0. Hardcoded values. **This is purely for debugging, prototyping, and for
configuring below options.**
1. Files pointed to by environment variables. Docker friendly.
2. Secrets folder. Also Docker friendly.
3. [Pass: the standard unix password
manager](https://www.passwordstore.org/). Most suited for personal
usage; very unsuited for server environments. Requires `pass` installed
locally, and configuration of the `PASS_STORE_SUBFOLDER` through one of the above
methods.
4. Vault instance if configured. Suited for production environments.
## TODO
- [ ] Avoid leakage to swap files.
* Possibly Mlock? [Does not seem to work](https://stackoverflow.com/questions/29524020/prevent-ram-from-paging-to-swap-area-mlock)
* Alternatively use [mmap](https://docs.python.org/3/library/mmap.html) and [memoryview](https://stackoverflow.com/questions/18655648/what-exactly-is-the-point-of-memoryview-in-python)?§
- [ ] Wrap secrets in intelligent strings:
* Instead of returning None on unloaded, return UnknownSecret, that produce
error when formatted.
*`repr(secret)` should not include contents, but only the secret and how