I have a Spring Boot application with Actuator and Caching running.
When I call
http://localhost:8080/actuator/caches/myCacheName
I only get some basic information about target, name and cacheManager.
But I want to see all entries of this particular cache.
So is it possible to customize this endpoint that it gives me more information?
you can customize current endpoints by extending them. This is an example using the #EndpointWebExtension annotation to extend the standard info actuator endpoint with more functionality.
example is taken from here:
Extend actuator endpoints
Here is springs official documentation about extending endpoints:
Spring extending endpoints
#Component
#EndpointWebExtension(endpoint = InfoEndpoint.class)
public class InfoWebEndpointExtension {
private InfoEndpoint delegate;
// standard constructor
#ReadOperation
public WebEndpointResponse<Map> info() {
Map<String, Object> info = this.delegate.info();
Integer status = getStatus(info);
return new WebEndpointResponse<>(info, status);
}
private Integer getStatus(Map<String, Object> info) {
// return 5xx if this is a snapshot
return 200;
}
}
Related
I'm trying to get some metrics (client lag, ...) from kafka to provide it for consumption by prometheus.
My approach would be to write a simple springboot application which exposes the metrics for prometheus. I understand that kafka provides metrics to all its consumers via the interface MetricsReporter.
So I implemented a class which should do exactly that:
public class MonitoringIntegration implements MetricsReporter {
#Override
public void init(List<KafkaMetric> list) {
System.out.println("init");
for (KafkaMetric kafkaMetric : list) {
System.out.println(kafkaMetric.metricName());
System.out.println(kafkaMetric.metricValue());
}
}
#Override
public void metricChange(KafkaMetric kafkaMetric) {
System.out.println("Metric Change");
System.out.println(kafkaMetric.metricName());
System.out.println(kafkaMetric.metricValue());
}
#Override
public void metricRemoval(KafkaMetric kafkaMetric) {
System.out.println("Removal");
System.out.println(kafkaMetric.metricName());
System.out.println(kafkaMetric.metricValue());
}
#Override
public void close() {
System.out.println("close");
}
#Override
public void configure(Map<String, ?> map) {
System.out.println("Configuring");
System.out.println(map);
}
}
I registered this class with a bean:
#Configuration
public class MetricConfiguration {
#Bean
public ProducerFactory<?, ?> kafkaProducerFactory(KafkaProperties properties) {
Map<String, Object> producerProperties = properties.buildProducerProperties();
producerProperties.put(CommonClientConfigs.METRIC_REPORTER_CLASSES_CONFIG,
MonitoringIntegration.class.getName());
return new DefaultKafkaProducerFactory<>(producerProperties);
}
#Bean
public ConsumerFactory<?, ?> kafkaConsumerFactory(KafkaProperties properties) {
Map<String, Object> consumererProperties = properties.buildConsumerProperties();
consumererProperties.put(CommonClientConfigs.METRIC_REPORTER_CLASSES_CONFIG,
MonitoringIntegration.class.getName());
return new DefaultKafkaConsumerFactory<>(consumererProperties);
}
}
When I start the application some metrics will be printed out to cmd, but they have all default values (0.0, infinite, ..) and they will only be provided once after the application started.
Why am I not getting the metrics? What did I do wrong?
Cheers,
Fabian
Spring Kafka already exposes Kafka metrics as a JMX metrics. You dont need to update/send the metrics to Prometheus. Prometheus server will automatically read from your application's "/prometheus" endpoint. Enable Spring Actuator with Prometheus in your Spring project and configure the Prometheus server to read from it.
Here is a great example using Spring Boot - https://www.callicoder.com/spring-boot-actuator-metrics-monitoring-dashboard-prometheus-grafana/
MetricsReporter is not used to "report" metric values as they change. Check the docs. (For some reason I cant find the latest API).
https://archive.apache.org/dist/kafka/0.8.2-beta/java-doc/org/apache/kafka/common/metrics/MetricsReporter.html
A plugin interface to allow things to listen as new metrics are created so they can be reported.
metricChange() method will only be called when a metric is changed. This is the reason you see the first few outputs during application startup, because the metrics were created.
The consumer metrics support are only available on spring boot 2.1+ versions.
