Resolving: MNG-767, MNG-768

o We should have a viable offline mode now. Plugin sensitivity updates to follow.

o See it0069 and it1014 for offline mode tests.

o Brett, building maven-plugins in offline mode with org/apache/maven/plugin/* removed will now give a nice error message. :)



git-svn-id: https://svn.apache.org/repos/asf/maven/components/trunk@291124 13f79535-47bb-0310-9956-ffa450edef68

maven-artifact-manager/src/main/java/org/apache/maven/artifact/deployer/DefaultArtifactDeployer.java

@@ -57,6 +57,12 @@ public class DefaultArtifactDeployer
                         ArtifactRepository localRepository )
         throws ArtifactDeploymentException
     {
+        if ( !wagonManager.isOnline() )
+        {
+            getLogger().warn( "System is offline. Cannot deploy artifact: " + artifact.getId() + "." );
+            return;
+        }
+        
         try
         {
             transformationManager.transformForDeployment( artifact, deploymentRepository, localRepository );

maven-artifact-manager/src/main/java/org/apache/maven/artifact/manager/DefaultWagonManager.java

@@ -70,6 +70,8 @@ public class DefaultWagonManager
 
     private TransferListener downloadMonitor;
     
+    private boolean online = true;
+
     public Wagon getWagon( String protocol )
         throws UnsupportedProtocolException
     {
@@ -105,6 +107,8 @@ public class DefaultWagonManager
                                 TransferListener downloadMonitor )
         throws TransferFailedException
     {
+        failIfNotOnline();
+        
         String protocol = repository.getProtocol();
 
         Wagon wagon;
@@ -278,6 +282,8 @@ public class DefaultWagonManager
     {
         // TODO: better excetpions - transfer failed is not enough?
         
+        failIfNotOnline();
+        
         Wagon wagon;
 
         ArtifactRepository mirror = getMirror( repository.getId() );
@@ -454,6 +460,14 @@ public class DefaultWagonManager
         }
     }
 
+    private void failIfNotOnline() throws TransferFailedException
+    {
+        if ( !isOnline() )
+        {
+            throw new TransferFailedException( "System is offline." );
+        }
+    }
+
     private void handleChecksumFailure( String checksumPolicy, String message, Throwable cause )
         throws ChecksumFailedException
     {
@@ -640,4 +654,14 @@ public class DefaultWagonManager
 
         mirrors.put( mirrorOf, mirror );
     }
+
+    public void setOnline( boolean online )
+    {
+        this.online = online;
+    }
+    
+    public boolean isOnline()
+    {
+        return online;
+    }
 }

maven-artifact-manager/src/main/java/org/apache/maven/artifact/manager/WagonManager.java

@@ -57,6 +57,10 @@ public interface WagonManager
                               String checksumPolicy )
         throws TransferFailedException, ResourceDoesNotExistException;
     
+    void setOnline( boolean online );
+    
+    boolean isOnline();
+
     void addProxy( String protocol, String host, int port, String username, String password, String nonProxyHosts );
 
     void addAuthenticationInfo( String repositoryId, String username, String password, String privateKey,

maven-artifact-manager/src/main/java/org/apache/maven/artifact/repository/DefaultArtifactRepositoryFactory.java

@@ -29,8 +29,6 @@ public class DefaultArtifactRepositoryFactory
 
     private String globalChecksumPolicy;
 
-    private boolean globalEnable = true;
-
     public ArtifactRepository createArtifactRepository( String id, String url,
                                                         ArtifactRepositoryLayout repositoryLayout )
     {
@@ -64,13 +62,6 @@ public class DefaultArtifactRepositoryFactory
             releases.setChecksumPolicy( globalChecksumPolicy );
         }
 
-        // TODO: needed, or can offline cover it?
-        if ( !globalEnable )
-        {
-            snapshots.setEnabled( false );
-            releases.setEnabled( false );
-        }
-
         return new DefaultArtifactRepository( id, url, repositoryLayout, snapshots, releases );
     }
 
@@ -84,8 +75,11 @@ public class DefaultArtifactRepositoryFactory
         this.globalChecksumPolicy = checksumPolicy;
     }
 
