fuzz: reduce log level when running under fuzz engine. (envoyproxy#4161)

The ClusterFuzz stats indicated a lot of log spew, this is a structural
attempt to reduce it. We now run with logging off when under the engine,
but at ::info when running under bazel test. This can be further
overrides when debugging with -l to more verbose levels. The usual flow
is we download a repeater from the database and then reproduce with
logs.

There's still some log spam from libproto, will look into that
separately.

Risk Level: low
Testing: manual tests on CLI with different combinations of flags.

Signed-off-by: Harvey Tuch <htuch@google.com>

test/fuzz/fuzz_runner.cc

@@ -9,21 +9,27 @@
 namespace Envoy {
 namespace Fuzz {
 
-void Runner::setupEnvironment(int argc, char** argv) {
+spdlog::level::level_enum Runner::log_level_;
+
+void Runner::setupEnvironment(int argc, char** argv, spdlog::level::level_enum default_log_level) {
   Event::Libevent::Global::initialize();
 
   TestEnvironment::initializeOptions(argc, argv);
 
   static auto* lock = new Thread::MutexBasicLockable();
   const auto environment_log_level = TestEnvironment::getOptions().logLevel();
-  Logger::Registry::initialize(std::min(environment_log_level, spdlog::level::info),
-                               TestEnvironment::getOptions().logFormat(), *lock);
+  // We only override the default log level if it looks like we're debugging;
+  // otherwise the default environment log level might override the default and
+  // spew too much when running under a fuzz engine.
+  log_level_ =
+      environment_log_level <= spdlog::level::debug ? environment_log_level : default_log_level;
+  Logger::Registry::initialize(log_level_, TestEnvironment::getOptions().logFormat(), *lock);
 }
 
 } // namespace Fuzz
 } // namespace Envoy
 
 extern "C" int LLVMFuzzerInitialize(int* /*argc*/, char*** argv) {
-  Envoy::Fuzz::Runner::setupEnvironment(1, *argv);
+  Envoy::Fuzz::Runner::setupEnvironment(1, *argv, spdlog::level::off);
   return 0;
 }

test/fuzz/fuzz_runner.h

@@ -6,6 +6,7 @@
 // Bring in DEFINE_PROTO_FUZZER definition as per
 // https://github.com/google/libprotobuf-mutator#integrating-with-libfuzzer.
 #include "libprotobuf_mutator/src/libfuzzer/libfuzzer_macro.h"
+#include "spdlog/spdlog.h"
 
 namespace Envoy {
 namespace Fuzz {
@@ -17,8 +18,17 @@ class Runner {
    * invoked in this environment.
    * @param argc number of command-line args.
    * @param argv array of command-line args.
+   * @param default_loglevel default log level (overridable with -l).
    */
-  static void setupEnvironment(int argc, char** argv);
+  static void setupEnvironment(int argc, char** argv, spdlog::level::level_enum default_log_level);
+
+  /**
+   * @return spdlog::level::level_enum the log level for the fuzzer.
+   */
+  static spdlog::level::level_enum logLevel() { return log_level_; }
+
+private:
+  static spdlog::level::level_enum log_level_;
 };
 
 } // namespace Fuzz

test/fuzz/main.cc

@@ -51,6 +51,6 @@ int main(int argc, char** argv) {
   RELEASE_ASSERT(Envoy::Filesystem::directoryExists(corpus_path), "");
   Envoy::test_corpus_ = Envoy::TestUtility::listFiles(corpus_path, true);
   testing::InitGoogleTest(&argc, argv);
-  Envoy::Fuzz::Runner::setupEnvironment(argc, argv);
+  Envoy::Fuzz::Runner::setupEnvironment(argc, argv, spdlog::level::info);
   return RUN_ALL_TESTS();
 }

test/mocks/server/mocks.cc

@@ -26,6 +26,7 @@ MockOptions::MockOptions(const std::string& config_path) : config_path_(config_p
   ON_CALL(*this, serviceClusterName()).WillByDefault(ReturnRef(service_cluster_name_));
   ON_CALL(*this, serviceNodeName()).WillByDefault(ReturnRef(service_node_name_));
   ON_CALL(*this, serviceZone()).WillByDefault(ReturnRef(service_zone_name_));
+  ON_CALL(*this, logLevel()).WillByDefault(Return(log_level_));
   ON_CALL(*this, logPath()).WillByDefault(ReturnRef(log_path_));
   ON_CALL(*this, maxStats()).WillByDefault(Return(1000));
   ON_CALL(*this, statsOptions()).WillByDefault(ReturnRef(stats_options_));

test/mocks/server/mocks.h

@@ -80,6 +80,7 @@ class MockOptions : public Options {
   std::string service_cluster_name_;
   std::string service_node_name_;
   std::string service_zone_name_;
+  spdlog::level::level_enum log_level_{spdlog::level::trace};
   std::string log_path_;
   Stats::StatsOptionsImpl stats_options_;
   bool hot_restart_disabled_{};

test/server/config_validation/config_fuzz_test.cc

@@ -22,6 +22,7 @@ DEFINE_PROTO_FUZZER(const envoy::config::bootstrap::v2::Bootstrap& input) {
   bootstrap_file << input.DebugString();
   options.config_path_ = bootstrap_path;
   options.v2_config_only_ = true;
+  options.log_level_ = Fuzz::Runner::logLevel();
 
   try {
     validateConfig(options, Network::Address::InstanceConstSharedPtr(), component_factory);

test/server/server_fuzz_test.cc

@@ -33,6 +33,7 @@ DEFINE_PROTO_FUZZER(const envoy::config::bootstrap::v2::Bootstrap& input) {
     bootstrap_file << input.DebugString();
     options.config_path_ = bootstrap_path;
     options.v2_config_only_ = true;
+    options.log_level_ = Fuzz::Runner::logLevel();
   }
 
   try {