moikot/metalogin repository overview

⁠Metalogin

Metalogin simplifies access to your lovely bare-metal Kubernetes cluster.

It receives necessary information from Kubernetes API node via SSH and creates a context in your local ~/.kube/config.

Literally, after executing this:

ssh -o StrictHostKeyChecking=no -o LogLevel=ERROR [user]@[cluster-IP] "sudo cat /etc/kubernetes/admin.conf" \
  | docker run -i --rm -v ~/.kube/:/kube moikot/metalogin -c /kube/config

You should be able to execute kubectl get nodes on your local machine. No installation, no fiddling with certificates, contexts or users. This command does require Docker though.

You can also build and run it locally if you have a Golang environment. In such case you need to run the following commands:

go get github.com/moikot/metalogin
ssh -o StrictHostKeyChecking=no -o LogLevel=ERROR [user]@[cluster-IP] "sudo cat /etc/kubernetes/admin.conf" | ~/go/bin/metalogin -c ~/.kube/config

⁠What it actually does

1. First of all, it receives config file from your Kubernetes API node and deserializes it.
2. It tries to find a cluster record in it with name kubernetes. This record corresponds to the bare-metal Kubernetes cluster.
3. It uses server field and assuming that it has a correct URI format, it tries to extract the server hostname. Usually, it's the IP address you used in the SSH call.
4. It creates a cluster record in the local configuration with name kubernetes-[host_name] where host_name is the hostname extracted on the previous step. All the other fields like certificate-authority-data and server are copied from the source record.
5. It tries to find a user record with name kubernetes-admin and when it succeeds it creates a user record in the local configuration with name kubernetes-admin-[host_name] and then copies content of client-certificate-data and client-key-data fields from the source.
6. It creates a context with name kubernetes-admin-[host_name]@kubernetes-[host_name] using previously created cluster and user.
7. Finally, it sets the created context as the current one.