Radicale 3.0

Free and Open-Source CalDAV and CardDAV Server

Getting started

About Radicale

Radicale is a small but powerful CalDAV (calendars, to-do lists) and CardDAV (contacts) server, that:

  • Shares calendars and contact lists through CalDAV, CardDAV and HTTP.
  • Supports events, todos, journal entries and business cards.
  • Works out-of-the-box, no complicated setup or configuration required.
  • Can limit access by authentication.
  • Can secure connections with TLS.
  • Works with many CalDAV and CardDAV clients.
  • Stores all data on the file system in a simple folder structure.
  • Can be extended with plugins.
  • Is GPLv3-licensed free software.

Installation

Radicale is really easy to install and works out-of-the-box.

$ python3 -m pip install --upgrade radicale
$ python3 -m radicale --storage-filesystem-folder=~/.var/lib/radicale/collections

When the server is launched, open http://localhost:5232/ in your browser! You can login with any username and password.

Want more? Check the tutorials and the documentation.

What's New?

Read the changelog on GitHub.

Tutorials

Simple 5-minute setup

You want to try Radicale but only have 5 minutes free in your calendar? Let's go right now and play a bit with Radicale!

When everything works, you can get a client and start creating calendars and address books. The server only binds to localhost (is not reachable over the network) and you can log in with any user name and password. If Radicale fits your needs, it may be time for some basic configuration.

Follow one of the chapters below depending on your operating system.

Linux / *BSD

First, make sure that python 3.5 or later (python ≥ 3.6 is recommended) and pip are installed. On most distributions it should be enough to install the package python3-pip.

Then open a console and type:

# Run the following command as root or
# add the --user argument to only install for the current user
$ python3 -m pip install --upgrade radicale
$ python3 -m radicale --storage-filesystem-folder=~/.var/lib/radicale/collections

Victory! Open http://localhost:5232/ in your browser! You can log in with any username and password.

Windows

The first step is to install Python. Go to python.org and download the latest version of Python 3. Then run the installer. On the first window of the installer, check the "Add Python to PATH" box and click on "Install now". Wait a couple of minutes, it's done!

Launch a command prompt and type:

C:\Users\User> python -m pip install --upgrade radicale
C:\Users\User> python -m radicale --storage-filesystem-folder=~/radicale/collections

Victory! Open http://localhost:5232/ in your browser! You can log in with any username and password.

Basic Configuration

Installation instructions can be found in the simple 5-minute setup tutorial.

Radicale tries to load configuration files from /etc/radicale/config and ~/.config/radicale/config. Custom paths can be specified with the --config /path/to/config command line argument or the RADICALE_CONFIG environment variable. Multiple configuration files can be separated by : (resp. ; on Windows). Paths that start with ? are optional.

You should create a new configuration file at the desired location. (If the use of a configuration file is inconvenient, all options can be passed via command line arguments.)

All configuration options are described in detail in the Configuration section.

Authentication

In its default configuration Radicale doesn't check user names or passwords. If the server is reachable over a network, you should change this.

First a users file with all user names and passwords must be created. It can be stored in the same directory as the configuration file.

The secure way

The users file can be created and managed with htpasswd:

# Create a new htpasswd file with the user "user1"
$ htpasswd -c /path/to/users user1
New password:
Re-type new password:
# Add another user
$ htpasswd /path/to/users user2
New password:
Re-type new password:

Authentication can be enabled with the following configuration:

[auth]
type = htpasswd
htpasswd_filename = /path/to/users
# encryption method used in the htpasswd file
htpasswd_encryption = md5
The simple but insecure way

Create the users file by hand with lines containing the user name and password separated by :. Example:

user1:password1
user2:password2

Authentication can be enabled with the following configuration:

[auth]
type = htpasswd
htpasswd_filename = /path/to/users
# encryption method used in the htpasswd file
htpasswd_encryption = plain

Addresses

The default configuration binds the server to localhost. It can't be reached from other computers. This can be changed with the following configuration options (IPv4 and IPv6):

[server]
hosts = 0.0.0.0:5232, [::]:5232

Storage

Data is stored in the folder /var/lib/radicale/collections. The path can be changed with the following configuration:

[storage]
filesystem_folder = /path/to/storage

Security: The storage folder should not be readable by unauthorized users. Otherwise, they can read the calendar data and lock the storage. You can find OS dependent instructions in the Running as a service section.

