205 lines
8.3 KiB
Markdown
205 lines
8.3 KiB
Markdown
# Substrate Node Template
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[](https://docs.substrate.io/playground/) [](https://matrix.to/#/#substrate-technical:matrix.org)
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A fresh FRAME-based [Substrate](https://www.substrate.io/) node, ready for hacking :rocket:
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## Getting Started
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Follow the steps below to get started with the Node Template, or get it up and running right from
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your browser in just a few clicks using
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the [Substrate Playground](https://docs.substrate.io/playground/) :hammer_and_wrench:
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### Using Nix
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Install [nix](https://nixos.org/) and optionally [direnv](https://github.com/direnv/direnv) and
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[lorri](https://github.com/target/lorri) for a fully plug and play experience for setting up the
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development environment. To get all the correct dependencies activate direnv `direnv allow` and
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lorri `lorri shell`.
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### Rust Setup
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First, complete the [basic Rust setup instructions](./docs/rust-setup.md).
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### Run
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Use Rust's native `cargo` command to build and launch the template node:
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```sh
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cargo run --release -- --dev --tmp
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```
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### Build
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The `cargo run` command will perform an initial build. Use the following command to build the node
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without launching it:
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```sh
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cargo build --release
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```
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### Embedded Docs
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Once the project has been built, the following command can be used to explore all parameters and
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subcommands:
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```sh
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./target/release/node-template -h
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```
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## Run
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The provided `cargo run` command will launch a temporary node and its state will be discarded after
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you terminate the process. After the project has been built, there are other ways to launch the
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node.
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### Single-Node Development Chain
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This command will start the single-node development chain with persistent state:
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```bash
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./target/release/node-template --dev
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```
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Purge the development chain's state:
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```bash
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./target/release/node-template purge-chain --dev
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```
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Start the development chain with detailed logging:
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```bash
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RUST_BACKTRACE=1 ./target/release/node-template -ldebug --dev
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```
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### Connect with Polkadot-JS Apps Front-end
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Once the node template is running locally, you can connect it with **Polkadot-JS Apps** front-end
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to interact with your chain. [Click
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here](https://polkadot.js.org/apps/#/explorer?rpc=ws://localhost:9944) connecting the Apps to your
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local node template.
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### Multi-Node Local Testnet
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If you want to see the multi-node consensus algorithm in action, refer to our
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[Start a Private Network tutorial](https://docs.substrate.io/tutorials/v3/private-network).
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## Template Structure
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A Substrate project such as this consists of a number of components that are spread across a few
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directories.
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### Node
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A blockchain node is an application that allows users to participate in a blockchain network.
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Substrate-based blockchain nodes expose a number of capabilities:
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- Networking: Substrate nodes use the [`libp2p`](https://libp2p.io/) networking stack to allow the
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nodes in the network to communicate with one another.
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- Consensus: Blockchains must have a way to come to
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[consensus](https://docs.substrate.io/v3/advanced/consensus) on the state of the
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network. Substrate makes it possible to supply custom consensus engines and also ships with
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several consensus mechanisms that have been built on top of
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[Web3 Foundation research](https://research.web3.foundation/en/latest/polkadot/NPoS/index.html).
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- RPC Server: A remote procedure call (RPC) server is used to interact with Substrate nodes.
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There are several files in the `node` directory - take special note of the following:
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- [`chain_spec.rs`](./node/src/chain_spec.rs): A
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[chain specification](https://docs.substrate.io/v3/runtime/chain-specs) is a
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source code file that defines a Substrate chain's initial (genesis) state. Chain specifications
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are useful for development and testing, and critical when architecting the launch of a
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production chain. Take note of the `development_config` and `testnet_genesis` functions, which
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are used to define the genesis state for the local development chain configuration. These
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functions identify some
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[well-known accounts](https://docs.substrate.io/v3/tools/subkey#well-known-keys)
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and use them to configure the blockchain's initial state.
