86 lines
2.4 KiB
Markdown
86 lines
2.4 KiB
Markdown
---
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title: "Docker metrics collector plugins"
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description: "Metrics plugins."
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keywords: "Examples, Usage, plugins, docker, documentation, user guide, metrics"
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---
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<!-- This file is maintained within the docker/cli GitHub
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repository at https://github.com/docker/cli/. Make all
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pull requests against that repo. If you see this file in
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another repository, consider it read-only there, as it will
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periodically be overwritten by the definitive file. Pull
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requests which include edits to this file in other repositories
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will be rejected.
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-->
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# Metrics Collector Plugins
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Docker exposes internal metrics based on the prometheus format. Metrics plugins
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enable accessing these metrics in a consistent way by providing a Unix
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socket at a predefined path where the plugin can scrape the metrics.
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> **Note**: that while the plugin interface for metrics is non-experimental, the naming
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of the metrics and metric labels is still considered experimental and may change
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in a future version.
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## Creating a metrics plugin
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You must currently set `PropagatedMount` in the plugin `config.json` to
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`/run/docker`. This allows the plugin to receive updated mounts
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(the bind-mounted socket) from Docker after the plugin is already configured.
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## MetricsCollector protocol
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Metrics plugins must register as implementing the`MetricsCollector` interface
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in `config.json`.
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On Unix platforms, the socket is located at `/run/docker/metrics.sock` in the
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plugin's rootfs.
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`MetricsCollector` must implement two endpoints:
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### `MetricsCollector.StartMetrics`
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Signals to the plugin that the metrics socket is now available for scraping
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**Request**
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```json
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{}
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```
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The request has no playload.
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**Response**
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```json
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{
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"Err": ""
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}
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```
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If an error occurred during this request, add an error message to the `Err` field
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in the response. If no error then you can either send an empty response (`{}`)
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or an empty value for the `Err` field. Errors will only be logged.
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### `MetricsCollector.StopMetrics`
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Signals to the plugin that the metrics socket is no longer available.
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This may happen when the daemon is shutting down.
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**Request**
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```json
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{}
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```
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The request has no playload.
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**Response**
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```json
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{
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"Err": ""
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}
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```
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If an error occurred during this request, add an error message to the `Err` field
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in the response. If no error then you can either send an empty response (`{}`)
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or an empty value for the `Err` field. Errors will only be logged.
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