Limits

Radicale enforces limits on the maximum number of parallel connections, the maximum file size (important for contacts with big photos) and the rate of incorrect authentication attempts. Connections are terminated after a timeout. The default values should be fine for most scenarios.

[server]
max_connections = 20
# 100 Megabyte
max_content_length = 100000000
# 30 seconds
timeout = 30

[auth]
# Average delay after failed login attempts in seconds
delay = 1

Running as a service

The method to run Radicale as a service depends on your host operating system. Follow one of the chapters below depending on your operating system and requirements.

Linux with systemd system-wide

Create the radicale user and group for the Radicale service. (Run useradd --system --home-dir / --shell /sbin/nologin radicale as root.) The storage folder must be writable by radicale. (Run mkdir -p /var/lib/radicale/collections && chown -R radicale:radicale /var/lib/radicale/collections as root.)

Security: The storage should not be readable by others. (Run chmod -R o= /var/lib/radicale/collections as root.)

Create the file /etc/systemd/system/radicale.service:

[Unit]
Description=A simple CalDAV (calendar) and CardDAV (contact) server
After=network.target
Requires=network.target

[Service]
ExecStart=/usr/bin/env python3 -m radicale
Restart=on-failure
User=radicale
# Deny other users access to the calendar data
UMask=0027
# Optional security settings
PrivateTmp=true
ProtectSystem=strict
ProtectHome=true
PrivateDevices=true
ProtectKernelTunables=true
ProtectKernelModules=true
ProtectControlGroups=true
NoNewPrivileges=true
ReadWritePaths=/var/lib/radicale/collections

[Install]
WantedBy=multi-user.target

Radicale will load the configuration file from /etc/radicale/config.

To enable and manage the service run:

# Enable the service
$ systemctl enable radicale
# Start the service
$ systemctl start radicale
# Check the status of the service
$ systemctl status radicale
# View all log messages
$ journalctl --unit radicale.service

Linux with systemd as a user

Create the file ~/.config/systemd/user/radicale.service:

[Unit]
Description=A simple CalDAV (calendar) and CardDAV (contact) server

[Service]
ExecStart=/usr/bin/env python3 -m radicale
Restart=on-failure

[Install]
WantedBy=default.target

Radicale will load the configuration file from ~/.config/radicale/config. You should set the configuration option filesystem_folder in the storage section to something like ~/.var/lib/radicale/collections.

To enable and manage the service run:

# Enable the service
$ systemctl --user enable radicale
# Start the service
$ systemctl --user start radicale
# Check the status of the service
$ systemctl --user status radicale
# View all log messages
$ journalctl --user --unit radicale.service

Windows with "NSSM - the Non-Sucking Service Manager"

First install NSSM and start nssm install in a command prompt. Apply the following configuration:

  • Service name: Radicale
  • Application
    • Path: C:\Path\To\Python\python.exe
    • Arguments: -m radicale --config C:\Path\To\Config
  • I/O redirection
    • Error: C:\Path\To\Radicale.log

Security: Be aware that the service runs in the local system account, you might want to change this. Managing user accounts is beyond the scope of this manual. Also, make sure that the storage folder and log file is not readable by unauthorized users.

The log file might grow very big over time, you can configure file rotation in NSSM to prevent this.

The service is configured to start automatically when the computer starts. To start the service manually open Services in Computer Management and start the Radicale service.

Reverse Proxy

When a reverse proxy is used, the path at which Radicale is available must be provided via the X-Script-Name header. The proxy must remove the location from the URL path that is forwarded to Radicale.

Example nginx configuration:

location /radicale/ { # The trailing / is important!
    proxy_pass        http://localhost:5232/; # The / is important!
    proxy_set_header  X-Script-Name /radicale;
    proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header  Host $http_host;
    proxy_pass_header Authorization;
}

Example Apache configuration:

RewriteEngine On
RewriteRule ^/radicale$ /radicale/ [R,L]

<Location "/radicale/">
    ProxyPass        http://localhost:5232/ retry=0
    ProxyPassReverse http://localhost:5232/
    RequestHeader    set X-Script-Name /radicale/
</Location>

Be reminded that Radicale's default configuration enforces limits on the maximum number of parallel connections, the maximum file size and the rate of incorrect authentication attempts. Connections are terminated after a timeout.

