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Signed-off-by: hagen1778 <roman@victoriametrics.com> Co-authored-by: hagen1778 <roman@victoriametrics.com>
279 lines
9.4 KiB
Markdown
279 lines
9.4 KiB
Markdown
---
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weight: 5
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title: How to use OpenTelemetry metrics with VictoriaMetrics
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menu:
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docs:
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parent: "guides"
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weight: 5
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---
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VictoriaMetrics supports metrics ingestion with [OpenTelemetry metrics format](https://opentelemetry.io/docs/specs/otel/metrics/).
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This guide covers data ingestion via [opentelemetry-collector](https://opentelemetry.io/docs/collector/) and direct metrics push from application.
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## Pre-Requirements
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* [kubernetes cluster](https://kubernetes.io/docs/tasks/tools/#kind)
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* [kubectl](https://kubernetes.io/docs/tasks/tools/#kubectl)
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* [helm](https://helm.sh/docs/intro/install/)
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### Install VictoriaMetrics single-server via helm chart
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Install single-server version:
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```sh
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helm repo add vm https://victoriametrics.github.io/helm-charts/
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helm repo update
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helm install victoria-metrics vm/victoria-metrics-single
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```
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Verify it's up and running:
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```sh
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kubectl get pods
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# victoria-metrics-victoria-metrics-single-server-0 1/1 Running 0 3m1s
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```
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Helm chart provides the following urls for reading and writing data:
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```text
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Write url inside the kubernetes cluster:
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http://victoria-metrics-victoria-metrics-single-server.default.svc.cluster.local:8428
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Read Data:
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The following url can be used as the datasource url in Grafana:
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http://victoria-metrics-victoria-metrics-single-server.default.svc.cluster.local:8428
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```
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## Using opentelemetry-collector with VictoriaMetrics
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<img src="/guides/getting-started-with-opentelemetry-collector.webp">
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### Deploy opentelemetry-collector and configure metrics forwarding
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```sh
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helm repo add open-telemetry https://open-telemetry.github.io/opentelemetry-helm-charts
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helm repo update
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# add values
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cat << EOF > values.yaml
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presets:
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clusterMetrics:
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enabled: true
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config:
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exporters:
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prometheusremotewrite:
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endpoint: "http://victoria-metrics-victoria-metrics-single-server.default.svc.cluster.local:8428/api/v1/write"
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service:
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pipelines:
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metrics:
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receivers: [otlp]
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processors: []
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exporters: [prometheusremotewrite]
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EOF
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# install helm chart
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helm upgrade -i otl-collector open-telemetry/opentelemetry-collector --set mode=deployment -f values.yaml
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# check if pod is healthy
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kubectl get pod
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NAME READY STATUS RESTARTS AGE
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otl-colletor-opentelemetry-collector-7467bbb559-2pq2n 1/1 Running 0 23m
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# forward port to local machine to verify metrics are ingested
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kubectl port-forward victoria-metrics-victoria-metrics-single-server-0 8428
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# check metric `k8s_container_ready` via browser http://localhost:8428/vmui/#/?g0.expr=k8s_container_ready
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```
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The full version of possible configuration options could be found in [OpenTelemetry docs](https://opentelemetry.io/docs/collector/configuration/).
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## Direct metrics push
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Metrics could be ingested into VictoriaMetrics directly with HTTP requests. You can use any compatible OpenTelemetry
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instrumentation [clients](https://opentelemetry.io/docs/languages/).
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In our example, we'll create a WEB server in [Golang](https://go.dev/) and instrument it with metrics.
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<img src="/guides/getting-started-with-opentelemetry-direct.webp">
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### Building the Go application instrumented with metrics
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See the full source code of the example [here](/guides/getting-started-with-opentelemetry-app.go.example).
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The list of OpenTelemetry dependencies for `go.mod` is the following:
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```go
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go 1.20
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require (
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go.opentelemetry.io/otel v1.7.0
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go.opentelemetry.io/otel/exporters/otlp/otlpmetric v0.30.0
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go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v0.30.0
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go.opentelemetry.io/otel/metric v0.30.0
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go.opentelemetry.io/otel/sdk v1.7.0
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go.opentelemetry.io/otel/sdk/metric v0.30.0
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)
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```
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Let's create a new file `main.go` with basic implementation of the WEB server:
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```go
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package main
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func main() {
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mux := http.NewServeMux()
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mux.HandleFunc("/api/fast", func(writer http.ResponseWriter, request *http.Request) {
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writer.WriteHeader(http.StatusOK)
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writer.Write([]byte(`fast ok`))
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})
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mux.HandleFunc("/api/slow", func(writer http.ResponseWriter, request *http.Request) {
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time.Sleep(time.Second * 2)
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writer.WriteHeader(http.StatusOK)
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writer.Write([]byte(`slow ok`))
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})
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mw, err := newMetricsMiddleware(mux)
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if err != nil {
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panic(fmt.Sprintf("cannot build metricMiddleWare: %q", err))
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}
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go func() {
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http.ListenAndServe("localhost:8081", mw)
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}()
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}
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```
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In the code above, we used `newMetricsMiddleware` function to create a `handler` for our server.
