This is a guide for running a private build agent on docker.

https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/docker?view=azure-devops

And this is a sample yaml file. Line 37 is mounting to docker.sock, https://github.com/ghoshasish99/AzureDevOps-SelfHostedAgents-AKS/blob/main/ReplicationController.yml#L37

Unfortunately this won't work on Kubernetes as stated in the article:

Caution

Doing this has serious security implications. The code inside the container can now run as root on your Docker host.

So, how else do you run a private build agent on Kubernetes?