Manage user accounts with the reverse proxy

Set the configuration option type in the auth section to http_x_remote_user. Radicale uses the user name provided in the X-Remote-User HTTP header and disables HTTP authentication.

Example nginx configuration:

location /radicale/ {
    proxy_pass           http://localhost:5232/;
    proxy_set_header     X-Script-Name /radicale;
    proxy_set_header     X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header     X-Remote-User $remote_user;
    proxy_set_header     Host $http_host;
    auth_basic           "Radicale - Password Required";
    auth_basic_user_file /etc/nginx/htpasswd;
}

Example Apache configuration:

RewriteEngine On
RewriteRule ^/radicale$ /radicale/ [R,L]

<Location "/radicale/">
    AuthType      Basic
    AuthName      "Radicale - Password Required"
    AuthUserFile  "/etc/radicale/htpasswd"
    Require       valid-user

    ProxyPass        http://localhost:5232/ retry=0
    ProxyPassReverse http://localhost:5232/
    RequestHeader    set X-Script-Name /radicale/
    RequestHeader    set X-Remote-User expr=%{REMOTE_USER}
</Location>

Security: Untrusted clients should not be able to access the Radicale server directly. Otherwise, they can authenticate as any user.

Secure connection between Radicale and the reverse proxy

SSL certificates can be used to encrypt and authenticate the connection between Radicale and the reverse proxy. First you have to generate a certificate for Radicale and a certificate for the reverse proxy. The following commands generate self-signed certificates. You will be asked to enter additional information about the certificate, the values don't matter and you can keep the defaults.

$ openssl req -x509 -newkey rsa:4096 -keyout server_key.pem -out server_cert.pem -nodes -days 9999
$ openssl req -x509 -newkey rsa:4096 -keyout client_key.pem -out client_cert.pem -nodes -days 9999

Use the following configuration for Radicale:

[server]
ssl = True
certificate = /path/to/server_cert.pem
key = /path/to/server_key.pem
certificate_authority = /path/to/client_cert.pem

Example nginx configuration:

location /radicale/ {
    proxy_pass https://localhost:5232/;
    ...
    # Place the files somewhere nginx is allowed to access (e.g. /etc/nginx/...).
    proxy_ssl_certificate         /path/to/client_cert.pem;
    proxy_ssl_certificate_key     /path/to/client_key.pem;
    proxy_ssl_trusted_certificate /path/to/server_cert.pem;
}

WSGI Server

Radicale is compatible with the WSGI specification.

A configuration file can be set with the RADICALE_CONFIG environment variable, otherwise no configuration file is loaded and the default configuration is used.

Example uWSGI configuration:

[uwsgi]
http-socket = 127.0.0.1:5232
processes = 8
plugin = python3
module = radicale
env = RADICALE_CONFIG=/etc/radicale/config

Example Gunicorn configuration:

gunicorn --bind '127.0.0.1:5232' --workers 8 --env 'RADICALE_CONFIG=/etc/radicale/config' radicale

Manage user accounts with the WSGI server

Set the configuration option type in the auth section to remote_user. Radicale uses the user name provided by the WSGI server and disables authentication over HTTP.

Versioning with Git

This tutorial describes how to keep track of all changes to calendars and address books with git (or any other version control system).

The repository must be initialized by running git init in the file system folder. Internal files of Radicale can be excluded by creating the file .gitignore with the following content:

.Radicale.cache
.Radicale.lock
.Radicale.tmp-*

The configuration option hook in the storage section must be set to the following command:

git add -A && (git diff --cached --quiet || git commit -m "Changes by "%(user)s)

The command gets executed after every change to the storage and commits the changes into the git repository.

Documentation

Configuration

Radicale can be configured with a configuration file or with command line arguments.

An example configuration file looks like:

[server]
# Bind all addresses
hosts = 0.0.0.0:5232, [::]:5232

[auth]
type = htpasswd
htpasswd_filename = ~/.config/radicale/users
htpasswd_encryption = md5

[storage]
filesystem_folder = ~/.var/lib/radicale/collections

Radicale tries to load configuration files from /etc/radicale/config and ~/.config/radicale/config. Custom paths can be specified with the --config /path/to/config command line argument or the RADICALE_CONFIG environment variable. Multiple configuration files can be separated by : (resp. ; on Windows). Paths that start with ? are optional.

