hyperhive/nix/host-modules/swarm-nats.nix
atlas 850cc2c1d3 fix(#3363): give the queue's auth responder the hive CA
The responder introspects authelia over https by name. It had no CA trust
at all, so the handshake failed UnknownIssuer, introspection failed, and it
denied every client -- surfacing at the controller as a 60s
authorization-violation loop, two layers from the cause.

Adds a shared trustBundle helper to lib/hive-ca-trust.nix rather than a
fifth hand-rolled concat. Four containers were each assembling this
themselves, which is how they came to share one defect: wantedBy + before
express ordering but not success, so a failed assembly let the consumer
start against a missing file and trust nothing at all.

The helper fixes both halves of that. requires goes on the consumer, so a
failed bundle stops it and the dependency is visible in systemctl status
where someone debugging a TLS failure looks. And the script assembles to a
temp path, checks the result actually contains a certificate, and only then
moves it into place -- cat of an empty bind exits 0, so set -e does not
catch it and a partial bundle must never appear under the final name.

Returns a module rather than bare services: a caller that already writes
systemd.services.<consumer> cannot also write systemd.services in the same
attrset.
2026-08-17 19:57:44 +02:00

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{
pkgs,
lib,
config,
...
}:
let
cfg = config.services.hyperhive.swarm.nats;
autheliaCfg = config.services.hyperhive.swarm.authelia;
autheliaUrl = autheliaCfg.url;
networkCfg = config.services.hyperhive.network;
# Read even when the controller runs on a different host: what is needed
# is the client id that module *declares*, which is the same string
# everywhere, not whether the daemon happens to be enabled here.
controllerCfg = config.services.hyperhive.swarm.controller;
# The account the callout responder authenticates as, and the account
# authorized clients are placed in. Two accounts rather than one: an
# account is NATS' isolation boundary, so a responder that shares an
# account with its clients can be published to by the things it
# authorizes.
calloutAccount = "AUTH";
clientAccount = "APP";
machine = "swarm-nats";
tlsCfg = config.services.hyperhive.tls;
gatewayCfg = config.services.hyperhive.gateway;
caTrust = import ./lib/hive-ca-trust.nix { inherit lib tlsCfg gatewayCfg; };
# The responder introspects authelia over https BY NAME. Its HTTP client is
# reqwest/rustls, and `rustls-platform-verifier` resolves roots through
# `rustls-native-certs`, which reads `SSL_CERT_FILE` — so the same assembled
# bundle the Go containers use applies here. Without it the handshake fails
# `UnknownIssuer`, introspection fails, and the responder denies *every*
# client: one missing trust anchor surfacing as `authorization violation` at
# every would-be queue user.
caBundleModule = caTrust.trustBundle {
inherit pkgs;
name = machine;
consumers = [ "swarm-nats-auth" ];
};
# Where the responder's credentials live *inside* the container, and the
# host path that resolves to. Two names for one location, because the
# host is the only place both filesystems are addressable.
secretDirInContainer = "/var/lib/swarm-nats-auth";
inContainer = name: "${secretDirInContainer}/${name}";
secretDir = "/var/lib/nixos-containers/${machine}${secretDirInContainer}";
hostPath = name: "${secretDir}/${name}";
