prometheus-client 1.0.0

Version 1.0.0 is a significant rewrite of some core parts of the API, as prometheus-effect has been deprecated in favour of this library.

Breaking Changes

New Metric API

The most substatial change regards the Metric interface. Unregistered counters are now wrapped in the Metric type (as before), but when registered, the Metric wrapper is removed. This change means that registered metrics are more lightweight (they are often just a newtype wrapper), but also helps users
distinguish between registered and unregistered metrics.

To adapt to this change, users should:

• Store and pass registered metrics. Rather than passing Metric Counter, prefer registering to obtain a Counter and pass that around.

• Top level registrations will no longer return Metric. If you have

  httpRequests :: Metric Counter
  httpRequests = unsafeRegisterIO $ counter (Info ...)

  This should change to

  httpRequests :: Counter
  httpRequests = unsafeRegister $ counter (Info ...)

Other Breaking Changes

• Prometheus.exportMetricsAsText now returns a lazy ByteString rather than a strict ByteString. This provides better streaming performance, and the underlying ByteString is built using a Builder for improved performance. You can convert the lazy ByteString into a strict one using Data.ByteString.Lazy.toStrict, but you should consider taking advantage of the lazy interface if possible.

• Prometheus.Info now uses Text instead of String. It is recommended that you use the OverloadedStrings extension.

• The label interface has been changed to only support tuples of Text. The tuple instances prevent any other tuple instances from being defined. This interface is in flux and may change again in the future. For now, OverloadedStrings will give you compatibility with the old interface.

Backwards Compatible Changes

• Many functions that were specialised to IO have been generalised to work in MonadIO.

Additions

• Prometheus.countExceptions to count the amount of exceptions a given monadic action throws.