High Availability Configuration with Pacemaker and Corosync
Description
This tutorial will demonstrate how you can use Corosync and Pacemaker with a Virtual IP to create a high availability server solution in MOR.
Requirements
- All public IP addresses have to be on same subnet.
- Virtual IP has to be free (not assigned to any device on the network). Virtual IP will be managed by Corosync itself.
- The following ports have to be open between nodes in cluster:
- UDP 5404, 5405, 5406 - used by Corosync
- TCP 2224 - used by pscd service
- TCP 3121 - used by Pacemaker
Install
Run commands below on both nodes to install Pacemaker and Corosync:
svn update /usr/src/k_framework/ /usr/src/k_framework/helpers/corosync/corosync_install.sh systemctl enable corosync systemctl enable pacemaker
If /usr/src/k_framework/ directory is not present, checkout it manually:
svn co http://svn.kolmisoft.com/k_framework/ /usr/src/k_framework
Configuration
Firsly, we need to configure hostnames in servers. You can find current hostname with command:
uname -n
We recommend to user hostname node01 for main server, and node02 for backup server, however you can use different hostnames if you wish. You can set hostname on server using command bellow:
hostnamectl set-hostname your-new-hostname
If you use different hostname, please replace node01 and node02 with actual hostname names in configuration examples bellow.
Once hostame setup is complete, on main server open file /etc/hosts, you will see something like this:
192.168.0.131 node01 #This is example. Change to correct IP 192.168.0.132 node02 #Change to correct IP here aswell
Replace IP addresses with actual IP of both servers. If servers hostnames are not node01/node02 replace them with actual hostanme name of servers.
Repeat this procedure on backup server too.
All examples assume that there are two nodes with hostnames node01 and node02 and they are reachable by their hostnames and IP addresses:
- node01 - 192.168.0.152
- node02 - 192.168.0.200
192.168.0.205 is Virtual IP address.
Also, in all following command line examples, convention is this:
- [root@node01 ~]# denotes a command which should be run on 'ONE' server in the cluster.
- [root@ALL ~]# denotes a command which should be run on 'ALL' servers (node01 and node02) in the cluster.
You should replace hostnames and IP addresses to match your setup.
Authenticate and Setup Cluster
Installation script will install all needed packages and configuration files. Firstly let's setup cluster authentication:
Copy password from node01 to node02
[root@node01 ~]# scp /root/hacluster_password root@node02:/root/hacluster_password
And apply password on node02
[root@node02 ~]# cat /root/hacluster_password | passwd --stdin hacluster
Now we can authenticate cluster:
[root@node01 ~]# pcs cluster auth node01 node02 -u hacluster -p $(cat /root/hacluster_password) node02: Authorized node01: Authorized
If you get any other output, it means something went wrong and you should not proceed until this is fixed. If everything is OK, then we can setup cluster:
[root@node01 ~]# pcs cluster setup --name cluster_asterisk node01 node02 Destroying cluster on nodes: node01, node02... node01: Stopping Cluster (pacemaker)... node02: Stopping Cluster (pacemaker)... node02: Successfully destroyed cluster node01: Successfully destroyed cluster Sending 'pacemaker_remote authkey' to 'node01', 'node02' node01: successful distribution of the file 'pacemaker_remote authkey' node02: successful distribution of the file 'pacemaker_remote authkey' Sending cluster config files to the nodes... node01: Succeeded node02: Succeeded Synchronizing pcsd certificates on nodes node01, node02... node02: Success node01: Success Restarting pcsd on the nodes in order to reload the certificates... node02: Success node01: Success [root@node01 ~]#
If everything went OK, there should be no errors in output. If this is the case, let's start cluster:
[root@node01 ~]# pcs cluster start --all node02: Starting Cluster... node01: Starting Cluster... [root@node01 ~]#
This will automatically start Corosync and Pacemaker services on both nodes. Now let's check if Corosync is happy and there are no errors (issue this command on both nodes separately):
[root@node01 ~]# corosync-cfgtool -s
Printing ring status.
Local node ID 1
RING ID 0
id = 192.168.0.152
status = ring 0 active with no faults
[root@node02 ~]# corosync-cfgtool -s
Printing ring status.
