[英]How to correctly use slf4j MDC in spring-webflux WebFilter
我參考了博客文章Contextual Logging with Reactor Context and MDC但我不知道如何在 WebFilter 中訪問反應器上下文。
@Component
public class RequestIdFilter implements WebFilter {
@Override
public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
List<String> myHeader = exchange.getRequest().getHeaders().get("X-My-Header");
if (myHeader != null && !myHeader.isEmpty()) {
MDC.put("myHeader", myHeader.get(0));
}
return chain.filter(exchange);
}
}
你可以做類似下面的事情,你可以用你喜歡的任何類設置context
,在這個例子中,我只使用了標題 - 但自定義類就可以了。 如果您在此處設置它,那么任何帶有處理程序等的日志記錄也將可以訪問context
。
下面的logWithContext
設置 MDC 並在之后清除它。 顯然,這可以用你喜歡的任何東西代替。
public class RequestIdFilter implements WebFilter {
private Logger LOG = LoggerFactory.getLogger(RequestIdFilter.class);
@Override
public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
HttpHeaders headers = exchange.getRequest().getHeaders();
return chain.filter(exchange)
.doAfterSuccessOrError((r, t) -> logWithContext(headers, httpHeaders -> LOG.info("Some message with MDC set")))
.subscriberContext(Context.of(HttpHeaders.class, headers));
}
static void logWithContext(HttpHeaders headers, Consumer<HttpHeaders> logAction) {
try {
headers.forEach((name, values) -> MDC.put(name, values.get(0)));
logAction.accept(headers);
} finally {
headers.keySet().forEach(MDC::remove);
}
}
}
這是一種基於最新方法的解決方案,截至2021 年 5 月,取自官方文檔:
import java.util.List;
import java.util.Optional;
import java.util.UUID;
import java.util.function.Consumer;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.MDC;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.HttpHeaders;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;
import reactor.core.publisher.Signal;
import reactor.util.context.Context;
@Slf4j
@Configuration
public class RequestIdFilter implements WebFilter {
@Override
public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
ServerHttpRequest request = exchange.getRequest();
String requestId = getRequestId(request.getHeaders());
return chain
.filter(exchange)
.doOnEach(logOnEach(r -> log.info("{} {}", request.getMethod(), request.getURI())))
.contextWrite(Context.of("CONTEXT_KEY", requestId));
}
private String getRequestId(HttpHeaders headers) {
List<String> requestIdHeaders = headers.get("X-Request-ID");
return requestIdHeaders == null || requestIdHeaders.isEmpty()
? UUID.randomUUID().toString()
: requestIdHeaders.get(0);
}
public static <T> Consumer<Signal<T>> logOnEach(Consumer<T> logStatement) {
return signal -> {
String contextValue = signal.getContextView().get("CONTEXT_KEY");
try (MDC.MDCCloseable cMdc = MDC.putCloseable("MDC_KEY", contextValue)) {
logStatement.accept(signal.get());
}
};
}
public static <T> Consumer<Signal<T>> logOnNext(Consumer<T> logStatement) {
return signal -> {
if (!signal.isOnNext()) return;
String contextValue = signal.getContextView().get("CONTEXT_KEY");
try (MDC.MDCCloseable cMdc = MDC.putCloseable("MDC_KEY", contextValue)) {
logStatement.accept(signal.get());
}
};
}
}
鑒於您的application.properties
有以下行:
logging.pattern.level=[%X{MDC_KEY}] %5p
那么每次調用端點時,您的服務器日志都會包含這樣的日志:
2021-05-06 17:07:41.852 [60b38305-7005-4a05-bac7-ab2636e74d94] INFO 20158 --- [or-http-epoll-6] my.package.RequestIdFilter : GET http://localhost:12345/my-endpoint/444444/
每次您想在反應式上下文中手動記錄某些內容時,您都必須將以下內容添加到您的反應式鏈中:
.doOnEach(logOnNext(r -> log.info("Something")))
如果您希望將X-Request-ID
傳播到其他服務以進行分布式跟蹤,您需要從響應式上下文(而不是從 MDC)讀取它並使用以下內容包裝您的WebClient
代碼:
Mono.deferContextual(
ctx -> {
RequestHeadersSpec<?> request = webClient.get().uri(uri);
request = request.header("X-Request-ID", ctx.get("CONTEXT_KEY"));
// The rest of your request logic...
