linkerd2/testutil/test_helper.go

package testutil

import (
	"bytes"
	"context"
	"encoding/base64"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"
	"testing"
	"time"

	log "github.com/sirupsen/logrus"
	corev1 "k8s.io/api/core/v1"
)

// TestHelper provides helpers for running the linkerd integration tests.
type TestHelper struct {
	linkerd              string
	version              string
	namespace            string
	vizNamespace         string
	upgradeFromVersion   string
	clusterDomain        string
	externalIssuer       bool
	externalPrometheus   bool
	multicluster         bool
	multiclusterSrcCtx   string
	multiclusterTgtCtx   string
	uninstall            bool
	cni                  bool
	calico               bool
	defaultInboundPolicy string
	httpClient           http.Client
	KubernetesHelper
	helm
	installedExtensions []string
}

type helm struct {
	path                    string
	charts                  string
	multiclusterChart       string
	vizChart                string
	vizStableChart          string
	releaseName             string
	multiclusterReleaseName string
	upgradeFromVersion      string
}

// DeploySpec is used to hold information about what deploys we should verify during testing
type DeploySpec struct {
	Namespace string
	Replicas  int
}

// Service is used to hold information about a Service we should verify during testing
type Service struct {
	Namespace string
	Name      string
}

// LinkerdDeployReplicasEdge is a map containing the number of replicas for each Deployment and the main
// container name in the current core installation
var LinkerdDeployReplicasEdge = map[string]DeploySpec{
	"linkerd-destination":    {"linkerd", 1},
	"linkerd-identity":       {"linkerd", 1},
	"linkerd-proxy-injector": {"linkerd", 1},
}

// LinkerdDeployReplicasStable is a map containing the number of replicas for
// each Deployment and the main container name. Override whenever edge deviates
// from stable.
var LinkerdDeployReplicasStable = LinkerdDeployReplicasEdge

// LinkerdVizDeployReplicas is a map containing the number of replicas for
// each Deployment and the main container name in the current linkerd-viz
// installation
var LinkerdVizDeployReplicas = map[string]DeploySpec{
	"prometheus":   {"linkerd-viz", 1},
	"metrics-api":  {"linkerd-viz", 1},
	"tap":          {"linkerd-viz", 1},
	"tap-injector": {"linkerd-viz", 1},
	"web":          {"linkerd-viz", 1},
}

// MulticlusterDeployReplicas is a map containing the number of replicas for
// each Deployment and the main container name for multicluster components
var MulticlusterDeployReplicas = map[string]DeploySpec{
	"linkerd-gateway": {"linkerd-multicluster", 1},
}

// ExternalVizDeployReplicas has an external prometheus instance that's in a
// separate namespace
var ExternalVizDeployReplicas = map[string]DeploySpec{
	"prometheus":   {"external-prometheus", 1},
	"metrics-api":  {"linkerd-viz", 1},
	"tap":          {"linkerd-viz", 1},
	"tap-injector": {"linkerd-viz", 1},
	"web":          {"linkerd-viz", 1},
}

// SourceContextKey represents the key used to get the name of the Kubernetes
// context corresponding to a source cluster in multicluster tests
var SourceContextKey = "source"

// TargetContextKey represents the key used to get the name of the Kubernetes
// context corresponding to a source cluster in multicluster tests
var TargetContextKey = "target"

// NewGenericTestHelper returns a new *TestHelper from the options provided as function parameters.
// This helper was created to be able to reuse this package without hard restrictions
// as seen in `NewTestHelper()` which is primarily used with integration tests
// See - https://github.com/linkerd/linkerd2/issues/4530
func NewGenericTestHelper(
	linkerd,
	version,
	namespace,
	vizNamespace,
	upgradeFromVersion,
	clusterDomain,
	helmPath,
	helmCharts,
	helmReleaseName,
	helmMulticlusterReleaseName,
	helmMulticlusterChart string,
	externalIssuer,
	externalPrometheus,
	multicluster,
	cni,
	calico,
	uninstall bool,
	httpClient http.Client,
	kubernetesHelper KubernetesHelper,
) *TestHelper {
	return &TestHelper{
		linkerd:            linkerd,
		version:            version,
		namespace:          namespace,
		vizNamespace:       vizNamespace,
		upgradeFromVersion: upgradeFromVersion,
		helm: helm{
			path:                    helmPath,
			charts:                  helmCharts,
			multiclusterChart:       helmMulticlusterChart,
			multiclusterReleaseName: helmMulticlusterReleaseName,
			releaseName:             helmReleaseName,
			upgradeFromVersion:      upgradeFromVersion,
		},
		clusterDomain:      clusterDomain,
		externalIssuer:     externalIssuer,
		externalPrometheus: externalPrometheus,
		uninstall:          uninstall,
		cni:                cni,
		calico:             calico,
		httpClient:         httpClient,
		multicluster:       multicluster,
		KubernetesHelper:   kubernetesHelper,
	}
}

