Apache Module mod_log_debug

Available Languages: en | + fr

+ + + + +

Description:	Additional configurable debug logging
Status:	Experimental
Module Identifier:	log_debug_module
Source File:	mod_log_debug.c
Compatibility:	Available in Apache 2.3.14 and later

Topics

Examples

Directives

LogMessage

Bugfix checklist

Examples

+ +

+ Log message after request to /foo/* is processed: + +

<Location "/foo/">
+  LogMessage "/foo/ has been requested"
+</Location>

+ +

+ Log message if request to /foo/* is processed in a sub-request: +
```
<Location "/foo/">
+  LogMessage "subrequest to /foo/" hook=type_checker "expr=-T %{IS_SUBREQ}"
+</Location>
```
+ + + The default log_transaction hook is not executed for sub-requests, + therefore we have to use a different hook. +
+ Log message if an IPv6 client causes a request timeout: +
```
LogMessage "IPv6 timeout from %{REMOTE_ADDR}" "expr=-T %{IPV6} && %{REQUEST_STATUS} = 408"
```
+ + Note the placing of the double quotes for the expr= argument. +
+ Log the value of the "X-Foo" request environment variable in each + stage of the request: +
```
<Location "/">
+  LogMessage "%{reqenv:X-Foo}" hook=all
+</Location>
```
+ + Together with microsecond time stamps in the error log, + hook=all also lets you determine the times spent + in the different parts of the request processing. +

LogMessage Directive

+ + + + + + + +

Description:	Log user-defined message to error log +
Syntax:	`LogMessage message +[hook=hook] [expr=expression] +`
Default:	`Unset`
Context:	directory
Status:	Experimental
Module:	mod_log_debug

This directive causes a user defined message to be logged to the + error log. The message can use variables and functions from the + ap_expr syntax. References to HTTP headers + will not cause header names to be added to the Vary header. The + messages are logged at loglevel info.

+ +

The hook specifies before which phase of request processing the message + will be logged. The following hooks are supported:

+ + + + + + + + + + + + + + +

Name
`translate_name`
`type_checker`
`quick_handler`
`map_to_storage`
`check_access`
`check_access_ex`
`insert_filter`
`check_authn`
`check_authz`
`fixups`
`handler`
`log_transaction`

+ +

The default is log_transaction. The special value + all is also supported, causing a message to be logged at each + phase. Not all hooks are executed for every request.

+ +

The optional expression allows to restrict the message if a + condition is met. The details of the expression syntax are described in + the ap_expr documentation. References to HTTP + headers will not cause the header names to be added to the Vary header.

+ + +