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#!/bin/sh
#
#
# An OCF RA that manages a symlink
#
# Copyright (c) 2011 Dominik Klein
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of version 2 of the GNU General Public License as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it would be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
#
# Further, this software is distributed without any warranty that it is
# free of the rightful claim of any third person regarding infringement
# or the like. Any license provided herein, whether implied or
# otherwise, applies only to this software file. Patent licenses, if
# any, provided herein do not apply to combinations of this program with
# other software, or any other product whatsoever.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write the Free Software Foundation,
# Inc., 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
#
#######################################################################
# Initialization:
: ${OCF_FUNCTIONS_DIR=${OCF_ROOT}/lib/heartbeat}
. ${OCF_FUNCTIONS_DIR}/ocf-shellfuncs
#######################################################################
meta_data() {
cat <<END
<?xml version="1.0"?>
<!DOCTYPE resource-agent SYSTEM "ra-api-1.dtd">
<resource-agent name="symlink" version="1.1">
<version>1.0</version>
<longdesc lang="en">
This resource agent that manages a symbolic link (symlink).
It is primarily intended to manage configuration files which should be
enabled or disabled based on where the resource is running, such as
cron job definitions and the like.
</longdesc>
<shortdesc lang="en">Manages a symbolic link</shortdesc>
<parameters>
<parameter name="link" required="1">
<longdesc lang="en">
Full path of the symbolic link to be managed. This must obviously be
in a filesystem that supports symbolic links.
</longdesc>
<shortdesc lang="en">Full path of the symlink</shortdesc>
<content type="string"/>
</parameter>
<parameter name="target" required="1">
<longdesc lang="en">
Full path to the link target (the file or directory which the symlink points to).
</longdesc>
<shortdesc lang="en">Full path to the link target</shortdesc>
<content type="string" />
</parameter>
<parameter name="backup_suffix">
<longdesc lang="en">
A suffix to append to any files that the resource agent moves out of
the way because they clash with "link".
If this is unset (the default), then the resource agent will simply
refuse to create a symlink if it clashes with an existing file.
</longdesc>
<shortdesc lang="en">Suffix to append to backup files</shortdesc>
<content type="string" />
</parameter>
</parameters>
<actions>
<action name="start" timeout="15s" />
<action name="stop" timeout="15s" />
<action name="monitor" depth="0" timeout="15s" interval="60s"/>
<action name="meta-data" timeout="5s" />
<action name="validate-all" timeout="10s" />
</actions>
</resource-agent>
END
}
symlink_monitor() {
# This applies the following logic:
#
# * If $OCF_RESKEY_link does not exist, then the resource is
# definitely stopped.
#
# * If $OCF_RESKEY_link exists and is a symlink that points to
# ${OCF_RESKEY_target}, then the resource is definitely started.
#
# * If $OCF_RESKEY_link exists, but is anything other than a
# symlink to ${OCF_RESKEY_target}, then the status depends on whether
# ${OCF_RESKEY_backup_suffix} is set:
#
# - if ${OCF_RESKEY_backup_suffix} is set, then the resource is
# simply not running. The existing file will be moved out of
# the way, to ${OCF_RESKEY_link}${OCF_RESKEY_backup_suffix},
# when the resource starts.
#
# - if ${OCF_RESKEY_backup_suffix} is not set, then an existing
# file ${OCF_RESKEY_link} is an error condition, and the
# resource can't start here.
rc=$OCF_ERR_GENERIC
# Using ls here instead of "test -e", as "test -e" returns false
# if the file does exist, but it a symlink to a file that doesn't
if ! ls "$OCF_RESKEY_link" >/dev/null 2>&1; then
ocf_log debug "$OCF_RESKEY_link does not exist"
rc=$OCF_NOT_RUNNING
elif [ ! -L "$OCF_RESKEY_link" ]; then
if [ -z "$OCF_RESKEY_backup_suffix" ]; then
ocf_exit_reason "$OCF_RESKEY_link exists but is not a symbolic link!"
exit $OCF_ERR_INSTALLED
else
ocf_log debug "$OCF_RESKEY_link exists but is not a symbolic link, will be moved to ${OCF_RESKEY_link}${OCF_RESKEY_backup_suffix} on start"
rc=$OCF_NOT_RUNNING
fi
elif readlink -m "$OCF_RESKEY_link" | egrep -q "^$(readlink -m ${OCF_RESKEY_target})$"; then
ocf_log debug "$OCF_RESKEY_link exists and is a symbolic link to ${OCF_RESKEY_target}."