Local node ID 2
RING ID 0
id = 192.168.0.200
status = ring 0 active with no faults
If you see different output, you should investigate before proceeding. Now let's check membership and quorum APIs, you should see both nodes with status Joined
[root@node01 ~]# corosync-cmapctl | grep members runtime.totem.pg.mrp.srp.members.1.config_version (u64) = 0 runtime.totem.pg.mrp.srp.members.1.ip (str) = r(0) ip(192.168.0.152) runtime.totem.pg.mrp.srp.members.1.join_count (u32) = 1 runtime.totem.pg.mrp.srp.members.1.status (str) = joined runtime.totem.pg.mrp.srp.members.2.config_version (u64) = 0 runtime.totem.pg.mrp.srp.members.2.ip (str) = r(0) ip(192.168.0.200) runtime.totem.pg.mrp.srp.members.2.join_count (u32) = 1 runtime.totem.pg.mrp.srp.members.2.status (str) = joined
Now disable STONITH and Ignore the Quorum Policy:
[root@node01 ~]# pcs property set stonith-enabled=false [root@node01 ~]# pcs property set no-quorum-policy=ignore [root@node01 ~]# pcs property list Cluster Properties: cluster-infrastructure: corosync cluster-name: cluster_asterisk dc-version: 1.1.18-11.el7_5.3-2b07d5c5a9 have-watchdog: false no-quorum-policy: ignore stonith-enabled: false
Finally, let check cluster status:
[root@node01 ~]# pcs status Cluster name: cluster_asterisk Stack: corosync svn update /usr/src/mor/sh_scripts /usr/src/mor/sh_scripts/corosync/corosync_install.sh systemctl enable corosync systemctl enable pacemaker Current DC: node02 (version 1.1.18-11.el7_5.3-2b07d5c5a9) - partition with quorum Last updated: Wed Oct 17 07:34:20 2018 Last change: Wed Oct 17 07:32:39 2018 by root via cibadmin on node01 2 nodes configured 0 resources configured Online: [ node01 node02 ] No resources Daemon Status: corosync: active/enabled pacemaker: active/enabled pcsd: active/enabled
We can see that both nodes are online, all daemons (corosync, pacemaker, pcsd) are active.
Configuring Asterisk HA solution with Virtual IP
Before proceeding we need to prepare Asterisk to be managed by Corosync with Virtual IP.
1. Make sure that Asterisk service is stopped and disabled on both nodes.
[root@ALL ~]# systemctl disable asterisk [root@ALL ~]# systemctl stop asterisk
2. Replace binaddr from 0.0.0.0 to VirtualIP in /etc/asterisk/sip.conf
3. Add Virtual IP in file /etc/asterisk/manager.conf
permit=192.168.0.205/255.255.255.0
4. Add VirtualIP in GUI Servers page and Global settings page.
5. In file /etc/mor/system.conf add variable VIRTUAL_IP with correct virtual IP
VIRTUAL_IP=xx.xx.xx.xx
This variable will be used by check scripts.
Adding VirtualIP resource
Now when cluster is ready, we can add resources (Virtual IP, Asterisk, httpd, opensips, etc). In this section we will show how to add Virtual IP and Asterisk resources.
Firstly, let's add Virtual IP resource. Do not forget replace ip, cidr_netmask values and nic name with values from your setup. Use subnet of main IP for cidr_netmask. Also, make sure that nic name is the same on both servers. If nic name is different, leave nic parameter out. System will find suitable nic for Virtual IP automatically.
[root@node01 ~]# pcs resource create VirtualIP ocf:heartbeat:IPaddr2 ip=192.168.0.205 cidr_netmask=32 nic=enp0s3 op monitor interval=30s [root@node01 ~]# pcs status Cluster name: cluster_asterisk Stack: corosync Current DC: node02 (version 1.1.18-11.el7_5.3-2b07d5c5a9) - partition with quorum Last updated: Wed Oct 17 07:49:56 2018 Last change: Wed Oct 17 07:49:51 2018 by root via cibadmin on node01 2 nodes configured 1 resource configured Online: [ node01 node02 ] Full list of resources: VirtualIP (ocf::heartbeat:IPaddr2): Started node01 Daemon Status: corosync: active/enabled pacemaker: active/enabled pcsd: active/enabled
Now let's confirm that Virtual IP has indeed been assigned to interface:
[root@node01 ~]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 08:00:27:90:37:9c brd ff:ff:ff:ff:ff:ff
inet 192.168.0.152/24 brd 192.168.0.255 scope global noprefixroute dynamic enp0s3
valid_lft 564sec preferred_lft 564sec
inet 192.168.0.205/24 brd 192.168.0.255 scope global enp0s3
valid_lft forever preferred_lft forever
inet6 fe80::eb74:dc5d:cdd:df23/64 scope link noprefixroute
valid_lft forever preferred_lft forever
If IP is not assigned, recheck if nic interface is correct. If nic was not used, check output of this command:
ip -o -f inet route list match 1.2.3.4 scope link
Where 1.2.3.4 is Virtual IP. If output is empty, it means that system cannot find interface automatically, most likely main IP/mask is set incorrectly.
