---
sidebar_position: 4
title: Multi-Node Cluster
description: Master-Agent mode — route backups to remote servers via HTTP long-polling.
---

# Multi-Node Cluster

BackupX supports Master-Agent mode: backup tasks can be routed to specific nodes. The Agent runs the backup locally and uploads straight to storage. All connections are initiated by the Agent, so remote networks only need outbound HTTP access.

## Architecture

```
[Web Console] ─── JWT ──→ [Master (backupx)]
                              ↑  ↓
                              │  │ HTTP long-poll (token auth)
                              │  ↓
                         [Agent (backupx agent)]   ← runs on remote host
                              ↓
                     [70+ Storage Backends]
```

- **Protocol** — HTTP long-polling; the Agent initiates every connection
- **Heartbeat** — Agent reports every 15s; Master marks nodes offline after 45s of silence
- **Dispatch** — Master persists `run_task` commands to a queue; Agent polls and claims them
- **Execution** — Agent reuses the same BackupRunner (file / mysql / postgresql / sqlite / saphana) and uploads directly to storage
- **Security** — Each node has its own token; the Agent never holds the Master's JWT secret or AES-256 key

## Walkthrough

### 1. Open the install wizard

In the Web Console → **Node Management** → **Add Node**. You'll see a three-step wizard.

- **Step 1 — Node info.** Give the node a name, or switch to batch mode and paste multiple names (one per line, max 50).
- **Step 2 — Deploy options.** Pick install mode (`systemd` recommended, `docker`, or `foreground` for debugging), architecture (auto-detect by default), agent version (defaults to the master's version), TTL for the install link (5 min / 15 min / 1 h / 24 h), and download source (`github` direct, or the `ghproxy` mirror for mainland China).
- **Step 3 — Copy the command.** A one-line install command is shown with a live countdown. Click copy, paste into the target machine, and run with root privileges. The default command embeds the rendered installer, so the target host does not need to fetch `/api/install/:token` through your reverse proxy. The public install URL is still available as a fallback.

### 2. One-line install on the target host

Use the command generated by the Web Console. It writes the installer to a temporary file, validates the `BACKUPX_AGENT_INSTALL_V1` marker, then runs it with root privileges.

The script runs automatically and:

1. Detects OS and architecture (`uname -m`)
2. Downloads the matching `backupx` binary from GitHub Release (or the ghproxy mirror)
3. Installs to `/opt/backupx-agent` and creates a `backupx` system user
4. Writes `/etc/systemd/system/backupx-agent.service` with the token baked into environment variables
5. Runs `systemctl enable --now backupx-agent`
6. Polls `/api/v1/agent/self` until the master confirms `status: online` (up to 30 s)

If you choose the URL-based fallback command and `curl` prints HTML or the shell reports `Syntax error: newline unexpected`, the install URL is being served by the web console instead of the backend. Ensure either `/api/install/` or `/install/` is forwarded to the BackupX backend, or use the embedded command generated by the console.

Reruns are idempotent — to upgrade or re-provision, simply generate a new install command and run it again. The one-time install link expires after its TTL or after first consumption, whichever is sooner.

### 3. Rotate agent tokens at any time

Go to the node's action menu (︙) → **Rotate Token**. The new token is shown once and the old token remains valid for 24 h, allowing rolling restarts without downtime. After 24 h, the old token is rejected.

### 4. Batch deployment

In Step 1 choose "Batch" and paste node names (one per line, max 50). Step 3 shows a table with one command per node plus a **Download .sh** button that bundles all commands into a shell script, convenient for SSH loops or Ansible tasks.

### 5. Route a task to the node

In the **Backup Tasks** page, pick the target node when creating the task. When the task runs:

- Local (`nodeId=0`) → Master executes in-process
- Remote node → Master enqueues the command → Agent claims → Agent runs locally → uploads → reports back

## Known limitations

- **Encrypted backups don't work via Agent** — the Agent doesn't hold Master's AES-256 key. Tasks with `encrypt: true` will fail if routed to an Agent
- **Directory browser timeout** — remote dir listing is a synchronous RPC through the queue (15s default)
- **Dispatched command timeout** — claimed-but-unfinished commands are marked `timeout` after 10 minutes

## CLI reference

```
backupx agent --help
  -master string    Master URL
  -token string     Agent auth token
  -config string    YAML config path (takes precedence over env)
  -temp-dir string  Local temp directory (default /tmp/backupx-agent)
  -insecure-tls     Skip TLS verification (testing only)
```

## systemd unit

```ini title="/etc/systemd/system/backupx-agent.service"
[Unit]
Description=BackupX Agent
After=network.target

[Service]
Type=simple
User=backupx
Environment="BACKUPX_AGENT_MASTER=https://master.example.com"
Environment="BACKUPX_AGENT_TOKEN=your-token"
ExecStart=/opt/backupx/backupx agent
Restart=on-failure
RestartSec=10s

[Install]
WantedBy=multi-user.target
```

Enable and start:

```bash
sudo systemctl enable --now backupx-agent
sudo journalctl -u backupx-agent -f
```
