https://github.com/Netflix/runtime-health
https://github.com/Netflix/runtime-health
Last synced: about 2 months ago
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- Host: GitHub
- URL: https://github.com/Netflix/runtime-health
- Owner: Netflix
- License: apache-2.0
- Archived: true
- Created: 2016-02-03T00:03:45.000Z (almost 10 years ago)
- Default Branch: master
- Last Pushed: 2024-12-10T21:05:09.000Z (about 1 year ago)
- Last Synced: 2025-07-01T23:36:24.616Z (6 months ago)
- Language: Java
- Size: 243 KB
- Stars: 46
- Watchers: 372
- Forks: 23
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-java - Health Check
README
Health check
----------------
Instance health is an important aspect of any cloud ready application. It is used for service discovery as well as bad instance termination. Through HealthCheck API an application can expose a REST endpoint for external monitoring to ping for health status or integrate with Eureka for service discovery registration based on instance health state. An instance can be in one of 2 lifecycle states: Healthy and Unhealthy.
The HealthCheck API is broken up into two abstractions to allow for maximum customization.
* HealthIndicator - boolean health indicator for a specific application features/aspect. For example, CPU usage.
* HealthCheckAggregator - combines indicators to derive a meaningful health state. Responsible caching of HealthIndicators, basic error handling and HealthIndicator timeouts. Also enriches Health information with details such as the indicator name and whether or not a Health entry was cached.
### Artifacts
Runtime-health is published as the following artifacts:
```
# api package for libraries
com.netflix.runtime:health-api
# core implementation of runtime-health for applications and services
com.netflix.runtime:health-core
# guice integration with module HealthModule() and netflix archaius2 integration for configuration
com.netflix.runtime:health-guice
# integration with netflix eureka and bridging of health state and eureka status
com.netflix.runtime:health-integrations
```
### Using HealthCheck in a Jersey resource
```java
@Path("/health")
public class HealthCheckResource {
@Inject
public HealthCheckResource(HealthCheckAggregator healthCheck) {
this.healthCheck = healthCheck;
}
@GET
public HealthCheckStatus doCheck() {
return healthCheck.check().get();
}
}
```
### Custom health check
To create a custom health indicator simply implement HealthIndicator, inject any objects that are needed to determine the health state, and implement you logic in check(). Note that check returns a future so that the healthcheck system can implement a timeout. The check() implementation is therefore expected to be well behaved and NOT block.
```java
public class MyHealthIndicator implements HealthIndicator {
@Inject
public MyHealthIndicator(MyService service) {
this.service = service;
}
@Override
public void check(HealthIndicatorCallback healthCallback) {
if (service.getErrorRate() > 0.1) {
healthCallback.inform(Health.unhealthy().withDetails("errorRate", service.getErrorRate()));
}
else {
healthCallback.inform(Health.healthy());
}
}
}
```
To register a HealthIndicator simply provide it when installing HealthModule. It will automatically be picked up by the default HealthCheckAggregator
```java
InjectorBuilder.fromModules(new HealthModule() {
protected void configureHealth() {
bindAdditionalHealthIndicator().to(MyHealthIndicator.class);
bindAdditionalHealthIndicator().to(AnotherHealthIndicator.class); //e.g. if you have a second indicator defined
}
}).createInjector()
```
### Additional Integrations
See [health-integrations](https://github.com/Netflix/runtime-health/tree/master/health-integrations) for additional integrations (e.g. with eureka)