Pulse/docs/KUBERNETES.md

# Pulse on Kubernetes

This guide explains how to deploy the Pulse Server (Hub) and Pulse Agents on Kubernetes clusters, including immutable distributions like Talos Linux.

## Prerequisites

*   A Kubernetes cluster (v1.19+)
*   `helm` (v3+) installed locally
*   `kubectl` configured to talk to your cluster

## 1. Deploying the Pulse Server

The Pulse Server is the central hub that collects metrics and manages agents.

### Option A: Using Helm (Recommended)

1.  Add the Pulse Helm repository:
    ```bash
    helm repo add pulse https://rcourtman.github.io/Pulse
    helm repo update
    ```

2.  Install the chart:
    ```bash
    helm upgrade --install pulse pulse/pulse \
      --namespace pulse \
      --create-namespace \
      --set persistence.enabled=true \
      --set persistence.size=10Gi
    ```

    > **Note**: For production, ensure you configure a proper `storageClass` or `deployment.strategy.type=Recreate` if using ReadWriteOnce (RWO) volumes.

### Option B: Generating Static Manifests (For Talos / GitOps)

If you cannot use Helm directly on the cluster (e.g., restricted Talos environment), you can generate standard Kubernetes YAML manifests:

```bash
helm repo add pulse https://rcourtman.github.io/Pulse
helm repo update
helm template pulse pulse/pulse \
  --namespace pulse \
  --set persistence.enabled=true \
  > pulse-server.yaml
```

You can then apply this file:

```bash
kubectl apply -f pulse-server.yaml
```

## 2. Deploying the Pulse Agent

### Important: Helm Chart Agent Is Legacy Docker-Only

The Helm chart includes an `agent` section, but it deploys the **deprecated** `pulse-docker-agent` (Docker socket metrics only). It does **not** deploy the unified `pulse-agent`.

If you need the unified agent on Kubernetes, use a custom DaemonSet as shown below.

### Unified Agent on Kubernetes (DaemonSet)

To monitor Kubernetes resources, run the unified agent as a DaemonSet and enable the Kubernetes module.

**Recommended options:**
- **Kubernetes-only monitoring**: `PULSE_ENABLE_KUBERNETES=true` and `PULSE_ENABLE_HOST=false` (no host mounts required).
- **Kubernetes + node metrics**: `PULSE_ENABLE_KUBERNETES=true` and `PULSE_ENABLE_HOST=true` (requires host mounts and privileged mode).

#### Minimal DaemonSet Example

This uses the main `rcourtman/pulse` image but runs the `pulse-agent` binary directly.

```yaml
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: pulse-agent
  namespace: pulse
spec:
  selector:
    matchLabels:
      app: pulse-agent
  template:
    metadata:
      labels:
        app: pulse-agent
    spec:
      serviceAccountName: pulse-agent
      containers:
        - name: pulse-agent
          image: rcourtman/pulse:latest
          command: ["/usr/local/bin/pulse-agent"]
          args:
            - --enable-kubernetes
          env:
            - name: PULSE_URL
              value: "http://pulse-server.pulse.svc.cluster.local:7655"
            - name: PULSE_TOKEN
              value: "YOUR_API_TOKEN_HERE"
            - name: PULSE_ENABLE_HOST
              value: "false"
          securityContext:
            readOnlyRootFilesystem: true
            allowPrivilegeEscalation: false
          resources: {}
```

Use a token scoped for the agent:
- `kubernetes:report` for Kubernetes reporting
- `host-agent:report` if you enable host metrics

#### Add Host Metrics (Optional)

If you want node CPU/memory/disk metrics, add privileged mode plus host mounts:

```yaml
          env:
            - name: PULSE_ENABLE_HOST
              value: "true"
            - name: HOST_PROC
              value: "/host/proc"
            - name: HOST_SYS
              value: "/host/sys"
            - name: HOST_ETC
              value: "/host/etc"
          securityContext:
            privileged: true
          volumeMounts:
            - name: host-proc
              mountPath: /host/proc
              readOnly: true
            - name: host-sys
              mountPath: /host/sys
              readOnly: true
            - name: host-root
              mountPath: /host/root
              readOnly: true
      volumes:
        - name: host-proc
          hostPath:
            path: /proc
        - name: host-sys
          hostPath:
            path: /sys
        - name: host-root
          hostPath:
            path: /
```

#### RBAC

The Kubernetes agent uses the in-cluster API and needs read access to cluster resources (nodes, pods, deployments, etc.). Create a read-only `ClusterRole` and bind it to the `pulse-agent` service account.

```yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  name: pulse-agent
  namespace: pulse
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: pulse-agent-read
rules:
  - apiGroups: [""]
    resources: ["nodes", "pods"]
    verbs: ["get", "list", "watch"]
  - apiGroups: ["apps"]
    resources: ["deployments"]
    verbs: ["get", "list", "watch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: pulse-agent-read
subjects:
  - kind: ServiceAccount
    name: pulse-agent
    namespace: pulse
roleRef:
  kind: ClusterRole
  name: pulse-agent-read
  apiGroup: rbac.authorization.k8s.io
```

## 3. Talos Linux Specifics

Talos Linux is immutable, so you cannot install the agent via the shell script. Use the DaemonSet approach above.

### Agent Configuration for Talos
*   **Storage**: Talos mounts the ephemeral OS on `/`. Persistent data is usually in `/var`. The Pulse agent generally doesn't store state, but if it did, ensure it maps to a persistent path.
*   **Network**: The agent will report the Pod IP by default. To report the Node IP, set `PULSE_REPORT_IP` using the Downward API:

    Add this to the DaemonSet `env` section:
    ```yaml
    - name: PULSE_REPORT_IP
      valueFrom:
        fieldRef:
          fieldPath: status.hostIP
    ```

## 4. Troubleshooting

*   **Agent not showing in UI**: Check logs for the DaemonSet pods, for example: `kubectl logs -l app=pulse-agent -n pulse`.
*   **"Permission Denied" on metrics**: Ensure `securityContext.privileged: true` is set or proper capabilities are added.
*   **Connection Refused**: Ensure `PULSE_URL` is correct and reachable from the agent pods.