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chain-spec/presets reference docs added (paritytech#4678)
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Added reference doc about:
- the pallet genesis config and genesis build, 
- runtime `genesis-builder` API,
- presets,
- interacting with the `chain-spec-builder` tool

I've added [minimal
runtime](https://github.com/paritytech/polkadot-sdk/tree/mku-chain-spec-guide/docs/sdk/src/reference_docs/chain_spec_runtime)
to demonstrate above topics.

I also sneaked in some little improvement to `chain-spec-builder` which
allows to parse output of the `list-presets` command.

---------

Co-authored-by: Alexandru Vasile <[email protected]>
Co-authored-by: Sebastian Kunert <[email protected]>
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3 people authored and hitchhooker committed Jun 5, 2024
1 parent 84177e8 commit ac2de17
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31 changes: 30 additions & 1 deletion Cargo.lock

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1 change: 1 addition & 0 deletions Cargo.toml
Original file line number Diff line number Diff line change
Expand Up @@ -144,6 +144,7 @@ members = [
"cumulus/test/service",
"cumulus/xcm/xcm-emulator",
"docs/sdk",
"docs/sdk/src/reference_docs/chain_spec_runtime",
"polkadot",
"polkadot/cli",
"polkadot/core-primitives",
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5 changes: 5 additions & 0 deletions docs/sdk/Cargo.toml
Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,7 @@ sc-consensus-manual-seal = { path = "../../substrate/client/consensus/manual-sea
sc-consensus-pow = { path = "../../substrate/client/consensus/pow" }
sc-executor = { path = "../../substrate/client/executor" }
sc-service = { path = "../../substrate/client/service" }
sc-chain-spec = { path = "../../substrate/client/chain-spec" }

substrate-wasm-builder = { path = "../../substrate/utils/wasm-builder" }

Expand Down Expand Up @@ -90,6 +91,7 @@ sp-core = { path = "../../substrate/primitives/core" }
sp-keyring = { path = "../../substrate/primitives/keyring" }
sp-runtime = { path = "../../substrate/primitives/runtime" }
sp-arithmetic = { path = "../../substrate/primitives/arithmetic" }
sp-genesis-builder = { path = "../../substrate/primitives/genesis-builder" }

# Misc pallet dependencies
pallet-referenda = { path = "../../substrate/frame/referenda" }
Expand All @@ -102,3 +104,6 @@ sp-version = { path = "../../substrate/primitives/version" }
# XCM
xcm = { package = "staging-xcm", path = "../../polkadot/xcm" }
xcm-docs = { path = "../../polkadot/xcm/docs" }