// NewTestHelper creates a new instance of TestHelper for the current test run.
// The new TestHelper can be configured via command line flags.
func NewTestHelper() *TestHelper {
	exit := func(code int, msg string) {
		fmt.Fprintln(os.Stderr, msg)
		os.Exit(code)
	}

	// TODO (matei): clean-up flags
	k8sContext := flag.String("k8s-context", "", "kubernetes context associated with the test cluster")
	linkerdExec := flag.String("linkerd", "", "path to the linkerd binary to test")
	namespace := flag.String("linkerd-namespace", "linkerd", "the namespace where linkerd is installed")
	vizNamespace := flag.String("viz-namespace", "linkerd-viz", "the namespace where linkerd viz extension is installed")
	multicluster := flag.Bool("multicluster", false, "when specified the multicluster install functionality is tested")
	multiclusterSourceCtx := flag.String("multicluster-source-context", "k3d-source", "the context belonging to source cluster in multicluster test")
	multiclusterTargetCtx := flag.String("multicluster-target-context", "k3d-target", "the context belonging to target cluster in multicluster test")
	helmPath := flag.String("helm-path", "target/helm", "path of the Helm binary")
	helmCharts := flag.String("helm-charts", "charts/linkerd2", "path to linkerd2's Helm charts")
	multiclusterHelmChart := flag.String("multicluster-helm-chart", "charts/linkerd-multicluster", "path to linkerd2's multicluster Helm chart")
	vizHelmChart := flag.String("viz-helm-chart", "charts/linkerd-viz", "path to linkerd2's viz extension Helm chart")
	vizHelmStableChart := flag.String("viz-helm-stable-chart", "charts/linkerd-viz", "path to linkerd2's viz extension stable Helm chart")
	helmReleaseName := flag.String("helm-release", "", "install linkerd via Helm using this release name")
	multiclusterHelmReleaseName := flag.String("multicluster-helm-release", "", "install linkerd multicluster via Helm using this release name")
	upgradeFromVersion := flag.String("upgrade-from-version", "", "when specified, the upgrade test uses it as the base version of the upgrade")
	clusterDomain := flag.String("cluster-domain", "cluster.local", "when specified, the install test uses a custom cluster domain")
	externalIssuer := flag.Bool("external-issuer", false, "when specified, the install test uses it to install linkerd with --identity-external-issuer=true")
	externalPrometheus := flag.Bool("external-prometheus", false, "when specified, the install test uses an external prometheus")
	runTests := flag.Bool("integration-tests", false, "must be provided to run the integration tests")
	verbose := flag.Bool("verbose", false, "turn on debug logging")
	upgradeHelmFromVersion := flag.String("upgrade-helm-from-version", "", "Indicate a version of the Linkerd helm chart from which the helm installation is being upgraded")
	uninstall := flag.Bool("uninstall", false, "whether to run the 'linkerd uninstall' integration test")
	cni := flag.Bool("cni", false, "whether to install linkerd with CNI enabled")
	calico := flag.Bool("calico", false, "whether to install calico CNI plugin")
	defaultInboundPolicy := flag.String("default-inbound-policy", "", "if non-empty, passed to --set proxy.defaultInboundPolicy at linkerd's install time")
	flag.Parse()

	if !*runTests {
		exit(0, "integration tests not enabled: enable with -integration-tests")
	}

	if *linkerdExec == "" {
		exit(1, "-linkerd flag is required")
	}

	linkerd, err := filepath.Abs(*linkerdExec)
	if err != nil {
		exit(1, fmt.Sprintf("abs: %s", err))
	}

