Once enabled, GitLab will automatically detect metrics from known services in the [metric library](#monitoring-cicd-environments). You are also able to [add your own metrics](#adding-additional-metrics-premium) as well.
Prometheus is deployed into the `gitlab-managed-apps` namespace, using the [official Helm chart](https://github.com/kubernetes/charts/tree/master/stable/prometheus). Prometheus is only accessible within the cluster, with GitLab communicating through the [Kubernetes API](https://kubernetes.io/docs/concepts/overview/kubernetes-api/).
The Prometheus server will [automatically detect and monitor](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#%3Ckubernetes_sd_config%3E) nodes, pods, and endpoints. To configure a resource to be monitored by Prometheus, simply set the following [Kubernetes annotations](https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/):
CPU and Memory consumption is monitored, but requires [naming conventions](prometheus_library/kubernetes.html#specifying-the-environment) in order to determine the environment. If you are using [Auto DevOps](../../../topics/autodevops/), this is handled automatically.
The [NGINX Ingress](../clusters/index.md#installing-applications) that is deployed by GitLab to clusters, is automatically annotated for monitoring providing key response metrics: latency, throughput, and error rates.
GitLab will automatically scan the Prometheus server for metrics from known servers like Kubernetes and NGINX, and attempt to identify individual environment. The supported metrics and scan process is detailed in our [Prometheus Metrics Library documentation](prometheus_library/index.md).
> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3799) in [GitLab Premium](https://about.gitlab.com/pricing/) 10.6.
Additional metrics can be monitored by adding them on the Prometheus integration page. Once saved, they will be displayed on the environment performance dashboard.
A few fields are required:
- **Name**: Chart title
- **Type**: Type of metric. Metrics of the same type will be shown together.
- **Y-axis label**: Y axis title to display on the dashboard.
- **Unit label**: Query units, for example `req / sec`. Shown next to the value.
Multiple metrics can be displayed on the same chart if the fields **Name**, **Type**, and **Y-axis label** match between metrics. For example, a metric with **Name**`Requests Rate`, **Type**`Business`, and **Y-axis label**`rec / sec` would display on the same chart as a second metric with the same values. A **Legend label** is suggested if this feature used.
#### Query Variables
GitLab supports a limited set of [CI variables](../../../ci/variables/README.html) in the Prometheus query. This is particularly useful for identifying a specific environment, for example with `CI_ENVIRONMENT_SLUG`. The supported variables are:
- CI_ENVIRONMENT_SLUG
- KUBE_NAMESPACE
To specify a variable in a query, enclose it in curly braces with a leading percent. For example: `%{ci_environment_slug}`.
> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/6590) in [GitLab Ultimate](https://about.gitlab.com/pricing/) 11.2 for [custom metrics](#adding-additional-metrics-premium), and 11.3 for [library metrics](prometheus_library/metrics.md).
For managed Prometheus instances using auto configuration, alerts for metrics [can be configured](#adding-additional-metrics-premium) directly in the performance dashboard.
To set an alert, click on the alarm icon in the top right corner of the metric you want to create the alert for. A dropdown
will appear, with options to set the threshold and operator. Click **Add** to save and activate the alert.
To remove the alert, click back on the alert icon for the desired metric, and click **Delete**.
#### External Prometheus instances
> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/9258) in [GitLab Ultimate](https://about.gitlab.com/pricing/) 11.8.
For manually configured Prometheus servers, a notify endpoint is provided to use with Prometheus webhooks. If you have manual configuration enabled, an **Alerts** section is added to **Settings > Integrations > Prometheus**. This contains the *URL* and *Authorization Key*. The **Reset Key** button will invalidate the key and generate a new one.
To send GitLab alert notifications, copy the *URL* and *Authorization Key* into the [`webhook_configs`](https://prometheus.io/docs/alerting/configuration/#webhook_config) section of your Prometheus Alertmanager configuration:
Once enabled, an issue will be opened automatically when an alert is triggered. The author of the issue will be the GitLab Alert Bot. To further customize the issue, you can add labels, mentions, or any other supported [quick action](../quick_actions.md) in the selected issue template.
If the metric exceeds the threshold of the alert for over 5 minutes, an email will be sent to all [Maintainers and Owners](../../permissions.md#project-members-permissions) of the project.
request workflow. When a source branch has been deployed to an environment, a sparkline and numeric comparison of the average memory consumption will appear. On the sparkline, a dot
performance data displayed before and after. The comparison shows the difference between the 30 minute average before and after the deployment. This information is updated after
