Spring REST using Jackson - 400 bad request logging

Question

I have spring REST set up fine using Jackson/JSON and everything works.

But I knowingly introduced an error in the structure of the message which resulted in a 400 - Bad Request. But there was no log output on the server. The error I would be expecting would be something like "Jackson unknown property exception" or whatever but it was caught and a 400 error was sent to the client, but no log of the exception on the server.

I don't want to debug everything on the server clearly, but I want Spring network level exceptions like this clearly labelled as error.

What is the correct way to switch this on?

Thanks!

Answer 1

@ExceptionHandler
@ResponseStatus(HttpStatus.BAD_REQUEST)
public void handle(HttpMessageNotReadableException e) {
    logger.warn("Returning HTTP 400 Bad Request", e);
}

Answer 2

Building on @Jukka's answer, you can enable this globally for all controllers using @ControllerAdvice (introduced in Spring 3.2). It does require a little code on your end, but in my experience you usually end up needing a global error handling configuration anyways and this allows you to set breakpoints / easily inspect the problems.

An example of this is below:

@ControllerAdvice
public class ControllerConfig {

    @ExceptionHandler
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    public void handle(HttpMessageNotReadableException e) {
        log.warn("Returning HTTP 400 Bad Request", e);
        throw e;
    }
}

Answer 3

In case anyone else stumbles on this issue, the following worked for me in Spring Boot 2 / Spring 5 and didn't require a code change.

I set the log level for org.springframework.web.servlet.mvc.method.annotation to DEBUG. In my case I was seeing 400 responses in my client code but no logging on the server side (even with a custom error handler). After changing that log level the problem was obvious:

DEBUG 172.19.0.16     cs              2018-Jun-08 20:55:08.415 [https-jsse-nio-443-exec-9] - method.annotation.RequestResponseBodyMethodProcessor[line ?] - Read [class java.lang.String] as "application/xml;charset=UTF-8" with [org.springframework.http.converter.xml.MarshallingHttpMessageConverter@2de50ee4]
DEBUG 172.19.0.16     cs              2018-Jun-08 20:55:08.418 [https-jsse-nio-443-exec-9] - method.annotation.ServletInvocableHandlerMethod[line ?] - Failed to resolve argument 0 of type 'java.lang.String'
org.springframework.beans.TypeMismatchException: Failed to convert value of type 'core.dto.RequestDTO' to required type 'java.lang.String'

Answer 4

You can set the log level to debug for this property in application.properties.

logging.level.org.springframework.web= DEBUG