We can write groovy applications and they don’t require any conventional Java project structure, imports, or even compilation.
// app.groovy
@RestController
class HelloController{
@GetMapping("/")
String hello(){
return "Hello Groovy!";
}
}
// run with: $ spring run app.groovy
Spring Boot CLI has removed the run command. How to run Groovy scripts effortlessy as it used to be done like above remains unanswered. Ref
Used to: Monitor and view internals of the Spring Boot application in runtime, we can control it too (like /shutdown).
Use below dependency to use actuator:
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
</dependencies>
Endpoints are exposed at: localhost:8080/actuator/<endpoint_name>. By default only the /health endpoint is exposed.
You can enable or disable each individual endpoint and expose them (make them remotely accessible) over HTTP or JMX. An endpoint is accessible only when it is both enabled and exposed.
/beans -> shows all beans' dependencies, scope, type
/autoconfig -> all autoconfigs done by Spring Boot
/metrics -> applications metrics like memory, heap, threads
/health -> "UP" status and diskSpace
/info
/shutdown
We can send our own definined information on the /info endpoint. Specify info using properties.
info.name.first=Abhishek
info.name.last=Arya
info.address=India
management.info.env.enabled=true
// hit /info with GET and we get the following JSON
{
"name": {
"first": "Abhishek",
"last": "Arya"
},
"address": "India"
}
It’s disabed by default since it can kill the app. Enable it by property as follows:
management.endpoint.shutdown.enabled=true
Hit with POST and it gives response back. This is the only endpoint with POST, all are GET otherwise.
// request - POST http://localhost:8080/shutdown
// response
{
"message": "Shutting down, bye..."
}
By default, all endpoints except /shutdown are enabled. We can often disable all (1) and enable only the ones we need (2).
management.endpoint.<endpoint_id>.enabled=false
(1)
management.endpoints.enabled-by-default=false
(2)
management.endpoint.info.enabled=true
Here endpoint_id is nothing but name of the endpoint like health, shutdown, etc…
expose only health and info:
management.endpoints.web.exposure.include=health,info
expose all:
management.endpoints.web.exposure.include=*
exclude env and beans:
management.endpoints.web.exposure.exclude=env,beans
Only the /health endpoint is exposed by default.
We can change /actuator base path to anything we like /foobar.
management.endpoints.web.base-path=/foobar
We can change endpoint_id, toggle sensitivity, secure endpoints with authentication.
We can write custom health indicators, or an entire custom endpoint.
References: