---
title: Rancher Agents
---

<head>
  <link rel="canonical" href="https://ranchermanager.docs.rancher.com/how-to-guides/new-user-guides/launch-kubernetes-with-rancher/about-rancher-agents"/>
</head>

There are two different agent resources deployed on Rancher managed clusters:

- [cattle-cluster-agent](#cattle-cluster-agent)
- [cattle-node-agent](#cattle-node-agent)

For a conceptual overview of how the Rancher server provisions clusters and communicates with them, refer to the [architecture](../../../reference-guides/rancher-manager-architecture/rancher-manager-architecture.md).

### cattle-cluster-agent

The `cattle-cluster-agent` is used to connect to the Kubernetes API of [Rancher Launched Kubernetes](launch-kubernetes-with-rancher.md) clusters. The `cattle-cluster-agent` is deployed using a Deployment resource.  It will always prefer control plane nodes over workers.

### cattle-node-agent

The `cattle-node-agent` is used to interact with nodes in a [Rancher Launched Kubernetes](launch-kubernetes-with-rancher.md) cluster when performing cluster operations. Examples of cluster operations are upgrading Kubernetes version and creating/restoring etcd snapshots. The `cattle-node-agent` is used as fallback option to connect to the Kubernetes API of [Rancher Launched Kubernetes](launch-kubernetes-with-rancher.md) clusters when `cattle-cluster-agent` is unavailable. The `cattle-node-agent` is deployed using a DaemonSet resource to make sure it runs on every node.

### Scheduling rules

The `cattle-cluster-agent` uses a fixed set of tolerations (listed below, if no controlplane nodes are visible in the cluster) or dynamically added tolerations based on taints applied to the controlplane nodes such that if controlplane nodes are present in the cluster, the cluster agent's tolerations will be replaced with tolerations matching the taints on the controlplane nodes. This structure allows for [Taint based Evictions](https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration/#taint-based-evictions) to work properly for `cattle-cluster-agent`. The default tolerations are described below:

| Component              | nodeAffinity nodeSelectorTerms             | nodeSelector | Tolerations                                                                    |
| ---------------------- | ------------------------------------------ | ------------ | ------------------------------------------------------------------------------ |
| `cattle-cluster-agent` | `beta.kubernetes.io/os:NotIn:windows`      | none         | **Note:** These are the default tolerations, and will be replaced by tolerations matching taints applied to controlplane nodes.<br/><br/>`effect:NoSchedule`<br/>`key:node-role.kubernetes.io/controlplane`<br/>`value:true`<br/><br/>`effect:NoSchedule`<br/>`key:node-role.kubernetes.io/control-plane`<br/>`operator:Exists`<br/><br/>`effect:NoSchedule`<br/>`key:node-role.kubernetes.io/master`<br/>`operator:Exists` |
| `cattle-node-agent`    | `beta.kubernetes.io/os:NotIn:windows`      | none         | `operator:Exists`                                                              |

The `cattle-cluster-agent` Deployment has preferred scheduling rules using `preferredDuringSchedulingIgnoredDuringExecution`, favoring to be scheduled on nodes with the `controlplane` node. When there are no controlplane nodes visible in the cluster (this is usually the case when using [Clusters from Hosted Kubernetes Providers](../kubernetes-clusters-in-rancher-setup/set-up-clusters-from-hosted-kubernetes-providers/set-up-clusters-from-hosted-kubernetes-providers.md)), you can add the label `cattle.io/cluster-agent=true` on a node to prefer scheduling the `cattle-cluster-agent` pod to that node.

See [Kubernetes: Assigning Pods to Nodes](https://kubernetes.io/docs/concepts/configuration/assign-pod-node/) to find more information about scheduling rules.

The `preferredDuringSchedulingIgnoredDuringExecution` configuration is shown in the table below:

| Weight | Expression                                       |
| ------ | ------------------------------------------------ |
| 100    | `node-role.kubernetes.io/controlplane:In:"true"` |
| 100    | `node-role.kubernetes.io/control-plane:In:"true"` |
| 100    | `node-role.kubernetes.io/master:In:"true"` |
| 1      | `cattle.io/cluster-agent:In:"true"`         |

