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

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.LbEndpoint_Endpoint 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.LbEndpoint_Endpoint

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:de6061508a1d7955dbb1a6ecb8ef8d8e19f35fa9eba8e8c087508f78ba06d34d","contract":["LbEndpoint_Endpoint wraps Endpoint and sets LbEndpoint HostIdentifier oneof","LbEndpoint GetEndpoint returns configured Endpoint via LbEndpoint_Endpoint"],"goal":"verify github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3.LbEndpoint_Endpoint 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.LbEndpoint_Endpoint"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","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.LbEndpoint_Endpoint"],"verifierAdapter":"golang@1"}

module sample

go 1.24.0

require github.com/envoyproxy/go-control-plane/envoy v1.37.0

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
	google.golang.org/protobuf v1.36.11 // 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.LbEndpoint_Endpoint 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.LbEndpoint_Endpoint"
  ]
}

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"
)

func main() {
	sockAddr := &corev3.SocketAddress{
		Protocol: corev3.SocketAddress_TCP,
		Address:  "127.0.0.1",
		PortSpecifier: &corev3.SocketAddress_PortValue{
			PortValue: 8080,
		},
	}

	addr := &corev3.Address{
		Address: &corev3.Address_SocketAddress{
			SocketAddress: sockAddr,
		},
	}

	ep := &endpointv3.Endpoint{
		Address:  addr,
		Hostname: "backend.local",
	}

	// Assertion 1: LbEndpoint_Endpoint wraps Endpoint and sets LbEndpoint HostIdentifier oneof
	lbEpWrapper := &endpointv3.LbEndpoint_Endpoint{
		Endpoint: ep,
	}

	lbEndpoint := &endpointv3.LbEndpoint{
		HostIdentifier: lbEpWrapper,
	}

	hostID := lbEndpoint.GetHostIdentifier()
	if hostID == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil HostIdentifier\n")
		os.Exit(1)
	}

	wrapper, ok := hostID.(*endpointv3.LbEndpoint_Endpoint)
	if !ok {
		fmt.Fprintf(os.Stderr, "expected *endpointv3.LbEndpoint_Endpoint, got %T\n", hostID)
		os.Exit(1)
	}

	if wrapper.Endpoint == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil Endpoint inside LbEndpoint_Endpoint\n")
		os.Exit(1)
	}

	if wrapper.Endpoint.GetHostname() != "backend.local" {
		fmt.Fprintf(os.Stderr, "expected hostname backend.local, got %s\n", wrapper.Endpoint.GetHostname())
		os.Exit(1)
	}

	// Assertion 2: LbEndpoint GetEndpoint returns configured Endpoint via LbEndpoint_Endpoint
	retrievedEp := lbEndpoint.GetEndpoint()
	if retrievedEp == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil Endpoint from GetEndpoint()\n")
		os.Exit(1)
	}

	if retrievedEp != ep {
		fmt.Fprintf(os.Stderr, "expected retrieved Endpoint to match configured Endpoint\n")
		os.Exit(1)
	}

	retrievedSock := retrievedEp.GetAddress().GetSocketAddress()
	if retrievedSock == nil || retrievedSock.GetAddress() != "127.0.0.1" || retrievedSock.GetPortValue() != 8080 {
		fmt.Fprintf(os.Stderr, "expected socket address 127.0.0.1:8080\n")
		os.Exit(1)
	}

	fmt.Println("PASS: LbEndpoint_Endpoint verification successful")
}