Adding Asterisk resource
Once Virtual IP resource is setup correctly, it is time to add Asterisk resource (Install script will add Asterisk resource in directory /usr/lib/ocf/resource.d/heartbeat/).
[root@node01 ~]# pcs resource create asterisk ocf:heartbeat:asterisk op monitor timeout="30"
Now add colocation so that both resources will start at the same node, and set ordering (so that VirtualIP would start before Asterisk):
[root@node01 ~]# pcs constraint colocation add asterisk with VirtualIP score=INFINITY [root@node01 ~]# pcs constraint order VirtualIP then asterisk Adding VirtualIP asterisk (kind: Mandatory) (Options: first-action=start then-action=start)
Let's check if Asterisk is running:
[root@localhost node01 ~]# pcs resource show VirtualIP (ocf::heartbeat:IPaddr2): Started node01 asterisk (ocf::heartbeat:asterisk): Started node01
Now make node01 preferd one. This means that if node01 fails and resources are moved node02, node01 will reclaim resources once it will be up again.
[root@node01 ~]# pcs resource defaults resource-stickiness=0 [root@node01 ~]# pcs constraint location asterisk prefers node01=50
Run once again:
systemctl enable corosync systemctl enable pacemaker
pcs status should show
Daemon Status: corosync: active/enabled pacemaker: active/enabled pcsd: active/enabled
Reboot servers to make sure that resources are switching correctly and services started as needed.
Configuring KSR HA solution with Virtual IP
1. Install Failover software as described here.
2. Configure the nodes and #Authenticate and Setup Cluster
3. On all failover servers, In file /etc/m2/system.conf add variable VIRTUAL_IP with correct virtual IP
VIRTUAL_IP=xx.xx.xx.xx
4. Virtual IP should be in the GUI servers list. Physical IPs should be added too.
5. Add Virtual IP resource.
6. Make the main node the preferred node for VirtualIP:
[root@node01 ~]# pcs resource defaults resource-stickiness=0 [root@node01 ~]# pcs constraint location VirtualIP prefers node01=50
7. Run /usr/src/m4/check.sh
[root@ALL ~]# /usr/src/m4/check.sh
8. Make changes as indicated by the check.
9. Manually grep for physical servers IP:
[root@ALL ~]# grep -F 'physical IP' /etc/kamailio/kamailio.cfg /etc/sysconfig/rtpengine /usr/local/etc/sems/etc/b2bua_topology_hiding.sbcprofile.conf /usr/local/etc/sems/sems.conf
If grep found anything, replace IPs manually with virtual IP.
10. Stop and disable services
[root@ALL ~]# systemctl disable kamailio [root@ALL ~]# systemctl stop kamailio [root@ALL ~]# systemctl disable sems [root@ALL ~]# systemctl stop sems [root@ALL ~]# systemctl disable rtpengine [root@ALL ~]# systemctl stop rtpengine
11. Create resources for rtpengine, seems, kamailio
pcs resource create rtpengine systemd:rtpengine pcs resource create sems systemd:sems pcs resource create kamailio systemd:kamailio
12. Create a new resource group (for example named ksr) and add all resources (including VirtualIP) into it. Resources in a group are started sequentially and stopped in the reverse order.
pcs resource group add ksr VirtualIP rtpengine sems kamailio
13. Check the output of pcs status. If any resource fails to start, subsequent will not start too. In such case, you will see an error like this (in this case example for rtpengine) in pcs status output
Resource Group: ksr
VirtualIP (ocf::heartbeat:IPaddr2): Started ksr-45
rtpengine (systemd:rtpengine): Stopped
sems (systemd:sems): Stopped
kamailio (systemd:kamailio): Stopped
Failed Resource Actions:
* rtpengine_start_0 on ksr-45 'unknown error' (1): call=20, status=complete, exitreason=,
last-rc-change='Fri Nov 18 11:07:54 2022', queued=0ms, exec=2060ms
To fix this, check failed resource logs to determine the reason (for example, wrong IP), fix it, and clear pcs with the command:
pcs resource cleanup rtpengine
(use the appropriate resources in your scenario)
If an error has been fixed, pcs will try to start service again, and all subsequent services:
Resource Group: ksr
VirtualIP (ocf::heartbeat:IPaddr2): Started ksr-45
rtpengine (systemd:rtpengine): Started ksr-45
sems (systemd:sems): Started ksr-45
kamailio (systemd:kamailio): Started ksr-45
14. If all services running, make a test call, check the sip trace, etc.
15. To test configuration on the backup node, use this command on the main node:
[root@node01 ~]# pcs cluster stop
And check the output on node02
[root@node02 ~]# pcs status
If there are any errors, fix them as described in 10. step If all services running, make a test call, check the sip trace, etc.
