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114 lines
3.6 KiB
Go
114 lines
3.6 KiB
Go
/*
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*
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* Copyright 2019 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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// Package client implementation a full fledged gRPC client for the xDS API
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// used by the xds resolver and balancer implementations.
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package xds
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import (
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"errors"
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"fmt"
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"time"
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"github.com/coredns/coredns/plugin/traffic/xds/bootstrap"
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"google.golang.org/grpc"
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)
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// Options provides all parameters required for the creation of an xDS client.
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type Options struct {
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// Config contains a fully populated bootstrap config. It is the
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// responsibility of the caller to use some sane defaults here if the
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// bootstrap process returned with certain fields left unspecified.
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Config bootstrap.Config
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// DialOpts contains dial options to be used when dialing the xDS server.
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DialOpts []grpc.DialOption
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}
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// Client is a full fledged gRPC client which queries a set of discovery APIs
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// (collectively termed as xDS) on a remote management server, to discover
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// various dynamic resources. A single client object will be shared by the xds
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// resolver and balancer implementations.
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type Client struct {
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opts Options
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cc *grpc.ClientConn // Connection to the xDS server
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v2c *v2Client // Actual xDS client implementation using the v2 API
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serviceCallback func(ServiceUpdate, error)
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}
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// New returns a new xdsClient configured with opts.
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func New(opts Options) (*Client, error) {
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switch {
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case opts.Config.BalancerName == "":
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return nil, errors.New("xds: no xds_server name provided in options")
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case opts.Config.Creds == nil:
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fmt.Printf("%s\n", errors.New("xds: no credentials provided in options"))
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case opts.Config.NodeProto == nil:
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return nil, errors.New("xds: no node_proto provided in options")
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}
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var dopts []grpc.DialOption
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if opts.Config.Creds == nil {
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dopts = append([]grpc.DialOption{grpc.WithInsecure()}, opts.DialOpts...)
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} else {
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dopts = append([]grpc.DialOption{opts.Config.Creds}, opts.DialOpts...)
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}
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cc, err := grpc.Dial(opts.Config.BalancerName, dopts...)
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if err != nil {
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// An error from a non-blocking dial indicates something serious.
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return nil, fmt.Errorf("xds: failed to dial balancer {%s}: %v", opts.Config.BalancerName, err)
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}
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println("dialed balancer at", opts.Config.BalancerName)
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c := &Client{
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opts: opts,
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cc: cc,
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v2c: newV2Client(cc, opts.Config.NodeProto, func(int) time.Duration { return 0 }),
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}
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return c, nil
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}
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// Close closes the gRPC connection to the xDS server.
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func (c *Client) Close() {
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// TODO: Should we invoke the registered callbacks here with an error that
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// the client is closed?
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c.v2c.close()
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c.cc.Close()
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}
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func (c *Client) Run() {
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c.v2c.run()
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}
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// ServiceUpdate contains update about the service.
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type ServiceUpdate struct {
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Cluster string
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}
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// WatchCluster uses CDS to discover information about the provided clusterName.
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func (c *Client) WatchCluster(clusterName string, cdsCb func(CDSUpdate, error)) (cancel func()) {
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return c.v2c.watchCDS(clusterName, cdsCb)
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}
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// WatchEndpoints uses EDS to discover information about the endpoints in a cluster.
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func (c *Client) WatchEndpoints(clusterName string, edsCb func(*EDSUpdate, error)) (cancel func()) {
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return c.v2c.watchEDS(clusterName, edsCb)
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}
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