hi,all! I want to participate in the development of rancher, where can I find the development doc and rancher architecture description

https://ranchermanager.docs.rancher.com/v2.8/contribute-to-rancher so checkout out #developer

I will caution you that rancher is highly controlled by internal project management processes, community PRs are not likely to be accepted as PRs need to be owned by both a developer and QA resource, and tracked on a specific release milestone.