# The responder needs all three credentials. Gating on them rather than
# on `cfg.enable` keeps a half-configured hive at "queue up, denying
# everyone" instead of "unit crash-looping on a missing file".
#
# In auto mode the seeds are minted on this host before the container
# starts, so they are configured by construction.
responderConfigured =
cfg.autoGenerateCallout || (cfg.calloutUserSeedFile != "" && cfg.calloutIssuerSeedFile != "");
clientSecretSource = "${autheliaCfg.hostClientSecretDir}/${cfg.clientId}.secret";
introspectionUrl = "${toString autheliaUrl}/api/oidc/introspection";
# Where the responder's seeds actually come from. One name for two
# origins, so everything downstream stops caring which mode it is in.
userSeedFile = if cfg.autoGenerateCallout then autoUserSeed else cfg.calloutUserSeedFile;
issuerSeedFile = if cfg.autoGenerateCallout then autoIssuerSeed else cfg.calloutIssuerSeedFile;
# Seeds stay on the host at 0600 and never enter the container or the
# store: only the responder needs them, and it reads them by
# `LoadCredential` from here.
autoSeedDir = "/var/lib/swarm-nats-callout";
autoUserSeed = "${autoSeedDir}/callout-user.seed";
autoIssuerSeed = "${autoSeedDir}/issuer.seed";
# The runtime config directory: wrapper, settings symlink and fragment.
# World-readable is correct (everything in it is public) and it is not in
# the 0700 responder secret dir, which the `nats` user cannot traverse.
#
# ⚠️ ONE DIRECTORY IS FORCED, NOT TIDINESS. NATS resolves an `include` with
# `filepath.Join(configDir, path)`, which strips a leading slash, so an
# absolute include silently becomes relative and is never found. The
# includes must therefore be bare filenames, i.e. siblings. Invisible to
# eval: the wrapper renders perfectly and the server refuses to start.
runtimeDir = "/var/lib/nats-callout";
runtimeWrapper = "${runtimeDir}/nats.conf";
hostRuntimeDir = "/var/lib/nixos-containers/${machine}${runtimeDir}";
natsFormat = pkgs.formats.json { };
# Upstream's rendered settings, re-rendered with the same generator on the
# same value — the artifact `services.nats` would have used, not a
# transcription. ⚠️ This reference is also the only thing keeping it alive:
# `ExecStart` names a runtime path, so nothing else in the closure names
# the store file, and its string context is what stops it being
# garbage-collected out from under a running server.
renderedSettings = natsFormat.generate "nats.conf" (
config.containers.${machine}.config.services.nats.settings
);
# Defined once, rendered twice: into `settings` with the operator's values,
# and into the runtime fragment with placeholders the generator fills in.
#
# 🪤 Do not inline these and hand-write the fragment instead. Both files are
# loaded and the fragment is the LATER definition, so it wins — a
# hand-written copy would make a future edit to `settings` silently
# ineffective on exactly the hives that use auto mode.
calloutBlocks =
{
userKey,
issuerKey,
}:
{
# Two accounts, and the callout user lives in neither of the accounts
# it authorizes into.
accounts = {
# ⚠️ The nkey is not decoration and its absence was a real hole: a
# `users` entry carrying only a `user` name has no credential, and
# `CONNECT {"user":"auth"}` is then accepted with no password at
# all. Since the name is a literal in this public module, that made
# the callout-exempt identity walk-in-able from every container on
# the shared netns — the same class of hole this module exists to
# close, moved rather than fixed. Caught in review on the first
# version of this file. An nkey and NOTHING else, both halves
# measured against a running server rather than reasoned about:
#
# { user = "auth"; } → `CONNECT {"user":"auth"}`
# is accepted with no
# credential at all
# { user = "auth"; nkey = "U…"; } → refuses to START:
# "Nkey users do not take
# usernames or passwords"
# { nkey = "U…"; } → what this is
#
# A malformed key is fail-closed too: the server exits with
# "Not a valid public nkey for a user" rather than starting with a
# hole. So the only way to get a live server here is a real key
# whose seed nobody but the responder holds.
#
# 🔒 That property is what makes auto mode safe: it renders as ""
# there, so any field the fragment fails to override keeps a value
# the server refuses to start on. An incomplete merge cannot leave
# a walk-in-able server.
${calloutAccount}.users = [ { nkey = userKey; } ];
