Import and deploy contracts from remote sources

[sideninja]

Issue To Be Solved

When deploying contracts we currently need to have a copy of that contract locally.

Suggest A Solution

Contract deployment functionality (project deploy) allows us to automatically resolve imports from contracts on the fly and replace them with addresses. These imports are currently relative file locations of the contract source code.

Besides having a relative file location we should allow importing from remote locations (URLs, github repos...). This files should be pulled on the fly and deployed. Another option is that this would first pull the file and save it locally and then deploy it.

This change should also be supported by the language server so it resolves the files.

[psiemens]

I think that both example you listed could be implemented as separate loaders.

• URL loader: download a Cadence source file from a URL.
• Git loader: import a file from a git repository, versioned by branch, tag or commit.

The URL loader is far simpler than git and would still unblock us in the short term. We can even achieve simple versioning by just specifying the right GitHub URL (e.g. https://github.com/onflow/flow-ft/blob/v0.1.2/src/contracts/FlowToken.cdc).

[sideninja]

I agree. Loaders are a perfect fit.

I think files should be loaded locally and then deployed, but if someone finds good reasons to not store them locally we can also avoid that and just deploy it without saving.

The other problem I see currently is with resolving imports in cadence files. Of course, a possible solution is to have an URL directly stated at import like import https://github.com/onflow/flow-ft/blob/v0.1.2/src/contracts/FlowToken.cdc but I don't really like this.
Another better solution would be to have a link included in the configuration as an alias:
Proposed new config:

"FungibleToken": {
  "source": "https://github.com/onflow/flow-ft/blob/v0.1.2/src/contracts/FlowToken.cdc",
  "aliases": {
    "emulator": "ee82856bf20e2aa6",
    "testnet": "9a0766d93b6608b7"
   }
}

But this solution then still leaves us with the problem of resolving imports in cadence files by the language processor. Another possible solution is to specify in config location for the contract after the download and the location of the remote file:

"FungibleToken": {
  "localSource": "cadence/kibble/contracts/FungibleToken.cdc",
  "remoteSource": "https://github.com/onflow/flow-ft/blob/v0.1.2/src/contracts/FlowToken.cdc",
  "aliases": {
    "emulator": "ee82856bf20e2aa6",
    "testnet": "9a0766d93b6608b7"
   }
}

The above configuration would instruct CLI when running deploy command to first load and save the contract locally (location specified under localSource) and after deploy it. This solution would involve contracts having imports that would work without changing language processing.
import cadence/kibble/contracts/FungibleToken.cdc

The last solution would also allow us to also add a new command similar to package manager install where you would add contract from a remote location in a separate step something like project add FlowToken (for standard contracts) or project add @onflow/Kibble for non-standard contracts, but this would be a separate feature.

Tagging @joshuahannan since I believe you are currently most burdened by this problem.

[bjartek]

This would be very nice so that you do not have to have the source code for all contracts locally at all times. Especially when there will be more standard flow contracts available.

What about pulling a contract down from testnet and deploying to emulator?

[sideninja]

What about pulling a contract down from testnet and deploying to the emulator?

Good idea.
We were thinking you would have some kind of remote resource formats and one of which could also be contracts from the Flow blockchain. So instead of URLs you would probably specify @onflow/kibble (not an actual solution just raw example) so you could have some kind of @testnet/address format.

[bjartek]

That would work really well @sideninja