Scout is a Ethereum 2.0 Phase 2 execution prototyping engine.
Warning: this is super experimental
- Create a (black boxed) execution prototyping engine
- Create some example contracts ("execution scripts")
- Enable "easy" onboarding for creating scripts
- By having actual real world use cases in scripts, we can benchmark the design and identify bottlenecks
This engine intentionally avoids a lot of details and therefore it is not usable as a Eth 2.0 client. Instead of being a client, it should support reading and outputting shard/beacon states in a YAML format.
Need Rust first. Then install chisel
using cargo:
cargo install chisel
There is a Makefile
to make building easy:
build
will build all components (the runner and the example scripts)test
will run tests using the YAML test filesall
will do both
The runner is called scout and is available at target/release/phase2-scout
after being built.
The runner expects a YAML test file:
beacon_state:
execution_scripts:
- scripts/helloworld/target/wasm32-unknown-unknown/release/phase2_helloworld.wasm
shard_pre_state:
exec_env_states:
- "0000000000000000000000000000000000000000000000000000000000000000"
shard_blocks:
- env: 0
data: ""
- env: 0
data: ""
shard_post_state:
exec_env_states:
- "0000000000000000000000000000000000000000000000000000000000000000"
The runner expects a filename pointing to the test file or will default to test.yaml
in the local directory if nothing was specified.
An example script is located in scripts/helloworld
. It uses ewasm-rust-api with the experimental eth2
feature.
extern crate ewasm_api;
use ewasm_api::*;
#[cfg(not(test))]
#[no_mangle]
pub extern "C" fn main() {
let pre_state_root = eth2::load_pre_state_root();
assert!(eth2::block_data_size() == 0);
// No updates were made to the state
let post_state_root = pre_state_root;
eth2::save_post_state_root(post_state)
}
A better example is located in scripts/bazaar
which is in essence a stateless contract. It uses SSZ serialisation. A test case is included in bazaar.yaml
.
It should be possible to import any Rust crate as long as it can be compiled to the wasm32 target.
- Alex Beregszaszi
Apache 2.0