Extended the MasterPromoteExtension to not only retain the hardcoded …

…gitflow-helper-maven-plugin itself and the maven-deploy-plugin, or the plugins related to explicit supplied command-line goals, but also allow a project to configure additional plugins that may also execute on master/support.

This serves two cases:

1) It solves the issue e-gineering#127 (though admittedly it still would be more clean to be able to download the pom file from the release repo)
2) It can serve as a basic extension point to allow other "things" to happen on a master build, that are beyond the scope of deploying maven artifacts (ie have some antrun script run)

README.md

@@ -332,8 +332,8 @@ directly from master**. Rather, master is really only used for tracking releases
 To accomplish this the `promote-master` goal and a Maven build extension work together.
 
 With the build extension added to your project, any build where the `gitBranchExpression` matches the `masterBranchPattern` or `supportBranchPattern` will have it's
-build lifecycle (plugins, goals, etc) altered. Any plugin other than the gitflow-helper-maven-plugin, the maven-deploy-plugin, or plugins with goals
- explicitly referenced on the command line will be ignored (removed from the project reactor). 
+build lifecycle (plugins, goals, etc) altered. Any plugin other than the gitflow-helper-maven-plugin, the maven-deploy-plugin, plugins with goals
+ explicitly referenced on the command line or those configured explicitly in the `retainPlugins` list, will be ignored (removed from the project reactor). 
 This allows us to enforce the ideal that code should never be built in the master branch.
 
 The `promote-master` goal executes when the `gitBranchExpression` resolves to a value matching the `masterBranchPattern` or `supportBranchPattern` regular expression.

src/main/java/com/e_gineering/maven/gitflowhelper/AbstractBranchDetectingExtension.java

@@ -13,6 +13,8 @@
 import org.codehaus.plexus.util.xml.Xpp3Dom;
 
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Properties;
 
 public abstract class AbstractBranchDetectingExtension extends AbstractMavenLifecycleParticipant {
@@ -34,6 +36,7 @@ public abstract class AbstractBranchDetectingExtension extends AbstractMavenLife
     String featureOrBugfixBranchPattern;
     String otherDeployBranchPattern;
     String otherBranchVersionDelimiter;
+    List<String> retainPlugins;
     GitBranchInfo branchInfo;
     Properties systemEnvVars;
 
@@ -93,6 +96,10 @@ public void afterProjectsRead(MavenSession session) throws MavenExecutionExcepti
                     if (gitBranchExpression == null) {
                         gitBranchExpression = extractPluginConfigValue("gitBranchExpression", plugin);
                     }
+
+                    if (retainPlugins == null) {
+                        retainPlugins = extractPluginConfigList("retainPlugins", plugin);
+                    }
                 }
             }
         }
@@ -145,6 +152,10 @@ public void afterProjectsRead(MavenSession session) throws MavenExecutionExcepti
                 logger.debug("Using default otherBranchVersionDelimiter.");
                 otherBranchVersionDelimiter = "+";
             }
+
+            if (retainPlugins == null) {
+                logger.debug("No additional plugin executions will be retained on master");
+            }
 
             ScmUtils scmUtils = new ScmUtils(systemEnvVars, scmManager, session.getTopLevelProject(), new PlexusLoggerToMavenLog(logger), masterBranchPattern, supportBranchPattern, releaseBranchPattern, hotfixBranchPattern, developmentBranchPattern);
             branchInfo = scmUtils.resolveBranchInfo(gitBranchExpression);
@@ -168,4 +179,25 @@ private String extractConfigValue(String parameter, Object configuration) {
         }
         return null;
     }
+
+    private List<String> extractPluginConfigList(String parameter, Plugin plugin) {
+        List<String> value = extractConfigList(parameter, plugin.getConfiguration());
+        for (int i = 0; i < plugin.getExecutions().size() && value == null; i++) {
+            value = extractConfigList(parameter, plugin.getExecutions().get(i).getConfiguration());
+        }
+        return value;
+    }
+
+    private List<String> extractConfigList(String parameter, Object configuration) {
+        try {
+            List<String> result = new ArrayList<>();
+            Xpp3Dom parameterNode = ((Xpp3Dom) configuration).getChild(parameter);
+            for (int i = 0; i < parameterNode.getChildCount(); i++) {
+                result.add(parameterNode.getChild(i).getValue());
+            }
+            return result;
+        } catch (Exception ignored) {
+        }
+        return null;
+    }
 }

