Gauges

What Are Gauges?

Gauges capture a series of measurements where each one represents the value under observation at one point in time. The value of a gauge typically varies between some known minimum and maximum. Examples of gauge measurements include the requests/second serviced by an application, the amount of available disk space, the current value of $AAPL, etc.

Properties

Gauges support all of the common metrics properties.

Display Attributes

Gauges support all of the common display attributes in addition to the following:

display_transform

A linear formula that is run on each measurement prior to visualization. Useful for translating between different units (e.g. Fahrenheit -> Celsius) or scales (e.g. Microseconds -> Milliseconds). The formula may only contain: numeric characters, whitespace, parentheses, the letter x, and approved mathematical operators ('+', '-', '*', '/'). The regular expression used is /^[\dx()*+-\/ ]+$/.

The formula is run on each measurement by substituting x with a given measurement's value. Although you could technically circumvent the lack of an exponential operator by multiplying x by itself (e.g. x*x), YOU SHOULD NOT DO THIS. Non-linear functions will not apply correctly against the automatically generated aggregate values meaning any visualization at a resolution other than the raw data stream would be at best garbage and at worst misleading.