2020-09-27 18:08:28 +00:00
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package client
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import (
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"strings"
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"google.golang.org/grpc/resolver"
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)
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// Modification of a default grpc passthrough resolver (google.golang.org/grpc/resolver/passthrough) allowing to use multiple addresses
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// in grpc endpoint. Example:
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// conn, err := grpc.DialContext(ctx, "127.0.0.1:4000,127.0.0.1:4001", grpc.WithInsecure(), grpc.WithResolvers(&multipleEndpointsGrpcResolverBuilder{}))
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// It can be used with any grpc load balancer (pick_first, round_robin). Default is pick_first.
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// Round robin can be used by adding the following option:
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// grpc.WithDefaultServiceConfig("{\"loadBalancingConfig\":[{\"round_robin\":{}}]}")
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type multipleEndpointsGrpcResolverBuilder struct{}
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2021-04-23 12:06:05 +00:00
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// Build creates and starts multiple endpoints resolver.
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2020-10-12 08:11:05 +00:00
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func (*multipleEndpointsGrpcResolverBuilder) Build(target resolver.Target, cc resolver.ClientConn, _ resolver.BuildOptions) (resolver.Resolver, error) {
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2020-09-27 18:08:28 +00:00
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r := &multipleEndpointsGrpcResolver{
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target: target,
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cc: cc,
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}
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r.start()
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return r, nil
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}
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2021-04-23 12:06:05 +00:00
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// Scheme returns default scheme.
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2020-09-27 18:08:28 +00:00
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func (*multipleEndpointsGrpcResolverBuilder) Scheme() string {
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return resolver.GetDefaultScheme()
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}
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type multipleEndpointsGrpcResolver struct {
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target resolver.Target
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cc resolver.ClientConn
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}
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func (r *multipleEndpointsGrpcResolver) start() {
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endpoints := strings.Split(r.target.Endpoint, ",")
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var addrs []resolver.Address
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for _, endpoint := range endpoints {
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addrs = append(addrs, resolver.Address{Addr: endpoint})
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}
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r.cc.UpdateState(resolver.State{Addresses: addrs})
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}
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2021-04-23 12:06:05 +00:00
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// ResolveNow --
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2020-10-12 08:11:05 +00:00
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func (*multipleEndpointsGrpcResolver) ResolveNow(_ resolver.ResolveNowOptions) {}
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2020-09-27 18:08:28 +00:00
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2021-04-23 12:06:05 +00:00
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// Close --
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2020-09-27 18:08:28 +00:00
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func (*multipleEndpointsGrpcResolver) Close() {}
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