# ⚠️ `services.nats.jetstream = true` gives the SERVER JetStream;
# an account gets it only from its own grant. Measured against a
# running 2.14.1 with this exact two-account shape, because the
# failure is invisible to any config-rendering check:
#
# global jetstream only → `nats kv add` from this account fails
# `code=503 err_code=10039 jetstream not enabled for account`,
# while the server starts cleanly and logs "Starting JetStream"
# + this line → the same command succeeds
#
# The grant is per-account by design, and that is worth keeping:
# the callout account above deliberately does NOT get it. The
# responder mints credentials; it has no business holding stream
# state.
#
# ⚠️ Also why the fragment renders the COMPLETE accounts block: if a
# later definition replaced rather than merged, a partial one would
# drop this grant and every KV op would fail on a healthy server.
${clientAccount} = {
jetstream = "enabled";
};
};
authorization = {
timeout = "2s";
# 🔒 THIS BLOCK IS THE FAIL-CLOSED STATE, and it is the measured
# one rather than the obvious one.
#
# Measured on the pinned nats-server 2.14.1: both
# `authorization { }` and `authorization { users: [] }` accept an
# anonymous client and answer PONG — they read like "authorize
# nobody" and are wide open. An auth_callout block sets
# `auth_required` and refuses every client whose credential no
# responder has approved, so a config whose responder does not
# exist yet denies everyone.
#
# `nats-server -t` calls all three valid; it parses, it does not
# authenticate. Only running them tells the difference.
#
# ⇒ this is both the safe interim state and the final shape.
# Nothing here has to be swapped out when the responder lands
# beside it — it only starts being able to say yes.
auth_callout = {
issuer = issuerKey;
auth_users = [ userKey ];
account = calloutAccount;
};
};
};
# The fragment as nix renders it, with placeholders where the runtime
# values go. Rendered by the same JSON generator upstream uses, so the
# fragment is generated rather than transcribed — NATS' config parser
# accepts JSON, and an `include` of it merges (measured).
calloutTemplate = natsFormat.generate "swarm-nats-callout-template.conf" (calloutBlocks {
userKey = "@USER_PUBKEY@";
issuerKey = "@ISSUER_PUBKEY@";
});
in
{
# The swarm's message queue: one NATS server, reached by every hive.
#
# ⚠️ There is deliberately NO gateway vhost here, and this is the first
# swarm service where that is true — the next reader will go looking for
# one. NATS speaks its own TCP protocol rather than HTTP, so nginx
# cannot front it the way it fronts the forge, matrix and authelia.
# Cross-hive reach is the wireguard mesh; `gateway.localNames` and the
# per-service vhost pattern do not apply.
options.services.hyperhive.swarm.nats = {
enable = lib.mkOption {
type = lib.types.bool;
default = false;
description = ''
Run the swarm's message queue in a `swarm-nats` container on this
host. A swarm has one queue, so this belongs on the same host as
the rest of the shared services.
Off by default, and off means *absent*: no container is created
and nothing else in the evaluated config changes.
'';
};
# ⚠️ Deliberately NO `package` option, unlike this module's siblings.
# `services.nats` upstream does not expose one — it resolves
# `pkgs.nats-server` itself — so an option here would either be
# ignored or need an overlay to mean anything, and an option that
# does not control what it names is worse than its absence. Pin the
# build with `nixpkgs.overlays` if you need to.
port = lib.mkOption {
type = lib.types.port;
default = 4222;
description = ''
TCP port the queue listens on. 4222 is upstream's default and
sits outside hyperhive's claimed ranges (dashboard 7000, forge
3000, matrix 8008, every agent in 8100..8999 via FNV-1a hash).
'';
};
clientId = lib.mkOption {
type = lib.types.str;
default = "swarm-nats";
description = ''
OAuth2 client id the queue's authentication path identifies
itself with. Must match the `id` of the corresponding entry in
`services.hyperhive.swarm.authelia.oidc.clients` which this
module contributes for you when both run on this host.
'';
};
autoGenerateCallout = lib.mkOption {
type = lib.types.bool;
default = false;
example = true;
description = ''
Generate the auth-callout nkeys on this host instead of taking
them from `calloutUserPublicKey` / `calloutIssuerPublicKey`.
