Should your Docker containers auto-update or just notify you? Watchtower and DIUN take fundamentally different approaches.
Quick Verdict
DIUN is the safer choice for most self-hosters. It notifies you when updates are available without touching your running containers, giving you full control over when and how you update. Watchtower is for people who want fully automatic updates and accept the risk that an unattended update could break a service.
Overview
Watchtower monitors your running Docker containers and automatically updates them when a new image is pushed to the registry. It pulls the new image, stops the old container, and restarts it with the same configuration. There is no web UI — it runs as a background daemon.
DIUN (Docker Image Update Notifier) monitors Docker images for updates and sends notifications through your preferred channel (Discord, Slack, Telegram, email, webhooks, and 15+ more). It never pulls images or restarts containers. You get notified, you decide what to do.
These tools have fundamentally different philosophies. Watchtower automates the entire update lifecycle. DIUN automates only the detection and notification. The question is whether you trust unattended updates.
Feature Comparison
| Feature | Watchtower | DIUN |
|---|---|---|
| Update detection | Yes — checks registries on schedule | Yes — checks registries on schedule |
| Automatic container updates | Yes — pull, stop, restart | No — notification only |
| Notification channels | Email, Slack, MS Teams, Gotify, Shoutrrr | 15+ channels: Discord, Slack, Telegram, email, Matrix, Gotify, Ntfy, webhooks, and more |
| Label-based filtering | Yes — include/exclude by label | Yes — include/exclude by label |
| Per-container control | Yes — enable/disable updates per container | Yes — monitor specific containers |
| Private registry support | Yes | Yes |
| Schedule/cron support | Yes — cron syntax | Yes — cron syntax |
| Monitor non-running images | No — only running containers | Yes — can watch any image tag |
| Multi-platform image support | Basic | Yes — tracks multiple architectures |
| Digest-based tracking | Yes | Yes — tracks manifests and digests |
| Metadata in notifications | Basic — container name, old/new image | Rich — image name, tag, digest, platform, link to registry |
| Cleanup old images | Yes — --cleanup flag |
No (not its job) |
| Rolling restart | No — stop then start | N/A |
| Run once mode | Yes — --run-once flag |
Yes — --test-notif for testing |
| Web UI | No | No |
| License | Apache 2.0 | MIT |
Installation Complexity
Both are single-container deployments with Docker socket access. Installation is equally simple.
Watchtower needs only the Docker socket mount and optional environment variables for notifications and scheduling. Minimal config — it works with zero env vars (default: check every 24 hours, update everything).
DIUN requires a config file or environment variables to set up notification providers. The initial setup is slightly more involved because you need to configure at least one notification channel, but the config format is straightforward YAML.
Performance and Resource Usage
| Metric | Watchtower | DIUN |
|---|---|---|
| Idle RAM | ~15-25 MB | ~20-30 MB |
| During check | ~30-50 MB | ~30-50 MB |
| CPU usage | Minimal (spikes during checks) | Minimal (spikes during checks) |
| Docker image size | ~15 MB | ~20 MB |
Both are extremely lightweight. Resource usage is negligible on any system. Neither has a web UI, so there is no frontend overhead.
Community and Support
| Metric | Watchtower | DIUN |
|---|---|---|
| GitHub stars | 19K+ | 3K+ |
| First release | 2015 | 2019 |
| Maintainer | containrrr team | crazy-max (single, very active) |
| Release cadence | Regular | Regular |
| Documentation | Good README + docs site | Excellent — detailed docs site |
Watchtower has higher name recognition and more stars, but DIUN's documentation is better organized and covers more edge cases. Both are actively maintained as of 2026.
Use Cases
Choose Watchtower If...
- You want fully automatic, hands-off container updates
- You run non-critical services where brief downtime during updates is acceptable
- You pin image tags and use Watchtower only for patch updates within a tag
- You want the simplest possible "set and forget" update solution
- You are comfortable with the risk of an update breaking a service while you are away
Choose DIUN If...
- You want to control exactly when updates happen
- You run services where unexpected restarts cause data loss (databases, media servers mid-transcode)
- You want rich notifications with update details before deciding to update
- You need to monitor images that are not currently running
- You run production or semi-production workloads
- You use a notification platform (Discord, Telegram, Ntfy) and want update alerts in your existing workflow
FAQ
Can I use both together?
Yes, but it is redundant. If you use Watchtower for auto-updates, you already know updates are happening. If you want notification before automatic updates, configure Watchtower's built-in notifications. Using DIUN alongside Watchtower adds no value.
Is Watchtower dangerous?
It can be. Automatic updates can break your services — a new image might have breaking changes, bugs, or incompatible config. Watchtower has no rollback mechanism. If an update breaks something, you need to manually pull the old image and redeploy. This is why many experienced self-hosters prefer DIUN's notify-only approach.
Can Watchtower be set to monitor-only mode?
Yes — use the --monitor-only flag. In this mode, Watchtower checks for updates and sends notifications but does not pull or restart containers. This effectively makes it behave like DIUN, though DIUN has better notification options.
What about Ouroboros as an alternative?
Ouroboros was a similar auto-update tool but has been abandoned. Use Watchtower or DIUN instead.
Final Verdict
DIUN is the better tool for most self-hosters. Automatic updates sound convenient, but unattended container restarts are a real risk — especially for stateful services like databases, media servers, and file sync tools. DIUN gives you awareness without risk. You see the update, you read the changelog, you update when ready.
Use Watchtower only if you are fully committed to automatic updates and accept the tradeoffs. Even then, use label filtering to exclude critical services from auto-updates and only let Watchtower manage low-risk containers.
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