src/main/java/com/e_gineering/maven/gitflowhelper/MasterPromoteExtension.java

@@ -9,8 +9,14 @@
 import org.codehaus.plexus.component.annotations.Component;
 
 import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
 
 /**
  * Maven extension which removes (skips) undesired plugins from the build reactor when running on a master branch.
@@ -19,6 +25,15 @@
  */
 @Component(role = AbstractMavenLifecycleParticipant.class, hint = "promote-master")
 public class MasterPromoteExtension extends AbstractBranchDetectingExtension {
+
+    private static final Set<String> PLUGIN_WHITELIST = Collections.unmodifiableSet(
+            new HashSet<>(
+                    Arrays.asList(
+                            "org.apache.maven.plugins:maven-deploy-plugin",
+                            "com.e-gineering:gitflow-helper-maven-plugin"
+                    )
+            )
+    );
 
     @Override
     public void afterProjectsRead(final MavenSession session) throws MavenExecutionException {
@@ -41,26 +56,25 @@ public void afterProjectsRead(final MavenSession session) throws MavenExecutionE
         }
 
         // Build up a map of plugins to remove from projects, if we're on the master branch.
-        HashMap<MavenProject, List<Plugin>> pluginsToDrop = new HashMap<>();
+        Map<MavenProject, List<Plugin>> pluginsToDrop = new HashMap<>();
+
+        final List<String> configuredPluginsToRetain;
+        if (this.retainPlugins != null) {
+            configuredPluginsToRetain = this.retainPlugins;
+        } else {
+            configuredPluginsToRetain = Collections.emptyList();
+        }
 
         for (MavenProject project : session.getProjects()) {
-            List<Plugin> dropPlugins = new ArrayList<>();
 
-            for (Plugin plugin : project.getModel().getBuild().getPlugins()) {
-                // Don't drop our plugin.
-                if (plugin.getKey().equals("com.e-gineering:gitflow-helper-maven-plugin")) {
-                    continue;
-                // Don't drop things we declare goals for.
-                } else if (pluginsToRetain.contains(plugin)) {
-                    logger.debug("gitflow-helper-maven-plugin retaining plugin: " + plugin + " from project: " + project.getName());
-                // Don't drop the maven-deploy-plugin
-                } else if (plugin.getKey().equals("org.apache.maven.plugins:maven-deploy-plugin")) {
-                    logger.debug("gitflow-helper-maven-plugin retaining plugin: " + plugin + " from project: " + project.getName());
-                } else {
-                    logger.debug("gitflow-helper-maven-plugin removing plugin: " + plugin + " from project: " + project.getName());
-                    dropPlugins.add(plugin);
-                }
-            }
+            // Create a list of all plugins that are not in the whitelist, not explicitly invoked from the commandline,
+            // and not configured to be allowed on master/support.
+            List<Plugin> dropPlugins = project.getModel().getBuild().getPlugins()
+                    .stream()
+                    .filter(plugin -> !PLUGIN_WHITELIST.contains(plugin.getKey()))
+                    .filter(plugin -> !pluginsToRetain.contains(plugin))
+                    .filter(plugin -> !configuredPluginsToRetain.contains(plugin.getKey()))
+                    .collect(Collectors.toList());
 
             pluginsToDrop.put(project, dropPlugins);
         }

src/main/java/com/e_gineering/maven/gitflowhelper/PromoteMasterMojo.java

@@ -4,6 +4,9 @@
 import org.apache.maven.plugin.MojoFailureException;
 import org.apache.maven.plugins.annotations.LifecyclePhase;
 import org.apache.maven.plugins.annotations.Mojo;
+import org.apache.maven.plugins.annotations.Parameter;
+
+import java.util.List;
 
 /**
  * If the build is being executed from a DEVELOPMENT, HOTFIX or RELEASE branch, attach an artifact containing a list of
@@ -17,6 +20,15 @@
 @Mojo(name = "promote-master", defaultPhase = LifecyclePhase.INSTALL)
 public class PromoteMasterMojo extends AbstractGitflowBasedRepositoryMojo {
 
