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A Node represents a physical or virtual machine running cara-agent. Nodes self-register with the control plane on startup and send periodic heartbeats so the controller manager can track their health. The scheduler only assigns new projects to nodes whose state is Ready.

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Adding a node

Start cara-agent on the machine you want to add. Set SERVER_URL to point at your control plane and NODE_NAME to the name the node should register under: 
SERVER_URL=http://cara-server:8080 \
NODE_NAME=worker-01 \
  ./bin/cara-agent
The agent registers itself with the control plane on startup, then begins sending heartbeats and polling for work. You do not need to apply a manifest — registration is automatic. If you want to pre-create a node record manually (for example to set labels before the agent connects), apply a Node manifest:
node.yaml
apiVersion: caravanserai/v1
kind: Node
metadata:
  name: worker-01
  labels:
    caravanserai.io/zone: ed312
    caravanserai.io/region: north
spec:
  hostname: worker-01.local
  unschedulable: false

caractrl apply -f node.yaml

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Listing nodes

List all nodes in the cluster: 
caractrl get nodes
Example output: 
NAME        STATE     CONDITIONS   AGE
worker-01   Ready     Healthy      2h
worker-02   NotReady  NoHeartbeat  5m
worker-03   Draining  Unschedulable 10m
The STATE column reflects the high-level health summary computed by the controller manager.
StateMeaning
ReadyThe agent is heartbeating and the node accepts new project assignments.
NotReadyHeartbeats have stopped or a critical condition is present. The scheduler skips this node.
Drainingspec.unschedulable is true. Existing projects continue running, but no new projects are scheduled here.

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Inspecting a node

Get a single node’s table summary: 
caractrl get nodes worker-01
For the full status object including network details, capacity, allocatable resources, heartbeat timestamp, and conditions, use JSON output: 
caractrl --output json get nodes worker-01
Key fields in the output:
FieldDescription
status.stateHigh-level state: Ready, NotReady, or Draining.
status.network.ipOverlay network IP assigned to the node.
status.network.agentPortTCP port the agent’s HTTP server listens on (used by port-forward).
status.lastHeartbeatTimestamp of the most recent heartbeat from the agent.
status.capacityRaw physical resources reported by the agent.
status.allocatableCapacity minus system-reserved amounts; used by the scheduler.
status.conditionsList of granular observable conditions on the node.

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Draining a node

Draining prevents new projects from being scheduled onto a node while allowing existing projects to keep running. To drain a node, set spec.unschedulable: true in its manifest and apply it:
worker-01-drain.yaml
apiVersion: caravanserai/v1
kind: Node
metadata:
  name: worker-01
spec:
  unschedulable: true

caractrl apply -f worker-01-drain.yaml
The controller manager detects the change and transitions the node state to Draining. The scheduler stops assigning new projects to the node immediately. Projects already running on the node are unaffected — they continue running until you delete them or they expire. To make the node schedulable again, set spec.unschedulable: false and re-apply the manifest.

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Removing a node

Delete a node record from the control plane: 
caractrl delete node worker-01
Deleting a node does not automatically stop or migrate the projects running on it. If the node has projects in Running phase, those projects lose their agent and will transition to Failed once heartbeats stop. Delete or migrate all running projects before removing a node from the cluster.
After deletion, the node no longer appears in caractrl get nodes. If cara-agent is still running on the machine, it will attempt to re-register with the control plane on its next startup.

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Heartbeat monitoring

cara-agent sends a heartbeat to the control plane on a configurable interval (default: 30s). Each heartbeat updates status.lastHeartbeat and refreshes the node’s reported capacity and network status. The control plane watches lastHeartbeat. When the timestamp is older than the heartbeat timeout threshold (90 seconds), it sets the node state to NotReady and adds a NoHeartbeat condition. Common causes of missed heartbeats:
  • cara-agent process crashed or was stopped.
  • Network partition between the agent machine and cara-server.
  • The machine running the agent was powered off or rebooted.
Check status.lastHeartbeat to see when the agent last checked in: 
caractrl --output json get nodes worker-01

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Node labels

Add labels to a node to express zone, region, or hardware characteristics. You can use labels for documentation and future scheduling constraints. 
apiVersion: caravanserai/v1
kind: Node
metadata:
  name: worker-01
  labels:
    caravanserai.io/zone: ed312
    caravanserai.io/region: north
spec:
  hostname: worker-01.local
  unschedulable: false
Apply the updated manifest to patch the node’s labels: 
caractrl apply -f worker-01.yaml