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Host metrics

The AppSignal agent collects various system metrics, which allows you to correlate performance issues and errors to abnormal host metrics. This data is available in the Host metrics section in the app overview, which allows you to inspect and compare multiple hosts. We also show a host metrics overview on the sample detail page for error and performance incidents.

For a preview of how host metrics look in the AppSignal interface, please see our host metrics tour page.

Note: This feature is available in the AppSignal for Ruby gem version 1.2 and newer. It's turned on by default since Ruby gem version 1.3.
Note: This feature available in AppSignal for Elixir package version 0.10.0 and newer. It's turned on by default since Elixir package version 0.10.0.

Note: This feature is not available on the following architectures:

  • macOS/OSX (darwin)
  • FreeBSD
A list of supported Operating Systems is available on the Supported Operating Systems page.

Table of Contents

Collected host metrics

The following host metrics are collected by the AppSignal agent for every minute on your system.

Metric Description
CPU usage User, nice, system, idle and iowait in percentages.
Read more about CPU metrics in our academy article.
Load average 1 minute load average on the host.
Memory usage Available, free and used memory. Also includes swap total and swap used.
Disk usage Percentage of every disk used.
Disk IO tdroughput of data read from and written to every disk.
Network traffic Throughput of data received and transmitted through every network interface.

These host metrics are collected by default. To disable it, use the enable_host_metrics configuration option, for Ruby and Elixir.

Heroku support

To use host metrics on Heroku, head to the Heroku host metrics page.

Docker/container support

Host metrics for containerized systems are fully supported since AppSignal for Ruby gem 2.9 and Elixir package 1.10. All earlier versions are affected by the incorrect container host metrics reported issue.

Warning: For container host metrics to be accurate, limits need to be set for every container. This means, configuring your container to have a limited number of CPUs and memory allocated to it. Without these limits the container reports the maximum possible value of these metrics, resulting in the host reporting Terabytes of available memory for example. A container without swap configured, or unsupported on the host system, will report a 0 value. For more information on how to limit your container's CPU and memory, please read the documentation on:

On systems that expose the /sys/fs virtual file system the following metrics are supported.

Metric Description
CPU usage User and system in percentages.
Read more about CPU metrics in our academy article.
Load average 1 minute load average on the host.
Memory usage Available, free and used memory. Also includes swap total and swap used.
Disk usage Percentage of every disk used.
Disk IO Throughput of data read from and written to every disk.
Network traffic Throughput of data received and transmitted through every network interface.

Note that while Heroku also runs on a containerized system (LXC), we do not support host metrics in the same way. Instead, please see the Heroku support section.

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