+    /**
+     * @deprecated. Not needed, use WagonManager.set/isOnline() instead.
+     */
     public void setGlobalEnable( boolean enable )
     {
-        this.globalEnable = enable;
+        // TODO: Remove this method from the API.
     }
 }

maven-artifact-manager/src/main/java/org/apache/maven/artifact/repository/metadata/AbstractRepositoryMetadata.java

@@ -178,4 +178,16 @@ public abstract class AbstractRepositoryMetadata
         AbstractRepositoryMetadata repoMetadata = (AbstractRepositoryMetadata) metadata;
         this.metadata.merge( repoMetadata.getMetadata() );
     }
+    
+    public String extendedToString()
+    {
+        StringBuffer buffer = new StringBuffer();
+        
+        buffer.append( "\nRepository Metadata\n--------------------------" );
+        buffer.append( "\nGroupId: " ).append( getGroupId() );
+        buffer.append( "\nArtifactId: " ).append( getArtifactId() );
+        buffer.append( "\nMetadata Type: " ).append(getClass().getName() );
+        
+        return buffer.toString();
+    }
 }

maven-artifact-manager/src/main/java/org/apache/maven/artifact/repository/metadata/DefaultRepositoryMetadataManager.java

@@ -183,6 +183,12 @@ public class DefaultRepositoryMetadataManager
                                ArtifactRepository remoteRepository )
         throws ArtifactMetadataRetrievalException
     {
+        if ( !wagonManager.isOnline() )
+        {
+            getLogger().debug( "System is offline. Cannot resolve metadata:\n" + metadata.extendedToString() + "\n\n" );
+            return;
+        }
+        
         File file = new File( localRepository.getBasedir(),
                               localRepository.pathOfLocalRepositoryMetadata( metadata, remoteRepository ) );
 
@@ -199,6 +205,12 @@ public class DefaultRepositoryMetadataManager
                                 String checksumPolicy )
         throws ArtifactMetadataRetrievalException
     {
+        if ( !wagonManager.isOnline() )
+        {
+            getLogger().debug( "System is offline. Cannot resolve metadata:\n" + metadata.extendedToString() + "\n\n" );
+            return;
+        }
+        
         try
         {
             wagonManager.getArtifactMetadata( metadata, repository, file, checksumPolicy );
@@ -228,6 +240,12 @@ public class DefaultRepositoryMetadataManager
                         ArtifactRepository deploymentRepository )
         throws ArtifactMetadataRetrievalException
     {
+        if ( !wagonManager.isOnline() )
+        {
+            getLogger().warn( "System is offline. Cannot deploy metadata:\n" + metadata.extendedToString() + "\n\n" );
+            return;
+        }
+        
         getLogger().info( "Retrieving previous metadata from " + deploymentRepository.getId() );
 
         File file = new File( localRepository.getBasedir(),

maven-artifact-manager/src/main/java/org/apache/maven/artifact/resolver/DefaultArtifactResolver.java

@@ -113,6 +113,13 @@ public class DefaultArtifactResolver
                 File destination = artifact.getFile();
                 if ( !destination.exists() || force )
                 {
+                    if ( !wagonManager.isOnline() )
+                    {
+                        getLogger().debug( "System is offline. Cannot resolve artifact: " + artifact.getId() + "." );
+                        
+                        return;
+                    }
+                    
                     try
                     {
                         if ( artifact.getRepository() != null )

maven-artifact-manager/src/main/java/org/apache/maven/artifact/transform/AbstractVersionTransformation.java

@@ -154,6 +154,15 @@ public abstract class AbstractVersionTransformation
         boolean alreadyResolved = alreadyResolved( artifact );
         if ( !alreadyResolved )
         {
+            if ( !wagonManager.isOnline() )
+            {
+                LegacyArtifactMetadata metadata = createLegacyMetadata( artifact );
+                getLogger().debug( "System is offline. Cannot resolve metadata:\n" + metadata.extendedToString() + "\n\n" );
+                
+                return null;
+            }
+            
+            
             boolean checkedUpdates = false;
             for ( Iterator i = remoteRepositories.iterator(); i.hasNext(); )
             {

maven-artifact-manager/src/main/java/org/apache/maven/artifact/transform/SnapshotTransformation.java

