RCMSCRIPT(5) File Formats and Configurations RCMSCRIPT(5)
NAME
rcmscript - script interface specification for the Reconfiguration
and Coordination Manager
SYNOPSIS
rcm_scriptname scriptinfo
rcm_scriptname register
rcm_scriptname resourceinfo
resourcename rcm_scriptname queryremove
resourcename rcm_scriptname preremove
resourcename rcm_scriptname postremove
resourcename rcm_scriptname undoremove
resourcenameDESCRIPTION
Reconfiguration and Coordination Manager (RCM) is a framework
designed to coordinate device consumers during Solaris Dynamic
Reconfiguration (DR). The interfaces specified in this man page allow
device consumers, such as application vendors or site administrators,
to act before and after DR operations take place by providing RCM
scripts. You can write your own RCM scripts to shut down your
applications, or to cleanly release the devices from your
applications during dynamic remove operations.
An RCM script is an executable perl script, a shell script or a
binary. Perl is the recommended language. Each script is run in its
own address space using the user-id of the script file owner.
An RCM script is invoked on demand in response to DR as follows:
<scriptname> <command> [
args ...]
Every script must implement the following RCM commands:
scriptinfo Get script information.
register Register devices the script handles.
resourceinfo Get resource information.
A script might include some or all the of the following commands:
queryremove Queries whether the resource can be released.
preremove Releases the resource.
postremove Provides post-resource removal notification.
undoremove Undo the actions done in preremove.
When a script's
register command is run, the script should supply, in
return data, all resource names the script or its application handles
that could potentially be removed by DR. A resource name refers to a
name in
/dev path name.
Below is a high-level overview of the sequence of script invocations
that occurs when dynamic removal of a script's registered resource is
attempted. See the COMMANDS section for a detailed description of the
commands.
1. Prior to removing the resource from the system during DR,
the script's
queryremove command is run:
<scriptname> queryremove
<resourcename> The script should check for obvious reasons why the
resource can not be removed from the perspective of its
service or application.
2. If the script indicates that the resource can be removed
in the
queryremove command. The script's
preremove command
is run:
<scriptname> preremove
<resourcename> The script releases the resource from the service or
application represented by the script and prepares for the
resource removal. Releasing the resource includes closing
the resource if the resource is currently opened by its
application.
3. The system then proceeds to remove the resource.
4. If the system has removed the resource successfully the
script's
postremove command is run:
<scriptname> postremove
<resourcename> Otherwise the script's
undoremove command is run:
<scriptname> undoremove
<resourcename> For any commands the script does not implement, it must exit with
exit status of 2. RCM silently returns success for the script's
unimplemented commands.
A script performs the following basic steps:
o Takes RCM command and additional arguments from the
command line and environment parameters.
o Processes the command.
o Writes the expected return data to stdout as
name=value pairs delimited by newlines, where
name is the name of the
return data item that RCM expects and
value is the value
associated with the data item.
Environment
The initial environment of RCM scripts is set as follows:
o Process UID is set to the UID of the script.
o Process GID is set to the GID of the script.
o
PATH variable is set to
/usr/sbin:/usr/bin.
o Current working directory is set to:
o
/var/run for scripts owned by root
o
/tmp for scripts not owned by root
o File descriptor 0 (stdin) is set to
/dev/null o Environment variable
RCM_ENV_DEBUG_LEVEL is set to the
debug level. Logging is discussed below.
o
The following environment variables are also set where
possible:
o
LANG o
LC_COLLATE o
LC_CTYPE o
LC_MESSAGES o
LC_MONETARY o
LC_NUMERIC o
LC_TIME o
LC_ALL o
TZ See
environ(7) for a description of these variables. See
gettext(1) for details on retrieving localized messages.
All environment variable names beginning with
RCM_ENV_ are reserved
for use by the RCM.
The character encoding used by the RCM and RCM scripts to exchange
RCM commands, environment parameters, and name-value pairs is ASCII
unless the controlling environment variables are specified otherwise.
Commands
scriptinfo The
scriptinfo command is invoked to gather information about the
script.
Return data: If successful, the script must write the following
name-value pairs to stdout and exit with status 0:
o
rcm_script_version=1 o
rcm_script_func_info=script_func_info o
rcm_cmd_timeout=command_timeout_value where
script_func_info is a localized human-readable
message describing the functionality of the script.
The RCM monitors the execution time of RCM commands
by RCM scripts.
command_timeout_value is the maximum
time in seconds the script is expected to take to
process any RCM command except the
scriptinfo command
itself. If an RCM script does not process the RCM
command and exit within this time, RCM sends a
SIGABRT signal to the script process. RCM then waits
for a few seconds for the script to finish the
processing of the current RCM command and exit. If
the script does not exit within this time, RCM sends
a
SIGKILL signal to the script.
The
rcm_cmd_timeout name-value pair is optional. It
is only needed if the script is expected to take more
than a few seconds to process any RCM command.
Setting this name to a value of 0 (zero) disables the
timer. If this name-value pair is not supplied, a
default value is assigned by the RCM.
