User Guide: CircleCI Service Account guidance

[sj-williams]

Background

Following k8s 1.24 upgrade and the associated change in service account token creation, we should add some simple guidance on how to use the terraform service account module for CircleCI, ie: how to extract required tokens/certs from SA secrets, and how to self-manage token rotation via the module.

This will probably prove useful when we look at asking users to migrate legacy yaml defined service accounts to terraform module managed.

Proposed user journey

Approach

Which part of the user docs does this impact

Service account guidance

Communicate changes

• [ ] post for #cloud-platform-update
• [ ] Weeknotes item
• [ ] Show the Thing/P&A All Hands/User CoP
• [ ] Announcements channel

Questions / Assumptions

Definition of done

• [ ] readme has been updated
• [ ] user docs have been updated
• [ ] another team member has reviewed
• [ ] smoke tests are green
• [ ] prepare demo for the team

Reference

How to write good user stories