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5.  Sample Data Service Defining the Resource Type Registration File Resource Properties in the Sample RTR File  Previous   Contents   Next 
   
 

Extension Properties in the RTR File

At the end of the sample RTR file are extension properties, as shown in the following listing

# Extension Properties

# The cluster administrator must set the value of this property to point to the 
# directory that contains the configuration files used by the application. 
# For this application, DNS, specify the path of the DNS configuration file on 
# PXFS (typically named.conf).
{
   PROPERTY = Confdir;
   EXTENSION;
   STRING;
   TUNABLE = AT_CREATION;
   DESCRIPTION = "The Configuration Directory Path";
}

# Time out value in seconds before declaring the probe as failed.
{
        PROPERTY = Probe_timeout;
        EXTENSION;
        INT;
        DEFAULT = 120;
        TUNABLE = ANYTIME;
        DESCRIPTION = "Time out value for the probe (seconds)";
}

The sample RTR file defines two extension properties, Confdir and Probe_timeout. Confdir specifies the path to the DNS configuration directory. This directory contains the in.named file, which DNS requires to operate successfully. The sample data service's Start and Validate methods use this property to verify that the configuration directory and the in.named file are accessible before starting DNS.

When the data service is configured, the Validate method verifies that the new directory is accessible.

The sample data services's PROBE method is not a Sun Cluster callback method but a user-defined method. Therefore, Sun Cluster doesn't provide a Probe_timeout property for it. The developer has defined an extension property in the RTR file to allow a cluster administrator to configure a Probe_timeout value.

Providing Common Functionality to All Methods

This section describes the following functionality that is used in all callback methods of the sample data service:

Identifying the Command Interpreter and Exporting the Path

The first line of a shell script must identify the command interpreter. Each of the method scripts in the sample data service identifies the command interpreter as follows:
#!/bin/ksh

All method scripts in the sample application export the path to the Sun Cluster binaries and libraries rather than rely on the user's PATH settings. 
#######################################################################
# MAIN
#######################################################################

export PATH=/bin:/usr/bin:/usr/cluster/bin:/usr/sbin:/usr/proc/bin:$PATH

Declaring the PMF_TAG and SYSLOG_TAG Variables

All the method scripts (with the exception of Validate) use pmfadm to launch (or stop) either the data service or the monitor, passing the name of the resource. Each script defines a variable, PMF_TAG that can be passed to pmfadm to identify either the data service or the monitor.

Likewise each method script uses the logger command to log messages with the system log. Each script defines a variable, SYSLOG_TAG that can be passed to logger with the -t option to identify the resource type, resource group, and resource name of the resource for which the message is being logged.

All methods define SYSLOG_TAG in the same way, as shown in the following sample. The dns_probe, dns_svc_start, dns_svc_stop, and dns_monitor_check methods define PMF_TAG as follows (the use of pmfadm and logger is from the dns_svc_stop method):

#########################################################################
# MAIN
#########################################################################

PMF_TAG=$RESOURCE_NAME.named

SYSLOG_TAG=$RESOURCETYPE_NAME,$RESOURCEGROUP_NAME,$RESOURCE_NAME

   # Send a SIGTERM signal to the data service and wait for 80% of the
   # total timeout value.
   pmfadm -s $PMF_TAG.named -w $SMOOTH_TIMEOUT TERM
   if [ $? -ne 0 ]; then 
      logger -p ${SYSLOG_FACILITY}.info \
          -t [$SYSLOG_TAG] \
          "${ARGV0} Failed to stop HA-DNS with SIGTERM; Retry with \
           SIGKILL"

The dns_monitor_start, dns_monitor_stop, and dns_update, methods define PMF_TAG as follows (the use of pmfadm is from the dns_monitor_stop method):

#########################################################################
# MAIN
#########################################################################

PMF_TAG=$RESOURCE_NAME.monitor
SYSLOG_TAG=$RESOURCETYPE_NAME,$RESOURCEGROUP_NAME,$RESOURCE_NAME
...

# See if the monitor is running, and if so, kill it. 
if pmfadm -q $PMF_TAG.monitor; then 
   pmfadm -s $PMF_TAG.monitor KILL

Parsing the Function Arguments

The RGM invokes all of the callback methods--with the exception of Validate--as follows. 
method_name -R resource_name -T resource_type_name -G resource_group_name

The method name is the path name of the program that implements the callback method. A data service specifies the path name for each method in the RTR file. These path names are relative to the directory specified by the Rt_basedir property, also in the RTR file. For example, in the sample data service's RTR file, the base directory and method names are specified as follows. 
RT_BASEDIR=/opt/SUNWsample/bin;
START = dns_svc_start;
STOP =  dns_svc_stop;
...

All callback method arguments are passed as flagged values, with -R indicating the name of the resource instance, -T indicating the type of the resource, and -G indicating the group into which the resource is configured. See the rt_callbacks(1HA) man page for more information on callback methods.

Note - The Validate method is called with additional arguments (the property values of the resource and resource group on which it is called). See Handling Property Updates for more information.

Each callback method needs a function to parse the arguments it is passed. Because the callbacks are all passed the same arguments, the data service provides a single parse function that is used in all the callbacks in the application.

The following shows the parse_args() function used for the callback methods in the sample application. 
#########################################################################
# Parse program arguments.
#
function parse_args # [args ...]
{
      typeset opt

      while getopts 'R:G:T:' opt
      do
             case "$opt" in
             R)
                  # Name of the DNS resource.
                  RESOURCE_NAME=$OPTARG
                  ;;
             G)
                  # Name of the resource group in which the resource is
                  # configured.
                  RESOURCEGROUP_NAME=$OPTARG
                  ;;
             T)
                  # Name of the resource type.
                  RESOURCETYPE_NAME=$OPTARG
                  ;;
             *)
                  logger -p ${SYSLOG_FACILITY}.err \
                  -t [$RESOURCETYPE_NAME,$RESOURCEGROUP_NAME,$RESOURCE_NAME] \
                  "ERROR: Option $OPTARG unknown"
                  exit 1
                      ;;
             esac
    done
}

 		 
 
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