github.com/envoyproxy/go-control-plane v0.14.0: v3.NewSnapshot

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/pkg/cache/v3.NewSnapshot in pkg:golang/github.com/envoyproxy/go-control-plane@v0.14.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/envoyproxy/go-control-plane@v0.14.0
Demonstrate these symbols/APIs:
  - github.com/envoyproxy/go-control-plane/pkg/cache/v3.NewSnapshot

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:sha256:628ea3ca221b6c72360dacbdd76a41bd0734861e571ba0ce0d4674a2453a3e82","contract":["NewSnapshot creates an internally consistent Snapshot for given version and resources map","Snapshot returns the configured version string via GetVersion","Snapshot returns expected resources keyed by resource name via GetResources","Snapshot Consistent validation succeeds for valid static cluster resources","Snapshot can be created with nil resources and maintains consistency"],"goal":"verify github.com/envoyproxy/go-control-plane/pkg/cache/v3.NewSnapshot in pkg:golang/github.com/envoyproxy/go-control-plane@v0.14.0","kind":"HOW","packages":["pkg:golang/github.com/envoyproxy/go-control-plane@v0.14.0"],"schemaVersion":1,"symbols":["github.com/envoyproxy/go-control-plane/pkg/cache/v3.NewSnapshot"]},"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@v0.14.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/envoyproxy/go-control-plane@v0.14.0","symbols":["github.com/envoyproxy/go-control-plane/pkg/cache/v3.NewSnapshot"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require (
	github.com/envoyproxy/go-control-plane v0.14.0
	github.com/envoyproxy/go-control-plane/envoy v1.36.0
)

require (
	cel.dev/expr v0.24.0 // indirect
	github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443 // indirect
	github.com/envoyproxy/protoc-gen-validate v1.2.1 // indirect
	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
	golang.org/x/net v0.42.0 // indirect
	golang.org/x/sys v0.34.0 // indirect
	golang.org/x/text v0.27.0 // indirect
	google.golang.org/genproto/googleapis/api v0.0.0-20250728155136-f173205681a0 // indirect
	google.golang.org/genproto/googleapis/rpc v0.0.0-20250728155136-f173205681a0 // indirect
	google.golang.org/grpc v1.75.1 // indirect
	google.golang.org/protobuf v1.36.10 // indirect
)