The same example configuration via command line arguments looks like:

python3 -m radicale --server-hosts 0.0.0.0:5232,[::]:5232 --auth-type htpasswd --htpasswd-filename ~/.config/radicale/users --htpasswd-encryption md5

Add the argument --config "" to stop Radicale from loading the default configuration files. Run python3 -m radicale --help for more information.

In the following, all configuration categories and options are described.

server

The configuration options in this category are only relevant in standalone mode. All options are ignored, when Radicale runs via WSGI.

hosts

A comma separated list of addresses that the server will bind to.

Default: localhost:5232

max_connections

The maximum number of parallel connections. Set to 0 to disable the limit.

Default: 8

max_content_length

The maximum size of the request body. (bytes)

Default: 100000000

timeout

Socket timeout. (seconds)

Default: 30

ssl

Enable transport layer encryption.

Default: False

certificate

Path of the SSL certifcate.

Default: /etc/ssl/radicale.cert.pem

key

Path to the private key for SSL. Only effective if ssl is enabled.

Default: /etc/ssl/radicale.key.pem

certificate_authority

Path to the CA certificate for validating client certificates. This can be used to secure TCP traffic between Radicale and a reverse proxy. If you want to authenticate users with client-side certificates, you also have to write an authentication plugin that extracts the user name from the certificate.

Default:

encoding

request

Encoding for responding requests.

Default: utf-8

stock

Encoding for storing local collections

Default: utf-8

auth

type

The method to verify usernames and passwords.

Available backends:

none : Just allows all usernames and passwords.

htpasswd : Use an Apache htpasswd file to store usernames and passwords.

remote_user : Takes the user name from the REMOTE_USER environment variable and disables HTTP authentication. This can be used to provide the user name from a WSGI server.

http_x_remote_user : Takes the user name from the X-Remote-User HTTP header and disables HTTP authentication. This can be used to provide the user name from a reverse proxy.

Default: none

htpasswd_filename

Path to the htpasswd file.

Default:

htpasswd_encryption

The encryption method that is used in the htpasswd file. Use the htpasswd or similar to generate this files.

Available methods:

plain : Passwords are stored in plaintext. This is obviously not secure! The htpasswd file for this can be created by hand and looks like:

user1:password1
user2:password2

bcrypt : This uses a modified version of the Blowfish stream cipher. It's very secure. The installation of radicale[bcrypt] is required for this.

md5 : This uses an iterated md5 digest of the password with a salt.

Default: md5

delay

Average delay after failed login attempts in seconds.

Default: 1

realm

Message displayed in the client when a password is needed.

Default: Radicale - Password Required

rights

type

The backend that is used to check the access rights of collections.

The recommended backend is owner_only. If access to calendars and address books outside the home directory of users (that's /USERNAME/) is granted, clients won't detect these collections and will not show them to the user. Choosing any other method is only useful if you access calendars and address books directly via URL.

Available backends:

authenticated : Authenticated users can read and write everything.

owner_only : Authenticated users can read and write their own collections under the path /USERNAME/.

owner_write : Authenticated users can read everything and write their own collections under the path /USERNAME/.

from_file : Load the rules from a file.

Default: owner_only

file

File for the rights backend from_file. See the Rights section.

storage

type

The backend that is used to store data.

Available backends:

multifilesystem : Stores the data in the filesystem.

Default: multifilesystem

filesystem_folder

Folder for storing local collections, created if not present.

Default: /var/lib/radicale/collections

max_sync_token_age

Delete sync-token that are older than the specified time. (seconds)

Default: 2592000

hook

Command that is run after changes to storage. Take a look at the Versioning with Git tutorial for an example.

Default:

web

type

The backend that provides the web interface of Radicale.

Available backends:

none : Just shows the message "Radicale works!".

internal : Allows creation and management of address books and calendars.

Default: internal

logging

level

Set the logging level.

Available levels: debug, info, warning, error, critical

Default: warning

mask_passwords

Don't include passwords in logs.

