Document gRPC code generation

Also:

- Allows configuring the `proto` directory (quarkusio#12802)
- Provides Gradle snippets (quarkusio#33854)

core/deployment/src/main/java/io/quarkus/deployment/CodeGenProvider.java

@@ -2,18 +2,19 @@
 
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.Map;
 
 import org.eclipse.microprofile.config.Config;
 import org.wildfly.common.annotation.NotNull;
 
+import io.quarkus.bootstrap.model.ApplicationModel;
 import io.quarkus.bootstrap.prebuild.CodeGenException;
 
 /**
  * Service providers for this interface are triggered during generate-sources phase of build of Quarkus applications
  */
 public interface CodeGenProvider {
     /**
-     *
      * @return unique name of the code gen provider, will correspond to the directory in <code>generated-sources</code>
      */
     @NotNull
@@ -38,6 +39,32 @@ public interface CodeGenProvider {
     @NotNull
     String inputDirectory();
 
+    /**
+     * Provides the possibility for the provider to override the default input directory.
+     * This method is called after {@link #init(ApplicationModel, Map)}.
+     * Returning {@code null} will result in the {@code inputDirectory} method being called to retrieve the default input
+     * directory.
+     * <p>
+     * The returned path must be an absolute path. However, pointing to a directory outside of the project structure should
+     * be avoided for security purposes.
+     *
+     * @return the input directory, must be an absolute path. {@code null} would result in the default input directory being
+     *         used.
+     */
+    default Path getInputDirectory() {
+        return null;
+    }
+
+    /**
+     * Provides the possibility for the provider to initialize itself using the application model and properties.
+     *
+     * @param model the application model
+     * @param properties the build time properties defined in the application build file (pom.xml or gradle.build)
+     */
+    default void init(ApplicationModel model, Map<String, String> properties) {
+        // No-op
+    }
+
     /**
      * Trigger code generation
      *

core/deployment/src/main/java/io/quarkus/deployment/CodeGenerator.java

@@ -64,7 +64,9 @@ public static void initAndRun(QuarkusClassLoader classLoader,
             PathCollection sourceParentDirs, Path generatedSourcesDir, Path buildDir,
             Consumer<Path> sourceRegistrar, ApplicationModel appModel, Properties properties,
             String launchMode, boolean test) throws CodeGenException {
-        final List<CodeGenData> generators = init(classLoader, sourceParentDirs, generatedSourcesDir, buildDir,
+        Map<String, String> props = new HashMap<>();
+        properties.entrySet().stream().forEach(e -> props.put((String) e.getKey(), (String) e.getValue()));
+        final List<CodeGenData> generators = init(appModel, props, classLoader, sourceParentDirs, generatedSourcesDir, buildDir,
                 sourceRegistrar);
         if (generators.isEmpty()) {
             return;
@@ -77,7 +79,10 @@ public static void initAndRun(QuarkusClassLoader classLoader,
         }
     }
 
-    private static List<CodeGenData> init(ClassLoader deploymentClassLoader,
+    private static List<CodeGenData> init(
+            ApplicationModel model,
+            Map<String, String> properties,
+            ClassLoader deploymentClassLoader,
             PathCollection sourceParentDirs,
             Path generatedSourcesDir,
             Path buildDir,
@@ -89,24 +94,29 @@ private static List<CodeGenData> init(ClassLoader deploymentClassLoader,
             }
             final List<CodeGenData> result = new ArrayList<>(codeGenProviders.size());
             for (CodeGenProvider provider : codeGenProviders) {
+                provider.init(model, properties);
                 Path outputDir = codeGenOutDir(generatedSourcesDir, provider, sourceRegistrar);
                 for (Path sourceParentDir : sourceParentDirs) {
+                    Path in = provider.getInputDirectory();
+                    if (in == null) {
+                        in = sourceParentDir.resolve(provider.inputDirectory());
+                    }
                     result.add(
-                            new CodeGenData(provider, outputDir, sourceParentDir.resolve(provider.inputDirectory()), buildDir));
+                            new CodeGenData(provider, outputDir, in, buildDir));
                 }
             }
             return result;
         });
     }
 
-    public static List<CodeGenData> init(ClassLoader deploymentClassLoader, Collection<ModuleInfo> modules)
+    public static List<CodeGenData> init(ApplicationModel model, Map<String, String> properties,
+            ClassLoader deploymentClassLoader, Collection<ModuleInfo> modules)
             throws CodeGenException {
         return callWithClassloader(deploymentClassLoader, () -> {
             List<CodeGenProvider> codeGenProviders = null;
             List<CodeGenData> codeGens = List.of();
             for (DevModeContext.ModuleInfo module : modules) {
                 if (!module.getSourceParents().isEmpty() && module.getPreBuildOutputDir() != null) { // it's null for remote dev
-
                     if (codeGenProviders == null) {
                         codeGenProviders = loadCodeGenProviders(deploymentClassLoader);
                         if (codeGenProviders.isEmpty()) {
@@ -115,14 +125,19 @@ public static List<CodeGenData> init(ClassLoader deploymentClassLoader, Collecti
                     }
 
                     for (CodeGenProvider provider : codeGenProviders) {
+                        provider.init(model, properties);
                         Path outputDir = codeGenOutDir(Path.of(module.getPreBuildOutputDir()), provider,
                                 sourcePath -> module.addSourcePathFirst(sourcePath.toAbsolutePath().toString()));
                         for (Path sourceParentDir : module.getSourceParents()) {
                             if (codeGens.isEmpty()) {
                                 codeGens = new ArrayList<>();
                             }
+                            Path in = provider.getInputDirectory();
+                            if (in == null) {
+                                in = sourceParentDir.resolve(provider.inputDirectory());
+                            }
                             codeGens.add(
-                                    new CodeGenData(provider, outputDir, sourceParentDir.resolve(provider.inputDirectory()),
+                                    new CodeGenData(provider, outputDir, in,
                                             Path.of(module.getTargetDir())));
                         }
 

core/deployment/src/main/java/io/quarkus/deployment/dev/CodeGenWatcher.java

@@ -27,7 +27,9 @@ class CodeGenWatcher {
 
     CodeGenWatcher(CuratedApplication curatedApplication, DevModeContext context) throws CodeGenException {
         final QuarkusClassLoader deploymentClassLoader = curatedApplication.createDeploymentClassLoader();
-        final List<CodeGenData> codeGens = CodeGenerator.init(deploymentClassLoader, context.getAllModules());
+        final List<CodeGenData> codeGens = CodeGenerator.init(curatedApplication.getApplicationModel(),
+                context.getBuildSystemProperties(),
+                deploymentClassLoader, context.getAllModules());
         if (codeGens.isEmpty()) {
             fsWatchUtil = null;
             this.deploymentClassLoader = null;