xds/resolver: make service config human readable in the log (#8958)

#### Prior to this change, the log looked like this:
third_party/golang/grpc/internal/grpctest/tlogger.go:133: INFO
xds_resolver.go:350 [xds] [xds-resolver 0xc000c185a0] For Listener
resource "listener-my-service-client-side-xds" and RouteConfiguration
resource "route-my-service-client-side-xds", generated service config:
[123 34 108 111 97 100 66 97 108 97 110 99 105 110 103 67 111 110 102
105 103 34 58 91 123 34 120 100 115 95 99 108 117 115 116 101 114 95 109
97 110 97 103 101 114 95 101 120 112 101 114 105 109 101 110 116 97 108
34 58 123 34 99 104 105 108 100 114 101 110 34 58 123 34 99 108 117 115
116 101 114 58 99 108 117 115 116 101 114 45 109 121 45 115 101 114 118
105 99 101 45 99 108 105 101 110 116 45 115 105 100 101 45 120 100 115
34 58 123 34 99 104 105 108 100 80 111 108 105 99 121 34 58 91 123 34 99
100 115 95 101 120 112 101 114 105 109 101 110 116 97 108 34 58 123 34
99 108 117 115 116 101 114 34 58 34 99 108 117 115 116 101 114 45 109
121 45 115 101 114 118 105 99 101 45 99 108 105 101 110 116 45 115 105
100 101 45 120 100 115 34 125 125 93 125 125 125 125 93 125]
(t=+311.705869ms)

#### Post this change, it looks like this:
third_party/golang/grpc/internal/grpctest/tlogger.go:133: INFO
xds_resolver.go:350 [xds] [xds-resolver 0xc000c72990] For Listener
resource "listener-my-service-client-side-xds" and RouteConfiguration
resource "route-my-service-client-side-xds", generated service config:
{"loadBalancingConfig":[{"xds_cluster_manager_experimental":{"children":{"cluster:cluster-my-service-client-side-xds":{"childPolicy":[{"cds_experimental":{"cluster":"cluster-my-service-client-side-xds"}}]}}}}]}
(t=+220.184355ms)

RELEASE NOTES: none
1 file changed
tree: 934be2293119f5cc5d427984d8b05c6bc5569a64
  1. .gemini/
  2. .github/
  3. admin/
  4. attributes/
  5. authz/
  6. backoff/
  7. balancer/
  8. benchmark/
  9. binarylog/
  10. channelz/
  11. cmd/
  12. codes/
  13. connectivity/
  14. credentials/
  15. Documentation/
  16. encoding/
  17. examples/
  18. experimental/
  19. gcp/
  20. grpclog/
  21. health/
  22. internal/
  23. interop/
  24. keepalive/
  25. mem/
  26. metadata/
  27. orca/
  28. peer/
  29. profiling/
  30. reflection/
  31. resolver/
  32. scripts/
  33. security/
  34. serviceconfig/
  35. stats/
  36. status/
  37. tap/
  38. test/
  39. testdata/
  40. xds/
  41. AUTHORS
  42. backoff.go
  43. balancer_wrapper.go
  44. balancer_wrapper_test.go
  45. call.go
  46. clientconn.go
  47. clientconn_authority_test.go
  48. clientconn_parsed_target_test.go
  49. clientconn_test.go
  50. CODE-OF-CONDUCT.md
  51. codec.go
  52. codec_test.go
  53. CONTRIBUTING.md
  54. default_dial_option_server_option_test.go
  55. dial_test.go
  56. dialoptions.go
  57. doc.go
  58. go.mod
  59. go.sum
  60. GOVERNANCE.md
  61. grpc_test.go
  62. interceptor.go
  63. LICENSE
  64. MAINTAINERS.md
  65. Makefile
  66. NOTICE.txt
  67. picker_wrapper.go
  68. picker_wrapper_test.go
  69. preloader.go
  70. producer_ext_test.go
  71. README.md
  72. resolver_balancer_ext_test.go
  73. resolver_test.go
  74. resolver_wrapper.go
  75. rpc_util.go
  76. rpc_util_test.go
  77. SECURITY.md
  78. server.go
  79. server_ext_test.go
  80. server_test.go
  81. service_config.go
  82. service_config_test.go
  83. stream.go
  84. stream_interfaces.go
  85. stream_test.go
  86. trace.go
  87. trace_notrace.go
  88. trace_test.go
  89. trace_withtrace.go
  90. version.go
README.md

gRPC-Go

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The Go implementation of gRPC: A high performance, open source, general RPC framework that puts mobile and HTTP/2 first. For more information see the Go gRPC docs, or jump directly into the quick start.

Prerequisites

Installation

Simply add the following import to your code, and then go [build|run|test] will automatically fetch the necessary dependencies:

import "google.golang.org/grpc"

Note: If you are trying to access grpc-go from China, see the FAQ below.

Learn more

FAQ

I/O Timeout Errors

The golang.org domain may be blocked from some countries. go get usually produces an error like the following when this happens:

$ go get -u google.golang.org/grpc
package google.golang.org/grpc: unrecognized import path "google.golang.org/grpc" (https fetch: Get https://google.golang.org/grpc?go-get=1: dial tcp 216.239.37.1:443: i/o timeout)

To build Go code, there are several options:

  • Set up a VPN and access google.golang.org through that.

  • With Go module support: it is possible to use the replace feature of go mod to create aliases for golang.org packages. In your project's directory:

    go mod edit -replace=google.golang.org/grpc=github.com/grpc/grpc-go@latest
    go mod tidy
    go mod vendor
    go build -mod=vendor
    

    Again, this will need to be done for all transitive dependencies hosted on golang.org as well. For details, refer to golang/go issue #28652.

Compiling error, undefined: grpc.SupportPackageIsVersion

Please update to the latest version of gRPC-Go using go get google.golang.org/grpc.

How to turn on logging

The default logger is controlled by environment variables. Turn everything on like this:

$ export GRPC_GO_LOG_VERBOSITY_LEVEL=99
$ export GRPC_GO_LOG_SEVERITY_LEVEL=info

The RPC failed with error "code = Unavailable desc = transport is closing"

This error means the connection the RPC is using was closed, and there are many possible reasons, including:

  1. mis-configured transport credentials, connection failed on handshaking
  2. bytes disrupted, possibly by a proxy in between
  3. server shutdown
  4. Keepalive parameters caused connection shutdown, for example if you have configured your server to terminate connections regularly to trigger DNS lookups. If this is the case, you may want to increase your MaxConnectionAgeGrace, to allow longer RPC calls to finish.

It can be tricky to debug this because the error happens on the client side but the root cause of the connection being closed is on the server side. Turn on logging on both client and server, and see if there are any transport errors.