Configure HTTP Access Logging in WSO2 products

If you want to analyze your application's usage activities such as who is accessing your page, number of hits, errors ect, you can use the HTTP access log files monitor and analyze the above measures. WSO2 products uses embedded tomcat as it's primary runtime therefore, you can use apache tomcat access logger to monitor your activity and performance of the server as well as any errors that may be occurring. This post explain how you can configure HTTP access logging in WSO2 products in order to get efficient monitoring.

In WSO2 products you can customize the http access log configuration by editing the catalina-server.xml which is located {CARBON_HOME}/repository/conf/tomcat directory, which is the server descripter file for the embedded tomcat integration. In the catalina-server.xml, under valves you have the HTTP access log configuration as shown below

<Valve className="org.apache.catalina.valves.AccessLogValve" directory="${carbon.home}/repository/logs"

               prefix="http_access_" suffix=".log"

               pattern="combined" />

The server access log records all requests processed by the server. You can modify the what to log and what not to log by customizing the pattern attribute.

In the pattern attribute we can define formatting layouts. A formatting layout identifying the various information fields from the request and response to be logged, or the word "common" or "combined" to select a standard format.

Values for the pattern attribute are made up of literal text strings, combined with pattern identifiers prefixed by the "%" character to cause replacement by the corresponding variable value from the current request and response. The following pattern codes are supported:

%a - Remote IP address

%A - Local IP address

%b - Bytes sent, excluding HTTP headers, or '-' if no bytes were sent

%B - Bytes sent, excluding HTTP headers

%h - Remote host name

%H - Request protocol

%l - Remote logical username from identd (always returns '-')

%m - Request method

%p - Local port

%q - Query string (prepended with a '?' if it exists, otherwise an empty string

%r - First line of the request

%s - HTTP status code of the response

%S - User session ID

%t - Date and time, in Common Log Format format

%u - Remote user that was authenticated

%U - Requested URL path

%v - Local server name

%D - Time taken to process the request, in millis

%T - Time taken to process the request, in seconds

%I - current request thread name (can compare later with stacktraces) 

In addition, the caller can specify one of the following aliases for commonly utilized patterns:

common - %h %l %u %t "%r" %s %b

combined - %h %l %u %t "%r" %s %b "%{Referer}i" "%{User-Agent}i"

Please note that the optimized access does only support common and combined as the value for this attribute.

If you want to change the format you can modify the as shown below

 <Valve className="org.apache.catalina.valves.AccessLogValve" directory="${carbon.home}/repository/logs"

               prefix="http_access_" suffix=".log"

               pattern="%h %l %u %t '%r' %s %b" />

You can further change the log file location by changing the directory, prefix is the name of the log file. By default logs are rotated daily and the date is appended to the log file name. However, you can disable the log rotation by adding the following attribute rotatable="false". If you want to not have the current date appended in the log file name however, need the date to the rotated log file you can add renameOnRotate="true" attribute the the valve configuration. Please refer Access Log Valve Attributes for the full list of supported attributes.