# runtime guides
chain-spec-guide-runtime = { path = "./src/reference_docs/chain_spec_runtime" }
187 changes: 184 additions & 3 deletions docs/sdk/src/reference_docs/chain_spec_genesis.rs
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@@ -1,4 +1,185 @@
//! Chain spec and genesis build.
//! # What is chain-spec.
//!
//! What is chain-spec.
//! What is genesis state and how to build it.
//! A chain specification file defines the set of properties that are required to run the node as
//! part of the chain. The chain specification consists of two main parts:
//! - initial state of the runtime,
//! - network / logical properties of the chain, the most important property being the list of
//! bootnodes.
//!
//! This document describes how initial state is handled in pallets and runtime, and how to interact
//! with the runtime in order to build genesis state.
//!
//! For more information on chain specification and its properties, refer to
//! [`sc_chain_spec#from-initial-state-to-raw-genesis`].
//!
//! The initial genesis state can be provided in the following formats:
//! - full
//! - patch
//! - raw
//!
//! Each of the formats is explained in [_chain-spec-format_][`sc_chain_spec#chain-spec-formats`].
//!
//!
//! # `GenesisConfig` for `pallet`
//!
//! Every frame pallet may have its initial state which is defined by the `GenesisConfig` internal
//! struct. It is a regular rust struct, annotated with [`pallet::genesis_config`] attribute.
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/pallets.rs", pallet_bar_GenesisConfig)]
//!
//! The struct shall be defined within the pallet `mod`, as in the following code:
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/pallets.rs", pallet_bar)]
//!
//! The initial state conveyed in the `GenesisConfig` struct is transformed into state storage
//! items by means of the [`BuildGenesisConfig`] trait which shall be implemented for the pallet's
//! `GenesisConfig` struct. The [`pallet::genesis_build`] attribute shall be attached to the `impl`
//! block:
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/pallets.rs", pallet_bar_build)]
//!
//! `GenesisConfig` may also contain more complicated types, including nested structs or enums, as
//! in the example for `pallet_foo`:
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/pallets.rs", pallet_foo_GenesisConfig)]
//!
//! Note that [`serde`] attributes can be used to control how the data
//! structures are being stored into JSON. In the following example [`sp_core::bytes`] function is
//! used to serialize the `values` field.
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/pallets.rs", SomeFooData2)]
//!
//! Please note that fields of `GenesisConfig` may not be directly mapped to storage items. In the
//! following example the initial struct fields are used to compute (sum) the value that will be
//! stored in state as `ProcessedEnumValue`:
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/pallets.rs", pallet_foo_build)]
//!
//! # `GenesisConfig` for `runtimes`
//!
//! The runtime genesis config struct consists of configs for every pallet. For [_demonstration
//! runtime_][`chain_spec_guide_runtime`] used in this guide, it consists of `SystemConfig`,
//! `BarConfig` and `FooConfig`. This structure was automatically generated by macro and it can be
//! sneak peaked here: [`RuntimeGenesisConfig`]. For further reading on generated runtime
//! types refer to [`frame_runtime_types`].
//!
//! The macro automatically adds an attribute that renames all the fields to [`camelCase`]. It is a
//! good practice to add it to nested structures too, to have the naming of the JSON keys consistent
//! across the chain-spec file.
//!
//! ## `Default` for `GenesisConfig`
//!
//! `GenesisConfig` of all pallets must implement `Defualt` trait. Those are aggregated into
//! runtime's `RuntimeGenesisConfig`'s `Default`.
//!
//! Default value of `RuntimeGenesisConfig` can be queried by [`GenesisBuilder::get_preset`]
//! function provided by runtime with `id:None`.
//!
//! A default value for RuntimeGenesisConfig usually is not operational. This is because for some
//! pallets it is not possible to define good defaults (e.g. an initial set of authorities).
//!
//! A default value is a base upon which a patch for `GenesisConfig` is applied. A good description
//! of how it exactly works is provided in [`get_storage_for_patch`] (and also in
//! [`GenesisBuilder::get_preset`]). A patch can be provided as a external file (manually created)
//! or as builtin runtime preset. More info on presets are in the material to follow.
//!
//! ## Implementing `GenesisBuilder` for runtime
//!
//! The runtime exposes a dedicated runtime API for interacting with its genesis config:
//! [`sp_genesis_builder::GenesisBuilder`]. The implementation shall be provided within
//! [`sp_api::impl_runtime_apis`] macro, typically making use of some helpers provided:
//! [`build_state`], [`get_preset`].
//! A typical implementation of [`sp_genesis_builder::GenesisBuilder`] looks as follows:
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/runtime.rs", runtime_impl)]
//!
//! Please note that two functions are customized: `preset_names` and `get_preset`. The first one
//! just provides a `Vec` of the names of supported presets, while the latter one delegates the call
//! to a function that maps the name to an actual preset:
//! [`chain_spec_guide_runtime::presets::get_builtin_preset`]
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/presets.rs", get_builtin_preset)]
//!
//! ## Genesis state presets for runtime
//!
//! The runtime may provide many flavors of initial genesis state. This may be useful for predefined
//! testing networks, local development, or CI integration tests. Predefined genesis state may
