Emma Thorpe
1cb8371775
Enable Docker and expose the daemon over TCP 2375 by extending the systemd docker.socket ListenStream (avoids the daemon.json hosts vs unit -H fd:// conflict). The port is not added to allowedTCPPorts; instead an nftables rule accepts it only from the trusted LAN subnet. Plain 2375 is root-equivalent, so the source restriction is the only safeguard -- mTLS on 2376 is the documented upgrade path.
35 lines
1.6 KiB
Nix
35 lines
1.6 KiB
Nix
# Docker host with the daemon socket exposed over the network.
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#
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# SECURITY: the daemon listens on plain TCP 2375 with NO TLS and NO auth. Access
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# to that port is root-equivalent on this host (the Docker API can mount the
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# host filesystem and run privileged containers). The ONLY thing protecting it
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# is the nftables rule below, which accepts 2375 solely from the trusted LAN
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# subnet. Do not widen that subnet to anything you do not fully trust. The
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# secure upgrade path is mutual TLS on 2376 (--tlsverify with client certs);
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# that needs out-of-band cert provisioning and is intentionally not wired here.
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{ ... }:
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{
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virtualisation.docker.enable = true;
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# Expose the daemon over TCP by extending systemd socket activation rather than
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# setting daemon.settings.hosts. The NixOS docker unit starts dockerd with
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# `-H fd://` and takes its listeners from this socket; putting `hosts` in
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# daemon.json as well would conflict with that and dockerd would refuse to
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# start. Adding the TCP listener here keeps a single source of truth.
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# The leading "" resets the unit's default (unix-socket-only) ListenStream list.
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systemd.sockets.docker.socketConfig.ListenStream = [
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""
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"/run/docker.sock"
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"0.0.0.0:2375"
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];
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# Source-restricted firewall rule for the Docker TCP port. 2375 is deliberately
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# NOT added to networking.firewall.allowedTCPPorts (that would open it to every
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# source); instead nftables accepts it only from the trusted subnet. Adjust the
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# CIDR to match the LAN that should reach the Docker API.
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networking.nftables.enable = true;
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networking.firewall.extraInputRules = ''
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ip saddr 10.187.1.0/24 tcp dport 2375 accept
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'';
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}
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