housecarl/docs/api.md

# The REST API

Everything the web UI and the CLI do goes through this API, under
`/api/v1`. Requests and answers are JSON.

## Authentication

* **API tokens**: `Authorization: Bearer housecarl_...`. Make one in the
  web UI (your account), with `hc token create NAME`, or with `housecarld
  user token USER NAME` on the server.
* **Sessions**: `POST /auth/login` with `{"username", "password"}` sets a
  cookie and returns `csrf_token`. Requests other than GET must send it as
  `X-CSRF-Token`.
* **The local socket** (`/run/housecarl/housecarl.sock`): root and
  housecarld's own user need nothing; others send a token. Changes made
  through it aren't on probation.

Failed logins and token attempts are rate limited per address and per
user name. [permissions.md](permissions.md) has what each call needs.

## Errors

```json
{"error": {"code": "validation", "message": "rule input #31: there is no set trusted",
           "problems": [{"severity": "error", "code": "unknown_set", "message": "from: there is no set trusted", "object": "rule input #31"}]}}
```

| Status | Code | |
|---|---|---|
| 400 | `bad_request` | the request can't be read |
| 401 | `unauthenticated`, `session_expired`, `login_failed` | |
| 403 | `forbidden`, `csrf` | |
| 404 | `not_found` | |
| 409 | `conflict` | e.g. undoing a change after the objects changed again |
| 422 | `validation` | the change would make the configuration invalid; `problems` lists why ([validation.md](validation.md)) |
| 422 | `firewall` | nftables refused the ruleset (`nft -c`), or applying it failed; the message has nftables' words. Nothing was changed |
| 429 | `rate_limited` | |

## Changes

Calls that change the configuration answer:

```json
{"applied": true, "history_id": 7,
 "changes": [{"kind": "rule", "id": 31, "label": "input #31 (SSH from home)", "after": {...}}],
 "warnings": [{"severity": "warning", "code": "set_empty", "message": "...", "object": "..."}],
 "object": {...},
 "confirm_by": "2026-10-19T10:02:00Z"}
```

* `confirm_by`: the change is on probation, and is rolled back at that
  time unless `POST /confirm` comes first. Missing for changes made
  through the socket.
* `?dry_run=1` checks the change, with nftables too, and returns what it
  would do, with `"applied": false, "dry_run": true`.
* `before` is missing for a create and `after` for a delete.
* `warnings` are the problems the change brings; older ones are in
  `/status`.
* `object` is the created or changed object.

Creating answers 201, other changes 200.

## Endpoints

### Status

| | |
|---|---|
| `GET /healthz` | `{"ok": true, "version"}`, without authentication |
| `GET /status` | `build`, `started`, `applied` (the ruleset is in force), `apply_error`, `problems`, `probation`, `interfaces`, `counts` (objects by kind), `other_tables` (other nftables tables, `"inet main"`) |
| `GET /interfaces` | the machine's interfaces: `name`, `up`, `addresses`, `zone` |
| `GET /ruleset` | the nftables ruleset Housecarl builds, as text |
| `GET /counters` | `{"since", "counters": {"r12": {"packets", "bytes"}, ...}}`, by mark ([design.md](design.md#its-own-table-only)); totals since housecarld started |
| `GET /log[?limit=&after=&q=]` | logged packets, newest first: `time`, `prefix`, `in`, `out`, `family`, `protocol`, `source`, `source_port`, `destination`, `destination_port`, `icmp_type`, `tcp_flags`, `length`, `mark` (the rule's). `after` (a time) for those since; `q` searches |
| `GET /catalog` | built-in services, chains, actions, roles, the log group |

### Settings

`GET /settings`, `PATCH /settings` with any of:

```json
{"input_policy": "drop", "forward_policy": "drop", "output_policy": "accept",
 "log_policy_drops": false,
 "builtins": {"loopback": true, "established": true, "drop_invalid": true, "icmpv6": true,
              "ping_internal": true, "dhcpv6_client": true, "antispoof": true, "mss_clamp": false},
 "own_prefixes": ["2001:db8:7f3d::/48"], "antispoof_v4": ["10.0.0.0/8", "..."], "antispoof_v6": ["fc00::/7", "..."],
 "flowtable_devices": ["wan", "enp2s0"], "probation_seconds": 120}
```

Lists replace the old ones. `probation_seconds` 0 is the default (120).

