A new FRAME-based Substrate node, ready for hacking :rocket:
Follow these steps to prepare a local Substrate development environment :hammer_and_wrench:
Install all the required dependencies with a single command (be patient, this can take up to 30 minutes).
curl https://getsubstrate.io -sSf | bash -s -- --fast
Find manual setup instructions at the Substrate Developer Hub.
Once the development environment is set up, build the node template. This command will build the Wasm and native code:
cargo build --release
Purge any existing dev chain state:
./target/release/node-template purge-chain --dev
Start a dev chain:
./target/release/node-template --dev
Or, start a dev chain with detailed logging:
RUST_LOG=debug RUST_BACKTRACE=1 ./target/release/node-template -lruntime=debug --dev
If you want to see the multi-node consensus algorithm in action, refer to our Start a Private Network tutorial.
A Substrate project such as this consists of a number of components that are spread across a few directories.
A blockchain node is an application that allows users to participate in a blockchain network. Substrate-based blockchain nodes expose a number of capabilities:
libp2p
networking stack to allow the
nodes in the network to communicate with one another.There are several files in the node
directory - take special note of the following:
chain_spec.rs
: A
chain specification is a
source code file that defines a Substrate chain's initial (genesis) state. Chain specifications
are useful for development and testing, and critical when architecting the launch of a
production chain. Take note of the development_config
and testnet_genesis
functions, which
are used to define the genesis state for the local development chain configuration. These
functions identify some
well-known accounts
and use them to configure the blockchain's initial state.service.rs
: This file defines the node implementation. Take note of
the libraries that this file imports and the names of the functions it invokes. In particular,
there are references to consensus-related topics, such as the
longest chain rule,
the Aura block authoring
mechanism and the
GRANDPA finality
gadget.After the node has been built, refer to the embedded documentation to learn more about the capabilities and configuration parameters that it exposes:
./target/release/node-template --help
In Substrate, the terms "runtime" and "state transition function" are analogous - they refer to the core logic of the blockchain that is responsible for validating blocks and executing the state changes they define. The Substrate project in this repository uses the FRAME framework to construct a blockchain runtime. FRAME allows runtime developers to declare domain-specific logic in modules called "pallets". At the heart of FRAME is a helpful macro language that makes it easy to create pallets and flexibly compose them to create blockchains that can address a variety of needs.
Review the FRAME runtime implementation included in this template and note the following:
impl $PALLET_NAME::Trait for Runtime
.construct_runtime!
macro, which is part of the core
FRAME Support
library.The runtime in this project is constructed using many FRAME pallets that ship with the
core Substrate repository and a
template pallet that is defined in the pallets
directory.
A FRAME pallet is compromised of a number of blockchain primitives:
Trait
configuration interface is used to define the types and parameters upon which
a FRAME pallet depends.First, install Docker and Docker Compose.
Then run the following command to start a single node development chain.
./scripts/docker_run.sh
This command will firstly compile your code, and then start a local development network. You can
also replace the default command (cargo build --release && ./target/release/node-template --dev --ws-external
)
by appending your own. A few useful ones are as follow.
# Run Substrate node without re-compiling
./scripts/docker_run.sh ./target/release/node-template --dev --ws-external
# Purge the local dev chain
./scripts/docker_run.sh ./target/release/node-template purge-chain --dev
# Check whether the code is compilable
./scripts/docker_run.sh cargo check