A first-boot unit mints both keypairs if absent, keeps the seeds
host-side at `0600`, and writes only the public halves into a
fragment the server reads. Nothing secret is evaluated, so
nothing secret reaches the nix store.
Leave it off wherever the queue and its clients are not the same
operator's problem: the seeds must reach whoever runs the
responder, and minting them here only moves that distribution
somewhere less visible. `enableAllLocalDefaults` turns it on.
'';
};
calloutUserPublicKey = lib.mkOption {
type = lib.types.str;
default = "";
example = "UDXU4RCSJNZOIQHZNWXHXORDPRTGNJAHAHFRGZNEEJCPQTT2M7NLCBBQ";
description = ''
Public half of the **user** nkey the auth-callout responder
authenticates as.
`auth_callout.auth_users` exempts this identity from needing
callout approval it is the one that answers auth requests, so
it cannot wait for itself. **That exemption is exactly why it
needs a credential of its own**: without one the escape hatch is
an open door, and on a container sharing the host netns it is an
open door reachable from every agent container.
An nkey rather than a password for the same reason
`calloutIssuerPublicKey` is: only the public half appears here,
and nix renders it into the world-readable store harmlessly. The
seed reaches the responder and nothing else, so until the
responder exists **nobody can authenticate as this user at all**
which is what makes a hive with no responder genuinely closed
rather than merely gated.
Required when `enable` is set.
'';
};
calloutIssuerPublicKey = lib.mkOption {
type = lib.types.str;
default = "";
example = "ACYR44YO3XZRZBJIYLI5SL6LOPIW37JTD52LNOBHUE34XMH7N5ABMFJH";
description = ''
Public half of the account nkey whose signature the server
accepts on a user JWT minted by the auth-callout responder.
**A public key, and therefore a value rather than a path**
the deliberate exception to the rule that credentials are
`*File` options. It is published to every client that connects
and its whole job is to be widely known; the matching *seed* is
the secret, is never named here, and reaches only the responder.
Required when `enable` is set. Without it the server has no
issuer to trust and no client can be authorized which is the
fail-closed state described below, but arrived at by accident
rather than on purpose, so it fails at eval instead.
'';
};
authPackage = lib.mkOption {
type = lib.types.package;
defaultText = lib.literalExpression "hyperhive.packages.\${system}.swarm-nats-auth";
description = ''
The auth-callout responder package.
Named `authPackage`, not `package`, on purpose: this module
deliberately has **no** `package` option for the server itself
(see the note above upstream's `services.nats` resolves
`pkgs.nats-server` on its own), so a bare `package` here would
read as "the NATS package" and mean something else entirely.
'';
};
calloutUserSeedFile = lib.mkOption {
type = lib.types.str;
default = "";
example = "/run/secrets/swarm-nats-callout-user.seed";
description = ''
Absolute host path to the **seed** whose public half is
`calloutUserPublicKey`. The responder authenticates to the queue
with it.
A `str` rather than a `path`, and the reason is not style: a
`path`-typed literal is hash-copied into the world-readable nix
store at eval time, which is the opposite of what a seed wants.
Same discipline as `otel.headersCredential`.
Until this is set the responder cannot start, and the queue
stays in its fail-closed state which is the correct behaviour,
not a gap.
'';
};
calloutIssuerSeedFile = lib.mkOption {
type = lib.types.str;
default = "";
example = "/run/secrets/swarm-nats-issuer.seed";
description = ''
Absolute host path to the **account** seed whose public half is
`calloutIssuerPublicKey`. The responder signs the user JWTs it
issues with it, so possession of this file is the authority to
admit anyone to the queue.
A `str` for the same store-leak reason as
`calloutUserSeedFile`.
'';
};
};
config = lib.mkIf cfg.enable {
assertions = [
{
# Fail at EVAL, not at boot: a queue that comes up unable to
# authenticate anyone presents as every client hanging, which is
# several layers from "the operator never set the issuer".
assertion = cfg.autoGenerateCallout || cfg.calloutIssuerPublicKey != "";
message = ''
services.hyperhive.swarm.nats.enable requires
nats.calloutIssuerPublicKey the public half of the account
nkey that signs user JWTs for this queue.
