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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.

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 Throughput 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.

Environment metadata

The AppSignal agent reports the following information of the host. Once received this metadata is shown on the host metrics index page per host to provide more detail of all hosts running an app. Use this metadata to spot any differences between hosts that could cause differences in behavior.

  • Host architecture, 32 or 64-bit.
  • Operating System, either Linux, macOS or Windows.
  • Operating System Distribution, for Linux this reports Ubuntu, Fedora, etc.
  • Operating System version, the version of the Operating System.
  • Kernel version, for Linux this reports the installed kernel version.

This metadata is collected by default. To disable it, use the send_environment_metadata configuration option, for Ruby.

Heroku support

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

Docker/container support

To use host metrics on (Docker) containers, head to the container host metrics page.

Dokku support

Dokku is very much like Heroku's setup. This is why the AppSignal agent thinks it's running on Heroku. The AppSignal integration turns off host metrics for Heroku automatically, as Heroku doesn't expose runtime metrics for LXC containers. Instead, we recommend using our Logplex drain.

Since Dokku emulates Heroku's environment by setting the DYNO environment variable, host metrics are disabled by default on Dokku as well. To turn them on anyway, you can unset the DYNO environment variable for your app. This will make AppSignal not recognize the system as Heroku.

Please note that unsetting the DYNO environment variable can have other effects on your Dokku system. Please check with Dokku if this is possible with your setup.

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