MaxScale & Pacemaker on CentOS 7
------

Install packages on **both** nodes
```
sudo yum install corosync pcs pacemaker maxscale
```

Set the password for the hacluster user [both nodes]

```
sudo passwd hacluster
```

Start the pcs daemon service [both nodes]

```
sudo systemctl start pcsd
```

Authenticate the cluster

```
sudo pcs cluster auth node01.domain.local node02.domain.local
```

Create cluster

```
sudo pcs cluster setup --name clustername node01.domain.local node02.domain.local
```
* Example output

  ```
  Shutting down pacemaker/corosync services...
  Redirecting to /bin/systemctl stop  pacemaker.service
  Redirecting to /bin/systemctl stop  corosync.service
  Killing any remaining services...
  Removing all cluster configuration files...
  node01.domain.local: Succeeded
  node02.domain.local: Succeeded
  ```
* Check the changes in: `nano /etc/corosync/corosync.conf`

Start the cluster

```
sudo pcs cluster start --all
```

Check the cluster status

```
sudo pcs status cluster
sudo pcs status nodes
sudo corosync-cmapctl | grep members
sudo pcs status corosync
sudo crm_verify -L -V
```

Set quorum settings

```
sudo pcs property set stonith-enabled=false
sudo pcs property set no-quorum-policy=ignore
```
* Verify the properties with: `sudo pcs property`

Create a virtual IP resource called `virtual_ip`

```
sudo pcs resource create virtual_ip ocf:heartbeat:IPaddr2 \
 ip=10.10.10.123 cidr_netmask=24 \
 op monitor interval=30s
```

Check the resource status

```
sudo pcs status resources
```

Prevent Resources from Moving after Recovery

```
sudo pcs resource defaults resource-stickiness=100
```

* Confirm the resource defaults with `sudo pcs resource defaults`

Create maxscale service resource called `maxscale_service`

* Note: for maxscale 1.1.1 and older change `systemd` to `lsb` in the command below as the startup scripts are invoked via systemd in version 1.2 and newer.
```
sudo pcs resource create maxscale_service systemd:maxscale \
  op monitor interval="10s" timeout="15s" \
  op start interval="0" timeout="15s" \
  op stop interval="0" timeout="30s"
```

Let the cluster control maxscale on **both** nodes

```
sudo systemctl stop maxscale
```

* According to [maxscale guide](https://mariadb.com/blog/how-make-maxscale-high-available-corosyncpacemaker) disable maxscale from starting automatically on **both** nodes

  ```
  sudo systemctl disable maxscale
  ```

Create constraints so that the VIP and maxscale stay together

```
sudo pcs constraint colocation add maxscale_service virtual_ip INFINITY
```

* View constraints with `sudo pcs constraint list`
* If desired, to keep the maxscale from starting before the VIP is started on the server add an ordering constraint

  ```
  sudo pcs constraint order virtual_ip then maxscale_service
  ```

Restart the cluster

```
sudo pcs cluster stop --all && sudo pcs cluster start --all
```

Check the status

```
sudo pcs status
```

Enable cluster services on both nodes

```
sudo systemctl enable pcsd
sudo systemctl enable corosync
sudo systemctl enable pacemaker
```

# Troubleshooting / Status

* Check cluster status with `sudo pcs status`
* Stop a node (force a failover) with `sudo pcs cluster stop node.domain.local`
* Start a node with `sudo pcs cluster start node.domain.local`

# Sources:

* [Clusterlabs official documentation](http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html/Clusters_from_Scratch/index.html)
* [Simple guide to getting this running with Apache](http://jensd.be/?p=156)
* [MariaDB documentation for EL 6](https://mariadb.com/blog/how-make-maxscale-high-available-corosyncpacemaker)