It is public and belongs in config; the matching seed is a
secret and is delivered to the callout responder instead. See
docs/swarm/secrets.md for which is which.
'';
}
{
# Without this the callout-exempt user has no credential, and
# NATS accepts `CONNECT {"user":"auth"}` from anyone. An eval
# failure is the only place to catch that: the rendered config is
# valid, the server starts, and the hole is invisible until
# somebody connects.
assertion = cfg.autoGenerateCallout || cfg.calloutUserPublicKey != "";
message = ''
services.hyperhive.swarm.nats.enable requires
nats.calloutUserPublicKey the public half of the user nkey
the auth-callout responder authenticates as.
It is exempt from callout approval by design, which is exactly
why it needs its own credential: a `users` entry with a name
and no key authenticates anyone who sends that name.
'';
}
{
assertion = autheliaUrl != null;
message = ''
services.hyperhive.swarm.nats.enable requires
services.hyperhive.swarm.authelia.url the queue authenticates
clients by validating tokens that authelia issued.
It defaults to this host's own instance only when this host
runs authelia. A hive that federates with a swarm sets it
explicitly to wherever that provider lives.
'';
}
];
# One declaration, two readers. The queue knows which client id it
# authenticates under; making the operator restate it in authelia's
# client list would be a second source of truth for a string whose
# mismatch is an opaque 401 from the token endpoint.
#
# `client_credentials` rather than an authorization-code flow: a
# queue's clients are daemons with nobody to redirect, so a
# non-interactive grant is what makes a hive able to authenticate at
# all. No redirect URI exists or is wanted.
#
# ⚠️ `kind` says that, and an empty `redirectUris` does NOT. This
# declaration carried the comment above while rendering as an
# interactive client, because authelia permits only the grants a
# client names and an omitted `grant_types` means authorization-code
# alone. Measured against 4.39.20: the token endpoint answered
# `unauthorized_client: The OAuth 2.0 Client is not allowed to use
# authorization grant 'client_credentials'`. Introspection — which
# is all the responder needs today — worked throughout, which is why
# nothing was visibly broken while the comment was untrue.
services.hyperhive.swarm.authelia.oidc.clients = lib.mkIf autheliaCfg.enable [
{
id = cfg.clientId;
description = "HyperHive swarm queue";
kind = "machine";
}
];
containers.swarm-nats = {
autoStart = true;
ephemeral = false;
# Shared host netns, like every sibling container.
#
# ⚠️ Which is exactly why the server below must refuse everyone
# until the callout responder exists: on this netns the queue is
# reachable from every agent container on the hive, so an
# unauthenticated interim state would be a hole rather than a
# rough edge.
privateNetwork = false;
# Binds only the public trust bundle, read-only. Empty when the gateway
# is not self-signed, so the whole trust path drops out cleanly.
bindMounts = caTrust.bindMount;
config =
{ ... }:
{
imports = [
(import ./swarm-container-resolver.nix {
inherit (networkCfg) bridgeIp;
# The responder introspects authelia BY NAME on every auth
# request, and a responder that cannot resolve it denies
# every client — so it must not start before the resolver
# file exists.
dnsConsumers = [ "swarm-nats-auth.service" ];
})
caBundleModule
];
system.stateVersion = "26.05";
# Shared host netns: this container's own firewall.service
# would rewrite the HOST ruleset at every boot. The host
# firewall owns all filtering.
networking.firewall.enable = false;
# resolvconf stays off because the resolver unit imported above
# owns /etc/resolv.conf. Leaving it on would let host-tracking
# regenerate the file empty, since the host's copy does not
# cross the boundary after start.
networking.resolvconf.enable = lib.mkForce false;
services.nats = {
enable = true;