	if *verbose {
		log.SetLevel(log.DebugLevel)
	} else {
		log.SetLevel(log.PanicLevel)
	}

	testHelper := &TestHelper{
		linkerd:            linkerd,
		namespace:          *namespace,
		vizNamespace:       *vizNamespace,
		upgradeFromVersion: *upgradeFromVersion,
		multicluster:       *multicluster,
		multiclusterSrcCtx: *multiclusterSourceCtx,
		multiclusterTgtCtx: *multiclusterTargetCtx,
		helm: helm{
			path:                    *helmPath,
			charts:                  *helmCharts,
			multiclusterChart:       *multiclusterHelmChart,
			vizChart:                *vizHelmChart,
			vizStableChart:          *vizHelmStableChart,
			releaseName:             *helmReleaseName,
			multiclusterReleaseName: *multiclusterHelmReleaseName,
			upgradeFromVersion:      *upgradeHelmFromVersion,
		},
		clusterDomain:        *clusterDomain,
		externalIssuer:       *externalIssuer,
		externalPrometheus:   *externalPrometheus,
		cni:                  *cni,
		calico:               *calico,
		uninstall:            *uninstall,
		defaultInboundPolicy: *defaultInboundPolicy,
	}

	version, err := testHelper.LinkerdRun("version", "--client", "--short")
	if err != nil {
		exit(1, fmt.Sprintf("error getting linkerd version: %s", err.Error()))
	}
	testHelper.version = strings.TrimSpace(version)

	kubernetesHelper, err := NewKubernetesHelper(*k8sContext, RetryFor)
	if err != nil {
		exit(1, fmt.Sprintf("error creating kubernetes helper: %s", err.Error()))
	}
	testHelper.KubernetesHelper = *kubernetesHelper

	testHelper.httpClient = http.Client{
		Timeout: 10 * time.Second,
	}

	return testHelper
}

// GetVersion returns the version of linkerd to test. This version corresponds
// to the client version of the linkerd binary provided via the -linkerd command
// line flag.
func (h *TestHelper) GetVersion() string {
	return h.version
}

// GetLinkerdNamespace returns the namespace where linkerd is installed. Set the
// namespace using the -linkerd-namespace command line flag.
func (h *TestHelper) GetLinkerdNamespace() string {
	return h.namespace
}

// GetVizNamespace returns the namespace where linkerd Viz Extension is installed. Set the
// namespace using the -linkerd-namespace command line flag.
func (h *TestHelper) GetVizNamespace() string {
	return h.vizNamespace
}

// GetMulticlusterNamespace returns the namespace where multicluster
// components are installed.
func (h *TestHelper) GetMulticlusterNamespace() string {
	return fmt.Sprintf("%s-multicluster", h.GetLinkerdNamespace())
}

// GetMulticlusterContexts returns a map with the context names for the clusters
// used in the test
func (h *TestHelper) GetMulticlusterContexts() map[string]string {
	return map[string]string{
		"source": h.multiclusterSrcCtx,
		"target": h.multiclusterTgtCtx,
	}
}

// GetTestNamespace returns the namespace for the given test. The test namespace
// is prefixed with the linkerd namespace.
func (h *TestHelper) GetTestNamespace(testName string) string {
	return h.namespace + "-" + testName
}

// GetHelmReleaseName returns the name of the Linkerd installation Helm release
func (h *TestHelper) GetHelmReleaseName() string {
	return h.helm.releaseName
}

// GetMulticlusterHelmReleaseName returns the name of the Linkerd multicluster installation Helm release
func (h *TestHelper) GetMulticlusterHelmReleaseName() string {
	return h.helm.multiclusterReleaseName
}

// GetHelmCharts returns the path to the Linkerd Helm chart
func (h *TestHelper) GetHelmCharts() string {
	return h.helm.charts
}

// GetMulticlusterHelmChart returns the path to the Linkerd multicluster Helm chart
func (h *TestHelper) GetMulticlusterHelmChart() string {
	return h.helm.multiclusterChart
}

// GetLinkerdVizHelmChart returns the path to the Linkerd viz Helm chart
func (h *TestHelper) GetLinkerdVizHelmChart() string {
	return h.helm.vizChart
}