cel.dev/expr v0.24.0 h1:56OvJKSH3hDGL0ml5uSxZmz3/3Pq4tJ+fb1unVLAFcY=
cel.dev/expr v0.24.0/go.mod h1:hLPLo1W4QUmuYdA72RBX06QTs6MXw941piREPl3Yfiw=
github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443 h1:aQ3y1lwWyqYPiWZThqv1aFbZMiM9vblcSArJRf2Irls=
github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443/go.mod h1:W+zGtBO5Y1IgJhy4+A9GOqVhqLpfZi+vwmdNXUehLA8=
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/envoyproxy/go-control-plane v0.14.0 h1:hbG2kr4RuFj222B6+7T83thSPqLjwBIfQawTkC++2HA=
github.com/envoyproxy/go-control-plane v0.14.0/go.mod h1:NcS5X47pLl/hfqxU70yPwL9ZMkUlwlKxtAohpi2wBEU=
github.com/envoyproxy/go-control-plane/envoy v1.36.0 h1:yg/JjO5E7ubRyKX3m07GF3reDNEnfOboJ0QySbH736g=
github.com/envoyproxy/go-control-plane/envoy v1.36.0/go.mod h1:ty89S1YCCVruQAm9OtKeEkQLTb+Lkz0k8v9W0Oxsv98=
github.com/envoyproxy/protoc-gen-validate v1.2.1 h1:DEo3O99U8j4hBFwbJfrz9VtgcDfUKS7KJ7spH3d86P8=
github.com/envoyproxy/protoc-gen-validate v1.2.1/go.mod h1:d/C80l/jxXLdfEIhX1W2TmLfsJ31lvEjwamM4DxlWXU=
github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
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/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
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=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
go.opentelemetry.io/auto/sdk v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
go.opentelemetry.io/otel v1.37.0 h1:9zhNfelUvx0KBfu/gb+ZgeAfAgtWrfHJZcAqFC228wQ=
go.opentelemetry.io/otel v1.37.0/go.mod h1:ehE/umFRLnuLa/vSccNq9oS1ErUlkkK71gMcN34UG8I=
go.opentelemetry.io/otel/metric v1.37.0 h1:mvwbQS5m0tbmqML4NqK+e3aDiO02vsf/WgbsdpcPoZE=
go.opentelemetry.io/otel/metric v1.37.0/go.mod h1:04wGrZurHYKOc+RKeye86GwKiTb9FKm1WHtO+4EVr2E=
go.opentelemetry.io/otel/sdk v1.37.0 h1:ItB0QUqnjesGRvNcmAcU0LyvkVyGJ2xftD29bWdDvKI=
go.opentelemetry.io/otel/sdk v1.37.0/go.mod h1:VredYzxUvuo2q3WRcDnKDjbdvmO0sCzOvVAiY+yUkAg=
go.opentelemetry.io/otel/sdk/metric v1.37.0 h1:90lI228XrB9jCMuSdA0673aubgRobVZFhbjxHHspCPc=
go.opentelemetry.io/otel/sdk/metric v1.37.0/go.mod h1:cNen4ZWfiD37l5NhS+Keb5RXVWZWpRE+9WyVCpbo5ps=
go.opentelemetry.io/otel/trace v1.37.0 h1:HLdcFNbRQBE2imdSEgm/kwqmQj1Or1l/7bW6mxVK7z4=
go.opentelemetry.io/otel/trace v1.37.0/go.mod h1:TlgrlQ+PtQO5XFerSPUYG0JSgGyryXewPGyayAWSBS0=
golang.org/x/net v0.42.0 h1:jzkYrhi3YQWD6MLBJcsklgQsoAcw89EcZbJw8Z614hs=
golang.org/x/net v0.42.0/go.mod h1:FF1RA5d3u7nAYA4z2TkclSCKh68eSXtiFwcWQpPXdt8=
golang.org/x/sys v0.34.0 h1:H5Y5sJ2L2JRdyv7ROF1he/lPdvFsd0mJHFw2ThKHxLA=
golang.org/x/sys v0.34.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
golang.org/x/text v0.27.0 h1:4fGWRpyh641NLlecmyl4LOe6yDdfaYNrGb2zdfo4JV4=
golang.org/x/text v0.27.0/go.mod h1:1D28KMCvyooCX9hBiosv5Tz/+YLxj0j7XhWjpSUF7CU=
gonum.org/v1/gonum v0.16.0 h1:5+ul4Swaf3ESvrOnidPp4GZbzf0mxVQpDCYUQE7OJfk=
gonum.org/v1/gonum v0.16.0/go.mod h1:fef3am4MQ93R2HHpKnLk4/Tbh/s0+wqD5nfa6Pnwy4E=
google.golang.org/genproto/googleapis/api v0.0.0-20250728155136-f173205681a0 h1:0UOBWO4dC+e51ui0NFKSPbkHHiQ4TmrEfEZMLDyRmY8=
google.golang.org/genproto/googleapis/api v0.0.0-20250728155136-f173205681a0/go.mod h1:8ytArBbtOy2xfht+y2fqKd5DRDJRUQhqbyEnQ4bDChs=
google.golang.org/genproto/googleapis/rpc v0.0.0-20250728155136-f173205681a0 h1:MAKi5q709QWfnkkpNQ0M12hYJ1+e8qYVDyowc4U1XZM=
google.golang.org/genproto/googleapis/rpc v0.0.0-20250728155136-f173205681a0/go.mod h1:qQ0YXyHHx3XkvlzUtpXDkS29lDSafHMZBAZDc03LQ3A=
google.golang.org/grpc v1.75.1 h1:/ODCNEuf9VghjgO3rqLcfg8fiOP0nSluljWFlDxELLI=
google.golang.org/grpc v1.75.1/go.mod h1:JtPAzKiq4v1xcAB2hydNlWI2RnF85XXcV0mhKXr2ecQ=
google.golang.org/protobuf v1.36.10 h1:AYd7cD/uASjIL6Q9LiTjz8JLcrh/88q5UObnmY3aOOE=
google.golang.org/protobuf v1.36.10/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package main

import (
	"fmt"

	clusterv3 "github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3"
	corev3 "github.com/envoyproxy/go-control-plane/envoy/config/core/v3"
	endpointv3 "github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3"
	"github.com/envoyproxy/go-control-plane/pkg/cache/types"
	cachev3 "github.com/envoyproxy/go-control-plane/pkg/cache/v3"
	"github.com/envoyproxy/go-control-plane/pkg/resource/v3"
)

func main() {
	clusterName := "service_backend"
	cluster := &clusterv3.Cluster{
		Name:                 clusterName,
		ClusterDiscoveryType: &clusterv3.Cluster_Type{Type: clusterv3.Cluster_STATIC},
		LoadAssignment: &endpointv3.ClusterLoadAssignment{
			ClusterName: clusterName,
			Endpoints: []*endpointv3.LocalityLbEndpoints{
				{
					LbEndpoints: []*endpointv3.LbEndpoint{
						{
							HostIdentifier: &endpointv3.LbEndpoint_Endpoint{
								Endpoint: &endpointv3.Endpoint{
									Address: &corev3.Address{
										Address: &corev3.Address_SocketAddress{
											SocketAddress: &corev3.SocketAddress{
												Protocol: corev3.SocketAddress_TCP,
												Address:  "127.0.0.1",
												PortSpecifier: &corev3.SocketAddress_PortValue{
													PortValue: 8080,
												},
											},
										},
									},
								},
							},
						},
					},
				},
			},
		},
	}

