Generated via `git diff v0.8.0-rc.1..v0.7.4 -- . ':!*_test.go' '!:vendor/*' ':!*.md' ':!Makefile' ':!examples/*' ':!hack/*'` to target only production changes.

0.7.4...0.8.0-rc.1.diff

diff --git a/cmd/operator/deploy/crds/monitoring.googleapis.com_operatorconfigs.yaml b/cmd/operator/deploy/crds/monitoring.googleapis.com_operatorconfigs.yaml
index 585713d9e..d61478b72 100644
--- a/cmd/operator/deploy/crds/monitoring.googleapis.com_operatorconfigs.yaml
+++ b/cmd/operator/deploy/crds/monitoring.googleapis.com_operatorconfigs.yaml
@@ -93,6 +93,16 @@ spec:
             type: object
             description: Features holds configuration for optional managed-collection features.
             properties:
+              config:
+                type: object
+                description: Settings for the collector configuration propagation.
+                properties:
+                  compression:
+                    type: string
+                    description: Compression enables compression of the config data propagated by the operator to collectors. It is recommended to use the gzip option when using a large number of ClusterPodMonitoring and/or PodMonitoring.
+                    enum:
+                    - none
+                    - gzip
               targetStatus:
                 type: object
                 description: Configuration of target status reporting.
diff --git a/cmd/rule-evaluator/main.go b/cmd/rule-evaluator/main.go
index 7ba9dda7f..56c120d13 100644
--- a/cmd/rule-evaluator/main.go
+++ b/cmd/rule-evaluator/main.go
@@ -36,7 +36,6 @@ import (
 	"github.com/oklog/run"
 	"google.golang.org/api/option"
 	apihttp "google.golang.org/api/transport/http"
-	"google.golang.org/grpc"
 	"gopkg.in/alecthomas/kingpin.v2"
 
 	"github.com/prometheus/client_golang/api"
@@ -82,6 +81,7 @@ func main() {
 	reg.MustRegister(
 		prometheus.NewGoCollector(),
 		prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{}),
+		grpc_prometheus.DefaultClientMetrics,
 	)
 
 	// The rule-evaluator version is identical to the export library version for now, so
@@ -163,12 +163,9 @@ func main() {
 	ctxRuleManger := context.Background()
 	ctxDiscover, cancelDiscover := context.WithCancel(context.Background())
 
-	grpc_prometheus.EnableClientHandlingTimeHistogram()
-
 	opts := []option.ClientOption{
 		option.WithScopes("https://www.googleapis.com/auth/monitoring.read"),
 		option.WithUserAgent(fmt.Sprintf("rule-evaluator/%s", version)),
-		option.WithGRPCDialOption(grpc.WithUnaryInterceptor(grpc_prometheus.UnaryClientInterceptor)),
 	}
 	if *queryCredentialsFile != "" {
 		opts = append(opts, option.WithCredentialsFile(*queryCredentialsFile))
@@ -178,9 +175,10 @@ func main() {
 		level.Error(logger).Log("msg", "Creating proxy HTTP transport failed", "err", err)
 		os.Exit(1)
 	}
+	roundTripper := makeInstrumentedRoundTripper(transport, reg)
 	client, err := api.NewClient(api.Config{
 		Address:      *targetURL,
-		RoundTripper: transport,
+		RoundTripper: roundTripper,
 	})
 	if err != nil {
 		level.Error(logger).Log("msg", "Error creating client", "err", err)
@@ -648,3 +646,28 @@ func (db *queryAccess) Select(sort bool, hints *storage.SelectHints, matchers ..
 func (db *queryAccess) Close() error {
 	return nil
 }
+
+// makeInstrumentedRoundTripper instruments the original RoundTripper with middleware to observe the request result.
+// The new RoundTripper counts the number of query requests sent to GCM and measures the latency of each request.
+func makeInstrumentedRoundTripper(transport http.RoundTripper, reg prometheus.Registerer) http.RoundTripper {
+	queryCounter := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "rule_evaluator_query_requests_total",
+			Help: "A counter for query requests sent to GCM.",
+		},
+		[]string{"code", "method"},
+	)
+	queryHistogram := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "rule_evaluator_query_requests_latency_seconds",
+			Help:    "Histogram of response latency of query requests sent to GCM.",
+			Buckets: prometheus.DefBuckets,
+		},
+		[]string{"code", "method"},
+	)
+	reg.MustRegister(queryCounter, queryHistogram)
+
+	return promhttp.InstrumentRoundTripperCounter(queryCounter,
+		promhttp.InstrumentRoundTripperDuration(queryHistogram, transport))
+
+}
diff --git a/go.mod b/go.mod
index 065fd4994..5e4c1f348 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/GoogleCloudPlatform/prometheus-engine
 
