Foreign assets creation via token reserve

[gonzamontiel]

What does it do?

• Introduces a new origin ForeignAssetOwnerOrigin. It validates that the origin is an XCM location, that contains another location. This is useful to validate that a parachain can create or modify an asset only if it contains the asset. It's based on an implementation of xcm_simulator.
• The allowed XCM origins are defined by LocationToAccountId
• The above origin affects all extrinsics inside the moonbeam foreign assets pallet
• create_foreign_asset now reserves a deposit from the caller (i.e. parachain sovereign accounts)
• The deposit amount is configurable (ForeignAssetCreationDeposit) and can be changed with pallet_parameters
• A new storage maps the asset creator, and the amount reserved at creation, by asset id. The creator is an enum that allows to be Governance (for old or migrated assets), and any account for new assets.

⚠️ Breaking Changes ⚠️

• The extrinsics create_foreign_asset, change_xcm_location, freeze_foreign_asset, unfreeze_foreign_asset can only be called by an XCM origin
• The account belonging to the caller of create_foreign_asset will need a deposit of funds that is configurable in the pallet.
• The initial deposit values are:
  • Moonbase: 100 DEV
  • Moonriver: 1000 MOVR
  • Moonbeam: 10000 GLMR

Disclaimer: the pallet is not in use and the functionality wasn't exposed publicly AFAIK. The changes are still breaking, but most likely harmless.

TODO

• Make deposit amount configurable (and changable with pallet parameters)
• Modify foreign assets migration to add the old assets to the new storage
• Add tests

What important points reviewers should know?

Some assumptions were made considering the current state of the pallet:

• There are no foreign assets yet created in live chains
• The AssetOwner was meant initially to be a descriptive enum of the possible sources of creation of an asset, but since there were no assets yet created, we only need to distinguish between migrated assets, and the ones created from now on (any account). Naming in this enum might be improved.
• The Foreign assets migration was modified to mark the migrated assets in the storage and distinguish them from the newly created ones.

Is there something left for follow-up PRs?

What alternative implementations were considered?

Using Fungibles was investigated, but the implementation uses ReservableCurrency, following the same pattern as pallet assets.

Are there relevant PRs or issues in other repositories (Substrate, Polkadot, Frontier, Cumulus)?

We should run the migration added here #3020 after this PR is merged.

What value does it bring to the blockchain users?

It should be easier for Parachain teams to register their assets natively in Moonbeam

[github-actions]

WASM runtime size check:

Compared to target branch

Moonbase runtime: 2280 KB (no changes) ✅

Moonbeam runtime: 2256 KB (no changes) ✅

Moonriver runtime: 2248 KB (no changes) ✅

Compared to latest release (runtime-3400)

Moonbase runtime: 2280 KB (+252 KB compared to latest release) ⚠️

Moonbeam runtime: 2256 KB (+244 KB compared to latest release) ⚠️

Moonriver runtime: 2248 KB (+236 KB compared to latest release) ⚠️

[RomarQ]

I still need to get more context about this feature, will probably ping you later.

Added a few remarks for now.

[RomarQ]

How important is this storage for assets that were created with governance? Asking because the assets were already migrated on stagenet, and I do not see it being breaking if we don't fix the storage there.

Seems only important for assets created by normal accounts.

[RomarQ]

@albertov19, is it expected that the asset creation deposit will be reserved forever?

[albertov19]

@albertov19, is it expected that the asset creation deposit will be reserved forever?

Yes, this is fine. @stiiifff and I discussed of initially rolling this feature enforcing origins to be another parachain

[gonzamontiel]

The PR is ready to be reviewed, only tests are missing. I have updated the description to help reviewers and describe the changes.