# Retention, so a reader can ask "what did this hive last
# say?" without anyone keeping a second copy. The upstream
# option also wires `settings.jetstream.store_dir = dataDir`;
# the container is `ephemeral = false`, so that survives a
# restart with no bind mount.
#
# ⚠️ Losing the store is not a correctness problem here: a
# reader then sees nothing for every hive, which is the true
# answer until each one publishes again. It degrades to
# honesty rather than to a stale "healthy".
jetstream = true;
serverName = "swarm-nats";
port = cfg.port;
# In auto mode the keys are empty until the generator runs,
# and `nats-server -t` rejects that ("Expected callout user to
# be a valid public account nkey, got \"\""), so leaving this
# on fails the BUILD of every all-local hive. Upstream's own
# description names the case: disable it when the config
# includes other files. The check moves to server start.
validateConfig = !cfg.autoGenerateCallout;
settings = calloutBlocks {
userKey = cfg.calloutUserPublicKey;
issuerKey = cfg.calloutIssuerPublicKey;
};
};
# A wrapper that includes upstream's rendered settings verbatim
# plus the runtime fragment; rendering the config ourselves
# instead would throw away upstream's `settings`, where the
# reviewed reasoning lives. The generator writes it, because the
# includes must be siblings of the fragment (see `runtimeDir`).
#
# `mkForce`: upstream defines ExecStart inside an `mkMerge`, so a
# plain override conflicts rather than wins.
systemd.services.nats.serviceConfig.ExecStart = lib.mkIf cfg.autoGenerateCallout (
lib.mkForce "${pkgs.nats-server}/bin/nats-server -c ${runtimeWrapper}"
);
# The auth-callout responder: the half that lets the server
# above say *yes*. Without it the `auth_callout` block is a
# door nobody can open, which is the deliberate interim state.
#
# ⚠️ It is gated on the seeds being configured rather than on
# `cfg.enable`, so a half-configured hive gets a running,
# refusing queue instead of a unit that crash-loops on a
# missing file. A queue that denies everyone is a legible
# failure; a restart loop is not.
systemd.services.swarm-nats-auth = lib.mkIf responderConfigured {
description = "swarm queue auth-callout responder";
after = [ "nats.service" ];
requires = [ "nats.service" ];
wantedBy = [ "multi-user.target" ];
serviceConfig = {
ExecStart = lib.concatStringsSep " " [
"${cfg.authPackage}/bin/swarm-nats-auth"
"--nats-url nats://127.0.0.1:${toString cfg.port}"
"--user-seed-file \${CREDENTIALS_DIRECTORY}/callout-user.seed"
"--issuer-seed-file \${CREDENTIALS_DIRECTORY}/issuer.seed"
"--client-secret-file \${CREDENTIALS_DIRECTORY}/oidc-client.secret"
"--client-id ${lib.escapeShellArg cfg.clientId}"
# The account admitted clients land in, by NAME: in
# server-config mode the server resolves `aud` against its
# own `accounts` block, so this and the block above have to
# be the same string — which is why both come from one let.
"--account ${lib.escapeShellArg clientAccount}"
"--introspection-url ${lib.escapeShellArg introspectionUrl}"
# Both of these name a principal some OTHER module mints,
# so both are read out of that module rather than spelled
# again here — same argument as `--account` above, one
# level wider. The responder denies a client id it does
# not recognise, and a NATS denial arrives as a timeout,
# so a drift here is silent at the point of change and
# misattributed at the point of failure.
"--hive-client-prefix ${lib.escapeShellArg autheliaCfg.hiveClientPrefix}"
"--reader-client ${lib.escapeShellArg controllerCfg.queueClientId}"
];