Upon failure, the script must specify the failure
reason using the name-value pair
rcm_failure_reason and exit with status 1.
register The
register command is invoked to allow a script to specify the
resources that it or its application handles that could potentially
be removed by DR. The script has to supply all its resource names to
RCM using the name-value pair
rcm_resource_name.
Return Data: If successful, the script must write the following
name-value pairs to stdout and exit with status 0:
rcm_resource_name=
resourcename rcm_resource_name=
resourcename .
.
.
where
resourcename is the name of the resource the
script is interested in.
Upon failure, the script must specify the failure
reason using the name-value pair
rcm_failure_reason and exit with status 1.
resourceinfo resourcename The
resourceinfo command is invoked to get the usage information
about
resourcename.
Return Data: If successful, the script must write the following
name-value pair to stdout and exit with status 0:
rcm_resource_usage_info=
resource_usage where
resource_usage is a localized human readable
message describing the usage of the resource by the
script.
Upon failure, the script must specify the failure
reason using the name-value pair
rcm_failure_reason and exit with status 1.
queryremove resourcename Prior to removing the resource from the system, the
queryremove command is invoked to query the script to determine whether the
script can release the given resource successfully from the service
or application it represents. The script does not actually release
the resource. The script might indicate that it is not able to
release the resource if the resource is critical for its service or
application.
Additional environment parameter:
RCM_ENV_FORCE Can be one of:
FALSE Normal request.
TRUE Request is urgent. The script should check
whether the resource can be released
successfully by force, such as by using the
force option to unmount a file system.
Return Data: If the command succeeds, the script must return no
data and exit with status 0.
If the script would not be able to release the
resource, it must specify the reason using the name-
value pair
rcm_failure_reason and exit with status 3.
Upon any other failure, the script must specify the
failure reason using the name-value pair
rcm_failure_reason and exit with status 1.
preremove resourcename The
preremove command is invoked prior to an attempt to remove the
given
resourcename. In response to this command the script can either
release the resource (including closing the device if the device is
currently opened) from the service or application it represents or
indicate that it can not release the resource if the resource is
critical for its service or application.
Additional environment parameter:
RCM_ENV_FORCE Can be one of:
FALSE Normal request.
TRUE Request is urgent. The script should make
extra effort to release the resource, such
as by using the force option to unmount a
file system.
Return Data: If the command succeeds, the script must return no
data and exit with status 0.
If the script cannot release the resource, it must
specify the reason using the name-value pair
rcm_failure_reason and exit with status 3.
Upon any other failure, the script must specify the
failure reason using the name-value pair
rcm_failure_reason and exit with status 1.
postremove resourcename The
postremove command is invoked after the given
resourcename has
been removed.
Return Data: If the command succeeds, the script must return no
data and exit with status 0.
Upon failure, the script must specify the failure
reason using the name-value pair
rcm_failure_reason and exit with status 1.
undoremove resourcename The
undoremove command is invoked to undo what was done in the
previous
preremove command for the given
resourcename. The script can
bring the state of the resource to the same state it was in when the
script received the
preremove command for that resource.
Return Data: If the command succeeds, the script must return no
data and exit with status 0.
Upon failure, the script must specify the failure
reason using the name-value pair
rcm_failure_reason and exit with status 1.
Logging
A script must log all error and debug messages by writing to stdout
the name-value pairs listed below. The logged messages go to
syslogd(8) with the
syslog facility of
LOG_DAEMON. See
syslog.conf(5).
rcm_log_err=message Logs the
message with the syslog level of
LOG_ERR.
rcm_log_warn=message Logs the
message with the syslog level of
LOG_WARNING.
rcm_log_info=message Logs the
message with the syslog level of
LOG_INFO.
rcm_log_debug=message Logs the
message with the syslog level of
LOG_DEBUG.
A script can use the environment variable
RCM_ENV_DEBUG_LEVEL to
control the amount of information to log.
RCM_ENV_DEBUG_LEVEL is a
numeric value ranging from 0 to 9, with 0 meaning log the least
amount of information and 9 meaning log the most.
Installing or Removing RCM Scripts
You must use the following format to name a script:
vendor,
service where
vendor is the stock symbol (or any distinctive name) of the
vendor providing the script and
service is the name of service the
script represents.
You must be a superuser (root) to install or remove an RCM script.
Select one of the following directories where you want to place the
script:
/etc/rcm/scripts Scripts for specific systems
/usr/platform/`uname -i`/lib/rcm/scripts Scripts for specific hardware implementation
/usr/platform/`uname -m`/lib/rcm/scripts Scripts for specific hardware class
/usr/lib/rcm/scripts Scripts for any hardware
Installing a Script
To install a script, copy the script to the appropriate directory
from the list above, change the userid and the groupid of the script
to the desired values, and send
SIGHUP to
rcm_daemon. For example:
# cp SUNW,sample.pl /usr/lib/rcm/scripts
# chown user[:group] /usr/lib/rcm/scripts/SUNW,sample.pl
# pkill -HUP -x -u root rcm_daemon
Removing a script
Remove the script from the appropriate directory from the list above
and send
SIGHUP to
rcm_daemon. For example:
# rm /usr/lib/rcm/scripts/SUNW,sample.pl
# pkill -HUP -x -u root rcm_daemon
EXAMPLES
Example 1: Site Customization RCM Script
#! /usr/bin/perl -w
#
# A sample site customization RCM script for a tape backup application.
#
# This script registers all tape drives in the system with RCM.
# When the system attempts to remove a tape drive by DR the script
# does the following:
# - if the tape drive is not being used for backup, it allows the
# DR to continue.
# - if the tape drive is being used for backup, and when DR is not
# forced (RCM_ENV_FORCE=FALSE) it indicates that it cannot release
# the tape drive with appropriate error message. When forced
# (RCM_ENV_FORCE=TRUE) it kills the tape backup application in
# order to allow the DR to continue.
#
# This script does not implement the postremove and undoremove commands
# since there is nothing to cleanup after DR remove operation is
# completed or failed. If any cleanup is needed after the DR removal
# completed, postremove command needs to implemented. If any cleanup is
# needed in the event of DR removal failure, undoremove command needs
# to be implemented.
#
use strict;
my ($cmd, %dispatch);
$cmd = shift(@ARGV);
# dispatch table for RCM commands
%dispatch = (
"scriptinfo" => do_scriptinfo,
"register" => do_register,
"resourceinfo" => do_resourceinfo,
"queryremove" => do_preremove,
"preremove" => do_preremove
);
if (defined($dispatch{$cmd})) {
&{$dispatch{$cmd}};
} else {
exit (2);
}
sub do_scriptinfo
{
print "rcm_script_version=1\n";
print "rcm_script_func_info=Tape backup appl script for DR\n";
exit (0);
}
sub do_register
{
my ($dir, $f, $errmsg);
$dir = opendir(RMT, "/dev/rmt");
if (!$dir) {
$errmsg = "Unable to open /dev/rmt directory: $!";
print "rcm_failure_reason=$errmsg\n";
exit (1);
}
while ($f = readdir(RMT)) {
# ignore hidden files and multiple names for the same device
if (($f !~ /^./) && ($f =~ /^[0-9]+$/)) {
print "rcm_resource_name=/dev/rmt/$f\n";
}
}
closedir(RMT);
exit (0);
}
sub do_resourceinfo
{
my ($rsrc, $unit);
$rsrc = shift(@ARGV);
if ($rsrc =~ /^\/dev\/rmt\/([0-9]+)$/) {
$unit = $1;
print "rcm_resource_usage_info=Backup Tape Unit Number $unit\n";
exit (0);
} else {
print "rcm_failure_reason=Unknown tape device!\n";
exit (1);
}
}
sub do_preremove
{
my ($rsrc);
$rsrc = shift(@ARGV);
# check if backup application is using this resource
# if (the backup application is not running on $rsrc) {
# allow the DR to continue
# exit (0);
#}
#
# If RCM_ENV_FORCE is FALSE deny the operation.
# If RCM_ENV_FORCE is TRUE kill the backup application in order
# to allow the DR operation to proceed
#
if ($ENV{RCM_ENV_FORCE} eq 'TRUE') {
if ($cmd eq 'preremove') {
# kill the tape backup application
}
exit (0);
} else {
#
# indicate that the tape drive can not be released
# since the device is being used for backup by the
# tape backup application
#
print "rcm_failure_reason=tape backup in progress pid=...\n";
exit (3);
}
}
EXIT STATUS
A script must exit with following exit status values:
0 Operation specified by the given RCM command has been executed
successfully by the script. For
queryremove command it also
means that the script can successfully release the resource.
1 An error occurred while processing the RCM command. The script
should provide the error message to RCM using the name-value
pair
rcm_failure_reason before exiting.
2 The script does not support the given RCM command. A script must
exit with this status if it cannot understand the given RCM
command.
3 Indicates that the script cannot release the resource for
preremove and
queryremove commands. The script should provide a
message to RCM specifying the reason for not being able to
release the resource using the name-value pair
rcm_failure_reason before exiting.
ERRORS
If a script cannot successfully process an RCM command, it must
supply to the RCM a message indicating the reason for failure by
writing a name-value pair, in the form shown below, to stdout and
exiting with the appropriate exit status.
rcm_failure_reason=
failure_reason where
failure_reason is a localized human readable message describing
the reason for failure of the RCM command.
ATTRIBUTES
See
attributes(7) for descriptions of the following attributes:
+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Evolving |
+--------------------+-----------------+
SEE ALSO
gettext(1),
syslog(3C),
signal.h(3HEAD),
syslog.conf(5),
attributes(7),
environ(7),
cfgadm(8),
cfgadm_pci(8),
cfgadm_scsi(8)NOTES
RCM scripts are expected to properly handle all RCM commands that the
script implements and to log all errors. Only root has permission to
add or remove an RCM script. An ill-behaved RCM script can cause
unexpected DR failures.
RCM commands are invoked only for the resources whose subsystems
participate within the RCM framework. Currently, not all subsystems
participate within the RCM framework.
February 18, 2003 RCMSCRIPT(5)
