Spring的Retryable或RetryTemplate可以使用Retry-After标头进行动态补偿吗? [英] Can Spring's Retryable or RetryTemplate use Retry-After header for dynamic backoff?

问题描述

我可以使Spring的@Retryable或@RetryTemplate使用HTTP 503服务不可用"响应中的Retry-After标头中接收的数字作为下一次重试迭代的延迟吗?

Can I make Spring's @Retryable or @RetryTemplate use the number received in a Retry-After header in an HTTP 503 "Service Unavailable" response as delay for the next retry iteration?

例如:

@Retryable(maxAttempts = 42,
           backoff = @Backoff(delay = 1000),
           value = NotYetReady.class)
public boolean isExternalComponentReadyToUse() throws NotYetReady {
    ResponseEntity<String> response = callRestEndpointToCheckReadiness();
    if (!response.getStatus().is2xxSuccessful()) {
        int retryAfterInSeconds = response.getHeaders().get("Retry-After");
        // tell @Retryable to run next attempt after retryAfterInSeconds?
        throw new NotYetReady();
    }
    return true;
}

我们的Java应用程序依赖一个外部组件，该组件需要花费几分钟的时间.该组件提供了一个REST端点来检查准备情况.如果端点可以估计剩余的设置将花费多长时间，则端点发送回带有Retry-After标头的503.

Our Java app relies on an external component that takes some minutes to come up. That component provides a REST endpoint to check readiness. The endpoint sends back 503 with a Retry-After header if it can estimate how long the remaining setup will take.

推荐答案

一种方法是将值存储在静态ThreadLocal(例如MyHolder.setDelay(...))中，并在@Backoff()中使用delayExpression检索该值.

One way would be to store the value in a static ThreadLocal (e.g. MyHolder.setDelay(...)) and use delayExpression in the @Backoff() to retrieve that value.

类似于"T(com.foo.MyHolder).getDelay()".

Something like "T(com.foo.MyHolder).getDelay()".

您需要使用自定义的BackoffPolicy将RetryOperationsInterceptor作为@Bean连接起来，并在@Retryable.interceptor属性中引用它.

You would need to wire up a RetryOperationsInterceptor as a @Bean with a custom BackoffPolicy and reference it in the @Retryable.interceptor property.

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