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https://github.com/substrate-developer-hub/substrate-node-template

A new FRAME-based Substrate node, ready for hacking.
https://github.com/substrate-developer-hub/substrate-node-template

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A new FRAME-based Substrate node, ready for hacking.

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README 

        
# Substrate Node Template



A fresh [Substrate](https://substrate.io/) node, ready for hacking :rocket:



A standalone version of this template is available for each release of Polkadot

in the [Substrate Developer Hub Parachain

Template](https://github.com/substrate-developer-hub/substrate-parachain-template/)

repository. The parachain template is generated directly at each Polkadot

release branch from the [Node Template in

Substrate](https://github.com/paritytech/polkadot-sdk/tree/master/substrate/bin/node-template)

upstream



It is usually best to use the stand-alone version to start a new project. All

bugs, suggestions, and feature requests should be made upstream in the

[Substrate](https://github.com/paritytech/polkadot-sdk/tree/master/substrate)

repository.



## Getting Started



Depending on your operating system and Rust version, there might be additional

packages required to compile this template. Check the

[Install](https://docs.substrate.io/install/) instructions for your platform for

the most common dependencies. Alternatively, you can use one of the [alternative

installation](#alternatives-installations) options.



### Build



Use the following command to build the node without launching it:



```sh

cargo build --release

```



### Embedded Docs



After you build the project, you can use the following command to explore its

parameters and subcommands:



```sh

./target/release/node-template -h

```



You can generate and view the [Rust

Docs](https://doc.rust-lang.org/cargo/commands/cargo-doc.html) for this template

with this command:



```sh

cargo +nightly doc --open

```



### Single-Node Development Chain



The following command starts a single-node development chain that doesn't

persist state:



```sh

./target/release/node-template --dev

```



To purge the development chain's state, run the following command:



```sh

./target/release/node-template purge-chain --dev

```



To start the development chain with detailed logging, run the following command:



```sh

RUST_BACKTRACE=1 ./target/release/node-template -ldebug --dev

```



Development chains:



- Maintain state in a `tmp` folder while the node is running.

- Use the **Alice** and **Bob** accounts as default validator authorities.

- Use the **Alice** account as the default `sudo` account.

- Are preconfigured with a genesis state (`/node/src/chain_spec.rs`) that

  includes several prefunded development accounts.



To persist chain state between runs, specify a base path by running a command

similar to the following:



```sh

// Create a folder to use as the db base path

$ mkdir my-chain-state



// Use of that folder to store the chain state

$ ./target/release/node-template --dev --base-path ./my-chain-state/



// Check the folder structure created inside the base path after running the chain

$ ls ./my-chain-state

chains

$ ls ./my-chain-state/chains/

dev

$ ls ./my-chain-state/chains/dev

db keystore network

```



### Connect with Polkadot-JS Apps Front-End



After you start the node template locally, you can interact with it using the

hosted version of the [Polkadot/Substrate

Portal](https://polkadot.js.org/apps/#/explorer?rpc=ws://localhost:9944)

front-end by connecting to the local node endpoint. A hosted version is also

available on [IPFS (redirect) here](https://dotapps.io/) or [IPNS (direct)

here](ipns://dotapps.io/?rpc=ws%3A%2F%2F127.0.0.1%3A9944#/explorer). You can

also find the source code and instructions for hosting your own instance on the

[`polkadot-js/apps`](https://github.com/polkadot-js/apps) repository.



### Multi-Node Local Testnet



If you want to see the multi-node consensus algorithm in action, see [Simulate a

network](https://docs.substrate.io/tutorials/build-a-blockchain/simulate-network/).



## Template Structure



A Substrate project such as this consists of a number of components that are

spread across a few directories.



### Node



A blockchain node is an application that allows users to participate in a

blockchain network. Substrate-based blockchain nodes expose a number of

capabilities:



- Networking: Substrate nodes use the [`libp2p`](https://libp2p.io/) networking

  stack to allow the nodes in the network to communicate with one another.

- Consensus: Blockchains must have a way to come to

  [consensus](https://docs.substrate.io/fundamentals/consensus/) on the state of

  the network. Substrate makes it possible to supply custom consensus engines

  and also ships with several consensus mechanisms that have been built on top

  of [Web3 Foundation

  research](https://research.web3.foundation/en/latest/polkadot/NPoS/index.html).

- RPC Server: A remote procedure call (RPC) server is used to interact with

  Substrate nodes.



There are several files in the `node` directory. Take special note of the

following:



- [`chain_spec.rs`](./node/src/chain_spec.rs): A [chain

  specification](https://docs.substrate.io/build/chain-spec/) 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,. These functions are

  used to define the genesis state for the local development chain

  configuration. These functions identify some [well-known

  accounts](https://docs.substrate.io/reference/command-line-tools/subkey/) and

  use them to configure the blockchain's initial state.

- [`service.rs`](./node/src/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 [block finalization and

  forks](https://docs.substrate.io/fundamentals/consensus/#finalization-and-forks)

  and other [consensus

  mechanisms](https://docs.substrate.io/fundamentals/consensus/#default-consensus-models)

  such as Aura for block authoring and GRANDPA for finality.



### Runtime



In Substrate, the terms "runtime" and "state transition function" are analogous.

Both terms 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

[FRAME](https://docs.substrate.io/learn/runtime-development/#frame) 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](https://docs.substrate.io/reference/frame-macros/) that makes it easy

to create pallets and flexibly compose them to create blockchains that can

address [a variety of needs](https://substrate.io/ecosystem/projects/).



Review the [FRAME runtime implementation](./runtime/src/lib.rs) included in this

template and note the following:



- This file configures several pallets to include in the runtime. Each pallet

  configuration is defined by a code block that begins with `impl

$PALLET_NAME::Config for Runtime`.

- The pallets are composed into a single runtime by way of the

  [`construct_runtime!`](https://paritytech.github.io/substrate/master/frame_support/macro.construct_runtime.html)

  macro, which is part of the [core FRAME pallet

  library](https://docs.substrate.io/reference/frame-pallets/#system-pallets).



### Pallets



The runtime in this project is constructed using many FRAME pallets that ship

with [the Substrate

repository](https://github.com/paritytech/polkadot-sdk/tree/master/substrate/frame) and a

template pallet that is [defined in the

`pallets`](./pallets/template/src/lib.rs) directory.



A FRAME pallet is comprised of a number of blockchain primitives, including:



- Storage: FRAME defines a rich set of powerful [storage

  abstractions](https://docs.substrate.io/build/runtime-storage/) that makes it

  easy to use Substrate's efficient key-value database to manage the evolving

  state of a blockchain.

- Dispatchables: FRAME pallets define special types of functions that can be

  invoked (dispatched) from outside of the runtime in order to update its state.

- Events: Substrate uses

  [events](https://docs.substrate.io/build/events-and-errors/) to notify users

  of significant state changes.

- Errors: When a dispatchable fails, it returns an error.



Each pallet has its own `Config` trait which serves as a configuration interface

to generically define the types and parameters it depends on.



## Alternatives Installations



Instead of installing dependencies and building this source directly, consider

the following alternatives.



### Nix



Install [nix](https://nixos.org/) and

[nix-direnv](https://github.com/nix-community/nix-direnv) for a fully

plug-and-play experience for setting up the development environment. To get all

the correct dependencies, activate direnv `direnv allow`.



### Docker



Please follow the [Substrate Docker instructions

here](https://github.com/paritytech/polkadot-sdk/blob/master/substrate/docker/README.md) to

build the Docker container with the Substrate Node Template binary.