Added AWS region provider

source/common/common/logger.h

@@ -20,8 +20,10 @@ namespace Envoy {
 namespace Logger {
 
 // clang-format off
+// TODO: find out a way for extensions to register new logger IDs
 #define ALL_LOGGER_IDS(FUNCTION) \
   FUNCTION(admin)                \
+  FUNCTION(aws)                  \
   FUNCTION(assert)               \
   FUNCTION(backtrace)            \
   FUNCTION(client)               \

source/extensions/filters/http/common/aws/BUILD

@@ -49,3 +49,19 @@ envoy_cc_library(
         "//source/common/http:headers_lib",
     ],
 )
+
+envoy_cc_library(
+    name = "region_provider_interface",
+    hdrs = ["region_provider.h"],
+    external_deps = ["abseil_optional"],
+)
+
+envoy_cc_library(
+    name = "region_provider_impl_lib",
+    srcs = ["region_provider_impl.cc"],
+    hdrs = ["region_provider_impl.h"],
+    deps = [
+        ":region_provider_interface",
+        "//source/common/common:logger_lib",
+    ],
+)

source/extensions/filters/http/common/aws/region_provider.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include "envoy/common/pure.h"
+
+#include "absl/types/optional.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace HttpFilters {
+namespace Common {
+namespace Aws {
+
+/**
+ * Interface for classes capable of discovering the AWS region from the execution environment.
+ */
+class RegionProvider {
+public:
+  virtual ~RegionProvider() = default;
+
+  /**
+   * Discover and return the AWS region.
+   * @return AWS region, or nullopt if unable to discover the region.
+   */
+  virtual absl::optional<std::string> getRegion() PURE;
+};
+
+typedef std::shared_ptr<RegionProvider> RegionProviderSharedPtr;
+
+} // namespace Aws
+} // namespace Common
+} // namespace HttpFilters
+} // namespace Extensions
+} // namespace Envoy

source/extensions/filters/http/common/aws/region_provider_impl.cc

@@ -0,0 +1,30 @@
+#include "extensions/filters/http/common/aws/region_provider_impl.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace HttpFilters {
+namespace Common {
+namespace Aws {
+
+static const char AWS_REGION[] = "AWS_REGION";
+
+StaticRegionProvider::StaticRegionProvider(const std::string& region) : region_(region) {}
+
+absl::optional<std::string> StaticRegionProvider::getRegion() {
+  return absl::optional<std::string>(region_);
+}
+
+absl::optional<std::string> EnvironmentRegionProvider::getRegion() {
+  const auto region = std::getenv(AWS_REGION);
+  if (region == nullptr) {
+    return absl::nullopt;
+  }
+  ENVOY_LOG(debug, "Found environment region {}={}", AWS_REGION, region);
+  return absl::optional<std::string>(region);
+}
+
+} // namespace Aws
+} // namespace Common
+} // namespace HttpFilters
+} // namespace Extensions
+} // namespace Envoy

source/extensions/filters/http/common/aws/region_provider_impl.h

@@ -0,0 +1,38 @@
+#pragma once
+
+#include "common/common/logger.h"
+
+#include "extensions/filters/http/common/aws/region_provider.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace HttpFilters {
+namespace Common {
+namespace Aws {
+
+/**
+ * Retrieve AWS region name from the environment
+ */
+class EnvironmentRegionProvider : public RegionProvider, public Logger::Loggable<Logger::Id::aws> {
+public:
+  absl::optional<std::string> getRegion() override;
+};
+
+/**
+ * Return statically configured AWS region name
+ */
+class StaticRegionProvider : public RegionProvider {
+public:
+  StaticRegionProvider(const std::string& region);
+
+  absl::optional<std::string> getRegion() override;
+
+private:
+  const std::string region_;
+};
+
+} // namespace Aws
+} // namespace Common
+} // namespace HttpFilters
+} // namespace Extensions
+} // namespace Envoy

test/extensions/filters/http/common/aws/BUILD

@@ -40,3 +40,12 @@ envoy_cc_test(
         "//test/test_common:utility_lib",
     ],
 )
+
+envoy_cc_test(
+    name = "region_provider_impl_test",
+    srcs = ["region_provider_impl_test.cc"],
+    deps = [
+        "//source/extensions/filters/http/common/aws:region_provider_impl_lib",
+        "//test/test_common:environment_lib",
+    ],
+)

test/extensions/filters/http/common/aws/region_provider_impl_test.cc

@@ -0,0 +1,42 @@
+#include "extensions/filters/http/common/aws/region_provider_impl.h"
+
+#include "test/test_common/environment.h"
+
+#include "gtest/gtest.h"
+
+namespace Envoy {
+namespace Extensions {
+namespace HttpFilters {
+namespace Common {
+namespace Aws {
+
+class EnvironmentRegionProviderTest : public testing::Test {
+public:
+  virtual ~EnvironmentRegionProviderTest() { TestEnvironment::unsetEnvVar("AWS_REGION"); }
+
+  EnvironmentRegionProvider provider_;
+};
+
+class StaticRegionProviderTest : public testing::Test {
+public:
+  StaticRegionProviderTest() : provider_("test-region") {}
+
+  StaticRegionProvider provider_;
+};
+
+TEST_F(EnvironmentRegionProviderTest, SomeRegion) {
+  TestEnvironment::setEnvVar("AWS_REGION", "test-region", 1);
+  EXPECT_EQ("test-region", provider_.getRegion().value());
+}
+
+TEST_F(EnvironmentRegionProviderTest, NoRegion) { EXPECT_FALSE(provider_.getRegion().has_value()); }
+
+TEST_F(StaticRegionProviderTest, SomeRegion) {
+  EXPECT_EQ("test-region", provider_.getRegion().value());
+}
+
+} // namespace Aws
+} // namespace Common
+} // namespace HttpFilters
+} // namespace Extensions
+} // namespace Envoy

test/test_common/environment.cc

@@ -315,7 +315,7 @@ void TestEnvironment::setEnvVar(const std::string& name, const std::string& valu
   if (!overwrite) {
     size_t requiredSize;
     const int rc = ::getenv_s(&requiredSize, nullptr, 0, name.c_str());
-    ASSERT_EQ(rc, 0);
+    ASSERT_EQ(0, rc);
     if (requiredSize != 0) {
       return;
     }
@@ -324,7 +324,17 @@ void TestEnvironment::setEnvVar(const std::string& name, const std::string& valu
   ASSERT_EQ(0, rc);
 #else
   const int rc = ::setenv(name.c_str(), value.c_str(), overwrite);
-  ASSERT_EQ(rc, 0);
+  ASSERT_EQ(0, rc);
+#endif
+}
+
+void TestEnvironment::unsetEnvVar(const std::string& name) {
+#ifdef WIN32
+  const int rc = ::_putenv_s(name.c_str(), "");
+  ASSERT_EQ(0, rc);
+#else
+  const int rc = ::unsetenv(name.c_str());
+  ASSERT_EQ(0, rc);
 #endif
 }
 

test/test_common/environment.h

@@ -203,6 +203,11 @@ class TestEnvironment {
    * Set environment variable. Same args as setenv(2).
    */
   static void setEnvVar(const std::string& name, const std::string& value, int overwrite);
+
+  /**
+   * Removes environment variable. Same args as unsetenv(3).
+   */
+  static void unsetEnvVar(const std::string& name);
 };
 
 } // namespace Envoy