# Substrate API Sidecar

REST API service intended to run next to Substrate, exposing a limited set of endpoints over HTTP
with meaningful responses.

### Installation

Make sure your machine has an
[up-to-date version of `rustup`](https://www.rust-lang.org/tools/install) installed to manage Rust
dependencies.

Install `wasm-pack` if your machine does not already have it:

```
cargo install wasm-pack
```

Use yarn to do the remaining setup:

```
yarn
```

### Running

```
yarn start
```

### Available paths

Block IDs may take two forms: a non-negative decimal integer that denotes the block _height_ **or**
a 32-byte hex string (`0x` followed by 64 hexadecimal digits) that denotes the block _hash_.

- `/block` fetch latest finalized block details.

- `/block/NUMBER` fetch block details at the block identified by 'NUMBER`.

- `/balance/ADDRESS` fetch balances for `ADDRESS` at latest finalized block.

- `/balance/ADDRESS/NUMBER` fetch balances for `ADDRESS` at the block identified by 'NUMBER`.

- `/staking/ADDRESS` fetch the staking info for `ADDRESS` at latest finalized block.

- `/staking/ADDRESS/NUMBER` fetch the staking info for `ADDRESS` at the block identified by 'NUMBER`.

- `/vesting/ADDRESS` fetch the vesting info for `ADDRESS` at latest finalized block.

- `/vesting/ADDRESS/NUMBER` fetch the vesting info for `ADDRESS` at the block identified by 'NUMBER`.

- `/metadata` fetch chain metadata at latest finalized block.

- `/metadata/NUMBER` fetch chain metadata at the block identified by 'NUMBER`.

- `/claims/ADDRESS` fetch claims data for an Ethereum `ADDRESS`.

- `/claims/ADDRESS/NUMBER` fetch claims data for an Ethereum `ADDRESS` at the block identified by 'NUMBER`.

- `/tx/artifacts/` fetch artifacts used for creating transactions at latest finalized block.

- `/tx/artifacts/NUMBER` fetch artifacts used for creating transactions at the block identified by 'NUMBER`.

- `/tx/fee-estimate` submit a transaction in order to get back a fee estimation. Expects a string
  with a hex-encoded transaction in a JSON POST body:
  ```
  curl localhost:8080/tx/fee-estimate -X POST --data '{"tx": "0x..."}' -H 'Content-Type: application/json'
  ```
  Expected result is a JSON with fee information:
  ```
  {
    "weight": "195000000",
    "class": "Normal",
    "partialFee": "165600000"
  }
  ```

- `/tx/` submit a signed transaction, expects a string with hex-encoded transaction in a JSON POST
  body:
  ```
  curl localhost:8080/tx/ -X POST --data '{"tx": "0x..."}' -H 'Content-Type: application/json'
  ```
  Expected result is a JSON with transaction hash:
  ```
  {
      "hash": "..."
  }
  ```

### Configuration

Following ENV variables can be set:

- `BIND_HOST`: address on which the server will be listening, defaults to `127.0.0.1`.
- `BIND_PORT`: port on which the server will be listening, defaults to `8080`.
- `NODE_WS_URL`: WebSocket URL to which the RPC proxy will attempt to connect to, defaults to
  `ws://127.0.0.1:9944`.
- `LOG_MODE`: enable console logging of "all" HTTP requests, only "errors", or nothing by setting it to anything else. LOG_MODE defaults to only "errors".

### Chain compatibility

Sidecar should be compatible with any [Substrate](https://substrate.dev/) based chain, given
constraints:

- The chain ought to use FRAME and the `balances` pallet.
- The chain is being finalized (by running `grandpa`).
- If the chain is running on custom Node binaries, the JSON-RPC API should be backwards compatible
  with the default Substrate Node.

### Contribute

We welcome contributions. Before submitting your PR, make sure to run the following commands:

- `yarn lint`: Make sure your code follows our linting rules. You can also run `yarn lint --fix` to automatically fix some of those errors.
- Testing coming soon!