+    /**
+     * List of groupId:artifactId strings that refer to plugins that should be retained while building on master.
+     *
+     * Note that this property is listed here for documentation purposes, but it is handled within
+     * {@link MasterPromoteExtension}.
+     */
+    @Parameter(property = "retainPlugins")
+    private List<String> retainPlugins;
+
     @Override
     protected void execute(final GitBranchInfo gitBranchInfo) throws MojoExecutionException, MojoFailureException {
         switch (gitBranchInfo.getType()) {

src/test/java/com/e_gineering/maven/gitflowhelper/MasterSupportBranchIT.java

@@ -71,6 +71,16 @@ public void promotionOfRelease() throws Exception {
 				// Otherwise, it's the VerificationException from looking for "Compiling", and that's expected to fail.
 			}
 
+			try {
+				// The flatten-maven-plugin should not activate, fail if it does.
+				verifier.verifyTextInLog("Generating flattened POM of project");
+				throw new VerificationException(PROMOTION_FAILED_MESSAGE);
+			} catch (VerificationException ve) {
+				if (ve.getMessage().equals(PROMOTION_FAILED_MESSAGE)) {
+					throw ve;
+				}
+			}
+
 			verifier.verifyTextInLog(
 				"gitflow-helper-maven-plugin: Enabling MasterPromoteExtension. GIT_BRANCH: [origin/master] matches masterBranchPattern");
 			verifier.verifyTextInLog("[INFO] Setting release artifact repository to: [releases]");
@@ -121,4 +131,46 @@ public void dontPruneExplicitlyInvokedPlugins() throws Exception {
 			verifier.resetStreams();
 		}
 	}
+
+	@Test
+	public void dontPruneExplicitlyConfiguredPlugins() throws Exception {
+		// Create a release version and get it deployed.
+		Verifier verifier = createVerifier("/project-stub", "origin/release/1.2.0", "1.2.0");
+
+		try {
+			verifier.executeGoal("deploy");
+
+			verifier.verifyErrorFreeLog();
+		} finally {
+			verifier.resetStreams();
+		}
+
+		// Promote (deploy) from /origin/master
+		verifier = createVerifier("/project-stub", "origin/master", "1.2.0");
+		// Activate a profile to enable the retainPlugins configuration
+		verifier.addCliOption("-Pretain-configuration");
+		try {
+			verifier.executeGoal("deploy");
+
+			try {
+				verifier.verifyTextInLog("Compiling");
+				throw new VerificationException(PROMOTION_FAILED_MESSAGE);
+			} catch (VerificationException ve) {
+				if (ve.getMessage().equals(PROMOTION_FAILED_MESSAGE)) {
+					throw ve;
+				}
+				// Otherwise, it's the VerificationException from looking for "Compiling", and that's expected to fail.
+			}
+
+			verifier.verifyTextInLog("Generating flattened POM of project"); // This should still be there.
+			verifier.verifyTextInLog(
+					"gitflow-helper-maven-plugin: Enabling MasterPromoteExtension. GIT_BRANCH: [origin/master] matches masterBranchPattern");
+			verifier.verifyTextInLog("[INFO] Setting release artifact repository to: [releases]");
+			verifier.verifyTextInLog(
+					"[INFO] Resolving & Reattaching existing artifacts from stageDeploymentRepository [test-releases");
+			verifier.verifyErrorFreeLog();
+		} finally {
+			verifier.resetStreams();
+		}
+	}
 }

src/test/resources/project-stub/pom.xml

@@ -118,7 +118,42 @@
 				<version>4.2.0</version>
 				<extensions>true</extensions>
 			</plugin>
+			<plugin>
+				<groupId>org.codehaus.mojo</groupId>
+				<artifactId>flatten-maven-plugin</artifactId>
+				<version>1.2.2</version>
+				<executions>
+					<execution>
+						<goals>
+							<goal>flatten</goal>
+						</goals>
+						<phase>process-resources</phase>
+					</execution>
+				</executions>
+			</plugin>
 		</plugins>
 	</build>
 
+	<profiles>
+		<profile>
+			<id>retain-configuration</id>
+			<build>
+				<pluginManagement>
+					<plugins>
+						<plugin>
+							<groupId>com.e-gineering</groupId>
+							<artifactId>gitflow-helper-maven-plugin</artifactId>
+							<version>${version.gitflow.plugin}</version>
+							<configuration>
+								<retainPlugins>
+									<retainPlugin>org.codehaus.mojo:flatten-maven-plugin</retainPlugin>
+								</retainPlugins>
+							</configuration>
+						</plugin>
+					</plugins>
+				</pluginManagement>
+			</build>
+		</profile>
+	</profiles>
+
 </project>