Add new MergeJsonKeys functionality to transformation filter.

api/envoy/config/filter/http/transformation/v2/transformation_filter.proto

@@ -267,6 +267,11 @@ message TransformationTemplate {
     // If you want to nest elements inside the body, use dot separator in the
     // extractor name.
     MergeExtractorsToBody merge_extractors_to_body = 6;
+    // A set of key-value pairs to merge into the JSON body.
+    // Each value will be rendered separately, and then placed into the JSON body at
+    // the specified key.
+    // This can only be used when the body is parsed as JSON.
+    MergeJsonKeys merge_json_keys = 13;
   }
 
   // Determines how the body will be parsed.
@@ -326,6 +331,17 @@ message Passthrough {}
 
 message MergeExtractorsToBody {}
 
+message MergeJsonKeys {
+  message OverridableTemplate {
+    // Template to render
+    InjaTemplate tmpl = 1;
+    // If set to true, the template will be set even if the rendered value is empty.
+    bool override_empty = 2;
+  }
+  // Map of key name -> template to render into the JSON body
+  map<string, OverridableTemplate> json_keys = 2;
+}
+
 message HeaderBodyTransform {
   // When transforming a request, setting this to true will additionally add
   // "queryString", "queryStringParameters", "multiValueQueryStringParameters",

bazel/repository_locations.bzl

@@ -3,8 +3,8 @@ REPOSITORY_LOCATIONS = dict(
     # order to accommodate `check_extensions_build_config.sh`
     envoy = dict(
         # envoy v1.30.2
-        commit = "d79f6e8d453ee260e9094093b8dd31af0056e67b",
-        remote = "https://github.com/envoyproxy/envoy",
+        commit = "316374fd9927754627ded8420a1944a8b4d8663d",
+        remote = "https://github.com/solo-io/envoy-fork",
     ),
     inja = dict(
         # Includes unmerged modifications for

source/extensions/filters/http/transformation/inja_transformer.cc

@@ -236,13 +236,13 @@ TransformerInstance::TransformerInstance(ThreadLocal::Slot &tls, Envoy::Random::
   env_.add_callback("clusterMetadata", 1, [this](Arguments &args) {
     return cluster_metadata_callback_deprecated(args);
   });
-  env_.add_callback("cluster_metadata", 1, [this](Arguments &args) {
+  env_.add_callback("cluster_metadata", [this](Arguments &args) {
     return cluster_metadata_callback(args);
   });
-  env_.add_callback("dynamic_metadata", 1, [this](Arguments &args) {
+  env_.add_callback("dynamic_metadata", [this](Arguments &args) {
     return dynamic_metadata_callback(args);
   });
-  env_.add_callback("host_metadata", 1, [this](Arguments &args) {
+  env_.add_callback("host_metadata", [this](Arguments &args) {
     return host_metadata_callback(args);
   });
   env_.add_callback("base64_encode", 1, [this](Arguments &args) {
@@ -772,6 +772,21 @@ InjaTransformer::InjaTransformer(const TransformationTemplate &transformation,
     merged_extractors_to_body_ = true;
     break;
   }
+  case TransformationTemplate::kMergeJsonKeys: {
+    if (transformation.parse_body_behavior() == TransformationTemplate::DontParse) {
+      throw EnvoyException("MergeJsonKeys requires parsing the body");
+    }
+    try {
+      for (const auto &named_extractor : transformation.merge_json_keys().json_keys()) {
+        merge_templates_.emplace_back(std::make_tuple(named_extractor.first, named_extractor.second.override_empty(), instance_->parse(named_extractor.second.tmpl().text())));
+      }
+
+    } catch (const std::exception &e) {
+      throw EnvoyException(
+          fmt::format("Failed to parse merge_body_key template {}", e.what()));
+    }
+    break;
+  }
   case TransformationTemplate::kPassthrough:
     break;
   case TransformationTemplate::BODY_TRANSFORMATION_NOT_SET: {
@@ -945,6 +960,38 @@ void InjaTransformer::transform(Http::RequestOrResponseHeaderMap &header_map,
   } else if (merged_extractors_to_body_) {
     std::string output = json_body.dump();
     maybe_body.emplace(output);
+  } else if (merge_templates_.size() > 0) {
+
+    for (const auto &merge_template : merge_templates_) {
+      const std::string &name = std::get<0>(merge_template);
+
+      // prepare variables for non-advanced_templates_ scenario
+      absl::string_view name_to_split;
+      json* current = nullptr;
+      // if (!advanced_templates_) {
+      name_to_split = name;
+      current = &json_body;
+      for (size_t pos = name_to_split.find("."); pos != std::string::npos;
+          pos = name_to_split.find(".")) {
+        auto &&field_name = name_to_split.substr(0, pos);
+        current = &(*current)[std::string(field_name)];
+        name_to_split = name_to_split.substr(pos + 1);
+      }
+      const auto rendered = instance_->render(std::get<2>(merge_template));
+      // Do not overwrite with empty unless specified
+      if (rendered.size() > 0 || std::get<1>(merge_template)) {
+        try {
+          auto rendered_json = json::parse(rendered);
+          (*current)[std::string(name_to_split)] = rendered_json;
+        } catch (const std::exception &e) {
+          ASSERT("failed to parse merge_json_key output");
+          (*current)[std::string(name_to_split)] = rendered;
+        }
+      }
+      // }
+    }
+    std::string output = json_body.dump();
+    maybe_body.emplace(output);
   }
 
