CLI & Emulator Feature: Flow network snapshots

[srinjoyc]

Description (Problem Statement)

The developer should be able to get a snapshot of the Flow mainnet/testnet blockchain at a specific time in history and inspect it locally using the emulator. This would allow developers to debug their contracts but also to compose on top of other existing applications deployed to the network. The CLI should be extended to support this functionality by implementing AN APIs to fetch the snapshot and then start the emulator configured to read from it.

Experience Required

• Experience with Go
• Understanding of the Flow's architecture
• Understanding of Cadence

Minimum Feature Set (Acceptance Criteria)

• The CLI supports fetching the snapshot from the Flow blockchain at a specified time (block height)
• The emulator is modified so it can start from the provided snapshot and allow read operations on it

Extension (Optional) Feature Set

• Interoperability with Emulator GUI for state inspection, loading the state and all other functionality possible with this feature

Milestone Requirements

1. Provide documentation on the implementation process and details
2. Implement snapshot fetching functionality in the CLI
3. Implement the emulator so it can be started from the provided snapshot

Software Requirements

Maintainability

• Code should be written with good practices in mind and allow extensibility

Testing

• This feature should have good test code coverage

Other Requirements

Documentation

This feature must be sufficiently documented in the CLI and the Emulator.

Code Standards, Guidelines

• follow code standards already in place
• follow the CLI guidelines
• follow contribution guide

Judging Criteria

• Technical & High-Level Judging Criteria apply
• How effectively does the tool help developers in the building process in making it easy for them to debug, test, and verify their logic?

Resources

• General Resource Guide
• Emulator
  • Repo
  • Docs
  • Original Reference Issue
• CLI
  • Repo
  • Docs

[psiemens]

Unfortunately it's not yet possible to implement this feature due to changes needed in the Flow access node and Access API.