What you need

A PDS holds the accounts of a few people and talks to the rest of the network for them. One small host is enough.

A host

Operating system	Linux, on amd64 or arm64
Software	Docker Engine with the Compose plugin
Memory	1 GiB is plenty. The server starts in a few MiB; Caddy takes a few tens
Disk	20 GB to start. Records live in SQLite files, images and videos as files beside them
Network	A public IP address, with ports 80 and 443 open to the internet

Check Docker on the host:

docker compose version

It prints Docker Compose version v2…. The older docker-compose with a hyphen, version 1, does not read the Compose file of this guide.

A domain name

The server needs a name of its own, such as pds.example.com, at a DNS provider where you can add a wildcard record. Each account gets a handle under that name, alice.pds.example.com, and each handle is a name the server answers for. Point DNS at the host has the records.

Keep the PDS on a domain of its own, not on a subdomain of a site that serves a web app. The server’s authorization pages and the blobs it serves should not share a parent domain with an app’s cookies.

An email address for the certificates

Caddy obtains the certificates from Let’s Encrypt and gives Let’s Encrypt this address for notices about expiry.

Optional: an SMTP account

The server sends mail to confirm an address and to reset a password. Without SMTP it sends none, which is fine for a server of one. Email has the setup.

Placeholders in this guide

Placeholder	Replace with
pds.example.com	the name of your server
203.0.113.10	the public IP address of your host
operator@example.com	your email address
alice	the first account’s handle

Commands run on the host as a user who may run Docker, from the directory that holds the Compose file, unless a page says otherwise. Each code block is one command.