SpringBoot MDC 仅作下日志

Question

关于 SpringBoot 应用的小问题，请 MDC 记录。

我有一个非常简单的 SpringBoot 网络处理程序：

  @GetMapping(path = "/mdcOnlyToThisLogPlease")
    public Mono<String> mdcOnlyToThisLogPlease(@RequestBody Book book) {
        MDC.setContextMap(Map.of("bookName", book.getTitle(), "bookAuthor", book.getAuthor()));
        LOGGER.info("I would like to have a log with bookName and bookValue as first level key for the MDC Json log, and only for this log please");
        return bookService.doSomething(book.getTitle(), book.getAuthor());
    }

在这里，我想在 json 中作为一级键登录书名和作者，我想得到这个：

{ 
    @timestamp:  2022-02-22T02:22:22.222Z 
    @version:  1 
    bookName: someName
    bookAuthor: someAuthor
    level:  INFO 
    level_value:  20000 
    logger_name:  MyClass 
    message: I would like to have a log with bookName and bookValue as first level key for the MDC Json log, and only for this log please
    spanId:  e58ad767e34525de 
    thread_name:  reactor-http-epoll-1 
    traceId:  ccf32f0b5d210aa2 
}

我认为这段代码可以做到这一点。不幸的是，它还记录了密钥，对于后面的每一个日志！

例如，我在 bookService.doSomething() 的日志、运行状况检查日志等中也看到了...


{
    @timestamp:  2022-05-02T04:31:30.648Z 
    @version:  1 
    bookName: someName
    bookAuthor: someAuthor
    level:  INFO 
    level_value:  20000 
    logger_name:  reactor.netty.http.server.AccessLog 
    message:  0:0:0:0:0:0:0:1%0 - - [02/May/2022:04:31:30 +0000] "GET /health/readiness HTTP/2.0" 200 5088 19 
    thread_name:  reactor-http-epoll-1 
}

{
    @timestamp:  2022-05-02T04:33:30.648Z 
    @version:  1 
    bookName: someName
    bookAuthor: someAuthor
    level:  INFO 
    level_value:  20000 
    logger_name:  bookService 
    message:  Log from book service. I do not wish to see bookName and bookAuthor as keys
    thread_name:  reactor-http-epoll-1 
}

{ 
    @timestamp:  2022-05-02T04:40:48.742Z 
    @version:  1 
    bookName: someName
    bookAuthor: someAuthor
    level:  INFO 
    level_value:  20000 
    logger_name:  reactor.netty.http.server.AccessLog 
    message:  0:0:0:0:0:0:0:1%0 - - [02/May/2022:04:40:48 +0000] "GET /health/liveness HTTP/2.0" 200 5088 25 
    thread_name:  reactor-http-epoll-1 
}

请问如何添加密钥，但只能用于下一个/一个日志？

谢谢

Answer 1

假设您使用的是 SLF4J MDC-

对于一次单个 key-value 对，MDC 附带 MDCCloseable，这使您可以利用 try-with-resources块：

log.info("This will be logged without myKey, myValue");
try (MDC.MDCCloseable ignored = MDC.putCloseable("myKey", "myValue")) {
    log.info("This will be logged with myKey, myValue");
}
log.info("This will be logged without myKey, myValue");

在此表单中，您在 MDC.putCloseable(...) 中输入的条目将在该块的末尾自动删除。见 Javadocs.

不幸的是，没有类似的方便方法可以一次完成多个条目。可以嵌套多个 try-with-resources/MDC.putCloseable() 块，但这样做会使代码变得混乱。

幸运的是，自己编写并不太难，只需实施 Closeable 并跟踪您输入 MDC 的密钥：

// MDCCloseableMap.java
public class MDCCloseableMap implements Closeable {
    private final Set<String> keys;

    public MDCCloseableMap(Map<String, String> entries) {
        this.keys = Collections.unmodifiableSet(entries.keySet());
        entries.forEach(MDC::put);
    }

    @Override
    public void close() {
        keys.forEach(MDC::remove);
    }
}

然后你可以用同样的方式使用：

log.info("This will be logged without myKeys, myValues");
Map<String, String> myEntries = Map.of("myKey1", "myValue1", "myKey2", "myValue2");
try (MDCCloseableMap ignored = new MDCCloseableMap(myEntries)) {
    log.info("This will be logged with myKeys, myValues");
}
log.info("This will be logged without myKeys, myValues");

SpringBoot MDC 仅作下日志

SpringBoot MDC only for the next log

mdc

spring-boot