phat_squid_demo: SQD Network indexer in a Phala Phat Contract

A demo Phala Network Phat Contract (ink!) that reads historical EVM data from SQD Network and writes the results to S3-compatible storage. It shows how to run an indexer as offchain logic inside a Phala Worker instead of a standalone service.

This is example code maintained by SQD (sqd.dev). It is meant as a starting point to copy and adapt, not a production indexer.

What it does

The contract (indexer_phat/contracts/http_client) is an ink! 4.2 contract built on the pink-extension, which lets a Phat Contract perform HTTP requests from inside a Phala Worker.

Its start_indexer(start, end) message loops over a block range and, for each block:

1. Requests a SQD Network worker URL for the ethereum-mainnet dataset from the SQD Network gateway.
2. Sends an EVM query to that worker for ERC-20 Transfer logs of the USDC contract (0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48).
3. Stores the raw response for that block in an S3-compatible bucket using the pink-s3 library, keyed as block-<number>.
4. Updates last_indexed_block.

get_last_indexed_block() returns the last block number the contract processed.

The query and the storage call are hardcoded in contracts/http_client/src/lib.rs. Change the query body to index different logs, transactions, or fields (see the SQD Network EVM API reference and the list of supported networks), and edit the store_s3 function to point at your own storage endpoint and credentials. The endpoint, bucket, and keys in store_s3 are placeholders and must be filled in before deployment.

Repository layout

indexer_phat/
  contracts/http_client/   ink! contract source (Cargo project)
  tests/http_client/        TypeScript integration test (devphase + @phala/sdk)
  stacks/                   local Phala dev stack binaries
  devphase.config.json      devphase configuration (local, poc5, poc6 networks)
  package.json              Node dependencies (@devphase/service, typescript)

Build

The contract is built with cargo contract. Set up the Rust and cargo-contract toolchain following the cargo-contract installation guide.

cd indexer_phat/contracts/http_client
cargo contract build

Test

Rust unit test (mocks the Phala HTTP extension locally):

cd indexer_phat/contracts/http_client
cargo test -- --nocapture

The repository also includes a TypeScript integration test under indexer_phat/tests, run through devphase with the local stack defined in devphase.config.json. Install the Node dependencies first:

cd indexer_phat
yarn install

Deploy

Deploy the compiled .contract artifact to Phala Network using the Phala tooling and UI. See the Phala Network documentation for current deployment instructions. The devphase.config.json in this repo includes endpoints for a local stack and the poc5 and poc6 test networks.

After deployment, the contract exposes:

• new(): initializes the contract.
• start_indexer(start: i32, end: i32): indexes blocks from start to end.
• get_last_indexed_block(): returns the last indexed block number.

Notes and limitations

• If a request to SQD Network fails for a block, the contract returns an error for that call. Retry logic is not implemented.
• The S3 credentials and endpoint in store_s3 are placeholders. They must be replaced with real values before the contract can store data.

Documentation

• SQD Network: https://docs.sqd.dev/subsquid-network/overview/
• SQD Network EVM API reference: https://docs.sqd.dev/subsquid-network/reference/evm-api/
• SQD docs home: https://docs.sqd.dev
• Phala Network docs: https://docs.phala.network/

License

MIT (see indexer_phat/package.json).