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service.go
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service.go
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/*
*
* Copyright 2018 gRPC 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 service manages connections between the VM application and the ALTS
// handshaker service.
package service
import (
"flag"
"sync"
grpc "google.golang.org/grpc"
)
var (
// hsServiceAddr specifies the default ALTS handshaker service address in
// the hypervisor.
hsServiceAddr = flag.String("handshaker_service_address", "metadata.google.internal:8080", "ALTS handshaker gRPC service address")
// hsConn represents a connection to hypervisor handshaker service.
hsConn *grpc.ClientConn
mu sync.Mutex
// hsDialer will be reassigned in tests.
hsDialer = grpc.Dial
)
type dialer func(target string, opts ...grpc.DialOption) (*grpc.ClientConn, error)
// Dial dials the handshake service in the hypervisor. If a connection has
// already been established, this function returns it. Otherwise, a new
// connection is created,
func Dial() (*grpc.ClientConn, error) {
mu.Lock()
defer mu.Unlock()
if hsConn == nil {
// Create a new connection to the handshaker service. Note that
// this connection stays open until the application is closed.
var err error
hsConn, err = hsDialer(*hsServiceAddr, grpc.WithInsecure())
if err != nil {
return nil, err
}
}
return hsConn, nil
}