# Every credential arrives by `LoadCredential` and is named
# on the command line only as a **path** — `argv` is
# world-readable via /proc/<pid>/cmdline, so a value there
# would be readable by every process on the host netns.
LoadCredential = [
"callout-user.seed:${inContainer "callout-user.seed"}"
"issuer.seed:${inContainer "issuer.seed"}"
"oidc-client.secret:${inContainer "oidc-client.secret"}"
];
DynamicUser = true;
Restart = "on-failure";
RestartSec = "5s";
SyslogIdentifier = "swarm-nats-auth";
};
};
# The server binary, so an operator with a shell in here can
# run `nats-server -t` against the generated config. The unit
# resolves ExecStart through the store path and puts nothing
# on PATH.
environment.systemPackages = [ pkgs.nats-server ];
};
};
# Deliver the responder's three credentials into the container before
# it starts. Same shape as `hive-matrix-oidc-secret`, and for the same
# reason it is a copy rather than a `bindMounts` entry: nixos-container
# refuses to start when a bind source is missing, so one absent seed
# would take down the **whole container including the queue**, not
# merely the responder. A far larger blast radius than the fault.
# Order the container after the host CA generator, so the bind source
# exists before nspawn sets the mount up. Without it a late CA fails the
# container start outright rather than degrading.
systemd.services."container@${machine}" = caTrust.containerOrdering;
systemd.services.swarm-nats-auth-secrets = lib.mkIf responderConfigured {
description = "deliver the swarm queue responder's credentials";
before = [ "container@swarm-nats.service" ];
wantedBy = [ "container@swarm-nats.service" ];
# In auto mode the seeds this copies do not exist until the generator
# has run. `requires` as well as `after`: if minting fails there is
# nothing to deliver, and a copy that silently succeeds with a stale
# or absent seed is worse than not running.
after =
lib.optional cfg.autoGenerateCallout "swarm-nats-callout-keys.service"
# The third credential does not come from the generator above — it is
# minted by authelia's FIRST BOOT, inside its own container. Ordering
# after that container is necessary and NOT sufficient: the container
# being up says nothing about whether its in-container secrets unit
# has finished. The wait in the script is what actually closes it;
# this only stops us spinning for the full timeout on every boot.
++ lib.optional autheliaCfg.enable "container@${autheliaCfg.machine}.service";
requires = lib.optional cfg.autoGenerateCallout "swarm-nats-callout-keys.service";
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
# Must exceed the script's own wait below, and is set rather than
# left to the default for exactly that reason: systemd's
# `DefaultTimeoutStartSec` is 90s, so a 120s wait would be killed at
# 90 and the operator would get a generic unit timeout instead of
# the message that names the missing file and says what to do.
# The bound that matters belongs in one place, and this makes the
# two visibly related.
TimeoutStartSec = "180s";
SyslogIdentifier = "swarm-nats-auth-secrets";
};
path = [ pkgs.coreutils ];
script = ''