Default: True

headers

In this section additional HTTP headers that are sent to clients can be specified.

An example to relax the same-origin policy:

Access-Control-Allow-Origin = *

Supported Clients

Radicale has been tested with:

Many clients do not support the creation of new calendars and address books. You can use Radicale's web interface (e.g. http://localhost:5232) to create and manage address books and calendars.

In some clients you can just enter the URL of the Radicale server (e.g. http://localhost:5232) and your user name. In others, you have to enter the URL of the collection directly (e.g. http://localhost:5232/user/calendar).

DAVx⁵

Enter the URL of the Radicale server (e.g. http://localhost:5232) and your user name. DAVx⁵ will show all existing calendars and address books and you can create new.

GNOME Calendar, Contacts and Evolution

GNOME Calendar and Contacts do not support adding WebDAV calendars and address books directly, but you can add them in Evolution.

In Evolution add a new calendar and address book respectively with WebDAV. Enter the URL of the Radicale server (e.g. http://localhost:5232) and your user name. Clicking on the search button will list the existing calendars and address books.

Thunderbird

CardBook

Add a new address book on the network with CardDAV. You have to enter the full URL of the collection (e.g. http://localhost:5232/user/addressbook) and your user name.

Lightning

Add a new calendar on the network with CalDAV. (Don't use iCalendar (ICS)!) You have to enter the full URL of the collection (e.g. http://localhost:5232/user/calendar). If you want to add calendars from different users on the same server, you can specify the user name in the URL (e.g. http://user@localhost...)

InfCloud, CalDavZAP and CardDavMATE

You can integrate InfCloud into Radicale's web interface with RadicaleInfCloud. No additional configuration is required.

Set the URL of the Radicale server in config.js. If InfCloud is not hosted on the same server and port as Radicale, the browser will deny access to the Radicale server, because of the same-origin policy. You have to add additional HTTP header in the headers section of Radicale's configuration. The documentation of InfCloud has more details on this.

Command line

This is not the recommended way of creating and managing your calendars and address books. Use Radicale's web interface or a client with support for it (e.g. DAVx⁵).

To create a new calendar run something like:

$ curl -u user -X MKCOL 'http://localhost:5232/user/calendar' --data \
'<?xml version="1.0" encoding="UTF-8" ?>
<create xmlns="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav" xmlns:I="http://apple.com/ns/ical/">
  <set>
    <prop>
      <resourcetype>
        <collection />
        <C:calendar />
      </resourcetype>
      <C:supported-calendar-component-set>
        <C:comp name="VEVENT" />
        <C:comp name="VJOURNAL" />
        <C:comp name="VTODO" />
      </C:supported-calendar-component-set>
      <displayname>Calendar</displayname>
      <C:calendar-description>Example calendar</C:calendar-description>
      <I:calendar-color>#ff0000ff</I:calendar-color>
    </prop>
  </set>
</create>'

To create a new address book run something like:

$ curl -u user -X MKCOL 'http://localhost:5232/user/addressbook' --data \
'<?xml version="1.0" encoding="UTF-8" ?>
<create xmlns="DAV:" xmlns:CR="urn:ietf:params:xml:ns:carddav">
  <set>
    <prop>
      <resourcetype>
        <collection />
        <CR:addressbook />
      </resourcetype>
      <displayname>Address book</displayname>
      <CR:addressbook-description>Example address book</CR:addressbook-description>
    </prop>
  </set>
</create>'

The collection /USERNAME will be created automatically, when the user authenticates to Radicale for the first time. Clients with automatic discovery of collections will only show calendars and address books that are direct children of the path /USERNAME/.

Delete the collections by running something like:

$ curl -u user -X DELETE 'http://localhost:5232/user/calendar'

Authentication and Rights

This section describes the format of the rights file for the from_file authentication backend. The configuration option file in the rights section must point to the rights file.

The recommended rights method is owner_only. If access to calendars and address books outside the home directory of users (that's /USERNAME/) is granted, clients won't detect these collections and will not show them to the user. This is only useful if you access calendars and address books directly via URL.

