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