Enabling the Load Balancer for the Kube API Server

Given below is an example configuration done on F5 devices and is needed only when we need to balance the load between multiple kube api servers in the case of multi DC support.

Prerequisite:

Create the TCP load balancer for Kube master API Server.

Note: This section is applicable only when the load balancer for the kube apiserver is not installed during the installation.

Sample Configuration:

Load balancer Configuration for Kube Master:

ltm virtual vs-appviewxmasterapi {
destination <IP Address>:sun-sr-https
ip-protocol tcp
mask XXX.XXX.XXX.XXX
pool pool-avxmasterapi
profiles {
fastL4 { }
}
serverssl-use-sni disabled
source 0.0.0.0/0
source-address-translation {
type automap
}
translate-address enabled
translate-port enabled
}

Pool Member Configuration for Kube Master

ltm pool pool-avxmasterapi {
 members {
 <Master Node IP Address>:sun-sr-https {
 address XXX.XXX.XXX.XXX
 session monitor-enabled
 state up
 }
 <Master Node IP Address>:sun-sr-https {
 address XXX.XXX.XXX.XXX
 session monitor-enabled
 state up
 }
 <Master Node IP Address>:sun-sr-https {
 address XXX.XXX.XXX.XXX
 session monitor-enabled
 state up
 }
 }
 monitor gateway_icmp
 }

To enable the load balancer for Kube Master:

To verify whether the load balancer is functioning normally, execute the curl command with endpoint /healthz or /version as shown below:
```
curl -k https://loadbalancer-ip:6443/healthz
```
Note: The /healthz endpoint should return an "OK" status, indicating that the Load Balancer is functioning properly and the API Server is reachable.
```
curl -k https://loadbalancer-ip:6443/version
```
Note: The /version endpoint may require an auhorizaiton. Using curl to access endpoints like /version without an authentication token will result in a 403 Forbidden error, as unauthenticated requests are not permitted.
Apply the latest script patch from the release portal.
Navigate to the <installerLocation>/appviewx_kubernetes/scripts/ directory.
Open the appviewx.conf file.
Search for the API_ADDRESS parameter.
Modify the value of the API_ADDRESS parameter to reflect the IP Address or the FQDN of the load balancer.
Navigate to the <installerLocation>/appviewx_kubernetes/scripts/loadbalancer/ directory.
To run the load balancer script, execute the following command:
```
./loadbalancer.sh
```
Enter the password of the nodes when prompted.
To verify the changes, execute the following command:
```
kubectl cluster-info
```
The output should contain the updated load balancer URL (IP Address or FQDN) of the kube API server.
Note: Once the LoadBalancer has been verified, proceed to delete the backup of the older control plane certificates using the following command:
```
rm -rf <actual_directory_path>/kubernetes_API_LB_backup_*
```
Replace <actual_directory_path> with the actual directory path.

Rollback Master LB

Modify the following parameters in the appviewx.conf file with the values as specified.
- API_ADDRESS = <IP of the Master Node>
- API_ADDRESS_LISTNER_PORT = 6443
Run the load balancer script, using the following command:
```
./loadbalancer.sh
```
Once the script completes successfully, execute the command below to confirm that the cluster is now pointing to the master IP.
```
kubectl cluster-info
```