An example rights file:

# Allow reading root collection for authenticated users
[root]
user: .+
collection:
permissions: R

# Allow reading and writing principal collection (same as user name)
[principal]
user: .+
collection: {user}
permissions: RW

# Allow reading and writing calendars and address books that are direct
# children of the principal collection
[calendars]
user: .+
collection: {user}/[^/]+
permissions: rw

The titles of the sections are ignored (but must be unique). The keys user and collection contain regular expressions, that are matched against the user name and the path of the collection. Permissions from the first matching section are used. If no section matches, access gets denied.

The user name is empty for anonymous users. Therefore, the regex .+ only matches authenticated users and .* matches everyone (including anonymous users).

The path of the collection is separated by / and has no leading or trailing /. Therefore, the path of the root collection is empty.

In the collection regex you can use {user} and get groups from the user regex with {0}, {1}, etc.

In consequence of the parameter substitution you have to write {{ and }} if you want to use regular curly braces in the user and collection regexes.

The following permissions are recognized:

  • R: read collections (excluding address books and calendars)
  • r: read address book and calendar collections
  • i: subset of r that only allows direct access via HTTP method GET (CalDAV/CardDAV is susceptible to expensive search requests)
  • W: write collections (excluding address books and calendars)
  • w: write address book and calendar collections

Storage

This document describes the layout and format of the file system storage (multifilesystem backend).

It's safe to access and manipulate the data by hand or with scripts. Scripts can be invoked manually, periodically (e.g. with cron) or after each change to the storage with the configuration option hook in the storage section (e.g. Versioning with Git).

Layout

The file system contains the following files and folders:

  • .Radicale.lock: The lock file for locking the storage.
  • collection-root: This folder contains all collections and items.

A collection is represented by a folder. This folder may contain the file .Radicale.props with all WebDAV properties of the collection encoded as JSON.

An item is represented by a file containing the iCalendar data.

All files and folders, whose names start with a dot but not .Radicale. (internal files) are ignored.

If you introduce syntax errors in any of the files, all requests that access the faulty data will fail. The logging output should contain the names of the culprits.

Caches and sync-tokens are stored in the .Radicale.cache folder inside of collections. This folder may be created or modified, while the storage is locked for shared access. In theory, it should be safe to delete the folder. Caches will be recreated automatically and clients will be told that their sync-token isn't valid anymore.

You may encounter files or folders that start with .Radicale.tmp-. Radicale uses them for atomic creation and deletion of files and folders. They should be deleted after requests are finished but it's possible that they are left behind when Radicale or the computer crashes. It's safe to delete them.

Locking

When the data is accessed by hand or by an externally invoked script, the storage must be locked. The storage can be locked for exclusive or shared access. It prevents Radicale from reading or writing the file system. The storage is locked with exclusive access while the hook runs.

Linux shell scripts

Use the flock utility.

# Exclusive
$ flock --exclusive /path/to/storage/.Radicale.lock COMMAND
# Shared
$ flock --shared /path/to/storage/.Radicale.lock COMMAND
Linux and MacOS

Use the flock syscall. Python provides it in the fcntl module.

Windows

Use LockFile for exclusive access or LockFileEx which also supports shared access. Setting nNumberOfBytesToLockLow to 1 and nNumberOfBytesToLockHigh to 0 works.

Manually creating collections

To create a new collection, you have to create the corresponding folder in the file system storage (e.g. collection-root/user/calendar). To tell Radicale and clients that the collection is a calendar, you have to create the file .Radicale.props with the following content in the folder:

{"tag": "VCALENDAR"}

The calendar is now available at the URL path /user/calendar. For address books the file must contain:

{"tag": "VADDRESSBOOK"}

Calendar and address book collections must not have any child collections. Clients with automatic discovery of collections will only show calendars and address books that are direct children of the path /USERNAME/.

Delete collections by deleting the corresponding folders.

Logging

Radicale logs to stderr. The verbosity of the log output can be controlled with --debug command line argument or the level configuration option in the logging section.

Architecture

Radicale is a small piece of software, but understanding it is not as easy as it seems. But don't worry, reading this short section is enough to understand what a CalDAV/CardDAV server is, and how Radicale's code is organized.

Protocol overview

Here is a simple overview of the global architecture for reaching a calendar or an address book through network:

Part Layer Protocol or Format
Server Calendar/Contact Storage iCal/vCard
Calendar/Contact Server CalDAV/CardDAV Server
Transfer Network CalDAV/CardDAV (HTTP + TLS)
Client Calendar/Contact Client CalDAV/CardDAV Client
GUI Terminal, GTK, Web interface, etc.

