Runtime Upgrades

You can simulate runtime upgrades in your code by authoring extrinsics for any account. The ease of this process may depend on whether your runtime has pallet-sudo or pallet-democracy.

If you have pallet-sudo then upgrading your runtime is as easy as authoring the frame_system::Call::set_code extrinsic using the sudo account. On the other hand if you have pallet-democracy then you’ll need to propose the runtime upgrade in simnode, upgrade it to a referrendum, vote for it using any account on-chain with a balance, and finally produce enough blocks that makes the enactment period configured in your runtime pass. Here’s an example of what that looked like in polkadot for an earlier version of simnode.

Parachains

Parachains cannot directly upgrade their own runtime. Instead, they must schedule their runtime to be upgraded on the relay chain first. Then, the relay chain sends a message to the parachain through the parachain_system inherents, letting the parachain know that it can start using the upgraded runtime.

Simnode supports inserting this inherent into your parachain blocks, which allows you to upgrade your runtime. After executing the frame_system::Call::set_code extrinsic, call this RPC API. Simnode will insert the upgrade signal inherent and produce a block that executes the pending runtime upgrade.

bash
curl http://127.0.0.1:9933 -d '{"id":29,"jsonrpc":"2.0","method":"simnode_upgradeSignal","params":[true]}' -H "Content-Type: application/json"
{"jsonrpc":"2.0","result":null,"id":29}

It’s probably a good idea to have this test automated and running in CI for every code that changes your runtime. Here’s an example of what that looks like.