set -euo pipefail
install -d -m 0700 ${lib.escapeShellArg secretDir}
install -m 0400 ${lib.escapeShellArg userSeedFile} \
${lib.escapeShellArg (hostPath "callout-user.seed")}
install -m 0400 ${lib.escapeShellArg issuerSeedFile} \
${lib.escapeShellArg (hostPath "issuer.seed")}
# Wait for authelia's minted secret rather than failing the instant
# it is absent. On a fresh boot this unit and authelia's first-boot
# generator race, and losing that race used to cost the WHOLE QUEUE:
# this exits 1, the responder never starts, and `auth_callout` with
# no responder refuses every client fail-closed by design, so the
# symptom appears on every queue client and nowhere near the cause.
#
# Bounded, not indefinite. Where authelia runs on another host the
# file is never going to appear, and blocking the queue container
# forever would replace a clear failure with a hang. After the
# timeout this fails exactly as it did before, having first given
# the co-located case the seconds it actually needs.
secret=${lib.escapeShellArg clientSecretSource}
deadline=$(( SECONDS + 120 ))
while [ ! -s "$secret" ]; do
if [ "$SECONDS" -ge "$deadline" ]; then
echo "the swarm queue responder's OIDC secret never appeared at $secret" >&2
echo "(authelia mints it on first boot; if authelia runs on another host," >&2
echo " copy the secret there and this unit will pick it up)" >&2
exit 1
fi
sleep 2
done
install -m 0400 "$secret" \
${lib.escapeShellArg (hostPath "oidc-client.secret")}
'';
};
# ⚠️ Minted on the HOST, not in the container, because the responder is
# a separate unit that needs the user seed: generating it inside would
# trap it there and require a secret-export path back out — the exact
# mechanism this is meant to avoid inventing. Only public halves cross.
systemd.services.swarm-nats-callout-keys = lib.mkIf cfg.autoGenerateCallout {
description = "mint the swarm queue's auth-callout nkeys";
before = [ "container@swarm-nats.service" ];
wantedBy = [ "container@swarm-nats.service" ];
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
SyslogIdentifier = "swarm-nats-callout-keys";
};
path = [
pkgs.coreutils
pkgs.nkeys
];
script = ''
set -euo pipefail
umask 077
install -d -m 0700 ${lib.escapeShellArg autoSeedDir}
# Mint iff absent. Idempotence is the whole contract: this runs on
# every boot, and regenerating would silently invalidate every
# credential the responder has already issued against the old
# issuer.
if [ ! -s ${lib.escapeShellArg autoUserSeed} ]; then
nk -gen user > ${lib.escapeShellArg autoUserSeed}.tmp
mv ${lib.escapeShellArg autoUserSeed}.tmp ${lib.escapeShellArg autoUserSeed}
fi
if [ ! -s ${lib.escapeShellArg autoIssuerSeed} ]; then
nk -gen account > ${lib.escapeShellArg autoIssuerSeed}.tmp
mv ${lib.escapeShellArg autoIssuerSeed}.tmp ${lib.escapeShellArg autoIssuerSeed}
fi
chmod 0600 ${lib.escapeShellArg autoUserSeed} ${lib.escapeShellArg autoIssuerSeed}
user_pub="$(nk -inkey ${lib.escapeShellArg autoUserSeed} -pubout)"
issuer_pub="$(nk -inkey ${lib.escapeShellArg autoIssuerSeed} -pubout)"
# Public halves only world-readable on purpose, since the server
# publishes them to every client that connects.
install -d -m 0755 ${lib.escapeShellArg hostRuntimeDir}
sed -e "s|@USER_PUBKEY@|$user_pub|g" \
-e "s|@ISSUER_PUBKEY@|$issuer_pub|g" \
${calloutTemplate} > ${lib.escapeShellArg hostRuntimeDir}/callout.conf.tmp
# Mode BEFORE the rename: a rename publishes whatever the file
# already is, so setting it afterwards leaves a window where the
# live path has the wrong mode. Same trap as the gateway's
# atomic-publish path.
chmod 0444 ${lib.escapeShellArg hostRuntimeDir}/callout.conf.tmp
mv ${lib.escapeShellArg hostRuntimeDir}/callout.conf.tmp \
${lib.escapeShellArg hostRuntimeDir}/callout.conf
# Upstream's rendered settings, as a sibling the wrapper can name
# without a leading slash. Refreshed unconditionally unlike the
# seeds, this one MUST track the current system, and a stale copy
# would silently run yesterday's config.
ln -sfn ${renderedSettings} ${lib.escapeShellArg hostRuntimeDir}/settings.conf
# The wrapper. Bare filenames see `runtimeDir`. printf rather than
# a heredoc, whose terminator would depend on nix's indentation
# stripping and break the next time `nix fmt` touched this block.
printf 'include "settings.conf"\ninclude "callout.conf"\n' \
> ${lib.escapeShellArg hostRuntimeDir}/nats.conf.tmp
chmod 0444 ${lib.escapeShellArg hostRuntimeDir}/nats.conf.tmp
mv ${lib.escapeShellArg hostRuntimeDir}/nats.conf.tmp \
${lib.escapeShellArg hostRuntimeDir}/nats.conf
'';
};
};
}