---
layout: docs
page_title: Observe service mesh telemetry on Kubernetes
description: >-
  Use the `connectInject.metrics` Helm values to enable Prometheus and Grafana integrations and capture metrics. Consul can collect metrics from the service mesh, sidecar proxies, agents, and gateways in a k8s cluster and then display service traffic metrics in Consul’s UI for additional observability.
---

# Observe service mesh telemetry on Kubernetes

Consul on Kubernetes integrates with Prometheus and Grafana to provide metrics for Consul service mesh. The metrics
available are:

- Mesh service metrics
- Mesh sidecar proxy metrics
- Consul agent metrics
- Ingress, terminating, and mesh gateway metrics

Specific sidecar proxy metrics can also be seen in the Consul UI Topology Visualization view. This section documents how to enable each of these.

## Mesh Service and Sidecar Metrics with Metrics Merging

Prometheus annotations are used to instruct Prometheus to scrape metrics from Pods. Prometheus annotations only support
scraping from one endpoint on a Pod, so Consul on Kubernetes supports metrics merging whereby service metrics and
sidecar proxy metrics are merged into one endpoint. If there are no service metrics, it also supports just scraping the
sidecar proxy metrics.

<!-- Diagram hidden for v1.14.0 release - needs updates for Dataplanes
The diagram below illustrates how the metrics integration works when merging is enabled:

[![Metrics Merging Architecture](/img/metrics-arch.png)](/img/metrics-arch.png)
-->

Metrics for services in the mesh can be configured with the Helm values nested under [`connectInject.metrics`](/consul/docs/reference/k8s/helm#v-connectinject-metrics).

Metrics and metrics merging can be enabled by default for all connect-injected Pods with the following Helm values:

```yaml
connectInject:
  metrics:
    defaultEnabled: true # by default, this inherits from the value global.metrics.enabled
    defaultEnableMerging: true
```

They can also be overridden on a per-Pod basis using the annotations `consul.hashicorp.com/enable-metrics` and
`consul.hashicorp.com/enable-metrics-merging`.

~> In most cases, the default settings are sufficient. If you encounter issues with colliding ports or service
metrics not being merged, you may need to change the defaults.

The Prometheus annotations specify which endpoint to scrape the metrics from. The annotations point to a listener on `0.0.0.0:20200` on the Envoy sidecar. You can configure the listener and the corresponding Prometheus annotations using the following Helm values. Alternatively, you can specify the `consul.hashicorp.com/prometheus-scrape-port` and `consul.hashicorp.com/prometheus-scrape-path` Consul annotations to override them on a per-Pod basis:

```yaml
connectInject:
  metrics:
    defaultPrometheusScrapePort: 20200
    defaultPrometheusScrapePath: "/metrics"
```

The Helm values specified in the previous example result in the following Prometheus annotations being automatically added to the Pod for scraping:

```yaml
metadata:
  annotations:
    prometheus.io/scrape: "true"
    prometheus.io/path: "/metrics"
    prometheus.io/port: "20200"
```

When metrics and metrics merging are both enabled, metrics are combined from the service and the sidecar proxy, and
exposed through a local server on the Consul Dataplane sidecar for scraping. This endpoint is called the merged metrics endpoint and
defaults to `127.0.0.1:20100/stats/prometheus`. The listener targets the merged metrics endpoint in the above case.
It can be configured with the following Helm values (or overridden on a per-Pod basis with
`consul.hashicorp.com/merged-metrics-port`:

```yaml
connectInject:
  metrics:
    defaultMergedMetricsPort: 20100
```

The endpoint to scrape service metrics from can be configured only on a per-Pod basis with the Pod annotations `consul.hashicorp.com/service-metrics-port` and `consul.hashicorp.com/service-metrics-path`. If these are not configured, the service metrics port  defaults to the port used to register the service with Consul (`consul.hashicorp.com/connect-service-port`), which in turn defaults to the first port on the first container of the Pod. The service metrics path defaults to `/metrics`.

## Consul Agent Metrics

Metrics from the Consul server Pods can be scraped with Prometheus by setting the field `global.metrics.enableAgentMetrics` to `true`. Additionally, one can configure the metrics retention time on the agents by configuring
the field `global.metrics.agentMetricsRetentionTime` which expects a duration and defaults to `"1m"`. This value must be greater than `"0m"` for the Consul servers to emit metrics at all. As the Prometheus deployment currently does not support scraping TLS endpoints, agent metrics are currently unsupported when TLS is enabled.

```yaml
global:
  metrics:
    enabled: true
    enableAgentMetrics: true
    agentMetricsRetentionTime: "1m"
```

## Gateway Metrics

Metrics from the Consul ingress, terminating, and mesh gateways can be scraped
with Prometheus by setting the field `global.metrics.enableGatewayMetrics` to `true`. The gateways emit standard Envoy proxy
metrics. To ensure that the metrics are not exposed to the public internet, as mesh and ingress gateways can have public
IPs, their metrics endpoints are exposed on the Pod IP of the respective gateway instance, rather than on all
interfaces on `0.0.0.0`.

```yaml
global:
  metrics:
    enabled: true
    enableGatewayMetrics: true
```

## Metrics in the UI Topology Visualization

Consul's built-in UI has a topology visualization for services that are part of the Consul service mesh. The topology visualization has the ability to fetch basic metrics from a metrics provider for each service and display those metrics as part of the [topology visualization](/consul/docs/observe/telemetry/vm).

The diagram below illustrates how the UI displays service metrics for a sample application:

![UI Topology View](/img/ui-service-topology-view-hover.png)

The topology view is configured under `ui.metrics`. This configuration enables the Consul UI to query the provider specified by
`ui.metrics.provider` at the URL of the Prometheus server `ui.metrics.baseURL`, and then display sidecar proxy metrics for the
service. The UI displays some specific sidecar proxy Prometheus metrics when `ui.metrics.enabled` is `true` and
`ui.enabled` is true. The value of `ui.metrics.enabled` defaults to `"-"` which means it inherits from the value of
`global.metrics.enabled.`

```yaml
ui:
  enabled: true
  metrics:
    enabled: true # by default, this inherits from the value global.metrics.enabled
    provider: "prometheus"
    baseURL: http://prometheus-server
```

## Deploying Prometheus (_for demo and non-production use-cases only_)

The Helm chart contains demo manifests for deploying Prometheus. It can be installed with Helm with `prometheus.enabled`. This manifest is based on the community manifest for Prometheus.
The Prometheus deployment is designed to allow quick bootstrapping for trial and demo use cases, and is not recommended for production use-cases.

Prometheus is be installed in the same namespace as Consul, and gets installed
and uninstalled along with the Consul installation.

Grafana can optionally be utilized with Prometheus to display metrics. The installation and configuration of Grafana must be managed separately from the Consul Helm chart. The [Layer 7 Observability with Prometheus, Grafana, and Kubernetes](/consul/tutorials/kubernetes/kubernetes-layer7-observability) tutorial provides an installation walkthrough using Helm.

```yaml
prometheus:
  enabled: true
```