@@ -126,6 +126,15 @@ public class SnapshotTransformation
     {
         RepositoryMetadata metadata = new SnapshotArtifactRepositoryMetadata( artifact );
 
+        if ( !wagonManager.isOnline() )
+        {
+            getLogger().debug( "System is offline. Cannot resolve metadata:\n" + metadata.extendedToString() + "\n\n" );
+            
+            getLogger().info( "System is offline. Assuming build number of 0 for " + metadata.getGroupId() + ":" + metadata.getArtifactId() + " snapshot." );
+
+            return 0;
+        }
+        
         getLogger().info( "Retrieving previous build number from " + remoteRepository.getId() );
         repositoryMetadataManager.resolveAlways( metadata, localRepository, remoteRepository );
 

maven-artifact/src/main/java/org/apache/maven/artifact/metadata/AbstractArtifactMetadata.java

@@ -48,4 +48,16 @@ public abstract class AbstractArtifactMetadata
     {
         return artifact.getArtifactId();
     }
+    
+    public String extendedToString()
+    {
+        StringBuffer buffer = new StringBuffer();
+        
+        buffer.append( "\nArtifact Metadata\n--------------------------" );
+        buffer.append( "\nGroupId: " ).append( getGroupId() );
+        buffer.append( "\nArtifactId: " ).append( getArtifactId() );
+        buffer.append( "\nMetadata Type: " ).append(getClass().getName() );
+        
+        return buffer.toString();
+    }
 }

maven-artifact/src/main/java/org/apache/maven/artifact/metadata/ArtifactMetadata.java

@@ -78,4 +78,6 @@ public interface ArtifactMetadata
      */
     void storeInLocalRepository( ArtifactRepository localRepository, ArtifactRepository remoteRepository )
         throws ArtifactMetadataRetrievalException;
+    
+    String extendedToString();
 }

maven-artifact/src/main/java/org/apache/maven/artifact/repository/ArtifactRepositoryFactory.java

@@ -35,5 +35,8 @@ public interface ArtifactRepositoryFactory
 
     void setGlobalChecksumPolicy( String checksumPolicy );
 
+    /**
+     * @deprecated. Not needed, use WagonManager.set/isOnline() instead.
+     */
     void setGlobalEnable( boolean enable );
 }

maven-artifact/src/main/java/org/apache/maven/artifact/resolver/ArtifactResolutionException.java

@@ -41,18 +41,24 @@ public class ArtifactResolutionException
 
     private List remoteRepositories;
 
+    private final String originalMessage;
+
+    private final String path;
+
     public ArtifactResolutionException( String message, String groupId, String artifactId, String version, String type,
                                         List remoteRepositories, String downloadUrl, List path, Throwable t )
     {
         super( constructMessage( message, groupId, artifactId, version, type, remoteRepositories, downloadUrl, path ),
                t );
         
+        this.originalMessage = message;
         this.groupId = groupId;
         this.artifactId = artifactId;
         this.type = type;
         this.version = version;
         this.remoteRepositories = remoteRepositories;
         this.downloadUrl = downloadUrl;
+        this.path = constructArtifactPath( path );
     }
 
     public ArtifactResolutionException( String message, String groupId, String artifactId, String version, String type,
@@ -66,16 +72,46 @@ public class ArtifactResolutionException
     {
         super( constructMessage( message, groupId, artifactId, version, type, remoteRepositories, downloadUrl, path ) );
 
+        this.originalMessage = message;
         this.groupId = groupId;
         this.artifactId = artifactId;
         this.type = type;
         this.version = version;
         this.remoteRepositories = remoteRepositories;
         this.downloadUrl = downloadUrl;
+        this.path = constructArtifactPath( path );
+    }
+    
+    public String getOriginalMessage()
+    {
+        return originalMessage;
     }
 
     private static final String LS = System.getProperty( "line.separator" );
 