// GetLinkerdVizHelmStableChart returns the path to the Linkerd viz Helm
// stable chart
func (h *TestHelper) GetLinkerdVizHelmStableChart() string {
	return h.helm.vizStableChart
}

// UpgradeHelmFromVersion returns the version from which Linkerd should be upgraded with Helm
func (h *TestHelper) UpgradeHelmFromVersion() string {
	return h.helm.upgradeFromVersion
}

// ExternalIssuer determines whether linkerd should be installed with --identity-external-issuer
func (h *TestHelper) ExternalIssuer() bool {
	return h.externalIssuer
}

// ExternalPrometheus determines whether linkerd should be installed with --set prometheusUrl
func (h *TestHelper) ExternalPrometheus() bool {
	return h.externalPrometheus
}

// Multicluster determines whether multicluster components should be installed
func (h *TestHelper) Multicluster() bool {
	return h.multicluster
}

// Uninstall determines whether the "linkerd uninstall" integration test should be run
func (h *TestHelper) Uninstall() bool {
	return h.uninstall
}

// DefaultInboundPolicy returns the override value for proxy.defaultInboundPolicy
func (h *TestHelper) DefaultInboundPolicy() string {
	return h.defaultInboundPolicy
}

// UpgradeFromVersion returns the base version of the upgrade test.
func (h *TestHelper) UpgradeFromVersion() string {
	return h.upgradeFromVersion
}

// GetClusterDomain returns the custom cluster domain that needs to be used during linkerd installation
func (h *TestHelper) GetClusterDomain() string {
	return h.clusterDomain
}

// CNI determines whether CNI should be enabled
func (h *TestHelper) CNI() bool {
	return h.cni
}

// Calico determines whether Calico CNI plug-in is enabled
func (h *TestHelper) Calico() bool {
	return h.calico
}

// AddInstalledExtension adds an extension name to installedExtensions to
// track the currently installed linkerd extensions.
func (h *TestHelper) AddInstalledExtension(extensionName string) {
	h.installedExtensions = append(h.installedExtensions, extensionName)
}

// GetInstalledExtensions gets a list currently installed extensions
// in a test run.
func (h *TestHelper) GetInstalledExtensions() []string {
	return h.installedExtensions
}

// CreateTLSSecret creates a TLS Kubernetes secret
func (h *TestHelper) CreateTLSSecret(name, root, cert, key string) error {
	secret := fmt.Sprintf(`
apiVersion: v1
data:
    ca.crt: %s
    tls.crt: %s
    tls.key: %s
kind: Secret
metadata:
    name: %s
type: kubernetes.io/tls`, base64.StdEncoding.EncodeToString([]byte(root)), base64.StdEncoding.EncodeToString([]byte(cert)), base64.StdEncoding.EncodeToString([]byte(key)), name)

	_, err := h.KubectlApply(secret, h.GetLinkerdNamespace())
	return err
}

// CmdRun executes an arbitrary command by calling the binary and return its
// output
func (h *TestHelper) CmdRun(cmd string, arg ...string) (string, error) {
	out, stderr, err := combinedOutput("", cmd, arg...)
	if err != nil {
		return out, fmt.Errorf("command failed: '%s %s'\n%w\n%s", cmd, strings.Join(arg, " "), err, stderr)
	}
	return out, nil
}

// LinkerdRun executes a linkerd command returning its stdout.
func (h *TestHelper) LinkerdRun(arg ...string) (string, error) {
	out, stderr, err := h.PipeToLinkerdRun("", arg...)
	if err != nil {
		return out, fmt.Errorf("command failed: linkerd %s\n%w\n%s", strings.Join(arg, " "), err, stderr)
	}
	return out, nil
}

// PipeToLinkerdRun executes a linkerd command appended with the
// --linkerd-namespace flag, and provides a string at Stdin.
func (h *TestHelper) PipeToLinkerdRun(stdin string, arg ...string) (string, string, error) {
	withParams := append([]string{"--linkerd-namespace", h.namespace, "--context=" + h.k8sContext}, arg...)
	return combinedOutput(stdin, h.linkerd, withParams...)
}

// HelmRun executes a helm command appended with the --context
func (h *TestHelper) HelmRun(arg ...string) (string, string, error) {
	return h.PipeToHelmRun("", arg...)
}

