Mod-Cluster_node_conf

Version 33

    mod_cluster first spec documentation is mod_jk oriented in the node description  mod-cluster document.

    mod_cluster should be based on mod_proxy and logic to guess the cluster configuration is not needed. Let's going through the worker ajp13 parameter and see what to do.

    The worker parameters are listed on http://tomcat.apache.org/connectors-doc/reference/workers.html only the ajp13-type worker directives make sense for us.

    In bold The parameters will be added to mod_jk existing worker parameters.

     

    General node definition:

    • host that is host of BalancerMember

      http://host:port

       

    • port that is port of BalancerMember

      http://host:port

       

    • type that is the scheme used ajp, http or https. (type already exists in mod_jk but that is not the scheme and only ajp scheme was supported).

    • route that is the JvmRoute. In mod_jk that is the name of the node.

    • socket_timeout  that could be ProxyTimeout or timeout of proxy backend parameters.

    • socket_keepalive  that is keepalive of proxy backend parameters.

     

    pool/opened connection directives.

    The mod_proxy directives are more accurate for mod_cluster than the mod_jk ones:

    • connection_pool_size that is max of proxy backend parameters.

    • connection_pool_minsize that is min of proxy backend parameters.

    • connection_pool_timeout that is ttl of proxy backend parameters

    We will use:

    • min Minumum number of connections that will always be kept open to the backend server.

    • max We probably shouldn't document it because it often causes problems at customer.

    • smax Soft Maximum number of connections will be created on demand. Any connections above smax are subject to a time to ttl.

    • acquire Maximum time to wait for a free connection in the connection pool. If there are no free connections in the pool the httpd will reject the connection.

    • ttl Time To Live for the inactive connections above the smax connections in seconds. httpd will close all connections that have not been used inside that time period.

     

    timeout directives.

    • connect_timeout that is timeout of proxy backend parameters. (Defaut to  ProxyTimeout and then to server TimeOut directive).

    • prepost_timeout that is ping of proxy backend parameter.

    • reply_timeout like connect_timeout.

     

    error handling directives;

    • retries NOT USED.

    • recovery_options NOT USED.

    • fail_on_status NOT USED.

    • recovery_options NOT USED.

    • fail_on_status NOT USED.

     

    Existing mod_proxy code will be changed to allow one retry if ping/pong it will use the next node if ping/pong still fails.

    503 be returned if the request can't be forwarded to any nodes.

     

    packet size definition

    max_packet_size that is iobuffersize of proxy backend parameter.

     

    other directives:

    • max_reply_timeouts NOT USED.

    • secret NOT USED that doesn't increase the security of the connection only SSL would be a safe option.

     

    routing directives:

    • domain The logic has to be added in mod_cluster code (See CONFIG in http://wiki.jboss.org/wiki/Wiki.jsp?page=Mod-Cluster_Management_Protocol)

    • distance NOT USED. The logic in the cluster to calculate load factor the should allow that.

    • redirect that will be the redirect proxy backend parameters (failover node). Even if the logic in the cluster could trigger it via the load factor in a domain that is usefull feature.

    • sticky_session  whether sticky sessions should be used

    • sticky_session_force whether failover should be disallowed once a session is established

    • sticky_id That is the stickysession mod_proxy that allow to change the name of parameter or the cookie containing the sessionid information.