+    private static String constructArtifactPath( List path )
+    {
+        StringBuffer sb = new StringBuffer();
+        
+        if ( path != null )
+        {
+            sb.append( LS );
+            sb.append( "Path to dependency: " );
+            sb.append( LS );
+            int num = 1;
+            for ( Iterator i = path.iterator(); i.hasNext(); )
+            {
+                sb.append( "\t" );
+                sb.append( num++ );
+                sb.append( ") " );
+                sb.append( i.next() );
+                sb.append( LS );
+            }
+        }
+        
+        return sb.toString();
+    }
+
     private static String constructMessage( String message, String groupId, String artifactId, String version,
                                             String type, List remoteRepositories, String downloadUrl, List path )
     {
@@ -106,22 +142,8 @@ public class ArtifactResolutionException
             }
         }
 
-        if ( path != null )
+        sb.append( constructArtifactPath( path ) );
-        {
         sb.append( LS );
-            sb.append( "Path to dependency: " );
-            sb.append( LS );
-            int num = 1;
-            for ( Iterator i = path.iterator(); i.hasNext(); )
-            {
-                sb.append( "\t" );
-                sb.append( num++ );
-                sb.append( ") " );
-                sb.append( i.next() );
-                sb.append( LS );
-            }
-            sb.append( LS );
-        }
 
         if ( downloadUrl != null && !type.equals( "pom" ) )
         {
@@ -168,6 +190,9 @@ public class ArtifactResolutionException
     public ArtifactResolutionException( String message, Throwable cause )
     {
         super( message, cause );
+        
+        this.originalMessage = message;
+        this.path = "";
     }
 
     public String getGroupId()
@@ -199,4 +224,10 @@ public class ArtifactResolutionException
     {
         return downloadUrl;
     }
+    
+    public String getArtifactPath()
+    {
+        return path;
+    }
+    
 }

maven-core-it/it0068/verifier.properties

@@ -0,0 +1 @@
+failOnErrorOutput=false

maven-core-it/it0069/cli-options.txt

@@ -0,0 +1 @@
+-o

maven-core-it/it0069/expected-results.txt

@@ -0,0 +1 @@
+target/classes/org/apache/maven/it0069/ProjectBasedThing.class

maven-core-it/it0069/goals.txt

@@ -0,0 +1 @@
+compile

maven-core-it/it0069/pom.xml

@@ -0,0 +1,14 @@
+<project>
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>org.apache.maven.it0069</groupId>
+  <artifactId>maven-it0069</artifactId>
+  <version>1.0-SNAPSHOT</version>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.apache.maven</groupId>
+      <artifactId>maven-project</artifactId>
+      <version>2.0-beta-2-SNAPSHOT</version>
+    </dependency>
+  </dependencies>
+</project>

maven-core-it/it0069/src/main/java/org/apache/maven/it0069/ProjectBasedThing.java

@@ -0,0 +1,9 @@
+package org.apache.maven.it0069;
+
+import org.apache.maven.project.MavenProject;
+
+public class ProjectBasedThing
+{
+    private MavenProject project;
+}
+

maven-core-it/it1014/cli-options.txt

@@ -0,0 +1 @@
+-o

maven-core-it/it1014/expected-results.txt

@@ -0,0 +1 @@
+target/classes/org/apache/maven/it0069/ProjectBasedThing.class

maven-core-it/it1014/goals.txt

@@ -0,0 +1 @@
+compile

maven-core-it/it1014/pom.xml

@@ -0,0 +1,14 @@
+<project>
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>org.apache.maven.it1014</groupId>
+  <artifactId>maven-it1014</artifactId>
+  <version>1.0-SNAPSHOT</version>
+
+  <dependencies>
+    <dependency>
+      <groupId>commons-logging</groupId>
+      <artifactId>commons-logging</artifactId>
+      <version>1.0.3</version>
+    </dependency>
+  </dependencies>
+</project>

maven-core-it/it1014/prebuild-hook.txt

@@ -0,0 +1 @@
+rm ${artifact:commons-logging:commons-logging:1.0.3:jar}

maven-core-it/it1014/src/main/java/org/apache/maven/it0069/ProjectBasedThing.java