//! contain a list of pre-funded accounts, predefined authorities for consensus, sudo key and many
//! others useful for testing.
//!
//! Internally presets can be provided in a number of ways:
//! - JSON in string form:
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/presets.rs", preset_1)]
//! - JSON using runtime types to serialize values:
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/presets.rs", preset_2)]
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/presets.rs", preset_3)]
//! It is worth noting that preset does not have to be the full `RuntimeGenesisConfig`, in that
//! sense that it does not have to contain all the keys of the struct. The preset is actually a JSON
//! patch that will be merged with default value of `RuntimeGenesisConfig`. This approach should
//! simplify maintanance of builtin presets. Following example illustrates runtime genesis config
//! patch:
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/presets.rs", preset_4)]
//!
//! ## Note on the importance of testing presets
//!
//! It is recommended to always test presets by adding the tests that convert the preset into the
//! raw storage. Converting to raw storage involves the deserialization of the provided JSON blob,
//! what enforces the verification of the preset. The following code shows one of the approaches
//! that can be taken for testing:
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/presets.rs", check_presets)]
//!
//! ## Note on tne importance of using `deny_unknown_fields` attribute
//!
//! It is worth noting that it is easy to make a hard to spot mistake as in the following example
//! ([`FooStruct`] does not contain `fieldC`):
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/presets.rs", preset_invalid)]
//! Even though `preset_invalid` contains a key that does not exist, the deserialization of the JSON
//! blob does not fail. The mispelling is silently ignored due to lack of [`deny_unknown_fields`]
//! attribute on the [`FooStruct`] struct, which is internally used in `GenesisConfig`.
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/src/presets.rs", invalid_preset_works)]
//!
//! ## Runtime `GenesisConfig` raw format
//!
//! A raw format of genesis config cotains just state's keys and values as they are stored in the
//! storage. This format is used to directly initialize the genesis storage. This format is useful
//! for long-term running chains, where the `GenesisConfig` stucture for pallets may be evolving
//! over the time. The JSON representation created at some point in time may no longer be
//! deserializable in future, making a chain specification useless. The raw format is recommended
//! for the production chains.
//!
//! For detailed description on how raw format is built please refer to
//! [_chain-spec-raw-genesis_][`sc_chain_spec#from-initial-state-to-raw-genesis`]. A plain and
//! corresponding raw examples of chain-spec are given in
//! [_chain-spec-examples_][`sc_chain_spec#json-chain-specification-example`].
//! The [`chain_spec_builder`] util supports building the raw storage.
//!
//! # Interacting with the tool
//!
//! The [`chain_spec_builder`] util allows to interact with runtime in order to list or display
//! presets and build the chain specification file. It is possible to use the tool with the
//! [_demonstration runtime_][`chain_spec_guide_runtime`]. To build required packages just run the
//! following command:
//! ```ignore
//! cargo build -p staging-chain-spec-builder -p chain-spec-guide-runtime --release
//! ```
//! The `chain-spec-builder` util can also be installed with `cargo install`:
//! ```ignore
//! cargo install staging-chain-spec-builder
//! cargo build -p chain-spec-guide-runtime --release
//! ```
//! Here are some examples in the form of rust tests:
//! ## Listing available presets names:
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/tests/chain_spec_builder_tests.rs", list_presets)]
//! ## Displaying preset with given name
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/tests/chain_spec_builder_tests.rs", get_preset)]
//! ## Building chain-spec using given preset
#![doc = docify::embed!("./src/reference_docs/chain_spec_runtime/tests/chain_spec_builder_tests.rs", generate_chain_spec)]
//!
//! [`RuntimeGenesisConfig`]:
//! chain_spec_guide_runtime::runtime::RuntimeGenesisConfig
//! [`FooStruct`]:
//! chain_spec_guide_runtime::pallets::FooStruct
//! [`impl_runtime_apis`]: frame::runtime::prelude::impl_runtime_apis
//! [`build_state`]: frame_support::genesis_builder_helper::build_state
//! [`get_preset`]: frame_support::genesis_builder_helper::get_preset
//! [`pallet::genesis_build`]: frame_support::pallet_macros::genesis_build
//! [`pallet::genesis_config`]: frame_support::pallet_macros::genesis_config
//! [`BuildGenesisConfig`]: frame_support::traits::BuildGenesisConfig
//! [`chain_spec_builder`]: ../../../staging_chain_spec_builder/index.html
//! [`serde`]: https://serde.rs/field-attrs.html
//! [`get_storage_for_patch`]: sc_chain_spec::GenesisConfigBuilderRuntimeCaller::get_storage_for_patch
//! [`GenesisBuilder::get_preset`]: sp_genesis_builder::GenesisBuilder::get_preset
//! [`deny_unknown_fields`]: https://serde.rs/container-attrs.html#deny_unknown_fields
//! [`camelCase`]: https://serde.rs/container-attrs.html#rename_all
71 changes: 71 additions & 0 deletions docs/sdk/src/reference_docs/chain_spec_runtime/Cargo.toml
Original file line number Diff line number Diff line change
@@ -0,0 +1,71 @@
[package]
name = "chain-spec-guide-runtime"
description = "A minimal runtime for chain spec guide"
version = "0.0.0"
license = "MIT-0"
authors.workspace = true
homepage.workspace = true
repository.workspace = true
edition.workspace = true
publish = false

