gRPC HTTP/1.1 bridge¶
This is a simple filter which enables the bridging of an HTTP/1.1 client which does not support response trailers to a compliant gRPC server. It works by doing the following:
- When a request is sent, the filter sees if the connection is HTTP/1.1 and the request content type is application/grpc.
- If so, when the response is received, the filter buffers it and waits for trailers and then checks the grpc-status code. If it is not zero, the filter switches the HTTP response code to 503. It also copies the grpc-status and grpc-message trailers into the response headers so that the client can look at them if it wishes.
- The client should send HTTP/1.1 requests that translate to the following psuedo headers:
- :method: POST
- :path: <gRPC-METHOD-NAME>
- content-type: application/grpc
- The body should be the serialized grpc body which is:
- 1 byte of zero (not compressed).
- network order 4 bytes of proto message length.
- serialized proto message.
- Because this scheme must buffer the response to look for the grpc-status trailer it will only work with unary gRPC APIs.
More info: http://www.grpc.io/docs/guides/wire.html
This filter also collects stats for all gRPC requests that transit, even if those requests are normal gRPC requests over HTTP/2.
Statistics¶
The filter emits statistics in the cluster.<route target cluster>.grpc. namespace.
Name | Type | Description |
---|---|---|
<grpc service>.<grpc method>.success | Counter | Total successful service/method calls |
<grpc service>.<grpc method>.failure | Counter | Total failed service/method calls |
<grpc service>.<grpc method>.total | Counter | Total service/method calls |