Kustomize is a tool which builds a complete deployment file for all config elements. You can edit the files in the uptime-kuma folder except the kustomization.yml until you know what you're doing. If you want to choose another namespace you can edit the kustomization.yml in the kubernetes-Folder and change the namespace: uptime-kuma to something you like.

It creates a certificate with the specified Issuer and creates the Ingress for the Uptime-Kuma ClusterIP-Service

What do i have to edit?

You have to edit the ingressroute.yml to your needs. This ingressroute.yml is for the nginx-ingress-controller in combination with the cert-manager.

host
secrets and secret names
(Cluster)Issuer (optional)
the Version in the Deployment-File
- update:
  - change to newer version and run the above commands, it will update the pods one after another

How To use:

install kustomize
Edit files mentioned above to your needs
run kustomize build > apply.yml
run kubectl apply -f apply.yml

Now you should see some k8s magic and Uptime-Kuma should be available at the specified address.