   // DynamicMetadata transform:

source/extensions/filters/http/transformation/inja_transformer.h

@@ -154,6 +154,7 @@ class InjaTransformer : public Transformer {
 
   absl::optional<inja::Template> body_template_;
   bool merged_extractors_to_body_{};
+  std::vector<std::tuple<std::string, bool, inja::Template>> merge_templates_;
   ThreadLocal::SlotPtr tls_;
   std::unique_ptr<TransformerInstance> instance_;
 };

test/extensions/filters/http/transformation/inja_transformer_test.cc

@@ -759,6 +759,47 @@ TEST_F(InjaTransformerTest, UseBodyFunction) {
   EXPECT_EQ(body.toString(), "1 1");
 }
 
+TEST_F(InjaTransformerTest, MergeJsonKeys) {
+  Http::TestRequestHeaderMapImpl headers{{":method", "GET"}, {":path", "/foo"}};
+  TransformationTemplate transformation;
+
+
+  // TransformationTemplate transformation;
+  // transformation.mutable_body()->set_text("{\"ext2\": \"{{header(\":path\")}\" }");
+
+  envoy::api::v2::filter::http::InjaTemplate inja_template;
+  inja_template.set_text("\"{{header(\":path\")}}\"");
+  envoy::api::v2::filter::http::MergeJsonKeys_OverridableTemplate tmpl;
+  (*tmpl.mutable_tmpl()) = inja_template;
+  (*transformation.mutable_merge_json_keys()->mutable_json_keys())["ext2"] = tmpl;
+
+  InjaTransformer transformer(transformation, rng_, google::protobuf::BoolValue(), tls_);
+
+  NiceMock<Http::MockStreamDecoderFilterCallbacks> callbacks;
+  Buffer::OwnedImpl body("{\"ext1\":\"123\"}");
+  transformer.transform(headers, &headers, body, callbacks);
+  EXPECT_EQ(body.toString(), "{\"ext1\":\"123\",\"ext2\":\"/foo\"}");
+}
+
+TEST_F(InjaTransformerTest, MergeJsonKeysEmpty ) {
+  Http::TestRequestHeaderMapImpl headers{{":method", "GET"}, {":path", "/foo"}};
+  TransformationTemplate transformation;
+
+  envoy::api::v2::filter::http::InjaTemplate inja_template;
+  // Should return "" and therefore not write the key at all
+  inja_template.set_text("{{header(\":status\")}}");
+  envoy::api::v2::filter::http::MergeJsonKeys_OverridableTemplate tmpl;
+  (*tmpl.mutable_tmpl()) = inja_template;
+  (*transformation.mutable_merge_json_keys()->mutable_json_keys())["ext2"] = tmpl;
+
+  InjaTransformer transformer(transformation, rng_, google::protobuf::BoolValue(), tls_);
+
+  NiceMock<Http::MockStreamDecoderFilterCallbacks> callbacks;
+  Buffer::OwnedImpl body("{\"ext1\":\"123\"}");
+  transformer.transform(headers, &headers, body, callbacks);
+  EXPECT_EQ(body.toString(), "{\"ext1\":\"123\"}");
+}
+
 TEST_F(InjaTransformerTest, UseDefaultNS) {
   Http::TestRequestHeaderMapImpl headers{{":method", "GET"}, {":path", "/foo"}};
   TransformationTemplate transformation;