Building a High-Availability Setup for Your HomeLab Using Keepalived

What You’ll Need

At least two servers or virtual machines (referred to as primary and backup nodes).
A Linux-based OS installed on both (Ubuntu 20.04 or newer is recommended).
A shared virtual IP address (VIP) for failover.

Step 1: Install Keepalived

Log into both nodes and update the system:
```
sudo apt update && sudo apt upgrade -y
```
Install Keepalived on both nodes:
```
sudo apt install -y keepalived
```
Verify the installation:
```
keepalived --version
```

Step 2: Configure Keepalived on the Primary Node

Edit the Keepalived configuration file:

sudo nano /etc/keepalived/keepalived.conf

Add the following configuration:

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass securepassword
    }
    virtual_ipaddress {
        192.168.1.100
    }
}

Replace eth0 with your network interface name (use ip a to find it).
Replace 192.168.1.100 with your desired virtual IP (VIP).
Use a secure password for auth_pass.

Restart Keepalived:
```
sudo systemctl restart keepalived
```
Enable Keepalived to start on boot:
```
sudo systemctl enable keepalived
```

Step 3: Configure Keepalived on the Backup Node

Edit the Keepalived configuration file:

sudo nano /etc/keepalived/keepalived.conf

Add the following configuration:

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass securepassword
    }
    virtual_ipaddress {
        192.168.1.100
    }
}

Ensure the state is set to BACKUP and priority is lower than the primary node.

Restart Keepalived:
```
sudo systemctl restart keepalived
```
Enable Keepalived to start on boot:
```
sudo systemctl enable keepalived
```

Step 4: Test the High-Availability Setup

Check the VIP on the primary node:
```
ip a | grep 192.168.1.100
```
The VIP should be bound to the primary node’s interface.
Simulate a failover:
- Stop Keepalived on the primary node:
```
sudo systemctl stop keepalived
```
- Check the VIP on the backup node:
```
ip a | grep 192.168.1.100
```
The VIP should now be assigned to the backup node.
Restart Keepalived on the primary node:
```
sudo systemctl start keepalived
```

Step 5: Monitor and Maintain

Check Keepalived logs for troubleshooting:
```
sudo journalctl -u keepalived
```
Verify that Keepalived is running:
```
sudo systemctl status keepalived
```
Update Keepalived and system packages regularly:
```
sudo apt update && sudo apt upgrade -y
```

FAQs

Q: Can I use Keepalived with multiple backup nodes?
A: Yes, Keepalived supports multiple backup nodes by assigning unique priorities to each one.

Q: Does Keepalived work with IPv6?
A: Yes, Keepalived supports both IPv4 and IPv6 addresses.

Q: How do I troubleshoot failover issues?
A: Check the following:

Logs in /var/log/syslog or journalctl.
Network configuration (correct interfaces and VIP settings).
Ensure the authentication auth_pass is identical on all nodes.

Q: Can I use Keepalived for load balancing?
A: Yes, Keepalived supports Layer 4 load balancing through the LVS (Linux Virtual Server) feature.

Q: How do I ensure the VIP is reachable across subnets?
A: Enable proxy ARP or configure static routes for the VIP.

Q: Can Keepalived monitor service health?
A: Yes, Keepalived can monitor services with health-check scripts and perform failover based on service availability.

By setting up Keepalived, you can create a highly available environment for critical services in your homelab. This ensures minimal downtime and a reliable infrastructure. Happy experimenting!

What You’ll Need#

Step 1: Install Keepalived#

Step 2: Configure Keepalived on the Primary Node#

Step 3: Configure Keepalived on the Backup Node#

Step 4: Test the High-Availability Setup#

Step 5: Monitor and Maintain#

FAQs#