maven_export support for bundling AARs

.bazelrc

@@ -1,3 +1,5 @@
+build --experimental_google_legacy_api
+
 build --java_language_version=11
 build --java_runtime_version=remotejdk_11
 

private/rules/has_maven_deps.bzl

@@ -95,6 +95,7 @@ _gathered = provider(
         "artifact_infos",
         "transitive_exports",
         "dep_infos",
+        "artifact_coordinates",
     ],
 )
 
@@ -104,7 +105,7 @@ def _extract_from(gathered, maven_info, dep, include_transitive_exports):
     gathered.all_infos.append(maven_info)
     gathered.label_to_javainfo.update(maven_info.label_to_javainfo)
     if java_info:
-        if maven_info.coordinates:
+        if maven_info.coordinates and maven_info.coordinates != gathered.artifact_coordinates:
             gathered.dep_infos.append(dep[JavaInfo])
         else:
             gathered.artifact_infos.append(dep[JavaInfo])
@@ -129,6 +130,7 @@ def _has_maven_deps_impl(target, ctx):
         transitive_exports = [],
         dep_infos = [],
         label_to_javainfo = {target.label: target[JavaInfo]},
+        artifact_coordinates = coordinates,
     )
 
     for attr in _ASPECT_ATTRS:

private/rules/maven_project_jar.bzl

@@ -1,5 +1,5 @@
 load(":has_maven_deps.bzl", "MavenInfo", "calculate_artifact_jars", "calculate_artifact_source_jars", "has_maven_deps")
-load(":maven_utils.bzl", "determine_additional_dependencies")
+load(":maven_utils.bzl", "determine_additional_dependencies", "unpack_coordinates")
 
 DEFAULT_EXCLUDED_WORKSPACES = [
     # Note: we choose to drop the dependency entirely because
@@ -64,7 +64,12 @@ def _maven_project_jar_impl(ctx):
     )
 
     # Merge together all the binary jars
-    bin_jar = ctx.actions.declare_file("%s.jar" % ctx.label.name)
+    packaging = unpack_coordinates(info.coordinates).type or "jar"
+    bin_jar = ctx.actions.declare_file("%s.%s" % (ctx.label.name, packaging))
+
+    if packaging == "aar" and AndroidLibraryAarInfo in target and target[AndroidLibraryAarInfo].aar:
+        artifact_jars = artifact_jars + [target[AndroidLibraryAarInfo].aar]
+
     _combine_jars(
         ctx,
         ctx.executable._merge_jars,

private/templates/pom.tpl

@@ -6,6 +6,7 @@
     <groupId>{groupId}</groupId>
     <artifactId>{artifactId}</artifactId>
     <version>{version}</version>
+    <packaging>{type}</packaging>
 
     <dependencies>
 {dependencies}

private/tools/java/com/github/bazelbuild/rules_jvm_external/jar/MergeJars.java

@@ -28,12 +28,15 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.PathMatcher;
 import java.nio.file.Paths;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.util.Arrays;
+import java.util.Enumeration;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
@@ -45,18 +48,27 @@
 import java.util.jar.Attributes;
 import java.util.jar.JarOutputStream;
 import java.util.jar.Manifest;
+import java.util.regex.Pattern;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 import java.util.zip.ZipInputStream;
 
 public class MergeJars {
 
+  private enum Packaging {
+    JAR, AAR;
+  }
+
   public static void main(String[] args) throws IOException {
     Path out = null;
     // Insertion order may matter
     Set<Path> sources = new LinkedHashSet<>();
     Set<Path> excludes = new HashSet<>();
     DuplicateEntryStrategy onDuplicate = LAST_IN_WINS;
+    Packaging packaging = Packaging.JAR;
+    PathMatcher aarMatcher = FileSystems.getDefault().getPathMatcher("glob:*.aar");
+    // AAR to build from
+    Path aarSource = null;
 
     for (int i = 0; i < args.length; i++) {
       switch (args[i]) {
@@ -75,6 +87,9 @@ public static void main(String[] args) throws IOException {
 
         case "--output":
           out = Paths.get(args[++i]);
+          if (aarMatcher.matches(out.getFileName())) {
+            packaging = Packaging.AAR;
+          }
           break;
 
         case "--sources":
@@ -87,6 +102,26 @@ public static void main(String[] args) throws IOException {
       }
     }
 