-go 1.18
+go 1.20
 
 require (
 	cloud.google.com/go/compute/metadata v0.2.2
@@ -34,7 +34,6 @@ require (
 	k8s.io/code-generator v0.26.8
 	k8s.io/utils v0.0.0-20221128185143-99ec85e7a448
 	sigs.k8s.io/controller-runtime v0.14.6
-	sigs.k8s.io/yaml v1.3.0
 )
 
 require (
@@ -118,6 +117,7 @@ require (
 	k8s.io/kube-openapi v0.0.0-20221207184640-f3cff1453715 // indirect
 	sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd // indirect
 	sigs.k8s.io/structured-merge-diff/v4 v4.2.3 // indirect
+	sigs.k8s.io/yaml v1.3.0 // indirect
 )
 
 // Exclude pre-go-mod kubernetes tags, as they are older
diff --git a/manifests/setup.yaml b/manifests/setup.yaml
index 096ad09fd..9de263914 100644
--- a/manifests/setup.yaml
+++ b/manifests/setup.yaml
@@ -929,6 +929,16 @@ spec:
             type: object
             description: Features holds configuration for optional managed-collection features.
             properties:
+              config:
+                type: object
+                description: Settings for the collector configuration propagation.
+                properties:
+                  compression:
+                    type: string
+                    description: Compression enables compression of the config data propagated by the operator to collectors. It is recommended to use the gzip option when using a large number of ClusterPodMonitoring and/or PodMonitoring.
+                    enum:
+                    - none
+                    - gzip
               targetStatus:
                 type: object
                 description: Configuration of target status reporting.
diff --git a/pkg/export/export.go b/pkg/export/export.go
index b9475bb41..fe8542084 100644
--- a/pkg/export/export.go
+++ b/pkg/export/export.go
@@ -522,7 +522,7 @@ const (
 	ClientName = "prometheus-engine-export"
 	// mainModuleVersion is the version of the main module. Align with git tag.
 	// TODO(TheSpiritXIII): Remove with https://github.com/golang/go/issues/50603
-	mainModuleVersion = "v0.7.4-rc.0"
+	mainModuleVersion = "v0.8.0-rc.0"
 	// mainModuleName is the name of the main module. Align with go.mod.
 	mainModuleName = "github.com/GoogleCloudPlatform/prometheus-engine"
 )
diff --git a/pkg/operator/apis/monitoring/v1/types.go b/pkg/operator/apis/monitoring/v1/types.go
index 4ff32fc6f..169d1cb44 100644
--- a/pkg/operator/apis/monitoring/v1/types.go
+++ b/pkg/operator/apis/monitoring/v1/types.go
@@ -117,6 +117,16 @@ type CollectionSpec struct {
 type OperatorFeatures struct {
 	// Configuration of target status reporting.
 	TargetStatus TargetStatusSpec `json:"targetStatus,omitempty"`
+	// Settings for the collector configuration propagation.
+	Config ConfigSpec `json:"config,omitempty"`
+}
+
+// ConfigSpec holds configurations for the Prometheus configuration.
+type ConfigSpec struct {
+	// Compression enables compression of the config data propagated by the operator to collectors.
+	// It is recommended to use the gzip option when using a large number of ClusterPodMonitoring
+	// and/or PodMonitoring.
+	Compression CompressionType `json:"compression,omitempty"`
 }
 
 // TargetStatusSpec holds configuration for target status reporting.
@@ -128,6 +138,9 @@ type TargetStatusSpec struct {
 // +kubebuilder:validation:Enum=none;gzip
 type CompressionType string
 
