
+    }
+}