:sparkles: Add support for Docker secrets

Context

I have a Docker container that expects a file in /run/secrets/admin_password (it is hard-coded).

In Docker Compose, this is done using:

secrets:
  admin_password:
    file: ./myadminpwd.txt

services:
  myservice:
    image: ...
    secrets:
      - admin_password

Though, docker run does not support secrets, as it is a feature only available with Docker Swarm. I wonder how Docker Compose implements it (do they simply bind-mount the file or do they initialize a Swarm?).

Does it make sense to have the Netbox Docker Agent initialize a Swarm on the host it runs on?

Feature Request

I would need a way to specify, when creating a container, a secret either from:

• a file on the host
• a base64 encoded string

If you consider that I should just "bind mount a file" and handle securing that file myself, feel free to close this feature request.

The issue names no files, tests, or entry points. First clarify whether secrets should be implemented through Docker Swarm or another mechanism, and define the security expectations for host files and base64 values. Done means container creation accepts both requested secret sources and makes the secret available at the required path.