This is a text-only version of the following page on https://raymii.org:
---
Title : Corosync Pacemaker - Execute script on failover
Author : Remy van Elst
Date : 20-11-2013
URL : https://raymii.org/s/tutorials/Corosync_Pacemaker_-_Execute_a_script_on_failover.html
Format : Markdown/HTML
---
With Corosync/Pacemaker there is no easy way to simply run a script on failover.
There are good reasons for this, but sometimes you want to do something simple.
This tutorial describes how to change the Dummy OCF resource to execute a script
on failover.
<p class="ad"> <b>Recently I removed all Google Ads from this site due to their invasive tracking, as well as Google Analytics. Please, if you found this content useful, consider a small donation using any of the options below:</b><br><br> <a href="https://leafnode.nl">I'm developing an open source monitoring app called Leaf Node Monitoring, for windows, linux & android. Go check it out!</a><br><br> <a href="https://github.com/sponsors/RaymiiOrg/">Consider sponsoring me on Github. It means the world to me if you show your appreciation and you'll help pay the server costs.</a><br><br> <a href="https://www.digitalocean.com/?refcode=7435ae6b8212">You can also sponsor me by getting a Digital Ocean VPS. With this referral link you'll get $100 credit for 60 days. </a><br><br> </p>
In this example it is a script which triggers a few SNMP traps, sends an alert
to Nagios and sends some data to Graphite. SNMP alone could be done with the
`ocf:heartbeat:ClusterMon` resource, but the other stuff not.
This is a very very simple way of doing it, I find it more a quick hack. For
example, the script path is hard coded. For me that is not a problem because
both the script as the Dummy resource are managed via Ansible, so I can change
them any time.
Start by copying the Dummy resource over to a new resource. On Ubuntu the
resource files are located here:
/usr/lib/ocf/resource.d/heartbeat/
In there, copy the `Dummy` file to a new resource, for example `FailOverScript`.
If you don't have the Dummy resource, you can also find it [here][2].
Edit the name and description:
Name:
meta_data() {
cat <<END
<?xml version="1.0"?>
<!DOCTYPE resource-agent SYSTEM "ra-api-1.dtd">
<resource-agent name="FailOverScript" version="0.9">
<version>1.0</version>
Description:
<longdesc lang="en">
Script ran on Failover
</longdesc>
<shortdesc lang="en">Script ran on Failover</shortdesc>
Make sure the script you want to execute is placed on the host, and is
executable (`chmod +x /usr/local/bin/script`).
A bit lower in the file, edit the `dummy_start` function. Add the script path
below the `if [ $? = $OCF_SUCCESS ]; then` and above the `return $OCF_SUCCESS`
lines. Like so:
dummy_start() {
dummy_monitor
/usr/local/bin/failover.sh
if [ $? = $OCF_SUCCESS ]; then
return $OCF_SUCCESS
fi
touch ${OCF_RESKEY_state}
}
After that has been done, replace all instances of Dummy and dummy with your
name of choice:
sed -i 's/Dummy/FailOverScript' /usr/lib/ocf/resource.d/heartbeat/FailOverScript
sed -i 's/dummy/failoverscript' /usr/lib/ocf/resource.d/heartbeat/FailOverScript
Test the script using the `ocf-tester` program to see if you have any mistakes:
ocf-tester -n resourcename /usr/lib/ocf/resource.d/heartbeat/FailOverScript
Output:
Beginning tests for /usr/lib/ocf/resource.d/heartbeat/FailOverScript...
/usr/sbin/ocf-tester: 214: /usr/sbin/ocf-tester: xmllint: not found
* rc=127: Your agent produces meta-data which does not conform to ra-api-1.dtd
* Your agent does not support the notify action (optional)
* Your agent does not support the demote action (optional)
* Your agent does not support the promote action (optional)
* Your agent does not support master/slave (optional)
Tests failed: /usr/lib/ocf/resource.d/heartbeat/FailOverScript failed 1 tests
Oops. Seems we need `xmllint`. On Ubuntu, install it:
apt-get install libxml2-utils
Test again, you'll see it will pass:
Beginning tests for /usr/lib/ocf/resource.d/heartbeat/FailOverScript...
* Your agent does not support the notify action (optional)
* Your agent does not support the demote action (optional)
* Your agent does not support the promote action (optional)
* Your agent does not support master/slave (optional)
/usr/lib/ocf/resource.d/heartbeat/FailOverScript passed all tests
As an extra test, to see if the script you've created is correctly executed, you
can do a test start of the resource:
export OCF_ROOT=/usr/lib/ocf
bash -x /usr/lib/ocf/resource.d/heartbeat/FailOverScript start
To use this resource, add it like so:
crm configure primitive script ocf:heartbeat:FailOverScript op monitor interval="30"
If you want to test it, you can for example let the script send you an email.
Put a node in standby and see if you get an email.
[1]: https://www.digitalocean.com/?refcode=7435ae6b8212
[2]: https://github.com/ClusterLabs/resource-agents/blob/master/heartbeat/Dummy
---
License:
All the text on this website is free as in freedom unless stated otherwise.
This means you can use it in any way you want, you can copy it, change it
the way you like and republish it, as long as you release the (modified)
content under the same license to give others the same freedoms you've got
and place my name and a link to this site with the article as source.
This site uses Google Analytics for statistics and Google Adwords for
advertisements. You are tracked and Google knows everything about you.
Use an adblocker like ublock-origin if you don't want it.
All the code on this website is licensed under the GNU GPL v3 license
unless already licensed under a license which does not allows this form
of licensing or if another license is stated on that page / in that software:
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
Just to be clear, the information on this website is for meant for educational
purposes and you use it at your own risk. I do not take responsibility if you
screw something up. Use common sense, do not 'rm -rf /' as root for example.
If you have any questions then do not hesitate to contact me.
See https://raymii.org/s/static/About.html for details.