clair/pkg/grpcutil/gateway.go
Jimmy Zelinskie 1ec2759550 pkg/grpcutil: init
This change refactors gRPC code used within the v3 API package into
generic code that can be used for managing gRPC and gRPC Gateway.
2018-09-11 14:46:52 -04:00

82 lines
2.7 KiB
Go

// Copyright 2018 clair authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package grpcutil
import (
"crypto/tls"
"net/http"
"strings"
"github.com/grpc-ecosystem/grpc-gateway/runtime"
"golang.org/x/net/context"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials"
)
// RegisterServiceHandlerFunc is a function that registers ServiceHandlers with
// a ServeMux.
type RegisterServiceHandlerFunc func(context.Context, *runtime.ServeMux, *grpc.ClientConn) error
// NewGateway creates a new http.Handler and grpc.ClientConn with the provided
// gRPC Services registered.
func NewGateway(addr string, tlsConfig *tls.Config, funcs []RegisterServiceHandlerFunc) (http.Handler, *grpc.ClientConn, error) {
// Configure the right DialOptions the for TLS configuration.
var dialOpts []grpc.DialOption
if tlsConfig != nil {
var gwTLSConfig *tls.Config
gwTLSConfig = tlsConfig.Clone()
gwTLSConfig.InsecureSkipVerify = true // Trust the local server.
dialOpts = append(dialOpts, grpc.WithTransportCredentials(credentials.NewTLS(gwTLSConfig)))
} else {
dialOpts = append(dialOpts, grpc.WithInsecure())
}
conn, err := grpc.DialContext(context.TODO(), addr, dialOpts...)
if err != nil {
return nil, nil, err
}
// Register services.
srvmux := runtime.NewServeMux()
for _, fn := range funcs {
err = fn(context.TODO(), srvmux, conn)
if err != nil {
return nil, nil, err
}
}
return srvmux, conn, nil
}
// IsGRPCRequest returns true if the provided request came from a gRPC client.
//
// Its logic is a partial recreation of gRPC's internal checks, see:
// https://github.com/grpc/grpc-go/blob/01de3de/transport/handler_server.go#L61:L69
func IsGRPCRequest(r *http.Request) bool {
return r.ProtoMajor == 2 && strings.Contains(r.Header.Get("Content-Type"), "application/grpc")
}
// HandlerFunc returns an http.Handler that delegates to grpc.Server on
// incoming gRPC connections otherwise serves with the provided handler.
func HandlerFunc(grpcServer *grpc.Server, otherwise http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if IsGRPCRequest(r) {
grpcServer.ServeHTTP(w, r)
} else {
otherwise.ServeHTTP(w, r)
}
})
}