Calendar Server

This repo runs a real CalDAV server with Docker Compose and connects MCP clients through an existing CalDAV MCP server.

Stack:

• CalDAV: Radicale in Docker using ghcr.io/kozea/radicale:3.7.6

• MCP HTTP: dav-mcp in Docker, built from mcp/Dockerfile

• Public access: Cloudflare Tunnel / Zero Trust

Requirements

• Docker Desktop or Docker Engine with Compose

• Node.js 20 or newer for npx MCP usage

• cloudflared for Cloudflare Tunnel

Related MCP server: Chronos MCP

Configure

cp .env.example .env

Edit .env:

CALDAV_PORT=5232
CALDAV_BASE_URL=http://127.0.0.1:5232
CALDAV_PUBLIC_URL=https://calendar.example.com
CALDAV_USER=calendar
CALDAV_PASSWORD=use-a-long-random-password
MCP_PORT=3000
MCP_BEARER_TOKEN=use-a-long-random-token

CALDAV_USER and CALDAV_PASSWORD are written into Radicale's htpasswd file when the container starts. Restart the container after changing them.

Start Radicale

docker compose up -d

If you want to use Apple Calendar locally, export and trust Caddy's local HTTPS CA:

npm run export:caddy-ca
npm run trust:caddy-ca

Create the initial calendar collection:

npm run create:default-calendar

Logs:

docker compose logs -f radicale

Stop:

docker compose down

Local CalDAV server:

http://127.0.0.1:5232/

Local HTTPS CalDAV proxy for Apple Calendar:

https://localhost:8443/

Default calendar URL:

http://127.0.0.1:5232/<CALDAV_USER>/default/

Apple Calendar

Use Other CalDAV Account with account type Advanced:

• Account type: Advanced

• User name: value of CALDAV_USER

• Password: value of CALDAV_PASSWORD

• Server address: 127.0.0.1

• Server path: /<CALDAV_USER>/

• Port: value of CALDAV_PORT, usually 5232

• Use SSL: off

• Use Kerberos: off

For your current .env values:

User name: coretracker
Server address: localhost
Server path: /coretracker/
Port: 8443
Use SSL: on

The calendar itself is at /<CALDAV_USER>/default/, but Apple Calendar should be pointed at the user collection /<CALDAV_USER>/ so it can discover the calendar home. Do not put https://... into Server Address in Advanced mode; use the host only.

If Apple logs anonymous user over plain HTTP, use the HTTPS Caddy endpoint above. Recent macOS builds may refuse to send Basic Auth credentials over plain HTTP even to localhost.

Before retrying Apple Calendar, verify Basic Auth from the terminal:

npm run check:auth

If Radicale logs only say anonymous user, Apple Calendar has not sent the username/password yet. Remove the failed account, delete saved Calendar/CalDAV passwords for the same host from Keychain Access, then add the account again with the fields above.

After Cloudflare is configured, use:

https://calendar.example.com/

Some Apple Calendar versions do not work well behind browser-based Cloudflare Access. Test local CalDAV first. If local works but the Cloudflare URL fails, use a Cloudflare Access service token or bypass Access for trusted client traffic.

HTTP MCP Setup

The Docker Compose stack runs an HTTP MCP server at:

http://127.0.0.1:<MCP_PORT>/mcp

With the current .env, that is:

http://127.0.0.1:9996/mcp

Use bearer authentication:

Authorization: Bearer <MCP_BEARER_TOKEN>

Generate a local MCP client config from .env:

npm run write:mcp-config

That writes mcp.local.json, which is ignored by git because it contains the bearer token.

Smoke test the HTTP MCP endpoint:

npm run smoke:mcp

The MCP container talks to Radicale internally at http://radicale:5232, so it does not need the local Caddy HTTPS certificate.

Logs:

npm run logs:mcp

Expected MCP tools include calendar, event, contact, and todo operations from dav-mcp.

Cloudflare Zero Trust Setup

Create a tunnel:

cloudflared tunnel login
cloudflared tunnel create calendar

Create ~/.cloudflared/config.yml:

tunnel: <TUNNEL_ID>
credentials-file: /Users/<you>/.cloudflared/<TUNNEL_ID>.json

ingress:
  - hostname: calendar.example.com
    service: http://127.0.0.1:5232
  - service: http_status:404

Route DNS:

cloudflared tunnel route dns calendar calendar.example.com

Run the tunnel:

cloudflared tunnel run calendar

In Cloudflare Zero Trust:

1. Go to Access -> Applications -> Add an application.

2. Choose Self-hosted.

3. Set the application domain to calendar.example.com.

4. Add an access policy for your user or device.

5. Save the application.

CalDAV clients still use Radicale Basic Auth with CALDAV_USER and CALDAV_PASSWORD.

Notes

• Calendar data is stored in radicale/data/.

• The Radicale config is in radicale/config/config.

• The Docker Compose file binds Radicale only to 127.0.0.1, so it is not exposed directly to the LAN.

• The htpasswd file uses plain text inside the local Docker volume because Radicale runs behind localhost binding and Cloudflare Access. Use filesystem permissions and full-disk encryption on the host.