9e44efa01f
The swarm-authelia module states that its users database is written by swarm-controller, but nothing ever granted the means. This adds the tool that does it. swarmctl runs as root on the controller's host and acts directly. The rootless alternative was examined and does not work: relocating the users file into a directory the controller owns only turns a write problem into a read problem, because authelia must then reach across the same boundary in the other direction. Making that read work needs either a hand-pinned gid or world-readable password hashes. The user store is two files, one authoritative: users.json is canonical, users.yml is a rendered artifact. That split is what lets the crate work without a YAML parser -- the workspace has none, and adding one costs a crates.io fetch, a lock update and a vendor hash for a schema we fully control and only ever emit. Passwords are generated by authelia rather than passed to it: argv is world-readable, so a password on a command line is readable by any local process for the lifetime of the call. The three derived facts swarmctl needs about the authelia container -- machine, unit and the host-side users path -- become readOnly options on the authelia module rather than literals repeated at the call site.
2.9 KiB
swarmctl
Swarm-level operator CLI. Runs as root on the host running
swarm-controller, and acts on that host directly.
Distinct from hivectl, which drives one hive's hive-c0re over its
admin socket. This crate does not link swarm-controller, for the same
reason hivectl does not link hive-c0re.
Why root, and why no socket
The first verb writes authelia's users database. Making that write
rootless was examined and rejected — relocating the file only turns a
write problem into a read problem. Move users.yml into a directory
the controller owns and the controller can write it, but authelia then
has to read it across the same boundary in the other direction. Making
that work needs either a hand-pinned gid (the container's uids are
allocated inside it, at activation — see the uid-assignment issue) or
world-readable password hashes. Both are worse than root.
So there is no socket, no HTTP route and no privileged helper here. When
a verb has to run as a non-root user or from another host, the answer is
a group-gated admin socket, separate from the controller's 0666
gateway-facing one — not a widening of what root does here.
Two files, one of them authoritative
users.json— canonical, ours, JSON.users.yml— a rendered artifact for authelia. Written, never read back.
The split is what lets this crate work without a YAML parser: the workspace has none, and adding one costs a crates.io fetch, a lock update and a vendor hash for a schema we fully control and only ever emit.
The shortcut of writing JSON into the .yml (JSON being a subset of
YAML) is deliberately not taken: authelia refuses to start on a users file
it cannot parse, so that file fronts the whole SSO provider's boot, and
"almost certainly parses" is not a claim worth betting a boot on without
running it.
Configuration
Every path comes from the nix module that installs the binary, because every one is derived from an option that module owns. They are required rather than defaulted — a default would be an address we hope points at something, and one that resolves cleanly to the wrong place is worse than an error.
| variable | what |
|---|---|
SWARMCTL_AUTHELIA_BIN |
the configured authelia; argon2 params must match the verifier's |
SWARMCTL_AUTHELIA_USERS_FILE |
host-side path of the users database |
SWARMCTL_AUTHELIA_MACHINE |
container name, for systemctl -M |
SWARMCTL_AUTHELIA_UNIT |
authelia's unit inside that container |
SWARMCTL_STORE |
canonical store (defaults to the controller's state dir) |
Usage
# swarmctl user add mara --display-name "Mara" --group admins
The password is generated by authelia (crypto hash generate argon2 --random) and printed once. It is never passed on a command line:
/proc/<pid>/cmdline is world-readable, so a password in argv is readable
by any local process for the lifetime of the call.