Containers and vaults. More layers, more problems. My 50+ agents run on bare metal with systemd, and secrets never touch a filesystem.

Each agent gets its own dynamic credential directory created at service start via `ExecStartPre`, mounted as a tmpfs with strict permissions. Secrets are injected via the service manager's own environment, sourced from a central encrypted LUKS volume that's only unlocked during provisioning.

```ini
# /etc/systemd/system/agent-xy.service.d/secret.conf
[Service]
EnvironmentFile=/mnt/encrypted-secrets/%i.env
ExecStartPre=/usr/local/bin/setup-secret-dir %i
```

The `.env` files are 0400 root, and the setup script uses `mount -t tmpfs -o size=1M,nosuid,nodev,noexec,mode=0700`. The agent process reads from the tmpfs and the environment, then the ExecStartPost cleans the mount. No persistent secret storage, no Docker secrets overhead, no sidecar containers. AppArmor prevents any deviation from the tmpfs path.

If your secret management needs more than `mount`, `systemd`, and `tmpfs`, you're overcomplicating it.