Docker metrics collector plugins

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Metrics Collector Plugins

Docker exposes internal metrics based on the prometheus format. Metrics plugins enable accessing these metrics in a consistent way by providing a Unix socket at a predefined path where the plugin can scrape the metrics.

Note: that while the plugin interface for metrics is non-experimental, the naming of the metrics and metric labels is still considered experimental and may change in a future version.

Creating a metrics plugin

You must currently set PropagatedMount in the plugin config.json to /run/docker. This allows the plugin to receive updated mounts (the bind-mounted socket) from Docker after the plugin is already configured.

MetricsCollector protocol

Metrics plugins must register as implementing theMetricsCollector interface in config.json.

On Unix platforms, the socket is located at /run/docker/metrics.sock in the plugin’s rootfs.

MetricsCollector must implement two endpoints:

MetricsCollector.StartMetrics

Signals to the plugin that the metrics socket is now available for scraping

Request

{}

The request has no playload.

Response

{
	"Err": ""
}

If an error occurred during this request, add an error message to the Err field in the response. If no error then you can either send an empty response ({}) or an empty value for the Err field. Errors will only be logged.

MetricsCollector.StopMetrics

Signals to the plugin that the metrics socket is no longer available. This may happen when the daemon is shutting down.

Request

{}

The request has no playload.

Response

{
	"Err": ""
}

If an error occurred during this request, add an error message to the Err field in the response. If no error then you can either send an empty response ({}) or an empty value for the Err field. Errors will only be logged.

Examples, Usage, plugins, docker, documentation, user guide, metrics