+const CompressionNone CompressionType = "none"
+const CompressionGzip CompressionType = "gzip"
+
 // KubeletScraping allows enabling scraping of the Kubelets' metric endpoints.
 type KubeletScraping struct {
 	// The interval at which the metric endpoints are scraped.
diff --git a/pkg/operator/apis/monitoring/v1/zz_generated.deepcopy.go b/pkg/operator/apis/monitoring/v1/zz_generated.deepcopy.go
index ee5189a0c..6ca4c5740 100644
--- a/pkg/operator/apis/monitoring/v1/zz_generated.deepcopy.go
+++ b/pkg/operator/apis/monitoring/v1/zz_generated.deepcopy.go
@@ -282,6 +282,22 @@ func (in *CollectionSpec) DeepCopy() *CollectionSpec {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *ConfigSpec) DeepCopyInto(out *ConfigSpec) {
+	*out = *in
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new ConfigSpec.
+func (in *ConfigSpec) DeepCopy() *ConfigSpec {
+	if in == nil {
+		return nil
+	}
+	out := new(ConfigSpec)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *ExportFilters) DeepCopyInto(out *ExportFilters) {
 	*out = *in
@@ -506,6 +522,7 @@ func (in *OperatorConfigList) DeepCopyObject() runtime.Object {
 func (in *OperatorFeatures) DeepCopyInto(out *OperatorFeatures) {
 	*out = *in
 	out.TargetStatus = in.TargetStatus
+	out.Config = in.Config
 	return
 }
 
diff --git a/pkg/operator/collection.go b/pkg/operator/collection.go
index c1920065c..a4b191f36 100644
--- a/pkg/operator/collection.go
+++ b/pkg/operator/collection.go
@@ -15,6 +15,8 @@
 package operator
 
 import (
+	"bytes"
+	"compress/gzip"
 	"context"
 	"encoding/json"
 	"fmt"
@@ -174,7 +176,7 @@ func (r *collectionReconciler) Reconcile(ctx context.Context, req reconcile.Requ
 		return reconcile.Result{}, fmt.Errorf("ensure collector daemon set: %w", err)
 	}
 
-	if err := r.ensureCollectorConfig(ctx, &config.Collection); err != nil {
+	if err := r.ensureCollectorConfig(ctx, &config.Collection, config.Features.Config.Compression); err != nil {
 		return reconcile.Result{}, fmt.Errorf("ensure collector config: %w", err)
 	}
 
@@ -255,7 +257,7 @@ func (r *collectionReconciler) ensureCollectorDaemonSet(ctx context.Context, spe
 		flags = append(flags, fmt.Sprintf("--export.credentials-file=%q", p))
 	}
 
-	if len(spec.Compression) > 0 && spec.Compression != "none" {
+	if len(spec.Compression) > 0 && spec.Compression != monitoringv1.CompressionNone {
 		flags = append(flags, fmt.Sprintf("--export.compression=%s", spec.Compression))
 	}
 
@@ -300,8 +302,20 @@ func resolveLabels(opts Options, externalLabels map[string]string) (projectID st
 	return
 }
 
+func gzipData(data []byte) ([]byte, error) {
+	var b bytes.Buffer
+	gz := gzip.NewWriter(&b)
+	if _, err := gz.Write(data); err != nil {
+		return nil, err
+	}
+	if err := gz.Close(); err != nil {
+		return nil, err
+	}
+	return b.Bytes(), nil
+}
+
 // ensureCollectorConfig generates the collector config and creates or updates it.
-func (r *collectionReconciler) ensureCollectorConfig(ctx context.Context, spec *monitoringv1.CollectionSpec) error {
+func (r *collectionReconciler) ensureCollectorConfig(ctx context.Context, spec *monitoringv1.CollectionSpec, compression monitoringv1.CompressionType) error {
 	cfg, err := r.makeCollectorConfig(ctx, spec)
 	if err != nil {
 		return fmt.Errorf("generate Prometheus config: %w", err)
@@ -316,9 +330,26 @@ func (r *collectionReconciler) ensureCollectorConfig(ctx context.Context, spec *
 			Namespace: r.opts.OperatorNamespace,
 			Name:      NameCollector,
 		},
-		Data: map[string]string{
+	}
+
+	// Thanos config-reloader detects gzip compression automatically, so no sync with
+	// config-reloaders is needed when switching between these.
+	switch compression {
+	case monitoringv1.CompressionGzip:
+		compressedCfg, err := gzipData(cfgEncoded)
+		if err != nil {
+			return fmt.Errorf("gzip Prometheus config: %w", err)
+		}
+
+		cm.BinaryData = map[string][]byte{
+			configFilename: compressedCfg,
+		}
+	case "", monitoringv1.CompressionNone:
+		cm.Data = map[string]string{
 			configFilename: string(cfgEncoded),
-		},
+		}
+	default:
+		return fmt.Errorf("unknown compression type: %q", compression)
 	}
 
