# Swarm secrets: what exists, and where each one lives A swarm's credentials are generated in three different places and read in a fourth, so "where does this file go" has a different answer per deployment. This page is that answer, one row per secret. Two rules run through all of it. **Private key material and access tokens are paths, never values.** Every option carrying one takes a file path (`*File`), because a literal written into a nix expression is rendered into the nix store — world-readable and permanent. No option in this tree accepts one inline, and adding one would be a leak rather than a convenience. The rule is about what must stay secret, not about credentials generally. **Public material is a value**: a certificate, or a public nkey like `swarm.nats.calloutUserPublicKey`, is published to every client that connects, so the store is a perfectly good place for it. **The generator and the reader are usually in different containers.** They share the host's network namespace, which makes them feel co-located, but their filesystem roots are separate. That is why delivery is a **host-side copy rather than a bind mount**: `nixos-container` refuses to start when a bind source is missing, and a secret minted on another container's first boot does not exist yet. Binding it would make one container wait on a file that waits on a container that starts after it. ## The three topologies Every row below is read against one of these. | topology | what it means | who places secrets | |---|---|---| | **all-local** | one host runs the swarm's shared services and its own hive | nobody — each secret is generated where it is read, or copied by a host unit | | **swarm-managed** | the swarm's services run on a host with `swarmctl` | `swarmctl` writes what it owns; the rest is still generated in place | | **hive elsewhere** | a hive that federates with a swarm it does not host | the operator provides the file and names it in config | ## Swarm-level — one of each per swarm | secret | generated by | lives at | hive elsewhere | |---|---|---|---| | swarm root CA cert | `swarm-ca.nix` first-boot unit, when `autoConfigure` is set | `/var/lib/swarm-ca/root.pem` | operator copies the **cert** in; it is public | | swarm root CA key | same unit | `/var/lib/swarm-ca/root-key.pem`, `0600` | stays on whichever host holds it — see the constraint below | | swarm-services sub-CA (cert + key) | `swarm-ca.nix`, signed by the root | `/var/lib/swarm-ca/services-ca{,-key}.pem` | issued where the root lives | | authelia session, JWT and storage-encryption keys | authelia's first-boot unit, in-container | `/var/lib/authelia-swarm/{session,jwt,storage-encryption}.key` | generated in place; nothing outside that container reads them | | authelia OIDC HMAC key | same unit | `/var/lib/authelia-swarm/oidc-hmac.key` | same | | authelia OIDC issuer key (RSA) | same unit | `/var/lib/authelia-swarm/oidc-issuer.key` | same — relying parties verify against the **public** half at `/jwks.json` | | OIDC client secret, plaintext half | `authelia crypto hash generate --random` | `/var/lib/authelia-swarm/oidc-clients/.secret` | operator provides the file and names it in whichever option reads it — `sso.clientSecretFile` for a service, `otel.clientSecretFile` for the hive's telemetry collector | | OIDC client secret, digest half | the same mint | `oidc-clients/.digest` | authelia's own half; merged at runtime via `settingsFiles` | | authelia subject store | `swarmctl` and `swarm-authelia-bridge` | `users.yml` — one file, read and written by both | `swarmctl`, on the host that runs authelia | | wireguard private key | **the operator** — `wg genkey` | whatever `swarm.wireguard.privateKeyFile` names | always operator-provided; nothing generates this for you | | queue auth-callout nkeys (user seed + account seed) | `swarm-nats-callout-keys` first-boot unit, when `nats.autoGenerateCallout` is set | `/var/lib/swarm-nats-callout/{callout-user,issuer}.seed`, `0600` | operator mints both with `nk` and names them in `nats.calloutUserSeedFile` / `nats.calloutIssuerSeedFile` | The three keys authelia mints for itself are generated in-container precisely because nothing outside that container ever reads them. **That is the test worth applying to any secret added here** — and the client secret's plaintext half is the one row that fails it, which is the entire reason a delivery step exists. One reader needs no delivery step: the **hive's telemetry collector**, which authenticates to the swarm's collector as its own hive. It is a host unit rather than a container, so on an all-local swarm it reads authelia's file where it lies (through `LoadCredential`) and no second copy is made. On any other topology it is an ordinary "operator provides the file" case — see `services.hyperhive.otel.clientSecretFile`. ### Minting the queue's callout nkeys `nats.autoGenerateCallout` mints both keypairs on the host before the queue starts. It is on by default only under `enableAllLocalDefaults` — the one topology where the queue, its responder and the operator are the same person. On every other topology, mint them yourself: ``` nk -gen user > callout-user.seed # the responder's own identity nk -gen account > issuer.seed # signs the user JWTs it hands out nk -inkey callout-user.seed -pubout # → calloutUserPublicKey nk -inkey issuer.seed -pubout # → calloutIssuerPublicKey ``` Keep both seeds at `0600` and name them in `calloutUserSeedFile` / `calloutIssuerSeedFile`. Possession of the **issuer** seed is the authority to admit anyone to the queue, so it belongs wherever the responder runs and nowhere else. A hive that sets neither the public keys nor `autoGenerateCallout` fails at eval, naming the option it wants. That is deliberate: a queue that started without them would accept `CONNECT {"user":"auth"}` from anyone sharing the host's network namespace, and nothing would look wrong until somebody connected. One consequence of the generated path worth knowing before you debug it: with `autoGenerateCallout` set, the queue's config is assembled at boot rather than at build time, so a malformed one surfaces when the container starts instead of when the system builds. The server names the offending file and refuses to run. ## Hive-level — one of each per hive | secret | generated by | lives at | |---|---|---| | hive CA cert + key | `hive-tls.nix` first-boot unit | `/ca.pem`, `ca-key.pem` (`0600`) | | hive leaf certs | `hive-tls.nix`, signed by the hive CA | `/.pem` | | matrix registration token | a host activation script, on first boot | `/var/lib/hyperhive/matrix-register-token` (`0600`) | | the forge's copy of its OIDC secret | `hive-forge-oidc-secret.service` copies it from authelia's tree | `/var/lib/forgejo-oidc/.secret` inside the forge container | | the homeserver's copy of its OIDC secret | `hive-matrix-oidc-secret.service`, same shape | `/var/lib/tuwunel-oidc/.secret`, handed to tuwunel through `LoadCredential` | Both delivery units wait for authelia's first boot to mint the secret — a bounded wait, 120s — and then **fail loudly** rather than skipping. A silent skip produces a service whose login button always fails, which is a symptom several layers from its cause. ## The constraint that decides where the root lives A hive CA carries `nameConstraints=permitted;DNS:`, and **a swarm service name is a sibling of the hive domain rather than a child** — `forge.` next to `.`. So a hive CA cannot issue a certificate for a swarm service. Not by policy: by construction, and openssl enforces it. Whatever holds the swarm root is therefore what makes swarm-service certificates possible at all. Two things follow: - **The root's private key is a runtime file and must never enter the nix store**, so nothing build-time can name it — `security.pki.certificateFiles` is read when the system is built, and is the wrong tool here. Trust reaches containers through a bind-mounted bundle assembled at boot instead. - **On any topology other than all-local, placing that key is an operations decision**, not something this module tree makes for you. A hive that hosts no swarm services needs only the root's *cert*, to trust what others issue. ## Adding a secret State three things, in the row you add above: **who mints it**, **which container reads it**, and **what happens when they differ**. If they differ, it needs a delivery unit, and the unit copies — it does not bind.