Mask value of stacktrace does not work as expected

[nilsmagnus]

Describe the bug
I expected the valueMask to mask the string in the stacktrace as well as the message. It does not.

To Reproduce

Steps to reproduce the behavior:

1. Use this logback.xml configuration

<configuration>
  <appender name="json" class="ch.qos.logback.core.ConsoleAppender">
    <encoder class="net.logstash.logback.encoder.LogstashEncoder">
      <jsonGeneratorDecorator class="net.logstash.logback.mask.MaskingJsonGeneratorDecorator">
        <!---  apikey=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxx1234f)  -->

        <valueMask>
          <value>(.*apikey=)(.{36})(.*)</value>
          <mask>$1***$3</mask>
        </valueMask>
      </jsonGeneratorDecorator>

    </encoder>
  </appender>

  <root level="info">
    <appender-ref ref="json" />
  </root>
</configuration>

2. Execute this logger statement log.error("message key is apikey=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxx1234f", new RuntimeException("stacktrace key is apikey=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxx1234f"));
3. The output for the stacktrace is not masked, but the message is:

{"@timestamp":"2021-09-10T12:31:27.400+02:00","@version":"1","message":"message key is apikey=***","logger_name":"com.example.Main","thread_name":"main","level":"ERROR","level_value":40000,"stack_trace":"java.lang.RuntimeException: stacktrace key is apikey=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxx1234f\n\tat com.example.MainKt.main(Main.kt:45)\n\tat com.example.MainKt.main(Main.kt)\n"}

Expected behavior
The output for the stack_trace should not contain the apikey.

Additional context

• logstash-logback-encoder 6.6
• logback 1.2.5
• jackson 2.12.2
• java 15

[brenuart]

Hi Nils. Thanks for the report.

I think your issue is related to #400, and the comment #400 (comment) in particular.

The good news is I could reproduce your issue following your instructions with 6.6 but not with the current development version (7.0-SNAPSHOT) anymore. In the meantime I'm afraid your only option is to write a custom ValueMasker yourself like this:

public class StackTraceValueMasker implements ValueMasker {
    @Override
    public Object mask(JsonStreamContext context, Object value) {
        if ("stack_trace".equals(context.getCurrentName()) {
            return <masked value>;
        }
        else {
            return value;
        }
    }
}

and register it in your configuration as follows:

<jsonGeneratorDecorator class="net.logstash.logback.mask.MaskingJsonGeneratorDecorator">
    ...
    <valueMasker class="....StackTraceValueMasker"/>
</jsonGeneratorDecorator>

[nilsmagnus]

Ok, that solution is ok for me. Closing this issue and waiting for the 7.0 release 👍

[brenuart]

@nilsmagnus 7.0 shouldn't be too long now... stay tuned ;-)