 	if err := r.client.Update(ctx, cm); apierrors.IsNotFound(err) {
diff --git a/pkg/operator/endpoint_status_builder.go b/pkg/operator/endpoint_status_builder.go
index 758d15a8e..428d40a1a 100644
--- a/pkg/operator/endpoint_status_builder.go
+++ b/pkg/operator/endpoint_status_builder.go
@@ -55,7 +55,7 @@ type scrapeEndpointBuilder struct {
 }
 
 func (b *scrapeEndpointBuilder) add(target *prometheusv1.TargetsResult) error {
-	b.total += 1
+	b.total++
 	if target != nil {
 		for _, activeTarget := range target.Active {
 			if err := b.addActiveTarget(activeTarget, b.time); err != nil {
@@ -63,7 +63,7 @@ func (b *scrapeEndpointBuilder) add(target *prometheusv1.TargetsResult) error {
 			}
 		}
 	} else {
-		b.failed += 1
+		b.failed++
 	}
 	return nil
 }
@@ -135,7 +135,7 @@ func newScrapeEndpointStatusBuilder(target *prometheusv1.ActiveTarget, time meta
 
 // Adds a sample target, potentially merging with a pre-existing one.
 func (b *scrapeEndpointStatusBuilder) addSampleTarget(target *prometheusv1.ActiveTarget) {
-	b.status.ActiveTargets += 1
+	b.status.ActiveTargets++
 	errorType := target.LastError
 	lastError := &errorType
 	if target.Health == "up" {
@@ -143,7 +143,7 @@ func (b *scrapeEndpointStatusBuilder) addSampleTarget(target *prometheusv1.Activ
 			lastError = nil
 		}
 	} else {
-		b.status.UnhealthyTargets += 1
+		b.status.UnhealthyTargets++
 	}
 
 	sampleGroup, ok := b.groupByError[errorType]
@@ -160,7 +160,7 @@ func (b *scrapeEndpointStatusBuilder) addSampleTarget(target *prometheusv1.Activ
 		}
 		b.groupByError[errorType] = sampleGroup
 	}
-	*sampleGroup.Count += 1
+	*sampleGroup.Count++
 	sampleGroup.SampleTargets = append(sampleGroup.SampleTargets, sampleTarget)
 }
 
diff --git a/pkg/operator/operator.go b/pkg/operator/operator.go
index cbd215169..f8c04ae8b 100644
--- a/pkg/operator/operator.go
+++ b/pkg/operator/operator.go
@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package operator contains the Prometheus operator.
 package operator
 
 import (
@@ -19,8 +20,8 @@ import (
 	"encoding/base64"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"net"
+	"os"
 	"path/filepath"
 	"strconv"
 	"time"
@@ -57,26 +58,29 @@ const (
 	// configuration data.
 	DefaultPublicNamespace = "gmp-public"
 
-	// Fixed names used in various resources managed by the operator.
-	NameOperator  = "gmp-operator"
+	// NameOperator is a fixed name used in various resources managed by the operator.
+	NameOperator = "gmp-operator"
+	// componentName is a fixed name used in various resources managed by the operator.
 	componentName = "managed_prometheus"
 
 	// Filename for configuration files.
 	configFilename = "config.yaml"
 
-	// The well-known app name label.
+	// LabelAppName is the  well-known app name label.
 	LabelAppName = "app.kubernetes.io/name"
-	// The component name, will be exposed as metric name.
+	// AnnotationMetricName is the component name, will be exposed as metric name.
 	AnnotationMetricName = "components.gke.io/component-name"
 	// ClusterAutoscalerSafeEvictionLabel is the annotation label that determines
 	// whether the cluster autoscaler can safely evict a Pod when the Pod doesn't
 	// satisfy certain eviction criteria.
 	ClusterAutoscalerSafeEvictionLabel = "cluster-autoscaler.kubernetes.io/safe-to-evict"
 