Auto-configuration Support For New Metrics
Metrics coverage has been improved to include:
Hibernate metrics
Spring Frameworkâs WebClient
Kafka consumer metrics
Log4j2 metrics
Jetty server thread pool metrics
Server-side Jersey HTTP request metrics
https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.1-Release-Notes#auto-configuration-support-for-new-metrics
I recommend you to upgrade to newer versions. But if you really need to use Spring Boot prior versions, you can check my kafka metrics micrometer implementation at:
https://github.com/luiztoscano/spring-boot-kmetrics
We customize the Spring Boot Actuator Info endpoint to include the application version number generated during our Jenkins build. We're using gradle to do this:
if (project.hasProperty('BUILD_NUMBER')) {
version = "${BUILD_NUMBER}"
} else {
version = "0.0.1-SNAPSHOT"
}
That works great for adding the version to the /info endpoint, but I'd like to access it when the application starts and print it to the application log.
I'm hoping the values are exposed in some property value (similar to spring.profiles.active) or through a Java API. That way, I could do something like this:
public class MyApplication{
public static void main(String[] args) throws Exception {
SpringApplication.run(MyApplication.class, args);
ConfigurableEnvironment environment = applicationContext.getEnvironment();
System.out.println(environment.getProperty("spring.fancy.path.to.info.version"));
}
}
Looking through the docs, I'm not finding a way to access these values easily in code. Has anyone else had luck with this?
To get exactly the same properties of an actuator endpoint that are exposed through the REST endpoints, you can inject in one of your classes an instance of the respective endpoint class. In your case, the "right" endpoint class would be the InfoEndpoint. There are analogous endpoint classes for metrics, health, etc.
The interface has changed a little between Spring Boot 1.5.x and Spring Boot 2.x. So the exact fully qualified class name or read method name may vary based on the Spring Boot version that you are using. In Boot 1.5.x, you can find most of the endpoints in the org.springframework.boot.actuate.endpoint package.
Roughly, this is how you could build a simple component for reading your version property (assuming that the name of the property inside the info endpoint is simply build.version):
#Component
public class VersionAccessor {
private final InfoEndpoint endpoint;
#Autowired
public VersionAccessor(InfoEndpoint endpoint) {
this.endpoint = endpoint;
}
public String getVersion() {
// Spring Boot 2.x
return String.valueOf(getValueFromMap(endpoint.info()));
// Spring Boot 1.x
return String.valueOf(getValueFromMap(endpoint.invoke()));
}
// the info returned from the endpoint may contain nested maps
// the exact steps for retrieving the right value depends on
// the exact property name(s). Here, we assume that we are
// interested in the build.version property
private Object getValueFromMap(Map<String, Object> info) {
return ((Map<String, Object>) info.get("build")).get("version");
}
}
I have a spring boot app and want to create a Feign client which has a statically defined header value (for auth, but not basic auth). I found the #Headers annotation but it doesn't seem to work in the realm of Spring Boot. My suspicion is this has something to do with it using the SpringMvcContract.
Here's the code I want to work:
#FeignClient(name = "foo", url = "http://localhost:4444/feign")
#Headers({"myHeader:value"})
public interface LocalhostClient {
But it does not add the headers.
I made a clean spring boot app with my attempts and posted to github here: github example
The only way I was able to make it work was to define the RequestInterceptor as a global bean, but I don't want to do that because it would impact other clients.
You can also achieve this by adding header to individual methods as follows:
#RequestMapping(method = RequestMethod.GET, path = "/resource", headers = {"myHeader=value"})
Using #Headers with dynamic values in Feign client + Spring Cloud (Brixton RC2) discusses a solution for dynamic values using #RequestHeader.
You can set a specific configuration class on your feign interface and define a RequestInterceptor bean in there. For example:
#FeignClient(name = "foo", url = "http://localhost:4444/feign",
configuration = FeignConfiguration.class)
public interface LocalhostClient {
}
#Configuration
public class FeignConfiguration {
#Bean
public RequestInterceptor requestTokenBearerInterceptor() {
return new RequestInterceptor() {
#Override
public void apply(RequestTemplate requestTemplate) {
// Do what you want to do
}
};
}
}
You could specify that through the application.yml file:
feign:
client:
config:
default:
defaultRequestHeaders:
Authorization:
- Basic 3ncond2dS3cr2t
otherHeader:
- value
Note that this will be applicable to all your Feign Clients if it happened that you're using more than one. If that's the case, you could add a section per client instead of adding this to the default section.
Try this
#Component
public class AuthFeignInterceptor implements RequestInterceptor {
#Override
public void apply(RequestTemplate template) {
final RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
if (requestAttributes != null) {
final HttpServletRequest httpServletRequest = ((ServletRequestAttributes) requestAttributes).getRequest();
template.header("Header_name","Value");
}
}
}
I have a Spring boot application which uses Feign to call an external web service via Eureka. I'd like to be able to run the application using a mocked out implementation of the Feign interface, so I can run the application locally without necessarily having Eureka or the external web service running. I had imagined defining a run configuration that allowed me to do this, but am struggling to get this working. The issue is that the Spring "magic" is defining a bean for the Feign interface no matter what I try.