@@ -0,0 +1,6 @@
+package org.apache.maven.it0069;
+
+public class ProjectBasedThing
+{
+}
+

maven-core/src/main/java/org/apache/maven/DefaultMaven.java

@@ -103,7 +103,31 @@ public class DefaultMaven
     {
         if ( request.getSettings().isOffline() )
         {
-            getLogger().info( "Maven is running in offline mode." );
+            getLogger().info( "\n\nNOTE: Maven is running in offline mode.\n\n" );
+            
+            WagonManager wagonManager = null;
+
+            try
+            {
+                wagonManager = (WagonManager) container.lookup( WagonManager.ROLE );
+                
+                wagonManager.setOnline( false );
+            }
+            catch ( ComponentLookupException e )
+            {
+                throw new ReactorException( "Cannot retrieve WagonManager in order to set offline mode.", e );
+            }
+            finally
+            {
+                try
+                {
+                    container.release( wagonManager );
+                }
+                catch ( ComponentLifecycleException e )
+                {
+                    getLogger().warn( "Cannot release WagonManager.", e );
+                }
+            }
         }
 
         try
@@ -239,6 +263,8 @@ public class DefaultMaven
             }
             catch ( LifecycleExecutionException e )
             {
+                logFatal( e );
+                
                 throw new ReactorException( "Error executing project within the reactor", e );
             }
 
@@ -505,6 +531,19 @@ public class DefaultMaven
     // Reporting / Logging
     // ----------------------------------------------------------------------
     
+    protected void logFatal( Throwable error )
+    {
+        line();
+
+        getLogger().error( "FATAL ERROR" );
+
+        line();
+
+        diagnoseError( error );
+        
+        line();
+    }
+
     protected void logError( MavenExecutionResponse r )
     {
         line();
@@ -513,8 +552,17 @@ public class DefaultMaven
 
         line();
 
-        Throwable error = r.getException();
+        diagnoseError( r.getException() );
         
+        line();
+
+        stats( r.getStart(), r.getFinish() );
+
+        line();
+    }
+
+    private void diagnoseError( Throwable error )
+    {
         String message = null;
         if ( errorDiagnosers != null )
         {
@@ -538,13 +586,14 @@ public class DefaultMaven
 
         line();
 
-        getLogger().error( "Cause: ", r.getException() );
+        // TODO: needs to honour -e
+        if ( getLogger().isDebugEnabled() )
+        {
+            getLogger().debug( "Trace:\n", error );
 
             line();
+        }
 
-        stats( r.getStart(), r.getFinish() );
-
-        line();
     }
 
     protected void logFailure( MavenExecutionResponse r, Throwable error, String longMessage )

maven-core/src/main/java/org/apache/maven/cli/MavenCli.java

@@ -428,7 +428,6 @@ public class MavenCli
         {
             settings.setOffline( true );
             
-            artifactRepositoryFactory.setGlobalEnable( false );
             snapshotPolicySet = true;
         }
 

maven-core/src/main/java/org/apache/maven/plugin/DefaultPluginManager.java

@@ -188,11 +188,6 @@ public class DefaultPluginManager
 
                 project.addPlugin( plugin );
             }
-            catch ( PlexusContainerException e )
-            {
-                throw new PluginManagerException(
-                    "Error occurred in the artifact container attempting to download plugin " + plugin.getKey(), e );
-            }
             catch ( ArtifactResolutionException e )
             {
                 String groupId = plugin.getGroupId();
@@ -261,7 +256,7 @@ public class DefaultPluginManager
 
     protected void addPlugin( Plugin plugin, Artifact pluginArtifact, MavenProject project,
                               ArtifactRepository localRepository )
-        throws ArtifactResolutionException, PlexusContainerException
+        throws ArtifactResolutionException, PluginManagerException
     {
         // TODO: share with MMS? Not sure if it belongs here
         if ( project.getProjectReferences() != null && !project.getProjectReferences().isEmpty() )
@@ -277,10 +272,23 @@ public class DefaultPluginManager
 
         artifactResolver.resolve( pluginArtifact, project.getPluginArtifactRepositories(), localRepository );
         
