Title: Migrating prosody internal storage to SQLite on OpenBSD

	Title: Migrating prosody internal storage to SQLite on OpenBSD
	Author: Solène
	Date: 18 August 2023
	Tags: prosody xmpp openbsd
	Description: In this article, you will learn how to improve prosody
	storage on OpenBSD by switching to SQLite

	# Introduction

	As some may know, I'm an XMPP user, an instant messaging protocol which
	used to be known as Jabber. My server is running Prosody XMPP server
	on OpenBSD. Recently, I got more users on my server, and I wanted to
	improve performance a bit by switching from the internal storage to
	SQLite.

	Actually, prosody comes with a tool to switch from a storage to
	another, but I found the documentation lacking and on OpenBSD the
	migration tool isn't packaged (yet?).

	The switch to SQLite drastically reduced prosody CPU usage on my small
	server, and went pain free.

	Prosody documentation: Prosody migrator

	# Setup

	For the migration to be done, you will need a few prerequisites:

	* know your current storage, which is "internal" by default
	* know the future storage you want to use
	* know where prosody stores its files
	* the migration tool

	On OpenBSD, the migration tool can be retrieved by downloading the
	sources of prosody. If you have the ports tree available, just run
	`make extract` in `net/prosody` and cd into the newly extracted
	directory. The directory path can be retrieved using `make
	show=WRKSRC`.

	The migration tool can be found in the subdirectory `tools/migration`
	of the sources, the program `gmake` is required to build the program
	(it's only replacing a few variables in it, so no worry about a complex
	setup).

	In the migration directory, run `gmake`, you will obtain the migration
	tool `prosody-migrator.install` which is the program you will run for
	the migration to happen.

	# Prepare the configuration file

	In the migration directory, you will find a file
	`migrator.cfg.lua.install`, this is a configuration file describing
	your current prosody deployment and what you want with the migration,
	it defaults to a conversion from "internal" to "sqlite" which is what
	most users will want in my opinion.

	Make sure the variable `data_path` in the file refers to `/var/prosody`
	which is the default directory on OpenBSD, and check the hosts in the
	"input" part which describe the current storage. By default, the new
	storage will be in `/var/prosody/prosody.sqlite`.


	# Run the tool

	Once you have the migrator and its configuration file, it's super easy
	to proceed:

	* Stop the prosody server with `rcctl stop prosody`
	* Modify `/etc/prosody/prosody.cfg.lua` to use the sql driver instead
	of internal

	```
	storage = "sql"
	sql = {
	driver = "SQLite3";
	database = "prosody.sqlite";
	}
	```

	* Backup `/var/prosody` in case something is going bad
	* Run the migration with `lua53 prosody-migrator.install --config
	./migrator.cfg.lua.install`
	* Verify the file `/var/prosody/prosody.sqlite` exists and isn't empty
	* Chown `/var/prosody/prosody.sqlite` to `_prosody:_prosody`
	* Start the prosody server with `rcctl start prosody`, check everything
	is working fine

	If you had an error at the migration step, check the logs carefully to
	check if you missed something, a bad path, maybe.

	# Conclusion

	Prosody comes with a migration tool to switch from a storage backend to
	another, that's very handy when you didn't think about scaling the
	system correctly at first.

	The migrator can also be used to migrate from the server ejabberd to
	prosody.

	Thanks prx for your report about some missing steps!