});
從 Spring Boot 2.2 開始,有 Schedulers.onScheduleHook 可以讓您處理 MDC:
Schedulers.onScheduleHook("mdc", runnable -> {
Map<String, String> map = MDC.getCopyOfContextMap();
return () -> {
if (map != null) {
MDC.setContextMap(map);
}
try {
runnable.run();
} finally {
MDC.clear();
}
};
});
或者, Hooks.onEachOperator 可用於通過訂閱者上下文傳遞 MDC 值。
http://ttddyy.github.io/mdc-with-webclient-in-webmvc/
這不是完整的 MDC 解決方案,例如,在我的情況下,我無法清除 R2DBC 線程中的 MDC 值。
更新:這篇文章真的解決了我的 MDC 問題: https : //www.novatec-gmbh.de/en/blog/how-can-the-mdc-context-be-used-in-the-reactive-spring-applications/
它提供了基於訂閱者上下文更新 MDC 的正確方法。
將它與由AuthenticationWebFilter
填充的SecurityContext::class.java
鍵結合起來,您將能夠將用戶登錄放入您的日志中。
主要思想是通過以下方式使用Context進行 MDC 傳播:
.contextWrite(context -> Context.of(MDC.getCopyOfContextMap()))
).doFinally(signalType -> MDC.clear())
完成)主要問題是在派生線程中訪問下游上下文。 您可以使用最方便的方法實施第 2 步)。 但這是我的解決方案:
webclient.post()
.bodyValue(someRequestData)
.retrieve()
.bodyToMono(String.class)
// By this action we wrap our response with a new Mono and also
// in parallel fill MDC with values from a downstream Context because
// we have an access to it
.flatMap(wrapWithFilledMDC())
.doOnSuccess(response -> someActionWhichRequiresFilledMdc(response)))
// Fill a downstream context with the current MDC state
.contextWrite(context -> Context.of(MDC.getCopyOfContextMap()))
// Allows us to clear MDC from derived threads
.doFinally(signalType -> MDC.clear())
.block();
// Function which implements second step from the above main idea
public static <T> Function<T, Mono<T>> wrapWithFilledMDC() {
// Using deferContextual we have an access to downstream Context, so
// we can just fill MDC in derived threads with
// values from the downstream Context
return item -> Mono.deferContextual(contextView -> {
// Function for filling MDC with Context values
// (you can apply your action)
fillMdcWithContextView(contextView);
return Mono.just(item);
});
}
public static void fillMdcWithContextValues(ContextView contextView) {
contextView.forEach(
(key, value) -> {
if (key instanceof String keyStr && value instanceof String valueStr) {
MDC.put(keyStr, valueStr);
}
});
}
這種方法也可以應用於 doOnError 和 onErrorResume 方法,因為主要思想是相同的。
使用的版本:
我通過以下方式實現了這一目標:-
package com.nks.app.filter;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.MDC;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;
/**
* @author nks
*/
@Component
@Slf4j
public class SessionIDFilter implements WebFilter {
private static final String APP_SESSION_ID = "app-session-id";
/**
* Process the Web request and (optionally) delegate to the next
* {@code WebFilter} through the given {@link WebFilterChain}.
*
* @param serverWebExchange the current server exchange
* @param webFilterChain provides a way to delegate to the next filter
* @return {@code Mono<Void>} to indicate when request processing is complete
*/
@Override
public Mono<Void> filter(ServerWebExchange serverWebExchange, WebFilterChain webFilterChain) {
serverWebExchange.getResponse()
.getHeaders().add(APP_SESSION_ID, serverWebExchange.getRequest().getHeaders().getFirst(APP_SESSION_ID));
MDC.put(APP_SESSION_ID, serverWebExchange.getRequest().getHeaders().getFirst(APP_SESSION_ID));
log.info("[{}] : Inside filter of SessionIDFilter, ADDED app-session-id in MDC Logs", MDC.get(APP_SESSION_ID));
return webFilterChain.filter(serverWebExchange);
}
}
並且,可以記錄與線程的app-session-id
關聯的值。
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