-        PlexusContainer child = container.createChildContainer( plugin.getKey(),
+        if ( !pluginArtifact.isResolved() )
+        {
+            throw new PluginContainerException( plugin, "Cannot resolve artifact for plugin." );
+        }
+
+        PlexusContainer child;
+        try
+        {
+            child = container.createChildContainer( plugin.getKey(),
                                                     Collections.singletonList( pluginArtifact.getFile() ),
                                                     Collections.EMPTY_MAP,
                                                     Collections.singletonList( pluginCollector ) );
+        }
+        catch ( PlexusContainerException e )
+        {
+            throw new PluginContainerException( plugin, "Failed to create plugin container.", e );
+        }
 
         // this plugin's descriptor should have been discovered in the child creation, so we should be able to
         // circle around and set the artifacts and class realm

maven-core/src/main/java/org/apache/maven/plugin/PluginContainerException.java

@@ -0,0 +1,38 @@
+package org.apache.maven.plugin;
+
+import org.apache.maven.model.Plugin;
+
+public class PluginContainerException
+    extends PluginManagerException
+{
+
+    private final Plugin plugin;
+    private final String originalMessage;
+
+    public PluginContainerException( Plugin plugin, String message, Exception e )
+    {
+        super( "Error configuring container for: " + plugin.getKey() + ". Message was: " + message, e );
+        
+        this.plugin = plugin;
+        this.originalMessage = message;
+    }
+
+    public PluginContainerException( Plugin plugin, String message )
+    {
+        super( "Error configuring container for: " + plugin.getKey() + ". Message was: " + message );
+        
+        this.plugin = plugin;
+        this.originalMessage = message;
+    }
+    
+    public String getOriginalMessage()
+    {
+        return originalMessage;
+    }
+    
+    public Plugin getPlugin()
+    {
+        return plugin;
+    }
+
+}

maven-core/src/main/java/org/apache/maven/usability/ArtifactResolverDiagnoser.java

@@ -18,7 +18,6 @@ package org.apache.maven.usability;
 
 import org.apache.maven.artifact.resolver.ArtifactResolutionException;
 import org.apache.maven.artifact.resolver.TransitiveArtifactResolutionException;
-import org.apache.maven.project.ProjectBuildingException;
 
 public class ArtifactResolverDiagnoser
     implements ErrorDiagnoser
@@ -26,45 +25,37 @@ public class ArtifactResolverDiagnoser
 
     public boolean canDiagnose( Throwable error )
     {
-        return error instanceof ArtifactResolutionException;
+        return DiagnosisUtils.containsInCausality( error, ArtifactResolutionException.class );
     }
 
     public String diagnose( Throwable error )
     {
-        Throwable root = DiagnosisUtils.getRootCause( error );
+        ArtifactResolutionException exception = (ArtifactResolutionException) DiagnosisUtils.getFromCausality( error, ArtifactResolutionException.class );
 
-        String message = null;
+        StringBuffer message = new StringBuffer();
         
-        if ( root instanceof ProjectBuildingException )
+        message.append( "Failed to resolve artifact." );
-        {
+        message.append( "\n");
-            StringBuffer messageBuffer = new StringBuffer();
+        message.append( "\nGroupId: " ).append( exception.getGroupId() );
+        message.append( "\nArtifactId: " ).append( exception.getArtifactId() );
+        message.append( "\nVersion: " ).append( exception.getVersion() );
+        message.append( "\nType: " ).append( exception.getType() );
         
-            if ( DiagnosisUtils.containsInCausality( error, TransitiveArtifactResolutionException.class ) )
+        if ( exception instanceof TransitiveArtifactResolutionException )
         {
-                messageBuffer.append(
+            message.append( exception.getArtifactPath() );
-                    "Error while transitively resolving artifacts (transitive path trace currently unavailable):\n\n" );
-            }
-            else
-            {
-                messageBuffer.append( "Error while resolving artifacts:\n\n" );
         }
         
-            messageBuffer.append( "Root Error:\n  " ).append( root.getMessage() );
+        message.append( DiagnosisUtils.getOfflineWarning() );
 
