Configure Consul in a Cluster¶

The Consul processes of all PLOSSYS 5 servers in a cluster have to be connected for cross-server service discovery and system configuration. If one PLOSSYS 5 server fails, the entire system remains functional.

Backup the Configuration¶

If you expand an already existent PLOSSYS 5 single server to a cluster, first export the configuration of PLOSSYS 5.

Perform the following configuration step on <server_1>:

plossys config export <plossys_5_backup>.yml

Hint - more options

For more information about the export via PLOSSYS CLI, refer to Administrate the System Configuration.

Adjust the Consul Services¶

Perform the following configuration steps on <server_1>, <server_2> and <server_3>:

Stop PLOSSYS 5
Open the Consul configuration file:
```
/opt/seal/etc/consul.json
```
Delete the following line:
```
"bind_addr": "127.0.0.1",
```
Hint - multiple network interfaces

If a server has several network interfaces with private IP addresses, do not delete the complete line but replace 127.0.0.1 with the appropriate IP address.
Search for the following line:
```
"bootstrap_expect": 1,
```
and replace it by the following line:
```
"bootstrap_expect": 3,
```
Add the following line at any position:
```
"retry_join": ["<server_1>", "<server_2>", "<server_3>"]
```
Caution - JSON structure

Pay attention to keep the JSON structure in the configuration file! For further information, refer to http://json.org/json-de.html.
Save the file.

Delete the contents of the following directory:

sudo rm -r /opt/seal/data/seal-consul-agent/raft

Start PLOSSYS 5.

Import the Backup of the Configuration¶

After the configuration has been changed on all PLOSSYS 5 servers, Consul runs in the cluster mode. Now, the backup of the configuration can be imported.

Hint - only one server

The configuration has to be imported on one PLOSSYS 5 server only due to the configuration is automatically update on all PLOSSYS 5 servers belonging to a cluster.

Perform the following configuration step on <server_1>:

plossys config import <plossys_5_backup>.yml

Hint - more options

For more information about the import via PLOSSYS CLI, refer to Administrate the System Configuration.