	resources := map[resource.Type][]types.Resource{
		resource.ClusterType: {cluster},
	}

	version := "v1"
	snapshot, err := cachev3.NewSnapshot(version, resources)
	if err != nil {
		panic(fmt.Sprintf("failed to create snapshot: %v", err))
	}

	if err := snapshot.Consistent(); err != nil {
		panic(fmt.Sprintf("snapshot is inconsistent: %v", err))
	}

	clusters := snapshot.GetResources(resource.ClusterType)
	fmt.Printf("Snapshot created with version %s containing %d cluster(s)\n", snapshot.GetVersion(resource.ClusterType), len(clusters))
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/envoyproxy/go-control-plane/pkg/cache/v3.NewSnapshot in pkg:golang/github.com/envoyproxy/go-control-plane@v0.14.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/envoyproxy/go-control-plane@v0.14.0"
  ],
  "symbols": [
    "github.com/envoyproxy/go-control-plane/pkg/cache/v3.NewSnapshot"
  ]
}

package main

import (
	"fmt"
	"os"

	clusterv3 "github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3"
	corev3 "github.com/envoyproxy/go-control-plane/envoy/config/core/v3"
	endpointv3 "github.com/envoyproxy/go-control-plane/envoy/config/endpoint/v3"
	"github.com/envoyproxy/go-control-plane/pkg/cache/types"
	cachev3 "github.com/envoyproxy/go-control-plane/pkg/cache/v3"
	"github.com/envoyproxy/go-control-plane/pkg/resource/v3"
)

func main() {
	clusterName := "service_backend"
	cluster := &clusterv3.Cluster{
		Name:                 clusterName,
		ClusterDiscoveryType: &clusterv3.Cluster_Type{Type: clusterv3.Cluster_STATIC},
		LoadAssignment: &endpointv3.ClusterLoadAssignment{
			ClusterName: clusterName,
			Endpoints: []*endpointv3.LocalityLbEndpoints{
				{
					LbEndpoints: []*endpointv3.LbEndpoint{
						{
							HostIdentifier: &endpointv3.LbEndpoint_Endpoint{
								Endpoint: &endpointv3.Endpoint{
									Address: &corev3.Address{
										Address: &corev3.Address_SocketAddress{
											SocketAddress: &corev3.SocketAddress{
												Protocol: corev3.SocketAddress_TCP,
												Address:  "127.0.0.1",
												PortSpecifier: &corev3.SocketAddress_PortValue{
													PortValue: 8080,
												},
											},
										},
									},
								},
							},
						},
					},
				},
			},
		},
	}

	// Contract 1: NewSnapshot creates a Snapshot with version and resource map
	version := "v1.0.0"
	resources := map[resource.Type][]types.Resource{
		resource.ClusterType: {cluster},
	}

	snapshot, err := cachev3.NewSnapshot(version, resources)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: NewSnapshot returned error: %v\n", err)
		os.Exit(1)
	}
	if snapshot == nil {
		fmt.Fprintln(os.Stderr, "FAIL: NewSnapshot returned nil snapshot")
		os.Exit(1)
	}

	// Contract 2: GetVersion returns the snapshot version for the registered resource type
	if gotVer := snapshot.GetVersion(resource.ClusterType); gotVer != version {
		fmt.Fprintf(os.Stderr, "FAIL: GetVersion got %q, want %q\n", gotVer, version)
		os.Exit(1)
	}

	// Contract 3: GetResources returns resource map keyed by name
	clusters := snapshot.GetResources(resource.ClusterType)
	if len(clusters) != 1 {
		fmt.Fprintf(os.Stderr, "FAIL: GetResources expected 1 cluster, got %d\n", len(clusters))
		os.Exit(1)
	}
	res, ok := clusters[clusterName]
	if !ok {
		fmt.Fprintf(os.Stderr, "FAIL: cluster %q not found in snapshot resources\n", clusterName)
		os.Exit(1)
	}
	retrievedCluster, ok := res.(*clusterv3.Cluster)
	if !ok || retrievedCluster.GetName() != clusterName {
		fmt.Fprintf(os.Stderr, "FAIL: retrieved resource is not expected cluster\n")
		os.Exit(1)
	}

	// Contract 4: Consistent returns nil for consistent static snapshot
	if err := snapshot.Consistent(); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: Consistent returned error: %v\n", err)
		os.Exit(1)
	}

	// Contract 5: NewSnapshot allows creating empty snapshot
	emptySnap, err := cachev3.NewSnapshot("v0", nil)
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: NewSnapshot with nil resources failed: %v\n", err)
		os.Exit(1)
	}
	if emptySnap == nil {
		fmt.Fprintln(os.Stderr, "FAIL: emptySnap is nil")
		os.Exit(1)
	}
	if err := emptySnap.Consistent(); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: empty snapshot Consistent returned error: %v\n", err)
		os.Exit(1)
	}

	fmt.Println("PASS: NewSnapshot contract assertions verified successfully")
}