// PipeToHelmRun executes a Helm command appended with the
// --context flag, and provides a string at Stdin.
func (h *TestHelper) PipeToHelmRun(stdin string, arg ...string) (string, string, error) {
	withParams := append([]string{"--kube-context=" + h.k8sContext}, arg...)
	return combinedOutput(stdin, h.helm.path, withParams...)
}

// LinkerdRunStream initiates a linkerd command appended with the
// --linkerd-namespace flag, and returns a Stream that can be used to read the
// command's output while it is still executing.
func (h *TestHelper) LinkerdRunStream(arg ...string) (*Stream, error) {
	withParams := append([]string{"--linkerd-namespace", h.namespace, "--context=" + h.k8sContext}, arg...)
	cmd := exec.Command(h.linkerd, withParams...)

	cmdReader, err := cmd.StdoutPipe()
	if err != nil {
		return nil, err
	}

	err = cmd.Start()
	if err != nil {
		return nil, err
	}

	time.Sleep(500 * time.Millisecond)

	if cmd.ProcessState != nil && cmd.ProcessState.Exited() {
		return nil, fmt.Errorf("Process exited: %s", cmd.ProcessState)
	}

	return &Stream{cmd: cmd, out: cmdReader}, nil
}

// KubectlStream initiates a kubectl command appended with the
// --namespace flag, and returns a Stream that can be used to read the
// command's output while it is still executing.
func (h *TestHelper) KubectlStream(arg ...string) (*Stream, error) {

	withContext := append([]string{"--namespace", h.namespace, "--context=" + h.k8sContext}, arg...)
	cmd := exec.Command("kubectl", withContext...)

	cmdReader, err := cmd.StdoutPipe()
	if err != nil {
		return nil, err
	}

	err = cmd.Start()
	if err != nil {
		return nil, err
	}

	time.Sleep(500 * time.Millisecond)

	if cmd.ProcessState != nil && cmd.ProcessState.Exited() {
		return nil, fmt.Errorf("Process exited: %s", cmd.ProcessState)
	}

	return &Stream{cmd: cmd, out: cmdReader}, nil
}

// HelmUpgrade runs the helm upgrade subcommand, with the provided arguments
func (h *TestHelper) HelmUpgrade(chart, releaseName string, arg ...string) (string, string, error) {
	withParams := append([]string{
		"upgrade",
		releaseName,
		"--kube-context", h.k8sContext,
		"--namespace", h.namespace,
		"--timeout", "60m",
		"--wait",
		chart,
	}, arg...)
	return combinedOutput("", h.helm.path, withParams...)
}

// HelmInstall runs the helm install subcommand, with the provided arguments
func (h *TestHelper) HelmInstall(chart, releaseName string, arg ...string) (string, string, error) {
	withParams := append([]string{
		"install",
		releaseName,
		chart,
		"--kube-context", h.k8sContext,
		"--namespace", h.namespace,
		"--create-namespace",
		"--timeout", "60m",
		"--wait",
	}, arg...)
	return combinedOutput("", h.helm.path, withParams...)
}

// HelmCmdPlain runs a helm subcommand, with the provided arguments and no defaults
func (h *TestHelper) HelmCmdPlain(cmd, chart, releaseName string, arg ...string) (string, string, error) {
	withParams := append([]string{
		cmd,
		releaseName,
		chart,
		"--kube-context", h.k8sContext,
	}, arg...)

	return combinedOutput("", h.helm.path, withParams...)
}

// HelmInstallMulticluster runs the helm install subcommand for multicluster, with the provided arguments
func (h *TestHelper) HelmInstallMulticluster(chart string, arg ...string) (string, string, error) {
	withParams := append([]string{
		"install",
		h.helm.multiclusterReleaseName,
		chart,
		"--kube-context", h.k8sContext,
		"--namespace", h.GetMulticlusterNamespace(),
		"--create-namespace",
		"--set", "linkerdNamespace=" + h.GetLinkerdNamespace(),
	}, arg...)
	return combinedOutput("", h.helm.path, withParams...)
}

// HelmUninstallMulticluster runs the helm delete subcommand for multicluster
func (h *TestHelper) HelmUninstallMulticluster(chart string) (string, string, error) {
	withParams := []string{
		"delete",
		h.helm.multiclusterReleaseName,
		"--kube-context", h.k8sContext,
	}
	return combinedOutput("", h.helm.path, withParams...)
}

