I'm working on a script that needs to fetch several secrets in order to function correctly. I currently use `secret-tool lookup` for this, and while it works seamlessly for a local user, I hit a wall when I try to run it as a cron job. The crux of the problem seems to be that `secret-tool` relies on a GUI to unlock the keyring, which obviously doesn't work in a non-interactive cron environment. There was a workaround I tried by passing an environment variable to keep the keyring unlocked, but even that didn't fully solve the issue, likely due to an incorrect d-bus address. I'm also considering switching to a cloud-based secret manager, but I'm worried I'd run into the same problem of securely storing API keys. Any advice on the proper approach for managing secrets in cron jobs would be greatly appreciated.
For context, I'm syncing a local mail server with a remote one using `mbsync`, which requires credentials for both servers. For example, I fetch the username for the remote server with a command like this: `UserCmd "secret-tool lookup remote_mail_server username"`. Right now, I'm using `gnome-keyring`. I did manage to get this working through some environment variable manipulation, but I'm not satisfied with that solution—especially not for a headless environment. What are the best practices for securely fetching secrets in a cron job?
5 Answers
If you're worried about storage for your API keys, consider using a service that supports machine identities, like AWS. They provide signed documents attesting the identity of the VM, enabling you to manage secrets more securely. Alternatively, for general secret management, tools like KeepassXC or TeamPasswordManager might be worth looking into.
For a more secure approach, mutual TLS is a solid option. You could deploy a certificate on the server that only the root user can access, using it to sign the connection to your secret retrieval tool. This way, you can safely pass necessary secrets as environment variables to your cron job.
Why not look into using HashiCorp Vault? You can replace your `secret-tool` with a local Vault instance running in server mode using file storage. Authenticate your script securely with a Vault token and retrieve secrets in a cron-friendly manner without GUI dependencies.
You definitely need to keep your setup simple. If you're mainly looking to protect secrets from unauthorized users, securely keeping them in a file with the right permissions should suffice. Plus, ensure that your cron job runs as a user that has access to this secret file. I'd also recommend considering systemd timers instead of cron jobs. They offer better logging and debugging capabilities, making your life easier when troubleshooting.
First off, it's crucial to avoid passing secrets as command arguments since they can be exposed through system processes. You've got a couple of main options for managing secrets:
1. Use environment variables to store sensitive information securely.
2. Store secrets in files, but make sure these files have strict permissions to prevent unauthorized access. Managing secrets in RAM with named pipes or using a temporary filesystem can add an extra layer of security. For high security, consider more advanced options like using Hardware Security Modules (HSMs) or TPM (Trusted Platform Module) to store keys that never leave the hardware.
Overall, ensure that the method you choose aligns with your security requirements and the environment you're working in.
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