How to look and add migrations while upgrading parachain to new version via runtime upgrade. We use example of simple [parachain node template] (https://github.com/substrate-developer-hub/substrate-parachain-template/) with tag `polkadot-v0.9.32` and upgrade it to `polkadot-v0.9.40`. To test this upgrade we need local testnet. How to create simple testnet [short guide here](https://dev.to/nikania/quick-list-starting-local-parachain-testnet-3ncg). ## Build `polkadot-v0.9.32` parachain-template version First, we add some pallets that changed between these two versions to parachain-template: `pallet-alliance` and `pallet_assets`. Then, we build and place parachain in `/bin` folder ```bash cargo build --release mkdir bin cp ./target/release/parachain-template-node \ ./bin/parachain-template-node-v0.9.32 ``` ##Prepare for runtime upgrade (official guide [here](https://docs.substrate.io/maintain/runtime-upgrades/)) a) change versions `polkadot-v0.9.32` to `polkadot-v0.9.40` in Cargo.toml b) fix compile errors🤯 a1)-b1) it's faster to use `polkadot-v0.9.40` parachain-template version instead upgrading in this example😎 c) change spec_version ###d) add migrations _this was the most unclear_ to me (do I need to apply them? where to find migrations? how to apply them?), but I'll show you **how to add substrate migrations** (not your own): - look through the [releases](https://github.com/paritytech/polkadot/releases) in Polkadot repo and search for migrations description, here I found migrations in [v0.9.34 release](https://github.com/paritytech/polkadot/releases/tag/v0.9.34), [v0.9.38 release](https://github.com/paritytech/polkadot/releases/tag/v0.9.38), [v0.9.40 release](https://github.com/paritytech/polkadot/releases/tag/v0.9.40) - download the source code and look for migrations in `runtime/polkadot/src/lib.rs` in struct `frame_executive::Executive`, migrations can be summed in type `Migrations` or just put there, here I found the following migrations: ```rust // in v0.9.34 pub type Migrations = ( //9320 // "Bound uses of call" pallet_preimage::migration::v1::Migration, pallet_scheduler::migration::v3::MigrateToV4, pallet_democracy::migrations::v1::Migration, pallet_multisig::migrations::v1::MigrateToV1, // "Properly migrate weights to v2" parachains_configuration::migration::v3::MigrateToV3, //9330 pallet_election_provider_multi_phase::migrations::v1::MigrateToV1, pallet_fast_unstake::migrations::v1::MigrateToV1, //9340 pallet_balances::migration::MigrateToTrackInactive, crowdloan::migration::MigrateToTrackInactive, ); ``` ```rust // in v.0.9.38 pub type Migrations = ( // "Use 2D weights in XCM v3" pallet_xcm::migration::v1::MigrateToV1, parachains_ump::migration::v1::MigrateToV1, // Remove stale entries in the set id -> session index storage map (after // this release they will be properly pruned after the bonding duration has // elapsed) pallet_grandpa::migrations::CleanupSetIdSessionMap, ); ``` ```rust // in v0.9.40 pub type Migrations = ( pallet_nomination_pools::migration::v4::MigrateToV4< Runtime, NominationPoolsMigrationV4OldPallet, >, ); ``` - also look for migrations in Cumulus repo, here I found [v9360](https://github.com/paritytech/cumulus/releases/tag/parachains-v9360) [v9330](https://github.com/paritytech/cumulus/releases/tag/parachains-v9330) [v9380](https://github.com/paritytech/cumulus/releases/tag/parachains-v9380) [v9400] (https://github.com/paritytech/cumulus/releases/tag/parachains-v9400) - migrations found in Cumulus: ```rust // v9400 pub type Migrations = (pallet_nfts::migration::v1::MigrateToV1,); // v9380 pub type Migrations = (pallet_contracts::Migration,); // v9360 type Migrations = ( pallet_alliance::migration::Migration, pallet_balances::migration::MigrateToTrackInactive, ); // v9330 pub type Executive = frame_executive::Executive< Runtime, Block, frame_system::ChainContext, Runtime, AllPalletsWithSystem, pallet_assets::migration::v1::MigrateToV1, >; ``` - for all pallet that exist in your chain, add migrations, here I added (don't need to add balances: read instructions in `pallet_balances::migration::MigrateToTrackInactive`): ```rust pub type Migrations = ( pallet_xcm::migration::v1::MigrateToV1, pallet_alliance::migration::Migration, pallet_assets::migration::v1::MigrateToV1, // added myself just to look in logs TestOnRuntimeUpgrade, ); ``` ```rust pub struct TestOnRuntimeUpgrade; impl OnRuntimeUpgrade for TestOnRuntimeUpgrade { fn on_runtime_upgrade() -> frame_support::weights::Weight { frame_support::log::info!("ಠ_ಠ 🤞🤞🤞🤞🤞🤞🤞🤞🤞🤞 migrations applied"); Weight::from_ref_time(1) } } ``` e) build `cargo b -r`, save wasm ## Perform upgrade and check everything is ok - run old-versioned parachain in local testnet (can use [quick list](https://dev.to/nikania/quick-list-starting-local-parachain-testnet-3ncg)) ```bash cargo run ./bin/parachain-template-node-v0.9.32 ``` - upgrade runtime ([official guide](https://docs.substrate.io/tutorials/build-a-blockchain/upgrade-a-running-network/)) Migrations of `pallet_xcm`, `pallet_alliance` and `pallet_assets` are needed only if there is something in the storage of these pallets. Therefore, in this example migrations are unnecessary. I did this example only to show how to find the migrations. Any comments, corrections and suggestions are appreciated!💬

runtimeupgrade

Updating parachain with migrations

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