Upgrading derivative canisters

[paulyoung]

OpenChat: A Truly Decentralized Alternative to WhatsApp

Hey! I’m one of the OpenChat devs (there are 3 of us). Each time a new user registers an account, an update command is sent to our ‘user_index’ canister. That canister creates the user a new canister, installs the latest version of the user canister wasm, and initialises it, passing in the new user’s principal in the init args. To upgrade the user canisters, we push the new canister wasm to the user_index canister, which then upgrades each of the user canisters using ‘heartbeat’. We also hav…

OpenChat: A Truly Decentralized Alternative to WhatsApp

We pull 5 canisters from the queue and upgrade them on each heartbeat. As we grow we will potentially have 10s or even 100s of thousands of canisters, so we can’t kick them all off at the same time as that would cause the system to become overloaded and unresponsive, so instead we opted for gradual rolling upgrades. @alexeychirkov yes exactly, we call the ‘upgrade_user_canister_wasm’ method on our user_index canister. This canister then holds that new wasm in a normal Rust struct. But if the u…