Radicale is only the server part of this architecture.

Please note that:

  • CalDAV and CardDAV are superset protocols of WebDAV,
  • WebDAV is a superset protocol of HTTP.

Radicale being a CalDAV/CardDAV server, it also can be seen as a special WebDAV and HTTP server.

Radicale is not the client part of this architecture. It means that Radicale never draws calendars, address books, events and contacts on the screen. It only stores them and give the possibility to share them online with other people.

If you want to see or edit your events and your contacts, you have to use another software called a client, that can be a "normal" applications with icons and buttons, a terminal or another web application.

Code Architecture

The radicale package offers the following modules.

__init__ : Contains the entry point for WSGI.

__main__ : Provides the entry point for the radicale executable and includes the command line parser. It loads configuration files from the default (or specified) paths and starts the internal server.

app : This is the core part of Radicale, with the code for the CalDAV/CardDAV server. The code managing the different HTTP requests according to the CalDAV/CardDAV specification can be found here.

auth : Used for authenticating users based on username and password, mapping usernames to internal users and optionally retrieving credentials from the environment.

config : Contains the code for managing configuration and loading settings from files.

ìtem : Internal representation of address book and calendar entries. Based on VObject.

log : The logger for Radicale based on the default Python logging module.

rights : This module is used by Radicale to manage access rights to collections, address books and calendars.

server : The integrated HTTP server for standalone use.

storage : This module contains the classes representing collections in Radicale and the code for storing and loading them in the filesystem.

web : This module contains the web interface.

utils : Contains general helper functions.

httputils : Contains helper functions for working with HTTP.

pathutils : Helper functions for working with paths and the filesystem.

xmlutils : Helper functions for working with the XML part of CalDAV/CardDAV requests and responses. It's based on the ElementTree XML API.

Plugins

Radicale can be extended by plugins for authentication, rights management and storage. Plugins are python modules.

Getting started

To get started we walk through the creation of a simple authentication plugin, that accepts login attempts with a static password.

The easiest way to develop and install python modules is Distutils. For a minimal setup create the file setup.py with the following content in an empty folder:

#!/usr/bin/env python3

from distutils.core import setup

setup(name="radicale_static_password_auth",
      packages=["radicale_static_password_auth"])

In the same folder create the sub-folder radicale_static_password_auth. The folder must have the same name as specified in packages above.

Create the file __init__.py in the radicale_static_password_auth folder with the following content:

from radicale.auth import BaseAuth
from radicale.log import logger

PLUGIN_CONFIG_SCHEMA = {"auth": {
    "password": {"value": "", "type": str}}}


class Auth(BaseAuth):
    def __init__(self, configuration):
        super().__init__(configuration.copy(PLUGIN_CONFIG_SCHEMA))

    def login(self, login, password):
        # Get password from configuration option
        static_password = self.configuration.get("auth", "password")
        # Check authentication
        logger.info("Login attempt by %r with password %r",
                    login, password)
        if password == static_password:
            return login
        return ""

Install the python module by running the following command in the same folder as setup.py:

python3 -m pip install .

To make use this great creation in Radicale, set the configuration option type in the auth section to radicale_static_password_auth:

[auth]
type = radicale_static_password_auth
password = secret

You can uninstall the module with:

python3 -m pip uninstall radicale_static_password_auth

Authentication plugins

This plugin type is used to check login credentials. The module must contain a class Auth that extends radicale.auth.BaseAuth. Take a look at the file radicale/auth/__init__.py in Radicale's source code for more information.

Rights management plugins

This plugin type is used to check if a user has access to a path. The module must contain a class Rights that extends radicale.rights.BaseRights. Take a look at the file radicale/rights/__init__.py in Radicale's source code for more information.

Web plugins

This plugin type is used to provide the web interface for Radicale. The module must contain a class Web that extends radicale.web.BaseWeb. Take a look at the file radicale/web/__init__.py in Radicale's source code for more information.

Storage plugins

This plugin is used to store collections and items. The module must contain a class Storage that extends radicale.storage.BaseStorage. Take a look at the file radicale/storage/__init__.py in Radicale's source code for more information.

