gRPC-JSON transcoder (proto)

This extension has the qualified name envoy.filters.http.grpc_json_transcoder


This extension is intended to be robust against untrusted downstream traffic. It assumes that the upstream is trusted.


This extension extends and can be used with the following extension category:

This extension must be configured with one of the following type URLs:

gRPC-JSON transcoder configuration overview.


[extensions.filters.http.grpc_json_transcoder.v3.GrpcJsonTranscoder proto]

GrpcJsonTranscoder filter configuration. The filter itself can be used per route / per virtual host or on the general level. The most specific one is being used for a given route. If the list of services is empty - filter is considered to be disabled. Note that if specifying the filter per route, first the route is matched, and then transcoding filter is applied. It matters when specifying the route configuration and paths to match the request - for per-route grpc transcoder configs, the original path should be matched, while in other cases, the grpc-like path is expected (the one AFTER the filter is applied).

  "proto_descriptor": ...,
  "proto_descriptor_bin": ...,
  "services": [],
  "print_options": {...},
  "match_incoming_request_route": ...,
  "ignored_query_parameters": [],
  "auto_mapping": ...,
  "ignore_unknown_query_parameters": ...,
  "convert_grpc_status": ...,
  "url_unescape_spec": ...,
  "query_param_unescape_plus": ...,
  "match_unregistered_custom_verb": ...,
  "request_validation_options": {...}

(string) Supplies the filename of the proto descriptor set for the gRPC services.

Precisely one of proto_descriptor, proto_descriptor_bin must be set.


(bytes) Supplies the binary content of the proto descriptor set for the gRPC services.

Precisely one of proto_descriptor, proto_descriptor_bin must be set.


(repeated string) A list of strings that supplies the fully qualified service names (i.e. “package_name.service_name”) that the transcoder will translate. If the service name doesn’t exist in proto_descriptor, Envoy will fail at startup. The proto_descriptor may contain more services than the service names specified here, but they won’t be translated.

By default, the filter will pass through requests that do not map to any specified services. If the list of services is empty, filter is considered disabled. However, this behavior changes if reject_unknown_method is enabled.


(extensions.filters.http.grpc_json_transcoder.v3.GrpcJsonTranscoder.PrintOptions) Control options for response JSON. These options are passed directly to JsonPrintOptions.


(bool) Whether to keep the incoming request route after the outgoing headers have been transformed to the match the upstream gRPC service. Note: This means that routes for gRPC services that are not transcoded cannot be used in combination with match_incoming_request_route.


(repeated string) A list of query parameters to be ignored for transcoding method mapping. By default, the transcoder filter will not transcode a request if there are any unknown/invalid query parameters.

Example :

service Bookstore {
  rpc GetShelf(GetShelfRequest) returns (Shelf) {
    option (google.api.http) = {
      get: "/shelves/{shelf}"

message GetShelfRequest {
  int64 shelf = 1;

message Shelf {}

The request /shelves/100?foo=bar will not be mapped to GetShelf` because variable binding for foo is not defined. Adding foo to ignored_query_parameters will allow the same request to be mapped to GetShelf.


(bool) Whether to route methods without the google.api.http option.

Example :

package bookstore;

service Bookstore {
  rpc GetShelf(GetShelfRequest) returns (Shelf) {}

message GetShelfRequest {
  int64 shelf = 1;

message Shelf {}

The client could post a json body {"shelf": 1234} with the path of /bookstore.Bookstore/GetShelfRequest to call GetShelfRequest.


(bool) Whether to ignore query parameters that cannot be mapped to a corresponding protobuf field. Use this if you cannot control the query parameters and do not know them beforehand. Otherwise use ignored_query_parameters. Defaults to false.


(bool) Whether to convert gRPC status headers to JSON. When trailer indicates a gRPC error and there was no HTTP body, take google.rpc.Status from the grpc-status-details-bin header and use it as JSON body. If there was no such header, make google.rpc.Status out of the grpc-status and grpc-message headers. The error details types must be present in the proto_descriptor.

For example, if an upstream server replies with headers:

grpc-status: 5

The grpc-status-details-bin header contains a base64-encoded protobuf message google.rpc.Status. It will be transcoded into:

HTTP/1.1 404 Not Found
content-type: application/json


In order to transcode the message, the google.rpc.RequestInfo type from the google/rpc/error_details.proto should be included in the configured proto descriptor set.


