This commit mentions the `management.health.probes.enabled`
configuration property in the Kubernetes Probes section of the Actuator
chapter.
Enabling this property is required if we need to expose Kubernetes
Probes in a non-Kubernetes environment.
Fixes gh-21505
This commit removes the support for Reactor Netty metrics since it
seems that Spring Boot should not use this feature:
* HTTP metrics are already covered by WebFlux
* TCP metrics are only meant to TCP server/clients
* allocator metrics are already provided by Netty and there is
no specific API to enable them here.
Closes gh-19388
This commit enables the production of TCP and buffer allocator metrics
for Reactor Netty, client and server.
When applications use auto-configured server
(`NettyReactiveWebServerFactory`) and client (through
`WebClient.Builder`) instances, metrics will be enabled.
Note that HTTP metrics are not enabled here, since similar metrics are
already produced at the WebFlux level. Also, to avoid cardinality
explosion of metrics (through the URI tag), Reactor Netty offers
configurable infrastructure to deduplicate URI tags by turning expanded
URI instances into templated URIs. This is not targeted for Spring
usage.
Closes gh-19388
This commit moves the core Liveness and Readiness support to its own
`availability` package. We've made this a core concept independent of
Kubernetes.
Spring Boot now produces `LivenessStateChanged` and
`ReadinessStateChanged` events as part of the typical application
lifecycle.
Liveness and Readiness Probes (`HealthIndicator` components and health
groups) are still configured only when deployed on Kubernetes.
This commit also improves the documentation around Probes best practices
and container lifecycle considerations.
See gh-19593
Prior to this commit and as of Spring Boot 2.2.0, we would advise
developers to use the Actuator health groups to define custom "liveness"
and "readiness" groups and configure them with subsets of existing
health indicators.
This commit addresses several limitations with that approach.
First, `LivenessState` and `ReadinessState` are promoted to first class
concepts in Spring Boot applications. These states should not only based
on periodic health checks. Applications should be able to track changes
(and adapt their behavior) or update states (when an error happens).
The `ApplicationStateProvider` can be injected and used by applications
components to get the current application state. Components can also
track specific `ApplicationEvent` to be notified of changes, like
`ReadinessStateChangedEvent` and `LivenessStateChangedEvent`.
Components can also publish such events with an
`ApplicationEventPublisher`. Spring Boot will track startup event and
application context state to update the liveness and readiness state of
the application. This infrastructure is available in the
main spring-boot module.
If Spring Boot Actuator is on the classpath, additional
`HealthIndicator` will be contributed to the application:
`"LivenessProveHealthIndicator"` and `"ReadinessProbeHealthIndicator"`.
Also, "liveness" and "readiness" Health groups will be defined if
they're not configured already.
Closes gh-19593
Previously, any HTTP request to an endpoint that included a principal
would bypass the cache. This prevented authenticated requests from
making use of the cache and its configurable time-to-live.
This commit updates the caching operation invoker to include the
principal, if any, in its cache key. As a result, requests that
include a principal will make use of the cache, potentially returning
the result of a previous invocation of the same endpoint by the same
principal.
Closes gh-19538