Set Up Metrics

Sentry metrics help you pinpoint and solve issues that impact user experience and app performance by measuring the data points that are important to you. You can track things like processing time, event size, user signups, and conversion rates, then correlate them back to tracing data in order to get deeper insights and solve issues faster.

First, turn on metrics usage in the SDK as follows:

Sentry.init do |config|
  # ...
  config.metrics.enabled = true

  # release and environment if set will be added to all metrics tags by default, recommended
  config.release = '1.0.0'
  config.environment = 'production'
end

Emit a Counter

Counters are one of the more basic types of metrics and can be used to count certain event occurrences.

To emit a counter, do the following:

# increment a simple counter
Sentry::Metrics.increment('button_click')

# set a value and tags
Sentry::Metrics.increment('button_click', 2, tags: { browser: 'firefox' })

Emit a Distribution

Distributions help you get the most insights from your data by allowing you to obtain aggregations such as p90, min, max, and avg.

To emit a distribution, do the following:

Sentry::Metrics.distribution('page_load', 15.0, unit: 'millisecond', tags: { page: '/home' })

Emit a Set

Sets are useful for looking at unique occurrences and counting the unique elements you added.

To emit a set, do the following:

Sentry::Metrics.set('user_view', 'jane', unit: 'username')

Emit a Gauge

Gauges let you obtain aggregates like min, max, avg, sum, and count. They can be represented in a more space-efficient way than distributions, but they can't be used to get percentiles. If percentiles aren't important to you, we recommend using gauges.

To emit a gauge, do the following:

# Add '15.0' to a gauge used for tracking the loading times for a page.
Sentry::Metrics.gauge('page_load', 15.0, unit: 'millisecond')

Emit a Timer

Timers can be used to measure the execution time of a specific block of code. They're implemented like distributions, but measured in seconds.

To emit a timer, do the following:

# Measure the time of execution of the `process` method in milliseconds.
Sentry::Metrics.timing('how_long_ms', unit: 'millisecond') do
  process
end

Code Locations

By default, the SDK will send code locations for unique metrics (defined by type, key and unit) once a day and with every startup/shutdown of your application. You can turn this off with the following:

Sentry.init do |config|
  # ...
  config.metrics.enable_code_locations = false
end

Filtering and Modifying Tags

You can filter some keys or update tags on the fly with the before_emit callback, which will be triggered before a metric is aggregated.

Sentry.init do |config|
  # ...
  # the 'foo' metric will be filtered and the tags will be updated to add :bar and remove :baz
  config.metrics.before_emit = lambda do |key, tags|
    return nil if key == 'foo'
    tags[:bar] = 42
    tags.delete(:baz)
    true
  end
end