As of Terraform 0.8, it has a built-in support for Vault, a secrets management tool from HashiCorp. It's also a big tool, deserving a book of its own. And it's a great solution in order to solve the sensitive data storage problem for Terraform. Consider learning it and using it.
In Chapter 7, Collaborative Infrastructure, we did not go too deeply into the details of the modern software development workflow. The basics we discussed -- code reviews, working through pull requests -- are just this: basics. There is a number of well-documented workflows that cover many different situations:
- GitHub Flow (https://guides.github.com/introduction/flow/): A very simplistic and popular approach
- GitLab Flow (https://docs.gitlab.com/ee/workflow/gitlab_flow.html ...