// ValidateOutput validates a string against the contents of a file in the
// test's testdata directory.
func (h *TestHelper) ValidateOutput(out, fixtureFile string) error {
	expected, err := ReadFile("testdata/" + fixtureFile)
	if err != nil {
		return err
	}

	if out != expected {
		return fmt.Errorf(
			"Expected:\n%s\nActual:\n%s", expected, out)
	}

	return nil
}

// CheckVersion validates the output of the "linkerd version" command.
func (h *TestHelper) CheckVersion(serverVersion string) error {
	out, err := h.LinkerdRun("version")
	if err != nil {
		return err
	}
	if !strings.Contains(out, fmt.Sprintf("Client version: %s", h.version)) {
		return fmt.Errorf("Expected client version [%s], got:\n%s", h.version, out)
	}
	if !strings.Contains(out, fmt.Sprintf("Server version: %s", serverVersion)) {
		return fmt.Errorf("Expected server version [%s], got:\n%s", serverVersion, out)
	}
	return nil
}

// RetryFor retries a given function every second until the function returns
// without an error, or a timeout is reached. If the timeout is reached, it
// returns the last error received from the function.
func RetryFor(timeout time.Duration, fn func() error) error {
	err := fn()
	if err == nil {
		return nil
	}

	timeoutAfter := time.NewTimer(timeout)
	defer timeoutAfter.Stop()
	retryAfter := time.NewTicker(time.Second)
	defer retryAfter.Stop()

	for {
		select {
		case <-timeoutAfter.C:
			return err
		case <-retryAfter.C:
			err = fn()
			if err == nil {
				return nil
			}
		}
	}
}

// HTTPGetURL sends a GET request to the given URL. It returns the response body
// in the event of a successful 200 response. In the event of a non-200
// response, it returns an error. It retries requests for up to 30 seconds,
// giving pods time to start.
func (h *TestHelper) HTTPGetURL(url string) (string, error) {
	var body string
	err := RetryFor(time.Minute, func() error {
		resp, err := h.httpClient.Get(url)
		if err != nil {
			return err
		}

		defer resp.Body.Close()
		bytes, err := io.ReadAll(resp.Body)
		if err != nil {
			return fmt.Errorf("Error reading response body: %w", err)
		}
		body = string(bytes)

		if resp.StatusCode != http.StatusOK {
			return fmt.Errorf("GET request to %s returned status code %d with body %q", url, resp.StatusCode, body)
		}

		return nil
	})

	return body, err
}

// WithDataPlaneNamespace is used to create a test namespace that is deleted before the function returns
func (h *TestHelper) WithDataPlaneNamespace(ctx context.Context, testName string, annotations map[string]string, t *testing.T, test func(t *testing.T, ns string)) {
	prefixedNs := h.GetTestNamespace(testName)
	if err := h.CreateDataPlaneNamespaceIfNotExists(ctx, prefixedNs, annotations); err != nil {
		AnnotatedFatalf(t, fmt.Sprintf("failed to create %s namespace", prefixedNs),
			"failed to create %s namespace: %s", prefixedNs, err)
	}
	test(t, prefixedNs)
	if err := h.DeleteNamespaceIfExists(ctx, prefixedNs); err != nil {
		AnnotatedFatalf(t, fmt.Sprintf("failed to delete %s namespace", prefixedNs),
			"failed to delete %s namespace: %s", prefixedNs, err)
	}
}

// GetReleaseChannelVersions is used to fetch the latest versions for Linkerd's
// release channels: edge and stable
func (h *TestHelper) GetReleaseChannelVersions() (map[string]string, error) {
	url := "https://versioncheck.linkerd.io/version.json"
	resp, err := h.httpClient.Get(url)
	if err != nil {
		return map[string]string{}, err
	}
	defer resp.Body.Close()

	var versions map[string]string
	if err := json.NewDecoder(resp.Body).Decode(&versions); err != nil {
		return map[string]string{}, err
	}

	return versions, nil
}

// DownloadCLIBinary is used to download the Linkerd CLI from GitHub Releases
// page. The method takes the version to download and a filepath where to save
// the binary.
func (h *TestHelper) DownloadCLIBinary(filepath, version string) error {
	url := fmt.Sprintf("https://github.com/linkerd/linkerd2/releases/download/%[1]s/linkerd2-cli-%[1]s-%s-%s", version, runtime.GOOS, runtime.GOARCH)
	resp, err := h.httpClient.Get(url)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	// Create if it doesn't already exist
	out, err := os.OpenFile(filepath, os.O_RDWR|os.O_CREATE, 0555)
	if err != nil {
		return err
	}
	defer out.Close()

