The base spec for a HAF server is extremely small (something like 6GB of storage space).

So I suspect you're looking at the storage needs to store the entire blockchain (theoretically around 3.5TB, but in practice only around 1.2TB using zfs with lz4).

But like I said, the above storage space is only needed for a full API server that needs access to all the blockchain data. When you setup your HAF server for your HAF app, you just need to add a line to your hived config.ini file to filter out all but the operations you want. Then you'll have a super small database.

As far as docker goes, the recommended way to setup a HAF server is using docker nowadays. We're also creating a docker compose script for a setup of a full API node, but for setup of a simple HAF server, it all fits in one docker container, so no need for docker compose.