[dependencies]
docify = "0.2.8"
parity-scale-codec = { version = "3.6.12", default-features = false }
scale-info = { version = "2.6.0", default-features = false }
serde = { workspace = true, default-features = false }
serde_json = { workspace = true }

# this is a frame-based runtime, thus importing `frame` with runtime feature enabled.
frame = { package = "polkadot-sdk-frame", path = "../../../../../substrate/frame", default-features = false, features = [
"experimental",
"runtime",
] }

# pallets that we want to use
pallet-balances = { path = "../../../../../substrate/frame/balances", default-features = false }
pallet-sudo = { path = "../../../../../substrate/frame/sudo", default-features = false }
pallet-timestamp = { path = "../../../../../substrate/frame/timestamp", default-features = false }
pallet-transaction-payment = { path = "../../../../../substrate/frame/transaction-payment", default-features = false }
pallet-transaction-payment-rpc-runtime-api = { path = "../../../../../substrate/frame/transaction-payment/rpc/runtime-api", default-features = false }

# genesis builder that allows us to interact with runtime genesis config
sp-genesis-builder = { path = "../../../../../substrate/primitives/genesis-builder", default-features = false }
sp-runtime = { path = "../../../../../substrate/primitives/runtime", default-features = false, features = ["serde"] }
sp-core = { path = "../../../../../substrate/primitives/core", default-features = false }
sp-std = { path = "../../../../../substrate/primitives/std", default-features = false }
sp-keyring = { path = "../../../../../substrate/primitives/keyring", default-features = false }
sp-application-crypto = { path = "../../../../../substrate/primitives/application-crypto", default-features = false, features = ["serde"] }

[build-dependencies]
substrate-wasm-builder = { path = "../../../../../substrate/utils/wasm-builder", optional = true }

[dev-dependencies]
chain-spec-builder = { package = "staging-chain-spec-builder", path = "../../../../../substrate/bin/utils/chain-spec-builder" }
sc-chain-spec = { path = "../../../../../substrate/client/chain-spec" }

[features]
default = ["std"]
std = [
"parity-scale-codec/std",
"scale-info/std",

"frame/std",

"pallet-balances/std",
"pallet-sudo/std",
"pallet-timestamp/std",
"pallet-transaction-payment-rpc-runtime-api/std",
"pallet-transaction-payment/std",

"sp-application-crypto/std",
"sp-core/std",
"sp-genesis-builder/std",
"sp-keyring/std",
"sp-runtime/std",
"sp-std/std",

"serde/std",
"serde_json/std",
"substrate-wasm-builder",
]
23 changes: 23 additions & 0 deletions docs/sdk/src/reference_docs/chain_spec_runtime/build.rs
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@@ -0,0 +1,23 @@
// This file is part of Substrate.

// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

fn main() {
#[cfg(feature = "std")]
{
substrate_wasm_builder::WasmBuilder::build_using_defaults();
}
}
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