github.com/envoyproxy/go-control-plane/envoy v1.32.2: v3.Cluster_LbPolicy

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/cluster/v3.Cluster_LbPolicy in pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.32.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.32.2
Demonstrate these symbols/APIs:
  - github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_LbPolicy

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:sha256:72bedcc3f3c11495d0800b7f36207d917f4447a101d0ed7e114e9c8fdd520606","contract":["Cluster_ROUND_ROBIN.String() returns \"ROUND_ROBIN\" and Number() returns 0","Cluster_LEAST_REQUEST.String() returns \"LEAST_REQUEST\" and Number() returns 1","Cluster_MAGLEV.String() returns \"MAGLEV\", Number() returns 5, and Enum() returns a pointer to Cluster_MAGLEV","Cluster_LbPolicy.Descriptor().Name() returns \"LbPolicy\" and Cluster.GetLbPolicy() returns the assigned policy"],"goal":"verify github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_LbPolicy in pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.32.2","kind":"HOW","packages":["pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.32.2"],"schemaVersion":1,"symbols":["github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_LbPolicy"]},"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@v1.32.2"],"schemaVersion":1,"subject":"pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.32.2","symbols":["github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_LbPolicy"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/envoyproxy/go-control-plane/envoy v1.32.2

require (
	github.com/cncf/xds/go v0.0.0-20240723142845-024c85f92f20 // indirect
	github.com/envoyproxy/protoc-gen-validate v1.1.0 // indirect
	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
	google.golang.org/protobuf v1.35.2 // indirect
)

github.com/cncf/xds/go v0.0.0-20240723142845-024c85f92f20 h1:N+3sFI5GUjRKBi+i0TxYVST9h4Ie192jJWpHvthBBgg=
github.com/cncf/xds/go v0.0.0-20240723142845-024c85f92f20/go.mod h1:W+zGtBO5Y1IgJhy4+A9GOqVhqLpfZi+vwmdNXUehLA8=
github.com/envoyproxy/go-control-plane/envoy v1.32.2 h1:zidqwmijfcbyKqVxjQDFx042PgX+p9U+/fu/f9VtSk8=
github.com/envoyproxy/go-control-plane/envoy v1.32.2/go.mod h1:eR2SOX2IedqlPvmiKjUH7Wu//S602JKI7HPC/L3SRq8=
github.com/envoyproxy/protoc-gen-validate v1.1.0 h1:tntQDh69XqOCOZsDz0lVJQez/2L6Uu2PdjCQwWCJ3bM=
github.com/envoyproxy/protoc-gen-validate v1.1.0/go.mod h1:sXRDRVmzEbkM7CVcM06s9shE/m23dg3wzjl0UWqJ2q4=
github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
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=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
google.golang.org/protobuf v1.35.2 h1:8Ar7bF+apOIoThw1EdZl0p1oWvMqTHmpA2fRTyZO8io=
google.golang.org/protobuf v1.35.2/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=

{
  "schemaVersion": 1,
  "goal": "verify github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_LbPolicy in pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.32.2",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.32.2"
  ],
  "symbols": [
    "github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_LbPolicy"
  ]
}

package main

import (
	"fmt"
	"os"

	clusterv3 "github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3"
)

func main() {
	var policy clusterv3.Cluster_LbPolicy = clusterv3.Cluster_ROUND_ROBIN
	if policy.String() != "ROUND_ROBIN" || int32(policy.Number()) != 0 {
		fmt.Fprintf(os.Stderr, "unexpected ROUND_ROBIN: %s (%d)\n", policy.String(), policy.Number())
		os.Exit(1)
	}

	leastReq := clusterv3.Cluster_LEAST_REQUEST
	if leastReq.String() != "LEAST_REQUEST" || int32(leastReq.Number()) != 1 {
		fmt.Fprintf(os.Stderr, "unexpected LEAST_REQUEST: %s (%d)\n", leastReq.String(), leastReq.Number())
		os.Exit(1)
	}

	maglev := clusterv3.Cluster_MAGLEV
	if maglev.String() != "MAGLEV" || int32(maglev.Number()) != 5 {
		fmt.Fprintf(os.Stderr, "unexpected MAGLEV: %s (%d)\n", maglev.String(), maglev.Number())
		os.Exit(1)
	}

	ptr := maglev.Enum()
	if ptr == nil || *ptr != clusterv3.Cluster_MAGLEV {
		fmt.Fprintf(os.Stderr, "Enum() returned unexpected value\n")
		os.Exit(1)
	}

	desc := policy.Descriptor()
	if desc == nil || string(desc.Name()) != "LbPolicy" {
		fmt.Fprintf(os.Stderr, "unexpected Descriptor name: %v\n", desc)
		os.Exit(1)
	}

	c := &clusterv3.Cluster{
		Name:     "service_a",
		LbPolicy: policy,
	}
	if c.GetLbPolicy() != clusterv3.Cluster_ROUND_ROBIN {
		fmt.Fprintf(os.Stderr, "unexpected Cluster.GetLbPolicy(): %v\n", c.GetLbPolicy())
		os.Exit(1)
	}
}