I can recommend radicale [1]. It's very simple and doesn't need a lot of resources. It also supports authentication via an IMAP server so you don't have to keep a separate user database.

1: http://radicale.org/

I also use Radicale. My only annoyance is that when you use its built-in HTTP server, the process eventually stops working if one of your clients has an intermittent connection (e.g. phone with a poor signal).

https://github.com/Kozea/Radicale/issues/266 https://github.com/Kozea/Radicale/issues/388

I'm told that using a dedicated HTTP + WSGI server solves this, just haven't done the work yet.

Would it be easier to just have a cron job that checks every five minutes if Radicale is running and if it has fallen over restart it?

Can we stop hacking ill-conceived one-offs like this and just start to assume that a monitoring utility (Monit, Supervisor, Munin, Nagios, ServerDensity, Solarwinds to name a few) in some form is the standard for notifying of anomalies and automation of process recovery?

Moreover, systemd has a OnFailure directive that activates other units when the process exits uncleanly. Upstart has a similar directive. With a more classical approach, `respawn' is a utility that can invoke and maintain the running status of a process launched from System V Init, or you could use the regarded inittab solution.

I've seen answers to questions similar to this on StackOverflow respond with scripts that are nothing more than a while(true) loop that checks to see if a PID exists in languages ranging from Bourne shell to Python and NodeJS. This is the wrong way to do it, especially the Node one. Lets take a language intended to be used inside a web browser client and slap it onto a server to be used for process monitoring. I'm sure it does a fine job with it's while loop, but we're hitting copper pipe with a tire iron wondering why our lightbulb isn't turning on here.

The GP's using it for personal use (I think). OP merely suggested a hack to let GP get on with their life as quickly as possible in 2 lines of bash and one crontab entry - and without learning a new process monitoring utility's configuration. Obviously this wouldn't be suitable for a production site for many users.

I have the same experience. It works perfectly for me with ldap authentication (which I also use for my mailserver) over multiple devices (macOS, Windows, Android, Linux).

Started using it after Owncloud/Nextcloud broke their ldap auth.

Using it as well, pretty simple to setup & dockerization-friendly.

Not the parent, but I use Nextcloud for this (previously ownCloud). There are carddav and caldav sync applications for Android. I assume other operating systems have them too.

https://nextcloud.com

I've found Baïkal quite reliable over what must be a half decade of use. Integrates well with Apple devices (iOS/OS X 10.9), with the one Android I ever used, and via Lightning and Sogo Connector, also reasonably well with Thunderbird.