github.com/envoyproxy/go-control-plane/envoy v1.37.0: v3.LocalityLbEndpoints

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3.LocalityLbEndpoints in pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.37.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.37.0
Demonstrate these symbols/APIs:
  - github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3.LocalityLbEndpoints

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:1e78d69908018e4928485570aa47a5c90c5c72b770d8dfc79e65888f12adb491","contract":["LocalityLbEndpoints initializes with locality, priority, load balancing weight, and endpoint addresses","LocalityLbEndpoints GetLocality, GetPriority, GetLoadBalancingWeight, and GetLbEndpoints return configured values","LocalityLbEndpoints supports proto marshaling, unmarshaling, and cloning"],"goal":"verify github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3.LocalityLbEndpoints in pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.37.0","kind":"HOW","packages":["pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.37.0"],"schemaVersion":1,"symbols":["github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3.LocalityLbEndpoints"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.37.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.37.0","symbols":["github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3.LocalityLbEndpoints"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require (
	github.com/envoyproxy/go-control-plane/envoy v1.37.0
	google.golang.org/protobuf v1.36.11
)

require (
	github.com/cncf/xds/go v0.0.0-20251110193048-8bfbf64dc13e // indirect
	github.com/envoyproxy/protoc-gen-validate v1.3.0 // indirect
	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
)

github.com/cncf/xds/go v0.0.0-20251110193048-8bfbf64dc13e h1:gt7U1Igw0xbJdyaCM5H2CnlAlPSkzrhsebQB6WQWjLA=
github.com/cncf/xds/go v0.0.0-20251110193048-8bfbf64dc13e/go.mod h1:KdCmV+x/BuvyMxRnYBlmVaq4OLiKW6iRQfvC62cvdkI=
github.com/envoyproxy/go-control-plane/envoy v1.37.0 h1:u3riX6BoYRfF4Dr7dwSOroNfdSbEPe9Yyl09/B6wBrQ=
github.com/envoyproxy/go-control-plane/envoy v1.37.0/go.mod h1:DReE9MMrmecPy+YvQOAOHNYMALuowAnbjjEMkkWOi6A=
github.com/envoyproxy/protoc-gen-validate v1.3.0 h1:TvGH1wof4H33rezVKWSpqKz5NXWg5VPuZ0uONDT6eb4=
github.com/envoyproxy/protoc-gen-validate v1.3.0/go.mod h1:HvYl7zwPa5mffgyeTUHA9zHIH36nmrm7oCbo4YKoSWA=
github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 h1:GFCKgmp0tecUJ0sJuv4pzYCqS9+RGSn52M3FUwPs+uo=
github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10/go.mod h1:t/avpk3KcrXxUnYOhZhMXJlSEyie6gQbtLq5NM3loB8=
google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=

{
  "schemaVersion": 1,
  "goal": "verify github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3.LocalityLbEndpoints in pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.37.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.37.0"
  ],
  "symbols": [
    "github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3.LocalityLbEndpoints"
  ]
}

package main

import (
	"fmt"
	"os"

	corev3 "github.com/envoyproxy/go-control-plane/envoy/config/core/v3"
	endpointv3 "github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3"
	"google.golang.org/protobuf/proto"
	"google.golang.org/protobuf/types/known/wrapperspb"
)

func main() {
	if err := runTests(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract test failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All contract tests passed successfully.")
}

func runTests() error {
	// 1. LocalityLbEndpoints initializes with locality, priority, and load balancing weight
	locality := &corev3.Locality{
		Region:  "us-west",
		Zone:    "us-west-1a",
		SubZone: "rack1",
	}

	endpoint1 := &endpointv3.LbEndpoint{
		HostIdentifier: &endpointv3.LbEndpoint_Endpoint{
			Endpoint: &endpointv3.Endpoint{
				Address: &corev3.Address{
					Address: &corev3.Address_SocketAddress{
						SocketAddress: &corev3.SocketAddress{
							Protocol: corev3.SocketAddress_TCP,
							Address:  "10.0.0.1",
							PortSpecifier: &corev3.SocketAddress_PortValue{
								PortValue: 8080,
							},
						},
					},
				},
			},
		},
		LoadBalancingWeight: wrapperspb.UInt32(100),
	}

	endpoint2 := &endpointv3.LbEndpoint{
		HostIdentifier: &endpointv3.LbEndpoint_Endpoint{
			Endpoint: &endpointv3.Endpoint{
				Address: &corev3.Address{
					Address: &corev3.Address_SocketAddress{
						SocketAddress: &corev3.SocketAddress{
							Protocol: corev3.SocketAddress_TCP,
							Address:  "10.0.0.2",
							PortSpecifier: &corev3.SocketAddress_PortValue{
								PortValue: 8080,
							},
						},
					},
				},
			},
		},
		LoadBalancingWeight: wrapperspb.UInt32(50),
	}

	localityLbEndpoints := &endpointv3.LocalityLbEndpoints{
		Locality:            locality,
		LbEndpoints:         []*endpointv3.LbEndpoint{endpoint1, endpoint2},
		LoadBalancingWeight: wrapperspb.UInt32(1000),
		Priority:            1,
	}

	// Verify getters
	if localityLbEndpoints.GetLocality().GetRegion() != "us-west" {
		return fmt.Errorf("expected region us-west, got %s", localityLbEndpoints.GetLocality().GetRegion())
	}
	if localityLbEndpoints.GetLocality().GetZone() != "us-west-1a" {
		return fmt.Errorf("expected zone us-west-1a, got %s", localityLbEndpoints.GetLocality().GetZone())
	}
	if localityLbEndpoints.GetLocality().GetSubZone() != "rack1" {
		return fmt.Errorf("expected subzone rack1, got %s", localityLbEndpoints.GetLocality().GetSubZone())
	}
	if localityLbEndpoints.GetPriority() != 1 {
		return fmt.Errorf("expected priority 1, got %d", localityLbEndpoints.GetPriority())
	}
	if localityLbEndpoints.GetLoadBalancingWeight().GetValue() != 1000 {
		return fmt.Errorf("expected lb weight 1000, got %d", localityLbEndpoints.GetLoadBalancingWeight().GetValue())
	}
	if len(localityLbEndpoints.GetLbEndpoints()) != 2 {
		return fmt.Errorf("expected 2 lb endpoints, got %d", len(localityLbEndpoints.GetLbEndpoints()))
	}

	// 2. Proto serialization and deserialization round-trip
	data, err := proto.Marshal(localityLbEndpoints)
	if err != nil {
		return fmt.Errorf("failed to marshal LocalityLbEndpoints: %w", err)
	}

	decoded := &endpointv3.LocalityLbEndpoints{}
	if err := proto.Unmarshal(data, decoded); err != nil {
		return fmt.Errorf("failed to unmarshal LocalityLbEndpoints: %w", err)
	}

	if !proto.Equal(localityLbEndpoints, decoded) {
		return fmt.Errorf("unmarshaled object does not match original")
	}

	// 3. Proto clone preserves all fields
	cloned := proto.Clone(localityLbEndpoints).(*endpointv3.LocalityLbEndpoints)
	if !proto.Equal(localityLbEndpoints, cloned) {
		return fmt.Errorf("cloned object does not match original")
	}

	return nil
}