How to log which node handled a request from httpd?

Environment

• Red Hat Enterprise Linux (RHEL)
• Red Hat Software Collections (RHSCL)
• Red Hat JBoss Core Services (JBCS)
• JBoss Enterprise Web Server (EWS)
• Apache Web Server (HTTPD)
  • mod_cluster
  • mod_proxy
  • mod_jk

Issue

• We use an httpd balancer in front of JBoss. How can we log in the httpd access logs which JBoss node served the request?

Resolution

• You can add the following to your httpd LogFormat for more info on the request routing from mod_cluster and mod_proxy_balancer:
  • %{BALANCER_NAME}e: logs the name of the balancer that served the request
  • %{BALANCER_WORKER_NAME}e: logs the name of the balancer member that served the request
• For mod_jk, include %w in your JkRequestLogFormat or you can log the name of the mod_jk worker used in your httpd access log by including %{JK_WORKER_NAME}n in your httpd LogFormat(s).
  • If using load balancing worker i.e. type=lb, %{JK_WORKER_ROUTE}n can be used in the LogFormat(s) to print the mod_jk worker used in your httpd access log. More details can be referred to Content from tomcat.apache.org is not included.here.

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