bazel: Add custom rule to produce android debug info (#2047)

When building the jni dylib for android, we previously stripped all
debug info to decrease the artifact size. With this change we now
produce the same stripped binary as before, but before stripping it we
create a dump of the debug info suitable for crash reporting.

This is made overly difficult for a few reasons:

1. Bazel doesn't support fission for Android bazelbuild/bazel#14765
2. Extra outputs from rules are not propagated up the dependency tree,
   so just building `android_dist` at the top level, isn't enough to get
   the extra outputs built as well
3. Building the library manually alongside the android artifact on the
   command line results in 2 separate builds, one for android as a
   transitive dependency of `android_dist` and one for the host
   platform

This change avoids #1 fission for now, but the same approach could be used
once that change makes its way to a bazel release.

This change fixes #2 by using a separate output group that can be depended
on by the genrule that writes to dist while avoiding #3 because the custom
rule producing these uses the android transition.

Signed-off-by: Keith Smiley <keithbsmiley@gmail.com>
Signed-off-by: JP Simard <jp@jpsim.com>

mobile/.bazelrc

@@ -69,7 +69,7 @@ build:tsan-dev --test_env="TSAN_OPTIONS=report_atomic_races=0"
 
 # Exclude debug info from the release binary since it makes it too large to fit
 # into a zip file. This shouldn't affect crash reports.
-build:release-common --define=no_debug_info=1
+build:release-ios --define=no_debug_info=1
 
 # Flags for release builds targeting iOS
 build:release-ios --apple_bitcode=embedded

mobile/.gitignore

@@ -8,6 +8,7 @@
 /dist/*pom.xml
 /dist/*.aar
 /dist/*.jar
+/dist/*.objdump
 /dist/envoy_aar_sources.zip
 /dist/Envoy.framework
 /dist/*.asc

mobile/BUILD

@@ -52,6 +52,7 @@ genrule(
     srcs = [
         "//library/kotlin/io/envoyproxy/envoymobile:envoy_aar",
         "//library/kotlin/io/envoyproxy/envoymobile:envoy_aar_pom_xml",
+        "//library/kotlin/io/envoyproxy/envoymobile:envoy_aar_objdump_collector",
     ],
     outs = ["output_in_dist_directory"],
     cmd = """
@@ -60,6 +61,8 @@ genrule(
     chmod 755 $$2
     cp $$1 dist/envoy.aar
     cp $$2 dist/envoy-pom.xml
+    shift 2
+    cp $$@ dist/
     touch $@
     """,
     stamp = True,

mobile/bazel/android_artifacts.bzl

@@ -53,6 +53,13 @@ def android_artifacts(name, android_library, manifest, archive_name, native_deps
     _jni_archive = _create_jni_library(name, native_deps)
     _aar_output = _create_aar(name, archive_name, _classes_jar, _jni_archive, proguard_rules, visibility)
 
+    native.filegroup(
+        name = name + "_objdump_collector",
+        srcs = native_deps,
+        output_group = "objdump",
+        visibility = ["//visibility:public"],
+    )
+
     # Generate other needed files for a maven publish
     _sources_name, _javadocs_name = _create_sources_javadocs(name, android_library)
     _pom_name = _create_pom_xml(name, android_library, visibility)

mobile/bazel/android_debug_info.bzl

@@ -0,0 +1,61 @@
+"""
+Rule to create objdump debug info from a native dynamic library built for
+Android.
+
+This is a workaround for generally not being able to produce dwp files for
+Android https://github.com/bazelbuild/bazel/pull/14765
+
+But even if we could create those we'd need to get them out of the build
+somehow, this rule provides a separate --output_group for this
+"""
+
+def _impl(ctx):
+    library_outputs = []
+    objdump_outputs = []
+    for platform, dep in ctx.split_attr.dep.items():
+        # When --fat_apk_cpu isn't set, the platform is None
+        if len(dep.files.to_list()) != 1:
+            fail("Expected exactly one file in the library")
+
+        cc_toolchain = ctx.split_attr._cc_toolchain[platform][cc_common.CcToolchainInfo]
+        lib = dep.files.to_list()[0]
+        platform_name = platform or ctx.fragments.android.android_cpu
+        objdump_output = ctx.actions.declare_file(platform_name + "/" + platform_name + ".objdump")
+
+        ctx.actions.run_shell(
+            inputs = [lib],
+            outputs = [objdump_output],
+            command = cc_toolchain.objdump_executable + " --dwarf=info --dwarf=rawline " + lib.path + ">" + objdump_output.path,
+            tools = [cc_toolchain.all_files],
+        )
+
+        strip_output = ctx.actions.declare_file(platform_name + "/" + lib.basename)
+        ctx.actions.run_shell(
+            inputs = [lib],
+            outputs = [strip_output],
+            command = cc_toolchain.strip_executable + " --strip-debug " + lib.path + " -o " + strip_output.path,
+            tools = [cc_toolchain.all_files],
+        )
+
+        library_outputs.append(strip_output)
+        objdump_outputs.append(objdump_output)
+
+    return [
+        DefaultInfo(files = depset(library_outputs)),
+        OutputGroupInfo(objdump = objdump_outputs),
+    ]
+
+android_debug_info = rule(
+    implementation = _impl,
+    attrs = dict(
+        dep = attr.label(
+            providers = [CcInfo],
+            cfg = android_common.multi_cpu_configuration,
+        ),
+        _cc_toolchain = attr.label(
+            default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
+            cfg = android_common.multi_cpu_configuration,
+        ),
+    ),
+    fragments = ["cpp", "android"],
+)

mobile/library/common/jni/BUILD

@@ -1,4 +1,5 @@
 load("//bazel:kotlin_lib.bzl", "envoy_mobile_so_to_jni_lib")
+load("//bazel:android_debug_info.bzl", "android_debug_info")
 load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library")
 load("@envoy//bazel:envoy_build_system.bzl", "envoy_package")
 load("//bazel:envoy_mobile_test_extensions.bzl", "TEST_EXTENSIONS")
@@ -59,7 +60,7 @@ cc_binary(
         "-llog",
     ] + select({
         "@envoy//bazel:dbg_build": ["-Wl,--build-id=sha1"],
-        "//conditions:default": ["-Wl,-s"],
+        "//conditions:default": [],
     }),
     linkshared = True,
     deps = [
@@ -68,6 +69,11 @@ cc_binary(
     ],
 )
 
+android_debug_info(
+    name = "libenvoy_jni.so.debug_info",
+    dep = "libenvoy_jni.so",
+)
+
 ## Targets for local execution
 # OS X binary (.jnilib) for NDK testing
 envoy_mobile_so_to_jni_lib(

mobile/library/kotlin/io/envoyproxy/envoymobile/BUILD

@@ -11,7 +11,7 @@ android_artifacts(
     archive_name = "envoy",
     manifest = "EnvoyManifest.xml",
     native_deps = [
-        "//library/common/jni:libenvoy_jni.so",
+        "//library/common/jni:libenvoy_jni.so.debug_info",
     ],
     proguard_rules = "//library:proguard_rules",
     visibility = ["//visibility:public"],