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Initialization of On-Premise cluster provider

List of main attributes of the RMK configuration

name: rmk-test-develop # RMK config name, a unique identifier which consists of the project (tenant) name and the abbreviated name of the Git branch.
tenant: rmk-test # Tenant name, which is equivalent to the project name.
environment: develop # Environment name.
root-domain: rmk-test-develop.edenlab.dev # Root domain name used across the cluster.
cluster-provider: onprem # Selected cluster provider.
# ...
onprem:
  ssh-init-server-host: 10.1.1.10 # K3S init server host.
  ssh-private-key: /home/user/.ssh/id_rsa # Absolute path to SSH private key file. 
  ssh-user: user # SSH user.
# ...

Prerequisites

⚠ Important

The On-Premise provider is fundamentally different from cloud providers like AWS, Azure, GCP.

It requires manual preparation and configuration the underlying machines (bare-metal or VMs), low-level understanding of how Kubernetes and K3S behave in a non-cloud setup (control plane bootstrap, agents joining, resource planning, scheduling, etc.).

Additionally, you must ensure correct networking rules (firewall, routing, node-to-node connectivity).

  1. OS:

  2. Disk and filesystem:

    • Nodes should provide a dedicated disk or partition for container storage (optional but recommended).

  3. System user:

    • Shared system user must exist on all cluster nodes.
    • Requires sudo privileges without password prompt.

  4. SSH access:

    • SSH connectivity from the administrator machine to all cluster nodes must be available.
    • SSH authentication is done via a private key.
    • An absolute path to the private key must be specified during configuration initialization, or RMK will attempt to use the default path (e.g., ~/.ssh/id_[ed25519|rsa|ecdsa|dsa]).

  5. Networking:

    • Firewall must allow full bidirectional connectivity between all cluster nodes.
    • Required ports include (but are not limited to):

  6. DNS resolution:

    • If hostnames are used in the operator/K3S’s configuration, they must resolve to correct internal IPs using DNS.
    • Alternatively, configure /etc/hosts on all cluster nodes.

  7. K3S init server host:

    • An IP address must be allocated for the bootstrap control plane node (used by other nodes when joining the cluster).

Configuration

The 2 supported configuration scenarios are:

  • via RMK flags: 
    rmk config init --cluster-provider=onprem \
  --onprem-ssh-init-server-host=<k3s_init_server_ip> \
  --onprem-ssh-private-key=<ssh_private_key_path> \
  --onprem-ssh-user=<ssh_user>
  • via environment variables: RMK_ONPREM_SSH_INIT_SERVER_HOST, RMK_ONPREM_SSH_PRIVATE_KEY, RMK_ONPREM_SSH_USER. 
    export RMK_ONPREM_SSH_INIT_SERVER_HOST=<k3s_init_server_ip>
export RMK_ONPREM_SSH_PRIVATE_KEY=<ssh_private_key_path>
export RMK_ONPREM_SSH_USER=<ssh_user>
rmk config init --cluster-provider=onprem

If an environment variable or flag specifies a custom SSH private key, RMK will copy that key into the default SSH location (using the same file name), and will use it for subsequent operations.

If CLI flags are provided, RMK will prioritize them over environment variables, as CLI flags take precedence.

Reconfiguration of the On-Premise SSH private key

Modify the value of a specific flag if changes are needed:

rmk config init --onprem-ssh-private-key=<new_ssh_private_key_path>
Last update: September 19, 2025