README
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grpc
gRPC is an excellent, modern IDL and transport for microservices. If you're starting a greenfield project, Go kit strongly recommends gRPC as your default transport. And using gRPC and Go kit together is very simple.
First, define your service using protobuf3. This is explained in gRPC documentation. See add.proto for an example. Make sure the proto definition matches your service's Go kit (interface) definition.
Next, get the protoc compiler. Unfortunately, this needs to be done from source. Fortunately, it's pretty straightforward.
brew install autoconf automake libtool
git clone https://github.com/google/protobuf
cd protobuf
./autogen.sh ; ./configure ; make ; make install
Then, compile your service definition, from .proto to .go.
protoc add.proto --go_out=plugins=grpc:.
Finally, write a tiny binding from your service definition to the gRPC definition. It's a simple conversion from one domain to another. See grpc_binding.go for an example.
That's it! The gRPC binding can be bound to a listener and serve normal gRPC requests. And within your service, you can use standard Go kit components and idioms. See addsvc for a complete working example with gRPC support. And remember: Go kit services can support multiple transports simultaneously.
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func EncodeKeyValue ¶
EncodeKeyValue sanitizes a key-value pair for use in gRPC metadata headers.
Types ¶
type BadRequestError ¶
type BadRequestError struct {
Err error
}
BadRequestError is an error in decoding the request.
func (BadRequestError) Error ¶
func (err BadRequestError) Error() string
Error implements the error interface.
type Client ¶
type Client struct {
// contains filtered or unexported fields
}
Client wraps a gRPC connection and provides a method that implements endpoint.Endpoint.
func NewClient ¶
func NewClient( cc *grpc.ClientConn, serviceName string, method string, enc EncodeRequestFunc, dec DecodeResponseFunc, grpcReply interface{}, options ...ClientOption, ) *Client
NewClient constructs a usable Client for a single remote endpoint. Pass an zero-value protobuf message of the RPC response type as the grpcReply argument.
type ClientOption ¶
type ClientOption func(*Client)
ClientOption sets an optional parameter for clients.
func SetClientBefore ¶
func SetClientBefore(before ...RequestFunc) ClientOption
SetClientBefore sets the RequestFuncs that are applied to the outgoing gRPC request before it's invoked.
type DecodeRequestFunc ¶
DecodeRequestFunc extracts a user-domain request object from a gRPC request. It's designed to be used in gRPC servers, for server-side endpoints. One straightforward DecodeRequestFunc could be something that decodes from the gRPC request message to the concrete request type.
type DecodeResponseFunc ¶
DecodeResponseFunc extracts a user-domain response object from a gRPC response object. It's designed to be used in gRPC clients, for client-side endpoints. One straightforward DecodeResponseFunc could be something that decodes from the gRPC response message to the concrete response type.
type EncodeRequestFunc ¶
EncodeRequestFunc encodes the passed request object into the gRPC request object. It's designed to be used in gRPC clients, for client-side endpoints. One straightforward EncodeRequestFunc could something that encodes the object directly to the gRPC request message.
type EncodeResponseFunc ¶
EncodeResponseFunc encodes the passed response object to the gRPC response message. It's designed to be used in gRPC servers, for server-side endpoints. One straightforward EncodeResponseFunc could be something that encodes the object directly to the gRPC response message.
type Handler ¶
type Handler interface {
ServeGRPC(ctx context.Context, request interface{}) (context.Context, interface{}, error)
}
Handler which should be called from the grpc binding of the service implementation. The incoming request parameter, and returned response parameter, are both gRPC types, not user-domain.
type RequestFunc ¶
RequestFunc may take information from an gRPC request and put it into a request context. In Servers, BeforeFuncs are executed prior to invoking the endpoint. In Clients, BeforeFuncs are executed after creating the request but prior to invoking the gRPC client.
func SetRequestHeader ¶
func SetRequestHeader(key, val string) RequestFunc
SetRequestHeader returns a RequestFunc that sets the specified metadata key-value pair.
type ResponseFunc ¶
ResponseFunc may take information from a request context and use it to manipulate the gRPC metadata header. ResponseFuncs are only executed in servers, after invoking the endpoint but prior to writing a response.
func SetResponseHeader ¶
func SetResponseHeader(key, val string) ResponseFunc
SetResponseHeader returns a ResponseFunc that sets the specified metadata key-value pair.
type Server ¶
type Server struct {
// contains filtered or unexported fields
}
Server wraps an endpoint and implements grpc.Handler.
func NewServer ¶
func NewServer( ctx context.Context, e endpoint.Endpoint, dec DecodeRequestFunc, enc EncodeResponseFunc, options ...ServerOption, ) *Server
NewServer constructs a new server, which implements wraps the provided endpoint and implements the Handler interface. Consumers should write bindings that adapt the concrete gRPC methods from their compiled protobuf definitions to individual handlers. Request and response objects are from the caller business domain, not gRPC request and reply types.
type ServerOption ¶
type ServerOption func(*Server)
ServerOption sets an optional parameter for servers.
func ServerAfter ¶
func ServerAfter(after ...ResponseFunc) ServerOption
ServerAfter functions are executed on the HTTP response writer after the endpoint is invoked, but before anything is written to the client.
func ServerBefore ¶
func ServerBefore(before ...RequestFunc) ServerOption
ServerBefore functions are executed on the HTTP request object before the request is decoded.
func ServerErrorLogger ¶
func ServerErrorLogger(logger log.Logger) ServerOption
ServerErrorLogger is used to log non-terminal errors. By default, no errors are logged.
Source Files