Verifying the Configuration

In order to operate, DNS requires information from the named.conf file in the configuration directory. Therefore, the Start method performs some sanity checks to verify that the directory and file are accessible before attempting to start DNS.

The Confdir extension property provides the path to the configuration directory. The property itself is defined in the RTR file. However, the cluster administrator specifies the actual location when the cluster administrator configures the data service.

In the sample data service, the Start method retrieves the location of the configuration directory by using the scha_resource_get() function.

Because Confdir is an extension property, scha_resource_get() returns both the type and value. The awk command retrieves just the value and places that value in a shell variable, CONFIG_DIR.

# find the value of Confdir set by the cluster administrator at the time of
# adding the resource.
config_info=`scha_resource_get -O Extension -R $RESOURCE_NAME \
-G $RESOURCEGROUP_NAME Confdir`

# scha_resource_get returns the "type" as well as the "value" for the
# extension properties. Get only the value of the extension property 
CONFIG_DIR=`echo $config_info | awk '{print $2}'`

The Start method uses the value of CONFIG_DIR to verify that the directory is accessible. If it is not accessible, Start logs an error message and exits with an error status. See Start Exit Status.

# Check if $CONFIG_DIR is accessible.
if [ ! -d $CONFIG_DIR ]; then
   logger -p ${SYSLOG_FACILITY}.err \
         -t [$SYSLOG_TAG] \
         "${ARGV0} Directory $CONFIG_DIR is missing or not mounted"
   exit 1
fi

Before starting the application daemon, this method performs a final check to verify that the named.conf file is present. If the file is not present, Start logs an error message and exits with an error status.

# Change to the $CONFIG_DIR directory in case there are relative
# pathnames in the data files.
cd $CONFIG_DIR

# Check that the named.conf file is present in the $CONFIG_DIR directory
if [ ! -s named.conf ]; then
   logger -p ${SYSLOG_FACILITY}.err \
         -t [$SYSLOG_TAG] \
         "${ARGV0} File $CONFIG_DIR/named.conf is missing or empty"
   exit 1
fi