MetricMessage

A MetricMessage object allows tagging of metrics that are measured and emitted for the page.

MetricMessage objects are dispatched by the page when a handler is registered with page.on(‘metric’). For each metric that is measured and emitted for the page, the k6 browser module delivers a MetricMessage object to the registered handlers, allowing them to pattern match and tag metrics.

tag

The tag method matches the given matches with the current metric’s url and name tags. When a match is found, it will use name to replace the existing URL and name tag values.

Doing this helps group metrics with different URL and name tags that, in fact, reference the same resource, allowing for correlation over time and reducing the cardinality of the metrics.

Parameter	Type	Description
tagMatch	object	The tagMatch object and its properties that are used for matching metrics. Required.
tagMatch.name	string	The name value that replaces the current metric’s URL and name tag values, if a match is found. Required, and must not be an empty string.
tagMatch.matches	object[]	An array of objects containing the matchers which will be used to match against the current metric’s URL and name tags. Required.
tagMatch.matches.url	RegExp	The regular expression used to find matches in the current metric’s URL and name tags. Required.
tagMatch.matches.method	string?	Used to match the metric’s method tag. Valid values are `'GET'`, `'POST'`, `'PUT'`, `'DELETE'`, `'PATCH'`, `'OPTIONS'`, `'HEAD'`, `'TRACE'` and `'CONNECT'`. It’s optional, and when it’s not set it will group all metrics regardless of the method tag.

Example Usage

// First we need to register a handler with `page.on('metric')`.
page.on('metric', (metric) => {
  // It will find a match between the current metric url and name tags against
  // the supplied regular expression in `url`.
  metric.tag({
    // This is the new name value that will replace the existing value in the
    // url and name tags when a match is found.
    name: 'test',
    // You can provide multiple matches here.
    matches: [
      {
        url: /^https:\/\/test\.k6\.io\/\?q=[0-9a-z]+$/,
        // When a method is defined it will also need to match on that too. If a
        // method is not provided it will match on all method types.
        method: 'GET',
      },
    ],
  });
});