Docker Swarm encryption doesn't work for your use case. The documentation says that the secret is stored encrypted but can be decrypted by the swarm manager nodes and nodes running services that use the service, which both apply to your single node. If you're not having to unlock Docker Compose on startup, that means that the encrypted value and the decryption key live next to each other on the same computer and anyone who has access to the encrypted secrets can also decrypt them.