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gateway_builder.go
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/
gateway_builder.go
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// Copyright 2017 uSwitch
//
// 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 server
import (
"context"
"crypto/tls"
"crypto/x509"
"fmt"
grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware"
retry "github.com/grpc-ecosystem/go-grpc-middleware/retry"
grpc_prometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
pb "github.com/uswitch/kiam/proto"
"google.golang.org/grpc"
"google.golang.org/grpc/balancer/roundrobin"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/keepalive"
"google.golang.org/grpc/security/advancedtls"
"net"
"time"
)
const (
kDefaultRetryInterval = 10 * time.Millisecond
kMaxRetries = 0
)
// KiamGatewayBuilder helps to construct the KiamGateway for interacting with the KiamServer
type KiamGatewayBuilder struct {
address string
transportCreds credentials.TransportCredentials
keepaliveParams keepalive.ClientParameters
tlsConfig *dynamicTLSConfig
dialOptions []grpc.DialOption
retryInterval time.Duration
maxRetries uint
}
func NewKiamGatewayBuilder() *KiamGatewayBuilder {
return &KiamGatewayBuilder{retryInterval: kDefaultRetryInterval, maxRetries: kMaxRetries}
}
func (b *KiamGatewayBuilder) WithAddress(address string) *KiamGatewayBuilder {
b.address = address
return b
}
func (b *KiamGatewayBuilder) WithRetryInterval(dur time.Duration) *KiamGatewayBuilder {
b.retryInterval = dur
return b
}
func (b *KiamGatewayBuilder) WithMaxRetries(n uint) *KiamGatewayBuilder {
b.maxRetries = n
return b
}
// WithTLS configures the gRPC client with dynamic TLS.
func (b *KiamGatewayBuilder) WithTLS(cert, key, ca string) (*KiamGatewayBuilder, error) {
notifyFn := clientTLSMetrics.notifyFunc(x509.ExtKeyUsageClientAuth)
tlsConfig, err := newDynamicTLSConfig(cert, key, ca, notifyFn)
if err != nil {
return nil, fmt.Errorf("error reading tls certificates: %v", err)
}
b.tlsConfig = tlsConfig
defer func() {
if err != nil {
tlsConfig.Close()
}
}()
hostName, _, err := net.SplitHostPort(b.address)
if err != nil {
return nil, fmt.Errorf("error parsing hostname: %v", err)
}
creds, err := advancedtls.NewClientCreds(&advancedtls.ClientOptions{
GetClientCertificate: func(_ *tls.CertificateRequestInfo) (*tls.Certificate, error) {
return tlsConfig.LoadCert(), nil
},
RootCertificateOptions: advancedtls.RootCertificateOptions{
GetRootCAs: func(_ *advancedtls.GetRootCAsParams) (*advancedtls.GetRootCAsResults, error) {
return &advancedtls.GetRootCAsResults{TrustCerts: tlsConfig.LoadCACerts()}, nil
},
},
ServerNameOverride: hostName,
})
if err != nil {
return nil, fmt.Errorf("error creating grpc credentials: %v", err)
}
b.transportCreds = creds
return b, nil
}
func (b *KiamGatewayBuilder) WithKeepAlive(parameters keepalive.ClientParameters) *KiamGatewayBuilder {
b.keepaliveParams = parameters
return b
}
func (b *KiamGatewayBuilder) Build(ctx context.Context) (*KiamGateway, error) {
dialOpts := []grpc.DialOption{
grpc.WithKeepaliveParams(b.keepaliveParams),
grpc.WithTransportCredentials(b.transportCreds),
grpc.WithUnaryInterceptor(grpc_middleware.ChainUnaryClient(
grpc_prometheus.UnaryClientInterceptor,
retry.UnaryClientInterceptor(
retry.WithMax(b.maxRetries),
retry.WithBackoff(retry.BackoffLinear(b.retryInterval)),
),
)),
grpc.WithBalancerName(roundrobin.Name),
grpc.WithDisableServiceConfig(),
grpc.WithBlock(),
grpc.WithStreamInterceptor(grpc_prometheus.StreamClientInterceptor),
}
if b.dialOptions != nil {
dialOpts = append(dialOpts, b.dialOptions...)
}
conn, err := grpc.DialContext(ctx, "dns:///"+b.address, dialOpts...)
if err != nil {
return nil, fmt.Errorf("error dialing grpc server: %v", err)
}
gw := &KiamGateway{
conn: conn,
client: pb.NewKiamServiceClient(conn),
tlsConfig: b.tlsConfig,
}
return gw, nil
}
func (b *KiamGatewayBuilder) WithDialOption(opts ...grpc.DialOption) *KiamGatewayBuilder {
b.dialOptions = opts
return b
}