(extensions.filters.http.grpc_json_transcoder.v3.GrpcJsonTranscoder.UrlUnescapeSpec) URL unescaping policy. This spec is only applied when extracting variable with multiple segments in the URL path. For example, in case of /foo/{x=*}/bar/{y=prefix/*}/{z=**} x variable is single segment and y and z are multiple segments. For a path with /foo/first/bar/prefix/second/third/fourth, x=first, y=prefix/second, z=third/fourth. If this setting is not specified, the value defaults to ALL_CHARACTERS_EXCEPT_RESERVED.


(bool) If true, unescape ‘+’ to space when extracting variables in query parameters. This is to support HTML 2.0


(bool) If true, try to match the custom verb even if it is unregistered. By default, only match when it is registered.

According to the http template syntax, the custom verb is “:” LITERAL at the end of http template.

For a request with /foo/bar:baz and :baz is not registered in any url_template, here is the behavior change - if the field is not set, :baz will not be treated as custom verb, so it will match /foo/{x=*}. - if the field is set, :baz is treated as custom verb, so it will NOT match /foo/{x=*} since the template doesn’t use any custom verb.


(extensions.filters.http.grpc_json_transcoder.v3.GrpcJsonTranscoder.RequestValidationOptions) Configure the behavior when handling requests that cannot be transcoded.

By default, the transcoder will silently pass through HTTP requests that are malformed. This includes requests with unknown query parameters, unregister paths, etc.

Set these options to enable strict HTTP request validation, resulting in the transcoder rejecting such requests with a HTTP 4xx. See each individual option for more details on the validation. gRPC requests will still silently pass through without transcoding.

The benefit is a proper error message to the downstream. If the upstream is a gRPC server, it cannot handle the passed-through HTTP requests and will reset the TCP connection. The downstream will then receive a HTTP 503 Service Unavailable due to the upstream connection reset. This incorrect error message may conflict with other Envoy components, such as retry policies.


[extensions.filters.http.grpc_json_transcoder.v3.GrpcJsonTranscoder.PrintOptions proto]

  "add_whitespace": ...,
  "always_print_primitive_fields": ...,
  "always_print_enums_as_ints": ...,
  "preserve_proto_field_names": ...

(bool) Whether to add spaces, line breaks and indentation to make the JSON output easy to read. Defaults to false.


(bool) Whether to always print primitive fields. By default primitive fields with default values will be omitted in JSON output. For example, an int32 field set to 0 will be omitted. Setting this flag to true will override the default behavior and print primitive fields regardless of their values. Defaults to false.


(bool) Whether to always print enums as ints. By default they are rendered as strings. Defaults to false.


(bool) Whether to preserve proto field names. By default protobuf will generate JSON field names using the json_name option, or lower camel case, in that order. Setting this flag will preserve the original field names. Defaults to false.


[extensions.filters.http.grpc_json_transcoder.v3.GrpcJsonTranscoder.RequestValidationOptions proto]

  "reject_unknown_method": ...,
  "reject_unknown_query_parameters": ...,
  "reject_binding_body_field_collisions": ...

(bool) By default, a request that cannot be mapped to any specified gRPC services will pass-through this filter. When set to true, the request will be rejected with a HTTP 404 Not Found.


(bool) By default, a request with query parameters that cannot be mapped to the gRPC request message will pass-through this filter. When set to true, the request will be rejected with a HTTP 400 Bad Request.

The fields ignore_unknown_query_parameters and ignored_query_parameters have priority over this strict validation behavior.


(bool) “id: 456” in the body will override “id=123” in the binding.

If this field is set to true, the request will be rejected if the binding value is different from the body value.

Enum extensions.filters.http.grpc_json_transcoder.v3.GrpcJsonTranscoder.UrlUnescapeSpec

[extensions.filters.http.grpc_json_transcoder.v3.GrpcJsonTranscoder.UrlUnescapeSpec proto]


(DEFAULT) ⁣URL path parameters will not decode RFC 6570 reserved characters. For example, segment %2f%23/%20%2523 is unescaped to %2f%23/ %23.


⁣URL path parameters will be fully URI-decoded except in cases of single segment matches in reserved expansion, where %2F will be left encoded. For example, segment %2f%23/%20%2523 is unescaped to %2f#/ %23.


⁣URL path parameters will be fully URI-decoded. For example, segment %2f%23/%20%2523 is unescaped to /#/ %23.