Feign interface
#FeignClient(name = "http://foo-service")
public interface FooResource {
#RequestMapping(value = "/doSomething", method = GET)
String getResponse();
}
Service
public class MyService {
private FooResource fooResource;
...
public void getFoo() {
String response = this.fooResource.getResponse();
...
}
}
I tried adding a configuration class that conditionally registered a bean if the Spring profile was "local", but that was never called when I ran the application with that Spring profile:
#Configuration
public class AppConfig {
#Bean
#ConditionalOnProperty(prefix = "spring.profile", name = "active", havingValue="local")
public FooResource fooResource() {
return new FooResource() {
#Override
public String getResponse() {
return "testing";
}
};
}
}
At the point my service runs, the FooResource member variable in MyService is of type
HardCodedTarget(type=FoorResource, url=http://foo-service)
according to IntelliJ. This is the type that is automatically generated by the Spring Cloud Netflix framework, and so tries to actually communicate with the remote service.
Is there a way I can conditionally override the implementation of the Feign interface depending on a configuration setting?
the solution is like below:
public interface FeignBase {
#RequestMapping(value = "/get", method = RequestMethod.POST, headers = "Accept=application/json")
Result get(#RequestBody Token common);
}
then define your env based interface:
#Profile("prod")
#FeignClient(name = "service.name")
public interface Feign1 extends FeignBase
{}
#Profile("!prod")
#FeignClient(name = "service.name", url = "your url")
public interface Feign2 extends FeignBase
{}
finally, in your service impl:
#Resource
private FeignBase feignBase;
Having posted the same question on the Spring Cloud Netflix github repository, a useful answer was to use the Spring #Profile annotation.
I created an alternative entry point class that was not annotated with #EnabledFeignClients, and created a new configuration class that defined implementations for my Feign interfaces. This now allows me to run my application locally without the need to have Eureka running, or any dependent services.
I'm using a simpler solution to avoid having multiples interfaces for a variable parameter like url.
#FeignClient(name = "service.name", url = "${app.feign.clients.url}")
public interface YourClient{}
application-{profile}.properties
app.feign.clients.url=http://localhost:9999
I'm looking to implement a simple reverse proxy with Spring Boot that is:
Easy to add routes
Ability to add custom authentication on a per route basis
Add additional headers as needed
I've looked at the facilities provided by the #EnableZuulProxy annotation but it seems too heavyweight as I don't have a desire to use Eureka, Ribbon, or Hystrix. However, #EnableZuulServer is a bit light on configuration.
Would anyone be able to provide an example of what I'm after? Is Netflix Zuul the right choice for this or is there another library I should be looking at?
Thanks!
Simple Reverse Proxy Server
It's easy to set up a simple proxy reverse using Spring Boot without Ribbon, Eureka, or Hystrix.
Simply annotate your main application class with #EnableZuulProxy and set the following property in your configuration:
ribbon.eureka.enabled=false
Then define your routes in your configuration like such:
zuul.routes.<route_name>.path=<route_path>
zuul.routes.<route_name>.url=http://<url_to_host>/
where <route_name> is an arbitrary name for your route and <route_path> is a path using Ant-style path matching.
So a concrete example would be something like this
zuul.routes.userservice.path=users/**
zuul.routes.userservice.url=http://localhost:9999/
Custom Filters
You can also implement your custom authentication and any additional headers by extending and implementing the ZuulFilter class and adding it as an #Bean to your #Configuration class.
So another concrete example:
public class MyFilter extends ZuulFilter {
#Override
public String filterType() {
// can be pre, route, post, and error
return "pre";
}
#Override
public int filterOrder() {
return 0;
}
#Override
public boolean shouldFilter() {
return true;
}
#Override
public Object run() {
// RequestContext is shared by all ZuulFilters
RequestContext ctx = RequestContext.getCurrentContext();
HttpServletRequest request = ctx.getRequest();
// add custom headers
ctx.addZuulRequestHeader("x-custom-header", "foobar");
// additional custom logic goes here
// return isn't used in current impl, null is fine
return null;
}
}
and then
#Configuration
public class GatewayApplication {
#Bean
public MyFilter myFilter() {
return new myFilter();
}
}
Zuul is a good choice. Am not sure about other alternatives but, we've started building Zuul filters (Pre/Post and Route) that could intercept the request and do all pre/post processing and route based upon your need. It is not mandatory to use the whole bunch of Eureka, Ribbon and Hysterix along with Zuul.