The credentials configuration file is at ~/.aws/credentials.
Also, when running on root it uses the root home (so /root/.aws). This
was from my test at an ubuntu server.
## Pull Request Checklist
- [ ] The Certbot team has recently expressed interest in reviewing a PR
for this. If not, this PR may be closed due our limited resources and
need to prioritize how we spend them.
- [ ] If the change being made is to a [distributed
component](https://certbot.eff.org/docs/contributing.html#code-components-and-layout),
edit the `master` section of `certbot/CHANGELOG.md` to include a
description of the change being made.
- [ ] Add or update any documentation as needed to support the changes
in this PR.
- [ ] Include your name in `AUTHORS.md` if you like.