-            message = messageBuffer.toString();
+        Throwable root = DiagnosisUtils.getRootCause( exception );
-        }
+        
-        else
+        if ( root != null )
         {
-            StringBuffer messageBuffer = new StringBuffer();
+            message.append( "\n\nRoot Cause: " ).append( root.getMessage() ).append( "\n" );
-
-            messageBuffer.append( "Main Error:\n  " ).append( error.getMessage() );
-
-            messageBuffer.append( "\n\nRoot error:\n  " ).append( root.getMessage() );
-
-            message = messageBuffer.toString();
         }
         
-        return message;
+        return message.toString();
     }
 
 }

maven-core/src/main/java/org/apache/maven/usability/DiagnosisUtils.java

@@ -23,6 +23,12 @@ public final class DiagnosisUtils
     {
     }
     
+    public static String getOfflineWarning()
+    {
+        return "\nNOTE: If Maven is executing in offline mode, some artifacts may be missing from your" +
+                "\nlocal repository.\n";
+    }
+    
     public static boolean containsInCausality( Throwable error, Class test )
     {
         Throwable cause = error;

maven-core/src/main/java/org/apache/maven/usability/PluginContainerDiagnoser.java

@@ -0,0 +1,51 @@
+package org.apache.maven.usability;
+
+import org.apache.maven.model.Plugin;
+import org.apache.maven.plugin.PluginContainerException;
+
+public class PluginContainerDiagnoser
+    implements ErrorDiagnoser
+{
+
+    public boolean canDiagnose( Throwable error )
+    {
+        return DiagnosisUtils.containsInCausality( error, PluginContainerException.class );
+    }
+
+    public String diagnose( Throwable error )
+    {
+        PluginContainerException exception = (PluginContainerException) DiagnosisUtils.getFromCausality( error, PluginContainerException.class );
+        
+        // this is a little hackish, but it's simple.
+        String originalMessage = exception.getOriginalMessage();
+        Plugin plugin = exception.getPlugin();
+        
+        StringBuffer message = new StringBuffer();
+        
+        message.append( "Failed to prepare plugin for execution.");
+        message.append( "\n" );
+        message.append( "\nGroupId: " ).append( plugin.getGroupId() );
+        message.append( "\nArtifactId: " ).append( plugin.getArtifactId() );
+        message.append( "\nVersion: " ).append( plugin.getVersion() );
+        message.append( "\nReason: " ).append( originalMessage );
+        
+        if ( originalMessage.startsWith( "Cannot resolve artifact" ) )
+        {
+            message.append( DiagnosisUtils.getOfflineWarning() );
+        }
+        else
+        {
+            Throwable rootCause = DiagnosisUtils.getRootCause( exception );
+            
+            if ( rootCause != null )
+            {
+                message.append( "\nRoot Cause: " ).append( rootCause.getMessage() );
+            }
+        }
+        
+        message.append( "\n\n" );
+        
+        return message.toString();
+    }
+
+}

maven-core/src/main/resources/META-INF/plexus/components.xml

@@ -101,6 +101,16 @@
       <role-hint>PluginConfigurationDiagnoser</role-hint>
       <implementation>org.apache.maven.usability.PluginConfigurationDiagnoser</implementation>
     </component>
+    <!--
+     |
+     |PluginContainerDiagnoser
+     |
+     -->
+    <component>
+      <role>org.apache.maven.usability.ErrorDiagnoser</role>
+      <role-hint>PluginContainerDiagnoser</role-hint>
+      <implementation>org.apache.maven.usability.PluginContainerDiagnoser</implementation>
+    </component>
     <!--
      |
      |ArtifactResolverDiagnoser

maven-plugins/maven-release-plugin/src/main/java/org/apache/maven/plugins/release/PrepareReleaseMojo.java

@@ -961,8 +961,8 @@ public class PrepareReleaseMojo
                         String version;
                         try
                         {
-                            version = pluginVersionManager.resolvePluginVersion( plugin.getGroupId(), plugin
+                            version = pluginVersionManager.resolveReportPluginVersion( plugin.getGroupId(), plugin
-                                .getArtifactId(), project, settings, localRepository, true );
+                                .getArtifactId(), project, settings, localRepository );
                         }
                         catch ( PluginVersionResolutionException e )
                         {