Contribute

Chat with Us on IRC

Want to say something? Join our IRC room: ##kozea on Freenode.

Report Bugs

Found a bug? Want a new feature? Report a new issue on the Radicale bug-tracker.

Hack

Interested in hacking? Feel free to clone the git repository on GitHub if you want to add new features, fix bugs or update the documentation.

Documentation

To change or complement the documentation create a pull request to DOCUMENTATION.md.

Download

PyPI

Radicale is available on PyPI. To install, just type as superuser:

$ python3 -m pip install --upgrade radicale

Git Repository

If you want the development version of Radicale, take a look at the git repository on GitHub, or install it directly with:

$ python3 -m pip install --upgrade git+https://github.com/Kozea/Radicale

You can also download the content of the repository as an archive.

Source Packages

You can find the source packages of all releases on GitHub.

Linux Distribution Packages

Radicale has been packaged for:

Radicale is also available on Cloudron and has a Dockerfile.

If you are interested in creating packages for other Linux distributions, read the "Contribute" section.

About

Main Goals

Radicale is a complete calendar and contact storing and manipulating solution. It can store multiple calendars and multiple address books.

Calendar and contact manipulation is available from both local and distant accesses, possibly limited through authentication policies.

It aims to be a lightweight solution, easy to use, easy to install, easy to configure. As a consequence, it requires few software dependencies and is preconfigured to work out-of-the-box.

Radicale is written in Python. It runs on most of the UNIX-like platforms (Linux, *BSD, macOS) and Windows. It is free and open-source software.

What Radicale Will Never Be

Radicale is a server, not a client. No interfaces will be created to work with the server.

CalDAV and CardDAV are not perfect protocols. We think that their main problem is their complexity, that is why we decided not to implement the whole standard but just enough to understand some of its client-side implementations.

CalDAV and CardDAV are the best open standards available, and they are quite widely used by both clients and servers. We decided to use it, and we will not use another one.

Technical Choices

Important global development choices have been decided before writing code. They are very useful to understand why the Radicale Project is different from other CalDAV and CardDAV servers, and why features are included or not in the code.

Oriented to Calendar and Contact User Agents

Calendar and contact servers work with calendar and contact clients, using a defined protocol. CalDAV and CardDAV are good protocols, covering lots of features and use cases, but it is quite hard to implement fully.

Some calendar servers have been created to follow the CalDAV and CardDAV RFCs as much as possible: Davical, Baïkal and Darwin Calendar Server, for example, are much more respectful of CalDAV and CardDAV and can be used with many clients. They are very good choices if you want to develop and test new CalDAV clients, or if you have a possibly heterogeneous list of user agents.

Even if it tries it best to follow the RFCs, Radicale does not and will not blindly implement the CalDAV and CardDAV standards. It is mainly designed to support the CalDAV and CardDAV implementations of different clients.

Simple

Radicale is designed to be simple to install, simple to configure, simple to use.

The installation is very easy, particularly with Linux: one dependency, no superuser rights needed, no configuration required, no database. Installing and launching the main script out-of-the-box, as a normal user, are often the only steps to have a simple remote calendar and contact access.

Contrary to other servers that are often complicated, require high privileges or need a strong configuration, the Radicale Server can (sometimes, if not often) be launched in a couple of minutes, if you follow the tutorial.

Lazy

The CalDAV RFC defines what must be done, what can be done and what cannot be done. Many violations of the protocol are totally defined and behaviors are given in such cases.

Radicale often assumes that the clients are perfect and that protocol violations do not exist. That is why most of the errors in client requests have undetermined consequences for the lazy server that can reply good answers, bad answers, or even no answer.

History

Radicale has been started as a (free topic) stupid school project replacing another (assigned topic) even more stupid school project.

At the beginning, it was just a proof-of-concept. The main goal was to write a small, dirty and simple CalDAV server working with Lightning, using no external libraries. That's how we created a piece of code that's (quite) easy to understand, to use and to hack.

The first lines have been added to the SVN (!) repository as I was drinking (many) beers at the very end of 2008 (Python 2.6 and 3.0 were just released). It's now packaged for a growing number of Linux distributions.

And that was fun going from here to there thanks to you!