-	// The k8s Application, will be exposed as component name.
-	KubernetesAppName    = "app"
+	// KubernetesAppName is the k8s Application, will be exposed as component name.
+	KubernetesAppName = "app"
+	// RuleEvaluatorAppName is the name of the rule-evaluator application.
 	RuleEvaluatorAppName = "managed-prometheus-rule-evaluator"
-	AlertmanagerAppName  = "managed-prometheus-alertmanager"
+	// AlertmanagerAppName is the name of the alert manager application.
+	AlertmanagerAppName = "managed-prometheus-alertmanager"
 
 	// The level of concurrency to use to fetch all targets.
 	defaultTargetPollConcurrency = 4
@@ -167,7 +171,7 @@ func New(logger logr.Logger, clientConfig *rest.Config, opts Options) (*Operator
 		return nil, fmt.Errorf("invalid options: %w", err)
 	}
 	// Create temporary directory to store webhook serving cert files.
-	certDir, err := ioutil.TempDir("", "operator-cert")
+	certDir, err := os.MkdirTemp("", "operator-cert")
 	if err != nil {
 		return nil, fmt.Errorf("create temporary certificate dir: %w", err)
 	}
@@ -479,13 +483,13 @@ func (o *Operator) ensureCerts(ctx context.Context, dir string) ([]byte, error)
 		// Use crt as the ca in the the self-sign case.
 		caData = crt
 	} else {
-		return nil, errors.New("Flags key-base64 and cert-base64 must both be set.")
+		return nil, errors.New("flags key-base64 and cert-base64 must both be set")
 	}
 	// Create cert/key files.
-	if err := ioutil.WriteFile(filepath.Join(dir, "tls.crt"), crt, 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(dir, "tls.crt"), crt, 0666); err != nil {
 		return nil, fmt.Errorf("create cert file: %w", err)
 	}
-	if err := ioutil.WriteFile(filepath.Join(dir, "tls.key"), key, 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(dir, "tls.key"), key, 0666); err != nil {
 		return nil, fmt.Errorf("create key file: %w", err)
 	}
 	return caData, nil
diff --git a/pkg/operator/operator_config.go b/pkg/operator/operator_config.go
index 81bcb52d1..71f0568f7 100644
--- a/pkg/operator/operator_config.go
+++ b/pkg/operator/operator_config.go
@@ -57,6 +57,7 @@ const (
 	NameAlertmanager   = "alertmanager"
 )
 
+// Secret paths
 const (
 	RulesSecretName              = "rules"
 	CollectionSecretName         = "collection"
@@ -615,18 +616,18 @@ func (r *operatorConfigReconciler) makeAlertmanagerConfigs(ctx context.Context,
 
 // getSecretOrConfigMapBytes is a helper function to conditionally fetch
 // the secret or configmap selector payloads.
-func getSecretOrConfigMapBytes(ctx context.Context, kClient client.Reader, namespace string, scm *monitoringv1.SecretOrConfigMap) ([]byte, error) {
+func getSecretOrConfigMapBytes(ctx context.Context, c client.Reader, namespace string, scm *monitoringv1.SecretOrConfigMap) ([]byte, error) {
 	var (
 		b   []byte
 		err error
 	)
 	if secret := scm.Secret; secret != nil {
-		b, err = getSecretKeyBytes(ctx, kClient, namespace, secret)
+		b, err = getSecretKeyBytes(ctx, c, namespace, secret)
 		if err != nil {
 			return b, err
 		}
 	} else if cm := scm.ConfigMap; cm != nil {
-		b, err = getConfigMapKeyBytes(ctx, kClient, namespace, cm)
+		b, err = getConfigMapKeyBytes(ctx, c, namespace, cm)
 		if err != nil {
 			return b, err
 		}
@@ -635,7 +636,7 @@ func getSecretOrConfigMapBytes(ctx context.Context, kClient client.Reader, names
 }
 
