健康指标
报告应用及其依赖项的健康状况
健康指标 是 CoddyKit 上的免费 Spring Boot 4 Microservices & REST APIs 课时。 这是第 2 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 Spring Boot 4 Microservices & REST APIs 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Spring Boot 4 Microservices & REST APIs 课程共包含 4 节课。
本课时的部分内容尚未翻译，以英文显示。
The Health Endpoint
The /actuator/health endpoint reports whether the application and its dependencies are functioning. Load balancers and orchestrators poll it to decide if an instance should receive traffic.
GET /actuator/health
{ "status": "UP" }Aggregated Status
Overall health is an aggregate of many health indicators. If any critical indicator reports DOWN, the overall status becomes DOWN. Statuses include UP, DOWN, and OUT_OF_SERVICE.
Built-in Indicators
Boot auto-configures indicators for common dependencies — datasource, disk space, Redis, RabbitMQ, and others — whenever the corresponding starter is present. They contribute to the aggregate automatically.
Showing Health Details
By default details are hidden. Reveal per-component breakdowns with management.endpoint.health.show-details, ideally only to authenticated callers.
management:
endpoint:
health:
show-details: when-authorized
# or: always / neverDetailed Output
With details enabled, the response lists each component’s status and contributed data, making it easy to see which dependency is failing.
{
"status": "UP",
"components": {
"db": { "status": "UP", "details": { "database": "PostgreSQL" } },
"diskSpace": { "status": "UP" }
}
}A Custom HealthIndicator
Implement HealthIndicator to report on a dependency Boot does not cover — say, a downstream API. Return Health.up() or Health.down() with optional details.
@Component
public class PaymentApiHealthIndicator implements HealthIndicator {
private final PaymentClient client;
public PaymentApiHealthIndicator(PaymentClient client) { this.client = client; }
@Override
public Health health() {
return client.ping()
? Health.up().withDetail("latencyMs", client.lastLatency()).build()
: Health.down().withDetail("reason", "ping failed").build();
}
}Indicator Naming
The component name is derived from the bean/class name with the HealthIndicator suffix stripped. PaymentApiHealthIndicator appears as paymentApi in the output.
Liveness and Readiness Probes
In Kubernetes you distinguish liveness (is the app alive?) from readiness (can it serve traffic?). Boot exposes both as health groups when probes are enabled.
management:
endpoint:
health:
probes:
enabled: true
# exposes /actuator/health/liveness and /readinessHealth Groups
Group indicators under a named subset so probes only consider the relevant checks. Readiness might include the database; liveness usually should not, to avoid pod restarts on transient outages.
management:
endpoint:
health:
group:
readiness:
include: db,paymentApiTuning Status to HTTP Codes
Actuator maps health statuses to HTTP codes — UP to 200, DOWN to 503 by default — so infrastructure can act on the response code without parsing the body.
Designing Good Health Checks
Keep checks fast and meaningful:
- Probe real dependencies, not just process liveness
- Avoid heavy work that itself causes failures
- Separate liveness from readiness to prevent restart storms
Quick Check
Test your understanding of custom indicators.
Recap
Health endpoints signal operational status.
/actuator/healthaggregates many indicators- Built-in indicators cover common dependencies
- Implement
HealthIndicatorfor custom checks - Use
show-detailswisely; names strip the suffix - Enable liveness/readiness probes and groups for Kubernetes
常见问题解答
「健康指标」课时是免费的吗？
是的 — 「健康指标」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Spring Boot 4 Microservices & REST APIs 课程的其余内容，请升级到 CoddyKit PRO。 Spring Boot 4 Microservices & REST APIs 课程共包含 4 节课。
「健康指标」这节课中我会学到什么？
报告应用及其依赖项的健康状况 你通过在浏览器中直接运行的动手代码来练习 Spring Boot 4 Microservices & REST APIs，全天候 AI 导师会在你学习这节课的过程中回答你的问题。
学习 Spring Boot 4 Microservices & REST APIs 需要有经验吗？
无需任何先前经验。CoddyKit 上的 Spring Boot 4 Microservices & REST APIs 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 2 节课，共 4 节。
「健康指标」课时需要多长时间？
大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。
我能在这节 Spring Boot 4 Microservices & REST APIs 课中编写并运行代码吗？
能。每节 Spring Boot 4 Microservices & REST APIs 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。