The `ServerHttpObservationFilter` implementations record observations
for processed HTTP exchanges. The `Observation.Context` contains various
metadata contributed by the observation convention. The instrumentation
can also mark the observation as an error by setting any `Throwable` on
the context.
Because the instrumentation is done as filters, only exceptions reaching
the filter can be considered. Any error handled at a lower level by the
Framework can, or cannot be considered as an error for an observation.
This commit documents how a web application should opt-in for
considering a handled exception as an error for the current observation.
Closes gh-29848
This commit documents how Observation instrumentation should be
activated for `RestTemplate` and `WebClient`: they both need an
`ObservationRegistry` configured to create and record actual
observations.
This is being done automatically in Spring Boot if auto-configured
builders (`RestTemplateBuilder`, `WebClient.Builder`) are used.
Closes gh-29904
Prior to this commit, the "uri" KeyValue for low cardinality metadata
would contain the entire uri template given to the HTTP client when
creating the request. This was a breaking change for existing metrics
dashboards, as previous support was removing the protocol, host and port
parts of the URI.
Indeed, this information is available in the "client.name" and
"http.uri" KayValue.
This commit parses and removes the protocol+host+port information from
the uri template for the "uri" KeyValue.
Fixes gh-29885
Prior to this commit, the `"client.name"` key value for the
`"http.client.requests"` client HTTP observations would be considered as
high cardinality, as the URI host is technically unbounded.
In practice, the number of hosts used by a client in a given application
can be considered as low cardinality. This commit moves this keyvalue to
low cardinality so that it's present for both metrics and traces.
Closes gh-29839
The block title style previously used was not rendered in HTML and the
title couldn't be differentiated from the text. Though, it was in the
PDF, as italics.
Introducing delimited blocks in the open (`--`) style did introduce
styling, but the vertical alignment isn't great.
This commit turns these block titles to actual (deep) section titles.
In the final HTML, at this depth there is no numbering but bold styling
is there. The PDF rendering has also been verified to have relevant
style.
Closes gh-29694
The link was previously named "Compared to WebFlux", which is easy to
mix up with the various links to equivalent sections in the WebFlux
chapter. Here the links point to a small section comparing the Servlet
Async API to the WebFlux stack from a high perspective.
In this commit we eliminate most of these links, except at the
beginning of the Asynchronous section. We also add a small mention of
the Servlet configuration in the comparison paragraphs, since the
Configuring section is the one furthest from the comparison paragraphs
that used to have a link to it.
Closes gh-29694
- group code example callouts to ensure callouts are displayed for the
correct examples
- add missing callouts
- fix syntax, annotation attribute names, etc.
Sam Brannen
Brian Clozel
Sébastien Deleuze
rstoyanchev
Simon Baslé
IDJack
Sam Brannen
Marten Deinum
Johnny Lim
Yanming Zhou