	_, err = io.Copy(out, resp.Body)
	return err
}

// ReadFile reads a file from disk and returns the contents as a string.
func ReadFile(file string) (string, error) {
	b, err := os.ReadFile(file)
	if err != nil {
		return "", err
	}
	return string(b), nil
}

// combinedOutput executes a shell command and returns the output.
func combinedOutput(stdin string, name string, arg ...string) (string, string, error) {
	command := exec.Command(name, arg...)
	command.Stdin = strings.NewReader(stdin)
	var stderr bytes.Buffer
	command.Stderr = &stderr

	stdout, err := command.Output()
	return string(stdout), stderr.String(), err
}

// RowStat is used to store the contents for a single row from the stat command
type RowStat struct {
	Name               string
	Status             string
	Meshed             string
	Success            string
	Rps                string
	P50Latency         string
	P95Latency         string
	P99Latency         string
	TCPOpenConnections string
	UnauthorizedRPS    string
}

// CheckRowCount checks that expectedRowCount rows have been returned
func CheckRowCount(out string, expectedRowCount int) ([]string, error) {
	rows := strings.Split(strings.TrimSuffix(out, "\n"), "\n")
	if len(rows) < 2 {
		return nil, fmt.Errorf(
			"Expected at least 2 lines in %q",
			out,
		)
	}
	rows = rows[1:] // strip header
	if len(rows) != expectedRowCount {
		return nil, fmt.Errorf(
			"Expected %d rows in stat output but got %d in %q",
			expectedRowCount, len(rows), out)
	}

	return rows, nil
}

// ParseRows parses the output of linkerd stat into a map of resource names to RowStat objects
func ParseRows(out string, expectedRowCount, expectedColumnCount int) (map[string]*RowStat, error) {
	rows, err := CheckRowCount(out, expectedRowCount)
	if err != nil {
		return nil, err
	}

	rowStats := make(map[string]*RowStat)
	for _, row := range rows {
		fields := strings.Fields(row)

		if expectedColumnCount == 0 {
			expectedColumnCount = 8
		}
		if len(fields) != expectedColumnCount {
			return nil, fmt.Errorf(
				"Expected %d columns in stat output but got %d in %q",
				expectedColumnCount, len(fields), row)
		}

		rowStats[fields[0]] = &RowStat{
			Name: fields[0],
		}

		i := 0
		if expectedColumnCount == 9 {
			rowStats[fields[0]].Status = fields[1]
			i = 1
		}
		rowStats[fields[0]].Meshed = fields[1+i]
		rowStats[fields[0]].Success = fields[2+i]
		rowStats[fields[0]].Rps = fields[3+i]
		rowStats[fields[0]].P50Latency = fields[4+i]
		rowStats[fields[0]].P95Latency = fields[5+i]
		rowStats[fields[0]].P99Latency = fields[6+i]

		if 7+i < len(fields) {
			rowStats[fields[0]].TCPOpenConnections = fields[7+i]
		}
	}

	return rowStats, nil
}

// ParseEvents parses the output of kubectl events
func ParseEvents(out string) ([]*corev1.Event, error) {
	var list corev1.List
	if err := json.Unmarshal([]byte(out), &list); err != nil {
		return nil, fmt.Errorf("error unmarshaling list from `kubectl get events`: %w", err)
	}

	if len(list.Items) == 0 {
		return nil, errors.New("no events found")
	}

	var events []*corev1.Event
	for _, i := range list.Items {
		var e corev1.Event
		if err := json.Unmarshal(i.Raw, &e); err != nil {
			return nil, fmt.Errorf("error unmarshaling list event from `kubectl get events`: %w", err)
		}
		events = append(events, &e)
	}

	return events, nil
}