16. To move services to the main node, start the cluster again on the main node:
[root@node01 ~]# pcs cluster start
and check the status:
[root@node01 ~]# pcs status
17. Enable corosync and pacemaker again on both nodes:
[root@ALL ~]# systemctl enable corosync [root@ALL ~]# systemctl enable pacemaker
18. After all tests, run m2/check.sh to check final configuration
[root@node01 ~] /usr/src/m2/check.sh
Stickiness, constraints and moving resources
If one node fails, resources will be moved to other node. After first node recovers, should we move resources back to first one or leave the running on second one? This can be controlled using stickiness, if we set stickiness > prefer score, this mean that Pacemaker will prefer to leave resources running and avoid moving them between nodes:
[root@node01 ~]# pcs resource defaults resource-stickiness=100 Warning: Defaults do not apply to resources which override them with their own defined values [root@node01 ~]# pcs resource defaults resource-stickiness: 100 [root@node01 ~]#
With this settings, resources should not be moved back to original node if that node rebooted for example.
It is possible to move resource manually using pcs recourse move command. For example, let's move resources from current node to the other one:
[root@node01 ~]# pcs resource show VirtualIP (ocf::heartbeat:IPaddr2): Started node01 asterisk (ocf::heartbeat:asterisk): Started node01
[root@node01 ~]# pcs resource move VirtualIP Warning: Creating location constraint cli-ban-VirtualIP-on-node01 with a score of -INFINITY for resource VirtualIP on node node01. This will prevent VirtualIP from running on node01 until the constraint is removed. This will be the case even if node01 is the last node in the cluster. [root@node01 ~]#
[root@node01 ~]# pcs resource show VirtualIP (ocf::heartbeat:IPaddr2): Started node02 asterisk (ocf::heartbeat:asterisk): Started node02
As you can see, resources has been moved (as asterisk depends on VirtualIP, it is enough to move VirtualIP resource), however new location constraint has been created (cli-ban-VirtualIP-on-node01). We can check constraints this way:
[root@node01 ~]# pcs constraint --full
Location Constraints:
Resource: VirtualIP
Disabled on: node01 (score:-INFINITY) (role: Started) (id:cli-ban-VirtualIP-on-node01)
Ordering Constraints:
start VirtualIP then start asterisk (kind:Mandatory) (id:order-VirtualIP-asterisk-mandatory)
Colocation Constraints:
asterisk with VirtualIP (score:INFINITY) (id:colocation-asterisk-VirtualIP-INFINITY)
Ticket Constraints:
Now even if node02 will fail, resources will not be moved to node01. To remove constraint, we can use command pcs constraint remove <constraint-id>
[root@node01 ~]# pcs constraint remove cli-ban-VirtualIP-on-node01 [root@node01 ~]# pcs constraint --full Location Constraints: Ordering Constraints: start VirtualIP then start asterisk (kind:Mandatory) (id:order-VirtualIP-asterisk-mandatory) Colocation Constraints: asterisk with VirtualIP (score:INFINITY) (id:colocation-asterisk-VirtualIP-INFINITY) Ticket Constraints:
Maintenance mode
There is time when we need to stop, inspect or do other maintenance work on resources without interference from cluster management software. We can achieve this by putting cluster in maintenance mode
[root@node01 ~]# pcs property set maintenance-mode=true [root@node01 ~]# pcs property | grep -i maintenance maintenance-mode: true
[root@node01 ~]# pcs status
Cluster name: cluster_asterisk
Stack: corosync
Current DC: node02 (version 1.1.18-11.el7_5.3-2b07d5c5a9) - partition with quorum
Last updated: Wed Oct 17 10:45:24 2018
Last change: Wed Oct 17 10:39:18 2018 by root via cibadmin on node01
2 nodes configured
2 resources configured
*** Resource management is DISABLED ***
The cluster will not attempt to start, stop or recover services
Online: [ node01 node02 ]
Full list of resources:
VirtualIP (ocf::heartbeat:IPaddr2): Started node02 (unmanaged)
asterisk (ocf::heartbeat:asterisk): Started node02 (unmanaged)
Daemon Status:
corosync: active/enabled
pacemaker: active/enabled
pcsd: active/enabled
To move back cluster to normal operation, simply set maintenance mode to false
[root@node01 ~]# pcs property set maintenance-mode=false [root@node01 ~]# pcs property | grep -i maintenance maintenance-mode: false [root@node01 ~]#
Resource Clean Up
If the asterisk does not start on the node, due to such errors:
pcs status VirtualIP (ocf::heartbeat:IPaddr2): Started[ mor01 mor02 ] asterisk (ocf::heartbeat:asterisk): FAILED mor 01 (blocked)
or
pcs status Failed Resource Actions: * asterisk_start_0 on mor01 'unknown error' (1): call=24, status=Error, exitreason=, last-rc-change='Sun Jun 5 03:18:00 2022', queued=0ms, exec=6175ms
try to cleanup Asterisk resource
[root@mor01 ~]# pcs resource cleanup asterisk Cleaned up asterisk on mor02 Cleaned up asterisk on mor01 Waiting for 1 reply from the CRMd. OK
Replacing a Corosync Node
Example based on situation when node01 is being replaced.
