# Working with Prometheus Metrics

The Sysdig agent uses its visibility to all running processes (at both the host and container levels) to find eligible targets for scraping Prometheus metrics. By default, no scraping is attempted. Once the feature is enabled, the agent assembles a list of eligible targets, apply filtering rules, and sends back to the Sysdig collector.

## Prometheus Features Introduced in Agent v10.0.0

Sysdig agents v10.0 or above is required for the following capabilities:

• New capabilities of using Prometheus data:

• Ability to visualize data using PromQL queries. See Using PromQL.

• Backward compatibility for dashboards v2 and alerts.

### Note

The new PromQL data cannot be visualized by using the Dashboard v2 Histogram. Use time-series based visualization for the histogram metrics.

• New metrics limit per agent:

• Custom metrics: 10,000

This is in addition to the agent metrics that we provide out-of-the-box, such as host, container, and Kube State Metrics.

• Prometheus metrics: 8000

• StatsD metrics: 1000

• JMX metrics: 500

• AppChecks: 500

• 10-second data granularity

• Higher retention rate on the new metric store.

• New metrics naming convention:

• The legacy Prometheus metrics are available with the prefix promlegacy. The naming convention is promlegacy.<metrics> . For example, cortex_build_info is renamed as promlegacy.cortex_build_info.

## Prerequisites and Guidelines

• Sysdig agent v 10.0.0 and above is required for the latest Prometheus features.

• Prometheus feature is enabled in the dragent.yaml file.

prometheus:
enabled: true

• The endpoints of the target should be available on a TCP connection to the agent. The agent scrapes a target, remote or local, specified by the IP: Port or the URL in dragent.yaml.

## Service Discovery

To use native Prometheus service discovery, enable promscrape.v2 as described in Enable Prometheus Native Service Discovery. This section covers the Sysdig way of service discovery that involves configuring process filters in the Sysdig agent.

The way service discovery works in the Sysdig agent differs from that of the Prometheus server. While the Prometheus server has built-in integration with several service discovery mechanisms and the prometheus.yml file to read the configuration settings from, the Sysdig agent auto-discovers any process (exporter or instrumented) that matches the specifications in the dragent.yaml, file and instructs the embedded lightweight Prometheus server to retrieve the metrics from it.

The lightweight Prometheus server in the agent is named promscrape and is controlled by the flag of the same name in the dragent.yaml file. See Configuring Sysdig Agent for more information.

Unlike the Prometheus server that can scrape processes running on all the machines in a cluster, the agent can scrape only those processes that are running on the host that it is installed on.

Within the set of eligible processes/ports/endpoints, the agent scrapes only the ports that are exporting Prometheus metrics and will stop attempting to scrape or retry on ports based on how they respond to attempts to connect and scrape them. It is therefore strongly recommended that you create a configuration that restricts the process and ports for attempted scraping to the minimum expected range for your exporters. This minimizes the potential for unintended side-effects in both the Agent and your applications due to repeated failed connection attempts.

The end to end metric collection can be summarized as follows:

1. A process is determined to be eligible for possible scraping if it positively matches against a series of Process Filter include/exclude rules. See Process Filter for more information.

2. The Agent will then attempt to scrape an eligible process at a /metrics endpoint on all of its listening TCP ports unless the additional configuration is present to restrict scraping to a subset of ports and/or another endpoint name.

3. As of agent v9.8.0, filtering metrics at ingestion can be enabled. If enabled, filtering rules are applied at ingestion as it receives the metrics. See Filtering Prometheus Metrics for more information.

4. Upon receiving the metrics, the agent applies the following rules before sending them to the Sysdig collector.

• Applies the global metrics_filter rules.

• Imposes the configured max_metrics to limit the number of metrics.

The metrics ultimately appear in the Sysdig Monitor Explore interface in the Prometheus section.