+    if (packaging == Packaging.AAR) {
+      aarSource = sources.stream()
+              .filter(source ->  aarMatcher.matches(source.getFileName()))
+              .findFirst() // AAR is explicitly only added for top level distribution target, so we _should_ only ever have 1
+              .orElseThrow(() -> new IllegalArgumentException("For AAR packaging, we require a prebuilt AAR that already contains the Android resources that we'll add the transitive source closure to."));
+
+      sources.remove(aarSource);
+
+      // Pull out classes jar and add to source set
+      Path aarClassesJar = out.getParent().resolve("aar-classes.jar");
+      try (ZipFile aar = new ZipFile(aarSource.toFile())) {
+        ZipEntry classes = aar.getEntry("classes.jar");
+        try (InputStream is = aar.getInputStream(classes);
+             OutputStream fos = Files.newOutputStream(aarClassesJar)) {
+          ByteStreams.copy(is, fos);
+        }
+      }
+      sources.add(aarClassesJar);
+    }
+
     Objects.requireNonNull(out, "Output path must be set.");
     if (sources.isEmpty()) {
       // Just write an empty jar and leave
@@ -144,6 +179,12 @@ public static void main(String[] args) throws IOException {
             continue;
           }
 
+          // TODO: Why do we need to do this?? Is there a better way?
+          Pattern rClassMatcher = Pattern.compile("^.*\\/R(\\$.*)?\\.(class|java)");
+          if (rClassMatcher.asMatchPredicate().test(entry.getName())) {
+            continue;
+          }
+
           if (!entry.isDirectory()) {
             // Duplicate files, however may not be. We need the hash to determine
             // whether we should do anything.
@@ -171,6 +212,53 @@ public static void main(String[] args) throws IOException {
     // jar and not useful for consumers.
     manifest.getMainAttributes().remove(new Attributes.Name("Target-Label"));
 
+    switch (packaging) {
+      case JAR:
+        writeClassesJar(out, manifest, allServices, sources, fileToSourceJar);
+        break;
+      case AAR:
+        Path classesJar = out.getParent().resolve("classes.jar");
+        writeClassesJar(classesJar, manifest, allServices, sources, fileToSourceJar);
+        writeAar(out, aarSource, classesJar);
+    }
+  }
+
+  private static void writeAar(Path out, Path aarSource, Path classesJar) throws IOException {
+    try (OutputStream os = Files.newOutputStream(out);
+         JarOutputStream jos = new JarOutputStream(os)) {
+      ZipEntry je = new StableZipEntry(classesJar.toFile().getName());
+      jos.putNextEntry(je);
+
+      try (InputStream is = Files.newInputStream(classesJar)) {
+        ByteStreams.copy(is, jos);
+      }
+      jos.closeEntry();
+
+      try (ZipFile aar = new ZipFile(aarSource.toFile())) {
+        Enumeration<? extends ZipEntry> entries = aar.entries();
+        while (entries.hasMoreElements()) {
+          ZipEntry entry = entries.nextElement();
+
+          // transitive class closure is captured in our classes.jar
+          if ("classes.jar".equals(entry.getName())) {
+            continue;
+          }
+
+          jos.putNextEntry(entry);
+          try (InputStream is = aar.getInputStream(entry)) {
+            ByteStreams.copy(is, jos);
+          }
+          jos.closeEntry();
+        }
+      }
+    }
+  }
+
+  private static void writeClassesJar(Path out,
+                                      Manifest manifest,
+                                      Map<String, Set<String>> allServices,
+                                      Set<Path> sources,
+                                      Map<String, Path> fileToSourceJar) throws IOException {
     // Now create the output jar
     Files.createDirectories(out.getParent());
 

private/tools/java/com/github/bazelbuild/rules_jvm_external/maven/MavenPublisher.java

@@ -93,14 +93,15 @@ public static void main(String[] args)
 
     try {
       List<CompletableFuture<Void>> futures = new ArrayList<>();
-      futures.add(upload(repo, credentials, coords, ".pom", pom, gpgSign));
 
       if (mainArtifact != null) {
         String ext =
             com.google.common.io.Files.getFileExtension(mainArtifact.getFileName().toString());
         futures.add(upload(repo, credentials, coords, "." + ext, mainArtifact, gpgSign));
       }
 
+      futures.add(upload(repo, credentials, coords, ".pom", pom, gpgSign));
+
       if (args.length > 3 && !args[3].isEmpty()) {
         List<String> extraArtifactTuples = Splitter.onPattern(",").splitToList(args[3]);
         for (String artifactTuple : extraArtifactTuples) {