📅 Sync ICS Feeds to Your CalDAV Calendar with Emojis, Deduplication, and Docker

If you’re like me and obsessively track everything — from Austrian public holidays to Formula 1 races and even trash pickup days — you know how painful it can be managing all of that across calendars.

So I built a simple solution: a Python-based tool that syncs ICS feeds directly into a CalDAV calendar (like mailbox.org), complete with:

• ✅ Emoji support
• ✅ Deduplication of events
• ✅ Location-based filtering for Austria
• ✅ Docker support
• ✅ Dry-run mode so nothing breaks 🔥

🎥 Check out the console output in action

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💡 Why I Built This

There are lots of calendar tools, but none let me do exactly what I wanted:

• Pull in multiple .ics feeds
• Filter events based on location (e.g., only Kärnten, Steiermark)
• Add emojis to event names (🗑️ for trash, 🇦🇹 for public holidays)
• Avoid duplicate imports (using UID hashing)
• Easily run as a scheduled task on my Synology NAS

It started as a quick utility for my own use. Now it’s open source and available for anyone to use!

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🛠️ Features at a Glance

• 🔁 Sync any .ics feed to CalDAV
• 📅 All-day events handled properly
• 🇦🇹 Support for Austrian public holiday feed, with filtering by Bundesland
• 🧠 Deterministic UID generation using hashed content
• 🛑 Dry-run support to preview changes
• 🐳 Docker & Docker Compose support
• 💥 Built-in cleanup option for previously imported events

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🔧 How It Works

1. Loads your config.json with ICS feeds and emoji mappings
2. Connects to your CalDAV calendar (e.g., mailbox.org)
3. Checks for duplicate events using a unique hash-based UID
4. Applies emoji mappings to the event title
5. Filters events based on date range and, if set, import_locations
6. Imports events, replacing duplicates if needed

You can even preview everything with:

docker-compose run --rm calendar-sync --import --dry-run

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✍️ Example Config

{
  "caldav_url": "https://dav-sso.mailbox.org/caldav/...",
  "username": "you@mailbox.org",
  "password": "your-app-password",
  "timezone": "Europe/Vienna",
  "uid_prefix": "ICS-",
  "future_event_limit_days": 365,
  "ics_feeds": [
    {
      "url": "https://example.com/feiertage.ics",
      "import_locations": "K,St",
      "emoji_mapping": {
        "§": "🇦🇹",
        "default": "🗓️"
      }
    }
  ]
}

If you set "import_locations": "K,St", the log output will show you which events are skipped due to unmatched regions like this:

INFO: ⏭️ Skipping 'St. Florian' (2025-05-04) due to unmatched location: OÖ

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🧪 Use on Synology or Server

I run this on my Synology via a scheduled task:

cd /volume2/docker/appdata/calendar-sync
docker-compose run --rm calendar-sync --cleanup
docker-compose run --rm calendar-sync --import

Runs every day at 01:00 🕐 — and my calendar is always up to date.

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📦 Where to Get It

You’ll find the source, Dockerfile, instructions and everything here:
👉 GitHub – magicdude4eva/calendar-sync

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🤝 Support & Contributions

This project is MIT-licensed and open to PRs, ideas, or feedback.
If you found this useful, consider supporting my work:

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