---
title: Edge Failover
slug: solutions/edge-failover
docTags: 
createdAt: 2025-09-10T22:05:28.846Z
---

# Edge Failover - User Guide

## What Does This Solution Do?

This Docker container provides an automated backup system for edge computing devices. Think of it as a "smart switch" that automatically activates a backup device when your primary device stops working.

## The Problem It Solves

In industrial or remote environments, edge devices are critical for operations. When the main device fails, you need a backup to take over immediately to avoid downtime. Manually switching to a backup device can be slow and requires someone to be available 24/7.

## How It Works (Simple Version)

If you have two identical Edge Devices:

- **Parent Edge Device** (Primary): Handles your normal operations
- **Child Edge Device** (Backup): Sits idle, ready to help

This service acts like a "watchdog" that:

1. **Continuously monitors** Parent Edge Device via either PING or some equivalent API call to make sure it's working
2. **Copies the settings** from Parent Edge Device regularly (like backing up your phone contacts)
3. **When Parent Edge Device fails**: Automatically configures Child Edge Device with the same settings and puts it to work
4. **When Parent Edge Device comes back**: Switches back to monitoring Parent Edge Device and cleans up Child Edge Device

## What You Need to Provide

To run this container, you need to tell it:

- **Where is Parent Edge Device?** (`https://{Parent Edge Device URL}`)
- **Where is Child Edge Device?** (`https://{Child Edge Device URL}`)
- **How to connect to both Edge Devices** (API Keys)
- **PING\_INTERVAL aka How often to check** if Parent Edge Device is working (optional, defaults to every 30 seconds)

## Setting Up the Container

### Step 1: Prepare Your Information

- Parent Edge Device's web address
- Child Edge Device's web address
- Parent Edge Device's access token
- Child Edge Device's access token

### Step 2: Run the Container

Use Docker to start the container with your information:

(Please contact your Litmus representative for the docker image)

```bash
docker run -d \
  -e EDGE_URL_PARENT=https://{Parent Device URL} \
  -e EDGE_URL_CHILD=https://{Child Device URL} \
  -e EDGE_API_TOKEN_PARENT=parent_device_api_key \
  -e EDGE_API_TOKEN_CHILD=child_device_api_key \
  -e PING_INTERVAL=30 \
  {docker_image_name}:{latest}
```

## What Happens Next

Once running, the container will:

### Normal Operation (Both Edge Devices working)

- Check Parent Edge Device every 30 seconds: "Are you okay?"
- Parent Edge Device responds: "Yes, I'm working fine"
- Copy Parent Edge Device's current settings every few minutes
- Keep Child Edge Device on standby

### When Parent Edge Device Fails

- Check Parent Edge Device: "Are you okay?"
- No response from Parent Edge Device
- **ALERT**: "Parent Edge Device is down! Activating backup!"
- Copy all of Parent Edge Device's settings to Child Edge Device
- Child Edge Device starts handling the work

### When Parent Edge Device Recovers

- Check Parent Edge Device: "Are you okay?"
- Parent Edge Device responds: "Yes, I'm back!"
- **SWITCH BACK**: "Parent Edge Device is healthy again!"
- Clean up Child Edge Device (remove the copied settings)
- Parent Edge Device takes over the work again

## What You'll See in the Logs

The container will show you messages like:

- `"Parent is healthy"` - Everything is normal
- `"Parent is down - applying template to child"` - Backup is activating
- `"Parent is back online - cleaning up child"` - Switching back to main
- `"Successfully fetched template with X keys"` - Settings copied successfully

## Important Notes

### Data Storage

- The container saves Parent Edge Device's settings to disk
- If the container restarts, it can still use the saved settings
- You can optionally mount a folder to preserve these settings

### Network Requirements

- The container needs internet access to reach both Edge Devices
- Both Edge Devices need to be accessible via web addresses (HTTPS)
- The container acts as a "middle-man" between your two Edge Devices

### Security

- All communication uses secure HTTPS connections
- Your access tokens are kept private within the container
- No sensitive information is logged to the console

## Common Scenarios

### Scenario 1: Planned Maintenance

1. You need to update Parent Edge Device
2. Turn off Parent Edge Device
3. Container automatically switches to Child Edge Device
4. Do your maintenance on Parent Edge Device
5. Turn Parent Edge Device back on
6. Container automatically switches back

### Scenario 2: Unexpected Failure

1. Parent Edge Device crashes or loses network connection
2. Within 30 seconds, Container detects the problem
3. Container activates Child Edge Device immediately
4. Your operations continue without manual intervention
5. When Parent Edge Device is fixed, switching back happens automatically

### Scenario 3: Network Issues

1. If the container can't reach Parent Edge Device due to network problems
2. It assumes Parent Edge Device is down and activates Child Edge Device
3. When network is restored, it switches back to Parent Edge Device

## Troubleshooting

If something isn't working:

1. **Check the logs** - The container will tell you what's happening
2. **Verify addresses** - Make sure both Edge Device addresses are correct and reachable
3. **Check tokens** - Ensure access tokens are valid and have proper permissions
4. **Network connectivity** - Confirm the container can reach both Edge Devices

## Changelog

### v1.3.0

- Introduce cross compatibilty of integrations across multiple versions of LE

### v1.2.1

- Added general purpose documentation
- Fixed Logs being too noisy
- Fixes for more issues with devices not cleaned properly to the child device

### v1.2.0

- Fixed corner case logical issues with cleanup of Devices extracted from template
- Fixes for CC template application due to discrepancy in GET template call and POST template call

### v1.1.1

- Force Default PING interval to be minimum 30 seconds

### v1.1.0

- Added Default directory as `/data/` instead of `/tmp` for storing template from Parent device
- Clean up methods for extracting Parent and Child URLs
- Add skip components mechanism for any component other than integrations and DeviceHub for a faster template application

### v1.0.1

- Fix issues with HTTP timeouts to Parent device when downloading template
  - Added longer default timeout

### v1.0.0

- Initial Application ready
- Basic functionality of fetch and store template, apply template, Logic for when to apply templates