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Let's define it below:
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```go
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type metricMiddleWare struct {
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h http.Handler
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requestsCount syncint64.Counter
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requestsLatency syncfloat64.Histogram
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activeRequests int64
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}
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func newMetricsMiddleware(h http.Handler) (*metricMiddleWare, error) {
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mw := &metricMiddleWare{h: h}
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mc, err := newMetricsController(ctx)
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if err != nil {
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return nil, fmt.Errorf("cannot build metrics collector: %w", err)
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}
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global.SetMeterProvider(mc)
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prov := mc.Meter("")
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mw.requestsLatency, err = prov.SyncFloat64().Histogram("http_request_latency_seconds")
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if err != nil {
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return nil, fmt.Errorf("cannot create histogram: %w", err)
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}
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mw.requestsCount, err = prov.SyncInt64().Counter("http_requests_total")
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if err != nil {
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return nil, fmt.Errorf("cannot create syncInt64 counter: %w", err)
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}
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ar, err := prov.AsyncInt64().Gauge("http_active_requests")
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if err != nil {
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return nil, fmt.Errorf("cannot create AsyncInt64 gauge: %w", err)
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}
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if err := prov.RegisterCallback([]instrument.Asynchronous{ar}, func(ctx context.Context) {
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ar.Observe(ctx, atomic.LoadInt64(&mw.activeRequests))
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}); err != nil {
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return nil, fmt.Errorf("cannot Register int64 gauge: %w", err)
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}
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return mw, nil
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}
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```
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The new type `metricMiddleWare` is instrumented with 3 [metrics](https://opentelemetry.io/docs/specs/otel/metrics/data-model/#timeseries-model)
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initialized in `newMetricsMiddleware` method:
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* counter `http_requests_total`
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* histogram `http_request_latency_seconds`
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* gauge `http_active_requests`
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Let's implement http.Handler interface for `metricMiddleWare` by adding `ServeHTTP` method:
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```go
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func (m *metricMiddleWare) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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t := time.Now()
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path := r.URL.Path
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m.requestsCount.Add(nil, 1, attribute.String("path", path))
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atomic.AddInt64(&m.activeRequests, 1)
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defer func() {
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atomic.AddInt64(&m.activeRequests, -1)
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m.requestsLatency.Record(nil, time.Since(t).Seconds(), attribute.String("path", path))
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}()
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m.h.ServeHTTP(w, r)
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}
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```
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In method above, our middleware processes received HTTP requests and updates metrics with each new request.
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But for these metrics to be shipped we need to add a new method `newMetricsController` to organize metrics collection:
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```go
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func newMetricsController(ctx context.Context) (*controller.Controller, error) {
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options := []otlpmetrichttp.Option{
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otlpmetrichttp.WithEndpoint("<VictoriaMetrics endpoint - host:port>"),
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otlpmetrichttp.WithURLPath("/opentelemetry/api/v1/push"),
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}
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metricExporter, err := otlpmetrichttp.New(ctx, options...)
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if err != nil {
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return nil, fmt.Errorf("cannot create otlphttp exporter: %w", err)
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}
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resourceConfig, err := resource.New(ctx, resource.WithAttributes(attribute.String("job", "otlp"), attribute.String("instance", "localhost")))
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if err != nil {
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return nil, fmt.Errorf("cannot create meter resource: %w", err)
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}
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meterController := controller.New(
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processor.NewFactory(
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selector.NewWithHistogramDistribution(
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histogram.WithExplicitBoundaries([]float64{0.01, 0.05, 0.1, 0.5, 0.9, 1.0, 5.0, 10.0, 100.0}),
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),
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aggregation.CumulativeTemporalitySelector(),
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processor.WithMemory(true),
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),
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controller.WithExporter(metricExporter),
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controller.WithCollectPeriod(time.Second * 10),
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controller.WithResource(resourceConfig),
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)
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if err := meterController.Start(ctx); err != nil {
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return nil, fmt.Errorf("cannot start meter controller: %w", err)
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}
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return meterController, nil
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}
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```
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This controller will collect and push collected metrics to VictoriaMetrics address with interval of `10s`.
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See the full source code of the example [here](/guides/getting-started-with-opentelemetry-app.go.example).
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### Test metrics ingestion
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For metrics from our WEB server to be shipped to VictoriaMetrics we need make it available for ingestion.
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In previous steps we already deployed a single-server VictoriaMetrics, so let's make it available locally:
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```sh
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# port-forward victoriametrics to ingest metrics
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kubectl port-forward victoria-metrics-victoria-metrics-single-server-0 8428
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```
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Now let's run our WEB server and call its APIs:
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```sh
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# build and run the app
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go run main.go
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2024/03/25 19:27:41 Starting web server...
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2024/03/25 19:27:41 web server started at localhost:8081.
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# execute few queries with curl
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curl http://localhost:8081/api/fast
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curl http://localhost:8081/api/slow
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```
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Open [vmui](https://docs.victoriametrics.com/#vmui) and query `http_requests_total` or `http_active_requests`
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with [metricsql](https://docs.victoriametrics.com/metricsql/).
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<img src= "/guides/getting-started-with-opentelemetry-vmui.webp">
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## Limitations
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* VictoriaMetrics doesn't support experimental JSON encoding [format](https://github.com/open-telemetry/opentelemetry-proto/blob/main/examples/metrics.json).
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* VictoriaMetrics supports only `AggregationTemporalityCumulative` type for [histogram](https://opentelemetry.io/docs/specs/otel/metrics/data-model/#histogram) and [summary](https://opentelemetry.io/docs/specs/otel/metrics/data-model/#summary-legacy)
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