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Basic pallet integration

A fundamental pattern that all runtime engineers should internalize over time.

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Goal#

Learn the steps for integrating a pallet to your runtime.

Use cases#

  • Including a custom pallet that implements an event and a call for runtime.
  • Including a pallet from Crates.io to a runtime.

Overview#

This guide is an extension to the "Add a Pallet to Your Runtime" tutorial, intended as a resource for developers new to Substrate looking to quickly integrate a pallet to their runtime. It covers adding both local and external pallets to a runtime.

Steps#

1. Import your pallet#

For local pallets#

Assuming a pallet called pallet_something is created, the first step is to import it in /runtime/src/lib.rs:

// Import your pallet.
pub use pallet_something;

2. Include it in /runtime/src/lib.rs#

For local pallets#

Configure your pallet's runtime implementation. Assuming the local pallet only has Event and Call types exposed to the runtime:

// Configure your pallet.
impl pallet_something::Config for Runtime {
type Event = Event;
type Call = Call;
}

Then, declare your pallet and the items it exposes in construct_runtime!, including the additional Module and Storage types for the runtime macro:

construct_runtime!(
pub enum Runtime where
Block = Block,
NodeBlock = opaque::Block,
UncheckedExtrinsic = UncheckedExtrinsic
{
/* --snip-- */
Something: pallet_something::{Module, Call, Storage, Event<T>},
/* --snip-- */
}
);

For external pallets#

The same pattern applies as for declaring a local pallet, except you must ensure you include all the types your pallet exposes. In addition, don't forget to include relevant parameter types and constants if relevant. See this examples on how pallet_timestamp is declared.

3. Update /runtime/Cargo.toml#

For local pallets#

In /runtime/Cargo.toml, include your pallet as a local dependency, include it in std and add runtime-benchmarks:

/* --snip-- */
[dependencies.pallet-something]
default-features = false
path = '../pallets/something'
version = '3.0.0'
/* --snip-- */
[features]
default = ['std']
runtime-benchmarks = [
/* --snip */
'pallet-something/runtime-benchmarks',
]
std = [
'pallet-something/std',
/* --snip-- */
]

For external pallets#

Assuming the pallet is hosted in parity.crates.io, adding it to the runtime would look like this:

[dependencies.pallet-external]
default-features = false
git = 'https://github.com/paritytech/substrate.git'
rev = 'd6c33e7ec313f9bd5e319dc0a5a3ace5543f9617'
version = '3.0.0'
/* --snip-- */
runtime-benchmarks = [
/* --snip */
'pallet-external/runtime-benchmarks',
]
std = [
'pallet-external/std',
/* --snip-- */
]

Examples#

Related material#

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