# Substrate Node Template A new FRAME-based Substrate node, ready for hacking :rocket: ## Local Development Follow these steps to prepare a local Substrate development environment :hammer_and_wrench: ### Simple Setup Install all the required dependencies with a single command (be patient, this can take up to 30 minutes). ```bash curl https://getsubstrate.io -sSf | bash -s -- --fast ``` ### Manual Setup Find manual setup instructions at the [Substrate Developer Hub](https://substrate.dev/docs/en/knowledgebase/getting-started/#manual-installation). ### Build Once the development environment is set up, build the node template. This command will build the [Wasm](https://substrate.dev/docs/en/knowledgebase/advanced/executor#wasm-execution) and [native](https://substrate.dev/docs/en/knowledgebase/advanced/executor#native-execution) code: ```bash cargo build --release ``` ## Run ### Single Node Development Chain Purge any existing dev chain state: ```bash ./target/release/node-template purge-chain --dev ``` Start a dev chain: ```bash ./target/release/node-template --dev ``` Or, start a dev chain with detailed logging: ```bash RUST_LOG=debug RUST_BACKTRACE=1 ./target/release/node-template -lruntime=debug --dev ``` ### Multi-Node Local Testnet To see the multi-node consensus algorithm in action, run a local testnet with two validator nodes, Alice and Bob, that have been [configured](./node/src/chain_spec.rs) as the initial authorities of the `local` testnet chain and endowed with testnet units. Note: this will require two terminal sessions (one for each node). Start Alice's node first. The command below uses the default TCP port (30333) and specifies `/tmp/alice` as the chain database location. Alice's node ID will be `12D3KooWEyoppNCUx8Yx66oV9fJnriXwCcXwDDUA2kj6vnc6iDEp` (legacy representation: `QmRpheLN4JWdAnY7HGJfWFNbfkQCb6tFf4vvA6hgjMZKrR`); this is determined by the `node-key`. ```bash cargo run -- \ --base-path /tmp/alice \ --chain=local \ --alice \ --node-key 0000000000000000000000000000000000000000000000000000000000000001 \ --telemetry-url 'ws://telemetry.polkadot.io:1024 0' \ --validator ``` In another terminal, use the following command to start Bob's node on a different TCP port (30334) and with a chain database location of `/tmp/bob`. The `--bootnodes` option will connect his node to Alice's on TCP port 30333: ```bash cargo run -- \ --base-path /tmp/bob \ --bootnodes /ip4/127.0.0.1/tcp/30333/p2p/12D3KooWEyoppNCUx8Yx66oV9fJnriXwCcXwDDUA2kj6vnc6iDEp \ --chain=local \ --bob \ --port 30334 \ --ws-port 9945 \ --telemetry-url 'ws://telemetry.polkadot.io:1024 0' \ --validator ``` Execute `cargo run -- --help` to learn more about the template node's CLI options. ## 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://substrate.dev/docs/en/knowledgebase/advanced/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://substrate.dev/docs/en/knowledgebase/integrate/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, which are used to define the genesis state for the local development chain configuration. These functions identify some [well-known accounts](https://substrate.dev/docs/en/knowledgebase/integrate/subkey#well-known-keys) 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 [longest chain rule](https://substrate.dev/docs/en/knowledgebase/advanced/consensus#longest-chain-rule), the [Aura](https://substrate.dev/docs/en/knowledgebase/advanced/consensus#aura) block authoring mechanism and the [GRANDPA](https://substrate.dev/docs/en/knowledgebase/advanced/consensus#grandpa) finality gadget. After the node has been [built](#build), refer to the embedded documentation to learn more about the capabilities and configuration parameters that it exposes: ```shell ./target/release/node-template --help ``` ### Runtime In Substrate, the terms "[runtime](https://substrate.dev/docs/en/knowledgebase/getting-started/glossary#runtime)" and "[state transition function](https://substrate.dev/docs/en/knowledgebase/getting-started/glossary#stf-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](https://substrate.dev/docs/en/knowledgebase/runtime/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](https://substrate.dev/docs/en/knowledgebase/runtime/macros) that makes it easy to create pallets and flexibly compose them to create blockchains that can address [a variety of needs](https://www.substrate.io/substrate-users/). 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::Trait for Runtime`. - The pallets are composed into a single runtime by way of the [`construct_runtime!`](https://crates.parity.io/frame_support/macro.construct_runtime.html) macro, which is part of the core [FRAME Support](https://substrate.dev/docs/en/knowledgebase/runtime/frame#support-library) library. ### Pallets The runtime in this project is constructed using many FRAME pallets that ship with the [core Substrate repository](https://github.com/paritytech/substrate/tree/master/frame) and a template pallet that is [defined in the `pallets`](./pallets/template/src/lib.rs) directory. A FRAME pallet is compromised of a number of blockchain primitives: - Storage: FRAME defines a rich set of powerful [storage abstractions](https://substrate.dev/docs/en/knowledgebase/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://substrate.dev/docs/en/knowledgebase/runtime/events) to notify users of important changes in the runtime. - Errors: When a dispatchable fails, it returns an error. - Trait: The `Trait` configuration interface is used to define the types and parameters upon which a FRAME pallet depends. ## Generate a Custom Node Template Generate a Substrate node template based on a particular commit by running the following commands: ```bash # Clone from the main Substrate repo git clone https://github.com/paritytech/substrate.git cd substrate # Switch to the branch or commit to base the template on git checkout # Run the helper script to generate a node template. This script compiles Substrate, so it will take # a while to complete. It expects a single parameter: the location for the script's output expressed # as a relative path. .maintain/node-template-release.sh ../node-template.tar.gz ``` Custom node templates are not supported. Please use a recently tagged version of the [Substrate Developer Node Template](https://github.com/substrate-developer-hub/substrate-node-template) in order to receive support.