Disable selinux.
Make sure the node01 is completely stopped.
Give the new machine the same hostname and IP address as the old one.
Correct /etc/hosts on the node01.
Install the cluster software on node01. Run commands bellow on both nodes to install Pacemaker and Corosync:
svn update /usr/src/k_framework/ /usr/src/k_framework/helpers/corosync/corosync_install.sh systemctl enable corosync systemctl enable pacemaker
Copy /etc/corosync/corosync.conf from node02 to node01.
Copy password from node02 to node01:
[root@node02 ~]# scp /root/hacluster_password root@node01:/root/hacluster_password
And apply password on node01:
[root@node01 ~]# cat /root/hacluster_password | passwd --stdin hacluster
Copy authkey from node02 to node01:
[root@node02 ~]# scp /etc/pacemaker/authkey root@node01:/etc/pacemaker/authkey
Restart pcs Daemon on node02:
[root@node02 ~]# systemctl restart pcsd.service
Now we can authenticate cluster:
[root@node01 ~]# pcs cluster auth node01 node02 -u hacluster -p $(cat /root/hacluster_password) node02: Authorized node01: Authorized
If you get any other output, it means something went wrong and you should not proceed until this is fixed.
Remove VirtualIP resource and create it again:
[root@node01 ~]# pcs resource delete VirtualIP [root@node01 ~]# pcs resource create VirtualIP ocf:heartbeat:IPaddr2 ip=192.168.0.205 cidr_netmask=32 nic=enp0s3 op monitor interval=30s
Check more details about creating VirtualIP in the topics above.
Now add colocation so that both resources will start at the same node, and set ordering (so that VirtualIP would start before Asterisk):
[root@node01 ~]# pcs constraint colocation add asterisk with VirtualIP score=INFINITY [root@node01 ~]# pcs constraint order VirtualIP then asterisk Adding VirtualIP asterisk (kind: Mandatory) (Options: first-action=start then-action=start)
Make sure that everything is enabled and working by executing command:
[root@node01 ~]# pcs status
Increase totem timeout
Corosync runs in real-time priority, if corosync is not scheduled in time, such messages might appear
Corosync main process was not scheduled (@1687222876617) for 1587.5076 ms (threshold is 800.0000 ms). Consider token timeout increase. Corosync main process was not scheduled (@1687222961366) for 916.5676 ms (threshold is 800.0000 ms). Consider token timeout increase. Corosync main process was not scheduled (@1687222974600) for 2899.7456 ms (threshold is 800.0000 ms). Consider token timeout increase.
This usually happens when a hypervisor (VM) is used.
The procedure to increase timeout is:
1. Edit corosync file on node01
[root@node01 ~]# vi /etc/corosync/corosync.conf
totem {
version: 2
cluster_name: cluster_asterisk
secauth: off
transport: udpu
token: 5000 # <--- add this line with the proper value to your situation. The default value on Centos 7 is 1000, and the threshold is met at 80% of that value (so default is 800ms)
}
2. Sync file automatically to other node:
[root@node01 ~]# pcs cluster sync
3. Reload configuration (this will reload on both nodes automatically)
[root@node01 ~]# pcs cluster reload corosync
4. Check if changes are applied:
[root@node01 ~]# corosync-cmapctl | grep totem.token runtime.config.totem.token (u32) = 5000 runtime.config.totem.token_retransmit (u32) = 1190 runtime.config.totem.token_retransmits_before_loss_const (u32) = 4 totem.token (u32) = 5000
Incrasing might not help, if there are periodic freezes, for example, if the hypervisor takes VM backups periodically.
More Information
This guide is based on and more information can be found here:
http://www.alexlinux.com/asterisk-high-availability-cluster-with-pacemaker-on-centos-7/
https://clusterlabs.org/pacemaker/doc/en-US/Pacemaker/1.1/html/Clusters_from_Scratch/ch05.html
