Create an utility for IPFS Repo migrations

[pgte]

Repo migrations should, if possible, happen automatically.
This would minimize disruption on projects that are using long-running js-ipfs repos, like peerpad.

[daviddias]

I don't necessarily agree with the automatically part since that a bad repo migration might lead to data corruption. Of course, we will always strive to make it correct, but the user should be informed and make the decision.

This wasn't an issue before because there is a tool just for that -- https://github.com/ipfs/fs-repo-migrations --, but know that we have long-running browser applications such as PeerPad, we do need one in JavaScript as well 👍

[pgte]

A separate migration tool can be created, but we'll end up with these apps always including this if they want to be able to survive repo upgrades..
It should be seamless to the user anyway.
I'd prefer it being seamless for the app developer too..
Data corruption is always the responsibility of the library doing the migration, whether you choose to include that in js-ipfs or not.. :)

[mkg20001]

A good idea would be auto-migration and adding an option such as "disableAutoMigration" that would make IPFS throw an error if it needs to migrate such that the application could ask the user to backup the data first, etc.

[daviddias]

I was just coming here to also give the flag idea :) thanks @mkg20001 :)

[daviddias]

@pgte solution for PeerPad https://github.com/ipfs-shipyard/peerpad-core/blob/master/src/backend/migrate-ipfs-repo-if-necessary.js

[olizilla]

I'm a big +1 on this. We're working on adding js-ipfs to ipfs-companion and we're going to want to upgrade js-ipfs regularly. Any app developer that uses js-ipfs as a dep is going to need repo migration for existing users. I'd rather ask js-ipfs to do that migration than have to hand roll it with less context at the app level.