rc=$OCF_SUCCESS
else
if [ -z "$OCF_RESKEY_backup_suffix" ]; then
ocf_exit_reason "$OCF_RESKEY_link does not point to ${OCF_RESKEY_target}!"
exit $OCF_ERR_INSTALLED
else
ocf_log debug "$OCF_RESKEY_link does not point to ${OCF_RESKEY_target}, will be moved to ${OCF_RESKEY_link}${OCF_RESKEY_backup_suffix} on start"
rc=$OCF_NOT_RUNNING
fi
fi
return $rc
}
symlink_start() {
if ! symlink_monitor; then
if [ -e "$OCF_RESKEY_link" ]; then
if [ -z "$OCF_RESKEY_backup_suffix" ]; then
# Shouldn't happen, because symlink_monitor should
# have errored out. But there is a chance that
# something else put that file there after
# symlink_monitor ran.
ocf_exit_reason "$OCF_RESKEY_link exists and no backup_suffix is set, won't overwrite."
exit $OCF_ERR_GENERIC
else
ocf_log debug "Found $OCF_RESKEY_link, moving to ${OCF_RESKEY_link}${OCF_RESKEY_backup_suffix}"
ocf_run mv -v "$OCF_RESKEY_link" "${OCF_RESKEY_link}${OCF_RESKEY_backup_suffix}" \
|| exit $OCF_ERR_GENERIC
fi
fi
ocf_run ln -sv "$OCF_RESKEY_target" "$OCF_RESKEY_link"
symlink_monitor
return $?
else
return $OCF_SUCCESS
fi
}
symlink_stop() {
if symlink_monitor; then
ocf_run rm -vf "$OCF_RESKEY_link" || exit $OCF_ERR_GENERIC
if ! symlink_monitor; then
if [ -e "${OCF_RESKEY_link}${OCF_RESKEY_backup_suffix}" ]; then
ocf_log debug "Found backup ${OCF_RESKEY_link}${OCF_RESKEY_backup_suffix}, moving to $OCF_RESKEY_link"
# if restoring the backup fails then still return with
# $OCF_SUCCESS, but log a warning
ocf_run -warn mv "${OCF_RESKEY_link}${OCF_RESKEY_backup_suffix}" "$OCF_RESKEY_link"
fi
return $OCF_SUCCESS
else
ocf_exit_reason "Removing $OCF_RESKEY_link failed."
return $OCF_ERR_GENERIC
fi
else
return $OCF_SUCCESS
fi
}
symlink_validate_all() {
if [ "x${OCF_RESKEY_link}" = "x" ]; then
ocf_exit_reason "Mandatory parameter link is unset"
exit $OCF_ERR_CONFIGURED
fi
if [ "x${OCF_RESKEY_target}" = "x" ]; then
ocf_exit_reason "Mandatory parameter target is unset"
exit $OCF_ERR_CONFIGURED
fi
# Having a non-existant target is technically not an error, as
# symlinks are allowed to point to non-existant paths. But it
# still doesn't hurt to warn people if the target does not exist
# (but only during non-probes).
if [ ! -e "${OCF_RESKEY_target}" ]; then
ocf_log warn "${OCF_RESKEY_target} does not exist!"
fi
}
symlink_usage() {
cat <<EOF
usage: $0 {start|stop|monitor|validate-all|meta-data}
Expects to have a fully populated OCF RA-compliant environment set.
EOF
}
if [ $# -ne 1 ]; then
symlink_usage
exit $OCF_ERR_ARGS
fi
case $__OCF_ACTION in
meta-data)
meta_data
exit $OCF_SUCCESS
;;
usage)
symlink_usage
exit $OCF_SUCCESS
esac
# Everything except usage and meta-data must pass the validate test
symlink_validate_all || exit
case $__OCF_ACTION in
start)
symlink_start
;;
stop)
symlink_stop
;;
status|monitor)
symlink_monitor
;;
validate-all)
;;
*)
symlink_usage
exit $OCF_ERR_UNIMPLEMENTED
esac
# exit code is the exit code (return code) of the last command (shell function)
|
