proxy

Documentation

Overview

Package proxy provides a reverse proxy handler for gRPC.

The implementation allows a `grpc.Server` to pass a received ServerStream to a ClientStream without understanding the semantics of the messages exchanged. It basically provides a transparent reverse-proxy.

This package is intentionally generic, exposing a `StreamDirector` function that allows users of this package to implement whatever logic of backend-picking, dialing and service verification to perform.

Package is a revised version of https://github.com/mwitkow/grpc-proxy

Index

• func Codec() codec
• func CodecWithParent(fallback encoding.Codec) codec
• func RegisterService(server *grpc.Server, director StreamDirector, serviceName string, ...)
• func RegisterTestServiceServer(s *grpc.Server, srv TestServiceServer)
• func TransparentHandler(director StreamDirector) grpc.StreamHandler
• type Empty
  • func (*Empty) Descriptor() ([]byte, []int)
  • func (*Empty) ProtoMessage()
  • func (m *Empty) Reset()
  • func (m *Empty) String() string
• type PingRequest
  • func (*PingRequest) Descriptor() ([]byte, []int)
  • func (m *PingRequest) GetValue() string
  • func (*PingRequest) ProtoMessage()
  • func (m *PingRequest) Reset()
  • func (m *PingRequest) String() string
• type PingResponse
  • func (*PingResponse) Descriptor() ([]byte, []int)
  • func (m *PingResponse) GetCounter() int32
  • func (m *PingResponse) GetValue() string
  • func (*PingResponse) ProtoMessage()
  • func (m *PingResponse) Reset()
  • func (m *PingResponse) String() string
• type StreamDirector
• type TestServiceClient
  • func NewTestServiceClient(cc *grpc.ClientConn) TestServiceClient
• type TestServiceServer
• type TestService_PingListClient
• type TestService_PingListServer
• type TestService_PingStreamClient
• type TestService_PingStreamServer

Functions

func Codec

func Codec() codec

Codec returns a proxying codec with conforms both to encoding.Codec and grpc.Codec with the default protobuf codec as parent.

See CodecWithParent.

func CodecWithParent

func CodecWithParent(fallback encoding.Codec) codec

CodecWithParent returns a proxying encoding.Codec with a user provided codec as parent.

This codec is *crucial* to the functioning of the proxy. It allows the proxy server to be oblivious to the schema of the forwarded messages. It basically treats a gRPC message frame as raw bytes. However, if the server handler, or the client caller are not proxy-internal functions it will fall back to trying to decode the message using a fallback codec.

func RegisterService

func RegisterService(server *grpc.Server, director StreamDirector, serviceName string, methodNames ...string)

func RegisterTestServiceServer

func RegisterTestServiceServer(s *grpc.Server, srv TestServiceServer)

func TransparentHandler

func TransparentHandler(director StreamDirector) grpc.StreamHandler

TransparentHandler returns a handler that attempts to proxy all requests that are not registered in the server. The indented use here is as a transparent proxy, where the server doesn't know about the services implemented by the backends. It should be used as a `grpc.UnknownServiceHandler`.

This can *only* be used if the `server` also uses proxy.CustomCodec(proxy.Codec()) ServerOption.

Types

type Empty

type Empty struct {
}

func (*Empty) Descriptor

func (*Empty) Descriptor() ([]byte, []int)

func (*Empty) ProtoMessage

func (*Empty) ProtoMessage()

func (*Empty) Reset

func (m *Empty) Reset()

func (*Empty) String

func (m *Empty) String() string

type PingRequest

type PingRequest struct {
	Value string `protobuf:"bytes,1,opt,name=value" json:"value,omitempty"`
}

func (*PingRequest) Descriptor

func (*PingRequest) Descriptor() ([]byte, []int)

func (*PingRequest) GetValue

func (m *PingRequest) GetValue() string

func (*PingRequest) ProtoMessage

func (*PingRequest) ProtoMessage()

func (*PingRequest) Reset

func (m *PingRequest) Reset()

func (*PingRequest) String

func (m *PingRequest) String() string

type PingResponse

type PingResponse struct {
	Value   string `protobuf:"bytes,1,opt,name=Value" json:"Value,omitempty"`
	Counter int32  `protobuf:"varint,2,opt,name=counter" json:"counter,omitempty"`
}

func (*PingResponse) Descriptor

func (*PingResponse) Descriptor() ([]byte, []int)

func (*PingResponse) GetCounter

func (m *PingResponse) GetCounter() int32

func (*PingResponse) GetValue

func (m *PingResponse) GetValue() string

func (*PingResponse) ProtoMessage

func (*PingResponse) ProtoMessage()

func (*PingResponse) Reset

func (m *PingResponse) Reset()

func (*PingResponse) String

func (m *PingResponse) String() string

type StreamDirector

type StreamDirector func(ctx context.Context, fullMethodName string) (outgoingContext context.Context, backendConn *grpc.ClientConn, err error)

StreamDirector returns a gRPC ClientConn to be used to forward the call to.

The presence of the `Context` allows for rich filtering, e.g. based on Metadata (headers). If no handling is meant to be done, a `codes.NotImplemented` gRPC error should be returned.

The context returned from this function should be the context for the *outgoing* (to backend) call. In case you want to forward any Metadata between the inbound request and outbound requests, you should do it manually. However, you *must* propagate the cancel function (`context.WithCancel`) of the inbound context to the one returned.

It is worth noting that the StreamDirector will be fired *after* all server-side stream interceptors are invoked. So decisions around authorization, monitoring etc. are better to be handled there.

type TestServiceClient

type TestServiceClient interface {
	PingEmpty(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*PingResponse, error)
	Ping(ctx context.Context, in *PingRequest, opts ...grpc.CallOption) (*PingResponse, error)
	PingError(ctx context.Context, in *PingRequest, opts ...grpc.CallOption) (*Empty, error)
	PingList(ctx context.Context, in *PingRequest, opts ...grpc.CallOption) (TestService_PingListClient, error)
	PingStream(ctx context.Context, opts ...grpc.CallOption) (TestService_PingStreamClient, error)
}

func NewTestServiceClient

func NewTestServiceClient(cc *grpc.ClientConn) TestServiceClient

type TestServiceServer

type TestServiceServer interface {
	PingEmpty(context.Context, *Empty) (*PingResponse, error)
	Ping(context.Context, *PingRequest) (*PingResponse, error)
	PingError(context.Context, *PingRequest) (*Empty, error)
	PingList(*PingRequest, TestService_PingListServer) error
	PingStream(TestService_PingStreamServer) error
}

type TestService_PingListClient

type TestService_PingListClient interface {
	Recv() (*PingResponse, error)
	grpc.ClientStream
}

type TestService_PingListServer

type TestService_PingListServer interface {
	Send(*PingResponse) error
	grpc.ServerStream
}

type TestService_PingStreamClient

type TestService_PingStreamClient interface {
	Send(*PingRequest) error
	Recv() (*PingResponse, error)
	grpc.ClientStream
}

type TestService_PingStreamServer

type TestService_PingStreamServer interface {
	Send(*PingResponse) error
	Recv() (*PingRequest, error)
	grpc.ServerStream
}