How the Validate Method Works
The RGM calls the Validate method when a resource is created and when administrative action updates the properties of the resource or its containing group. The RGM calls Validate before the creation or update is applied, and a failure exit code from the method on any node or zone causes the creation or update to be canceled.
The RGM calls Validate only when resource or resource group properties are changed by the cluster administrator, not when the RGM sets properties or when a monitor sets the resource properties Status and Status_msg.
Note –
The Monitor_check method also explicitly calls the Validate method whenever the PROBE method attempts to fail over the data service to a new node or zone.
What the Validate Method Does
The RGM calls Validate with additional arguments to those that are passed to other methods, including the properties and values that are being updated. Therefore, this method in the sample data service must implement a different parse_args() function to handle the additional arguments.
The Validate method in the sample data service verifies a single property, the Confdir extension property. This property points to the DNS configuration directory, which is critical to the successful operation of DNS.
Note –
Because the configuration directory cannot be changed while DNS is running, the Confdir property is declared in the RTR file as TUNABLE = AT_CREATION. Therefore, the Validate method is never called to verify the Confdir property as the result of an update, but only when the data service resource is being created.
If Confdir is one of the properties that the RGM passes to Validate, the parse_args() function retrieves and saves its value. Validate verifies that the directory pointed to by the new value of Confdir is accessible and that the named.conf file exists in that directory and contains data.
If the parse_args() function cannot retrieve the value of Confdir from the command-line arguments that are passed by the RGM, Validate still attempts to validate the Confdir property. Validate uses scha_resource_get() to obtain the value of Confdir from the static configuration. Validate performs the same checks to verify that the configuration directory is accessible and contains a named.conf file that is not empty.
If Validate exits with failure, the update or creation of all properties, not just Confdir, fails.
Validate Method Parsing Function
Because the RGM passes the Validate method a different set of arguments than the other callback methods, Validate requires a different function for parsing arguments than the other methods. See the rt_callbacks(1HA) man page for more information about the arguments that are passed to Validate and the other callback methods. The following code sample shows the Validate parse_args() function.
#########################################################################
# Parse Validate arguments.
#
function parse_args # [args...]
{
typeset opt
while getopts 'cur:x:g:R:T:G:' 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
;;
r)
# The method is not accessing any system defined
# properties so this is a no-op
;;
g)
# The method is not accessing any resource group
# properties, so this is a no-op
;;
c)
# Indicates the Validate method is being called while
# creating the resource, so this flag is a no-op.
;;
u)
# Indicates the updating of a property when the
# resource already exists. If the update is to the
# Confdir property then Confdir should appear in the
# command-line arguments. If it does not, the method must
# look for it specifically using scha_resource_get.
UPDATE_PROPERTY=1
;;
x)
# Extension property list. Separate the property and
# value pairs using "=" as the separator.
PROPERTY=`echo $OPTARG | awk -F= '{print $1}'`
VAL=`echo $OPTARG | awk -F= '{print $2}'`
# If the Confdir extension property is found on the
# command line, note its value.
if [ $PROPERTY == "Confdir" ]; then
CONFDIR=$VAL
CONFDIR_FOUND=1
fi
;;
*)
logger -p ${SYSLOG_FACILITY}.err \
-t [$SYSLOG_TAG] \
"ERROR: Option $OPTARG unknown"
exit 1
;;
esac
done
}
As with the parse_args() function for other methods, this function provides a flag (R) to capture the resource name, (G) to capture the resource group name, and (T) to capture the resource type that is passed by the RGM.
The r flag (which indicates a system-defined property), g flag (which indicates a resource group property), and the c flag (which indicates that the validation is occurring during creation of the resource) are ignored. They are ignored because this method is being called to validate an extension property when the resource is being updated.
The u flag sets the value of the UPDATE_PROPERTY shell variable to 1 (TRUE). The x flag captures the names and values of the properties that are being updated. If Confdir is one of the properties being updated, its value is placed in the CONFDIR shell variable, and the variable CONFDIR_FOUND is set to 1 (TRUE).
Validating Confdir
In its MAIN function, Validate first sets the CONFDIR variable to the empty string and UPDATE_PROPERTY and CONFDIR_FOUND to 0.
CONFDIR="" UPDATE_PROPERTY=0 CONFDIR_FOUND=0
Validate calls parse_args() to parse the arguments that are passed by the RGM.
parse_args “$@”
Validate checks if Validate is being called as the result of an update of properties. Validate also checks if the Confdir extension property was on the command line. Validate verifies that the Confdir property has a value, and if not, exits with failure status and an error message.
if ( (( $UPDATE_PROPERTY == 1 )) && (( CONFDIR_FOUND == 0 )) ); then
config_info=`scha_resource_get -O Extension -R $RESOURCE_NAME \
-G $RESOURCEGROUP_NAME Confdir`
CONFDIR=`echo $config_info | awk '{print $2}'`
fi
# Verify that the Confdir property has a value. If not there is a failure
# and exit with status 1
if [[ -z $CONFDIR ]]; then
logger -p ${SYSLOG_FACILITY}.err \
"${ARGV0} Validate method for resource "$RESOURCE_NAME " failed"
exit 1
fi
Note –
Specifically, the preceding code checks if Validate is being called as the result of an update ($UPDATE_PROPERTY == 1) and if the property was not found on the command line (CONFDIR_FOUND == 0). In this case, the code retrieves the existing value of Confdir by using scha_resource_get(). If Confdir was found on the command line (CONFDIR_FOUND == 1), the value of CONFDIR comes from the parse_args() function, not from scha_resource_get().
The Validate method uses the value of CONFDIR to verify that the directory is accessible. If the directory is not accessible, Validate logs an error message and exits with error status.
# Check if $CONFDIR is accessible.
if [ ! -d $CONFDIR ]; then
logger -p ${SYSLOG_FACILITY}.err \
-t [$SYSLOG_TAG] \
"${ARGV0} Directory $CONFDIR missing or not mounted"
exit 1
fi
Before validating the update of the Confdir property, Validate performs a final check to verify that the named.conf file is present. If the file is not present, the method logs an error message and exits with error status.
# Check that the named.conf file is present in the Confdir directory
if [ ! -s $CONFDIR/named.conf ]; then
logger -p ${SYSLOG_FACILITY}.err \
-t [$SYSLOG_TAG] \
"${ARGV0} File $CONFDIR/named.conf is missing or empty"
exit 1
fi
If the final check is passed, Validate logs a message that indicates success and exits with success status.
# Log a message indicating that the Validate method was successful.
logger -p ${SYSLOG_FACILITY}.err \
-t [$SYSLOG_TAG] \
"${ARGV0} Validate method for resource "$RESOURCE_NAME \
" completed successfully"
exit 0
Validate Exit Status
If Validate exits with success (0), Confdir is created with the new value. If Validate exits with failure (1), Confdir and any other properties are not created and a message that indicates the reason is generated.
- © 2010, Oracle Corporation and/or its affiliates