#icsinvite

In OSS, it appears nobody wants to be responsible for sending email invitations. icsinvite does this for you.

#Features

icsinvite is designed to watch a calendar collection and send invites to attendees when it detects changes.

• The collection can be either a directory full of calendar events or a WebDAV calendar
• A database of state is maintained to provide resiliance and record invitation state
• Email responses (accept/decline/reschedule) are understood and update the calendar
• Can be run as a service or on-demand
• Emails can be handled as either piped data, or file handles
• Default behavior for reacting to changes configured in config file (email everyone, only changed, no-one) for running as server
• Per-event reaction handling is interactive when run on-demand
• PGP signing

#Non-features

• Event changes (e.g. reacting to reschedule events)
• Encrypted emails (must be decrypted before icsinvite)

#Design

icsmailer stands on the shoulders of:

• https://github.com/arran4/golang-ical, for managing ICS data
• https://github.com/cosiner/flag, for it's flag management[^1]
• https://github.com/gofrs/flock, for making the DB multi-process-safe

#Alts

• https://github.com/juju/fslock
• https://github.com/prologic/bitcask
• https://github.com/emersion/go-message
• https://github.com/timshannon/bolthold

[^1]: Over the years, I've tried 17 different flag libraries, if you include the stdlib flag. Lately, I've been using @cosiners. While I do not prefer the "parse-into-structs" model, @cosiner's library is a nice compromize between features, size (2300 LOC), and dependencies (1, another 600 LOC @cosiner utility package). @thatisuday's commando is a close second (1447 LOC, 1 utility dep), but I find it more verbose and it doesn't support 12-factor-style environment parameters.