How to log specific HTTP header using logback.xml - logback

Question

I would like to create a console appender that displays some log info, and also prints out a particular http header, similar to this:
> [INFO] { "time": "2017-08-31 12:14:32,583", "app-id": "my-app", "my-header": "my-header-value" } -- "Hello, World"
I have created a logback-spring.xml file like below, but "my-header" just prints out blank.
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<include resource="org/springframework/boot/logging/logback/defaults.xml"/>
<springProperty name="appId" source="spring.app.application_id"/>
<!-- Appender to log to console -->
<appender name="console" class="ch.qos.logback.core.ConsoleAppender">
<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
<!-- Minimum logging level to be presented in the console logs-->
<level>INFO</level>
</filter>
<encoder>
<pattern>
%clr(%5p) %clr({ "time": "%date{ISO8601}", "app-id": "${appId}", "my-header": "%X{my-header}"}){faint} -- %msg%n
</pattern>
<charset>utf8</charset>
</encoder>
</appender>
​
<root level="INFO">
<appender-ref ref="console"/>
</root>
</configuration>
I have read that using logback-access gives you access to HTTP request/response properties, but when I try setting the encoder class I cannot use any of the classic logback conversion words:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<include resource="org/springframework/boot/logging/logback/defaults.xml"/>
<!-- Appender to log to console -->
<appender name="console" class="ch.qos.logback.core.ConsoleAppender">
<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
<!-- Minimum logging level to be presented in the console logs-->
<level>INFO</level>
</filter>
<encoder class="ch.qos.logback.access.PatternLayoutEncoder">
<pattern class="ch.qos.logback.access.PatternLayoutEncoder">
%clr(%5p) %clr({ "time": "%date{ISO8601}", "app-id": "${appId}", "my-header": "%header{my-header}"}){faint} -- %msg%n
</pattern>
<charset>utf8</charset>
</encoder>
</appender>
​
<root level="INFO">
<appender-ref ref="console"/>
</root>
</configuration>
The logback above gives these errors:
[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:1.4.0.RELEASE:run (default-cli) on project pd-thundera-server: An exception occurred while running. null: InvocationTargetException: Logback configuration error detected:
[ERROR] ERROR in ch.qos.logback.core.pattern.parser.Compiler#4782f0a4 - There is no conversion class registered for conversion word [p]
[ERROR] ERROR in ch.qos.logback.core.pattern.parser.Compiler#4782f0a4 - [p] is not a valid conversion word
[ERROR] ERROR in ch.qos.logback.core.pattern.parser.Compiler#6071227e - There is no conversion class registered for conversion word [msg]
[ERROR] ERROR in ch.qos.logback.core.pattern.parser.Compiler#6071227e - [msg] is not a valid conversion word
How can I access a request header?

Answer 1

This configuration worked for me:
<encoder>
<charset>utf-8</charset>
<pattern>%t{yyyy-MM-dd HH:mm:ss,SSS} %h X-Forwarded-For: %header{X-Forwarded-For} "%r", Response status:%s, Bytes sent:%b, Response time:%D</pattern>
</encoder>
Name of the header goes in between curly braces, e.g. %header{Content-type} or %header{My-header}, or just %header if you want all headers to be logged.
Source:
https://logback.qos.ch/access.html#configuration
https://logback.qos.ch/manual/layouts.html#AccessPatternLayout

Answer 2

Please find below example with Spring
If you want to log http headers then you need to use MDC feature: http://logback.qos.ch/manual/mdc.html
create Filter:
#Component
class RequestHeaderFilterConfig : Filter {
private val xRequestId = "X-Request-Id"
override fun doFilter(request: ServletRequest?, response: ServletResponse?, chain: FilterChain?) {
val httpRequest = request as HttpServletRequest
MDC.put(xRequestId, httpRequest.getHeader(xRequestId))
chain?.doFilter(request, response)
}
override fun destroy() = MDC.remove(xRequestId)
}
Controller:
#PostMapping
fun operation(#RequestHeader(value = "X-Request-Id", required = false) xRequestId: String? = null): ResponseEntity<Output> {
....
}
logback.xml
<Pattern>%d{dd-MM-yyyy HH:mm:ss.SSS} [%thread] %-5level [X-Request-Id: %X{X-Request-Id}] %logger{36}.%M:%line - %msg%n</Pattern>