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- [`service.rs`](./node/src/service.rs): This file defines the node implementation. Take note of
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the libraries that this file imports and the names of the functions it invokes. In particular,
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there are references to consensus-related topics, such as the
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[longest chain rule](https://docs.substrate.io/v3/advanced/consensus#longest-chain-rule),
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the [Aura](https://docs.substrate.io/v3/advanced/consensus#aura) block authoring
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mechanism and the
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[GRANDPA](https://docs.substrate.io/v3/advanced/consensus#grandpa) finality
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gadget.
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After the node has been [built](#build), refer to the embedded documentation to learn more about the
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capabilities and configuration parameters that it exposes:
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```shell
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./target/release/node-template --help
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```
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### Runtime
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In Substrate, the terms
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"[runtime](https://docs.substrate.io/v3/getting-started/glossary#runtime)" and
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"[state transition function](https://docs.substrate.io/v3/getting-started/glossary#state-transition-function-stf)"
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are analogous - they refer to the core logic of the blockchain that is responsible for validating
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blocks and executing the state changes they define. The Substrate project in this repository uses
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the [FRAME](https://docs.substrate.io/v3/runtime/frame) framework to construct a
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blockchain runtime. FRAME allows runtime developers to declare domain-specific logic in modules
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called "pallets". At the heart of FRAME is a helpful
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[macro language](https://docs.substrate.io/v3/runtime/macros) that makes it easy to
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create pallets and flexibly compose them to create blockchains that can address
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[a variety of needs](https://www.substrate.io/substrate-users/).
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Review the [FRAME runtime implementation](./runtime/src/lib.rs) included in this template and note
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the following:
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- This file configures several pallets to include in the runtime. Each pallet configuration is
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defined by a code block that begins with `impl $PALLET_NAME::Config for Runtime`.
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- The pallets are composed into a single runtime by way of the
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[`construct_runtime!`](https://crates.parity.io/frame_support/macro.construct_runtime.html)
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macro, which is part of the core
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[FRAME Support](https://docs.substrate.io/v3/runtime/frame#support-crate)
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library.
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### Pallets
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The runtime in this project is constructed using many FRAME pallets that ship with the
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[core Substrate repository](https://github.com/paritytech/substrate/tree/master/frame) and a
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template pallet that is [defined in the `pallets`](./pallets/template/src/lib.rs) directory.
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A FRAME pallet is compromised of a number of blockchain primitives:
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- Storage: FRAME defines a rich set of powerful
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[storage abstractions](https://docs.substrate.io/v3/runtime/storage) that makes
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it easy to use Substrate's efficient key-value database to manage the evolving state of a
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blockchain.
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- Dispatchables: FRAME pallets define special types of functions that can be invoked (dispatched)
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from outside of the runtime in order to update its state.
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- Events: Substrate uses [events and errors](https://docs.substrate.io/v3/runtime/events-and-errors)
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to notify users of important changes in the runtime.
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- Errors: When a dispatchable fails, it returns an error.
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- Config: The `Config` configuration interface is used to define the types and parameters upon
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which a FRAME pallet depends.
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### Run in Docker
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First, install [Docker](https://docs.docker.com/get-docker/) and
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[Docker Compose](https://docs.docker.com/compose/install/).
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Then run the following command to start a single node development chain.
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```bash
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./scripts/docker_run.sh
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```
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This command will firstly compile your code, and then start a local development network. You can
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also replace the default command
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(`cargo build --release && ./target/release/node-template --dev --ws-external`)
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by appending your own. A few useful ones are as follow.
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```bash
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# Run Substrate node without re-compiling
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./scripts/docker_run.sh ./target/release/node-template --dev --ws-external
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# Purge the local dev chain
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./scripts/docker_run.sh ./target/release/node-template purge-chain --dev
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# Check whether the code is compilable
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./scripts/docker_run.sh cargo check
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```
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