 // getSecretKeyBytes processes the given NamespacedSecretKeySelector and returns the referenced data.
-func getSecretKeyBytes(ctx context.Context, kClient client.Reader, namespace string, sel *corev1.SecretKeySelector) ([]byte, error) {
+func getSecretKeyBytes(ctx context.Context, c client.Reader, namespace string, sel *corev1.SecretKeySelector) ([]byte, error) {
 	var (
 		secret = &corev1.Secret{}
 		nn     = types.NamespacedName{
@@ -644,7 +645,7 @@ func getSecretKeyBytes(ctx context.Context, kClient client.Reader, namespace str
 		}
 		bytes []byte
 	)
-	err := kClient.Get(ctx, nn, secret)
+	err := c.Get(ctx, nn, secret)
 	if err != nil {
 		return bytes, fmt.Errorf("unable to get secret %q: %w", sel.Name, err)
 	}
@@ -657,7 +658,7 @@ func getSecretKeyBytes(ctx context.Context, kClient client.Reader, namespace str
 }
 
 // getConfigMapKeyBytes processes the given NamespacedConfigMapKeySelector and returns the referenced data.
-func getConfigMapKeyBytes(ctx context.Context, kClient client.Reader, namespace string, sel *corev1.ConfigMapKeySelector) ([]byte, error) {
+func getConfigMapKeyBytes(ctx context.Context, c client.Reader, namespace string, sel *corev1.ConfigMapKeySelector) ([]byte, error) {
 	var (
 		cm = &corev1.ConfigMap{}
 		nn = types.NamespacedName{
@@ -666,7 +667,7 @@ func getConfigMapKeyBytes(ctx context.Context, kClient client.Reader, namespace
 		}
 		b []byte
 	)
-	err := kClient.Get(ctx, nn, cm)
+	err := c.Get(ctx, nn, cm)
 	if err != nil {
 		return b, fmt.Errorf("unable to get secret %q: %w", sel.Name, err)
 	}
diff --git a/pkg/operator/target_status.go b/pkg/operator/target_status.go
index e391c7f3e..3d49aba66 100644
--- a/pkg/operator/target_status.go
+++ b/pkg/operator/target_status.go
@@ -53,7 +53,7 @@ var (
 	}, []string{})
 
 	// Minimum duration between polls.
-	pollDurationMin = 10 * time.Second
+	minPollDuration = 10 * time.Second
 )
 
 // Responsible for fetching the targets given a pod.
@@ -154,7 +154,7 @@ func shouldPoll(ctx context.Context, cfgNamespacedName types.NamespacedName, kub
 // Reconcile polls the collector pods, fetches and aggregates target status and
 // upserts into each PodMonitoring's Status field.
 func (r *targetStatusReconciler) Reconcile(ctx context.Context, request reconcile.Request) (reconcile.Result, error) {
-	timer := r.clock.NewTimer(pollDurationMin)
+	timer := r.clock.NewTimer(minPollDuration)
 
 	now := time.Now()
 
@@ -403,9 +403,9 @@ func getTarget(ctx context.Context, logger logr.Logger, port int32, pod *corev1.
 	if pod.Status.PodIP == "" {
 		return nil, errors.New("pod does not have IP allocated")
 	}
-	podUrl := fmt.Sprintf("http://%s:%d", pod.Status.PodIP, port)
+	podURL := fmt.Sprintf("http://%s:%d", pod.Status.PodIP, port)
 	client, err := api.NewClient(api.Config{
-		Address: podUrl,
+		Address: podURL,
 	})
 	if err != nil {
 		return nil, fmt.Errorf("unable to create Prometheus client: %w", err)
diff --git a/pkg/ui/ui.go b/pkg/ui/ui.go
index 530f32584..c3d7fd8ec 100644
--- a/pkg/ui/ui.go
+++ b/pkg/ui/ui.go
@@ -17,7 +17,7 @@ package ui
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"net/url"
 	"path"
@@ -48,7 +48,7 @@ func Handler(externalURL *url.URL) http.Handler {
 				fmt.Fprintf(w, "Error opening React index.html: %v", err)
 				return
 			}
-			idx, err := ioutil.ReadAll(f)
+			idx, err := io.ReadAll(f)
 			if err != nil {
 				w.WriteHeader(http.StatusInternalServerError)
 				fmt.Fprintf(w, "Error reading React index.html: %v", err)