for users to get started. It also makes it more flexible if different
aggregation keys are needed depending on the environment. The most
important new feature is the
spring.metrics.export.redis.aggregateKeyPattern configuration, which
fits the *.redis.key and prefix defaults. The aggregate reader uses
a prefix based on the key by default, with a naming convention that
the key starts with "keys.".
Users can add @ExportMetric[Reader,Writer] to readers and writers that
they want to participate in the default exporter. There is also still an
@ActuatorMetricWriter that is used for the legacy (non-Java8) Gauge and
CounterServices.
The redis export and aggregate use case is a lot nicer with this
shared data between the two component types.
Also made MetricExportProperties itself a Trigger (so the default
delay etc. can be configured via spring.metrics.export.*).
Different physical sources for the same logical metric just need to
publish them with a period-separated prefix, and this reader will
aggregate (by truncating the metric names, dropping the prefix).
Very useful (for instance) if multiple application instances are
feeding to a central (e.g. redis) repository and you want to
display the results. Useful in conjunction with a
MetricReaderPublicMetrics for hooking up to the /metrics endpoint.
This seems pretty efficient (approx 12M write/s as opposed to 2M with
the DefaultCounterService). N.B. there is no need to change most of
the rest of the metrics stuff because metrics are write-often, read-
seldom, so we don't need high performance reads as much.
The Spring Integration configuration and Dropwizard support has changed
a bit. Functionally very similar and probably opaque to users, but now
the messaging operates as an Exporter on a @Scheduled method, and
Dropwizard is a replacement [Gauge,Counter]Service.
Metrics are all
collected live in-memory (and can be very fast with Java 8), buffered
there and shipped out to a MessageChannel (if one exists with id
"metricsChannel") in a background thread.
We can still use Java 8 library APIs (like LongAdder) but to compile
to java 7 compatible byte code we have to forgo the use of lambdas :-(
and shorthand generics (<>).
Fixes gh-2682, fixes gh-2513 (for Java 8 and Dropwizard users).
Update AbstractEndpoint so that the `enable` property is optional and
when it not specified the `endpoints.enabled` property will be used.
This allows users to switch the way that endpoints are enabled. Rather
than opting-out specific endpoint enablement the `endpoints.enabled`
property can be set to `false` and specific endpoints can be opted-in.
Fixes gh-2102
Phillip Webb
Dave Syer
izeye
Stephane Nicoll
Johannes Stelzer
Andy Wilkinson
Marcel Overdijk
StevenGeens
Eric Dahl
John