### Objects

Zones, sets, services, rules, port forwards, source NAT and redirects
share one pattern, `/{kind}` with kind `zones`, `sets`, `services`,
`rules`, `forwards`, `snats` or `redirects`:

| | |
|---|---|
| `GET /{kind}` | all of them, in order; `GET /rules?chain=input` for one chain; `GET /services` includes the built-in ones |
| `POST /{kind}` | create; rules, forwards and NAT rules go last unless given a `position` |
| `GET /{kind}/{ref}` | by ID, or name for zones, sets, services and forwards |
| `PATCH /{kind}/{ref}` | change the fields given (a JSON merge: `null` clears) |
| `DELETE /{kind}/{ref}` | refused while something uses it |
| `POST /{kind}/{ref}/move` | `{"before": ID}`, `{"after": ID}` or `{"to": "start"\|"end"}`; a rule can take `"chain"` too |

The objects:

```json
{"name": "lan", "interfaces": ["enp2s0", "enp2s0.*"], "external": false, "comment": ""}
{"name": "trusted", "entries": ["10.0.10.0/24", "2001:db8:7f3d:10::/64"], "dynamic": false, "timeout": 0, "comment": ""}
{"name": "jellyfin", "entries": ["tcp/8096", "tcp/8920"], "comment": ""}
{"chain": "input",
 "in_zones": ["wan"], "not_in": false, "out_zones": [], "not_out": false,
 "sources": ["trusted"], "not_sources": false, "destinations": [], "not_destinations": false,
 "services": ["ssh"], "family": "",
 "ct_state": ["new"], "ct_status": [], "days": [], "hour_from": "", "hour_to": "",
 "limit": {"rate": 3, "per": "minute", "burst": 5, "over": true, "per_source": true}, "conn_limit": 0,
 "action": "drop", "reject_with": "", "log": true, "log_prefix": "",
 "raw": "", "comment": "", "disabled": false}
{"name": "jellyfin", "protocols": ["tcp"], "ports": "8096", "public_addresses": ["203.0.113.7"], "sources": [],
 "to": "10.0.10.57", "to_port": "443", "to6": "2001:db8:7f3d:10::57", "hairpin": true, "hairpin_sources": [],
 "comment": "", "disabled": false}
```

A source NAT rule is a match (as a rule's, without the rule's other
fields) with `"to"` (empty: masquerade), a redirect a match with
`"to_port"`. Times are seconds (`timeout`).

### Dynamic sets' entries

| | |
|---|---|
| `GET /sets/{name}/elements` | `[{"address", "timeout"}]`, `timeout` the seconds left |
| `POST /sets/{name}/elements` | `{"address": "10.0.30.17", "timeout": 3600}`; `timeout` 0 is the set's |
| `DELETE /sets/{name}/elements/{address}` | |

These need `sets:read` or `sets:write`, for that set
([permissions.md](permissions.md)); they aren't on probation or in the
history, but are audited.

### Probation

| | |
|---|---|
| `GET /probation` | `{"pending": [history IDs], "takeovers": N, "deadline", "seconds_left"}` |
| `POST /confirm` | keep them: `{"confirmed": N}`; the ruleset is saved for the boot |
| `POST /rollback` | undo them now |

### History, import, takeover

| | |
|---|---|
| `GET /history[?limit=&before=]` | changes, newest first |
| `GET /history/{id}` | one, with each object before and after |
| `POST /history/{id}/revert` | undo it; 409 if an object it touched has changed since, or it was undone already |
| `POST /import/nft` | `{"json": NFT_JSON, "text": "nft -a list ruleset output", "defines": "ruleset file", "table": "inet main", "replace": false}` ([import.md](import.md)); answers with `state` (the imported configuration), `notes` and `raw` too |
| `POST /takeover` | `{"tables": ["inet main"]}`: delete these tables (administrators); on probation over the network |

### Certificate

Administrators only ([certificates.md](certificates.md)).

| | |
|---|---|
| `GET /certificate` | `{"configured", "source": "acme"\|"file"\|"none", "status": {"domain", "directory", "staging", "state": "none"\|"ok"\|"working"\|"error", "not_before", "not_after", "issuer", "renew_at", "last_error", "last_attempt", "next_attempt", "check"}}` |
| `POST /certificate/check` | run the check now (up to a few minutes); answers `{"time", "domain", "ok", "steps": [{"name", "status", "detail", "queries"}]}` |
| `POST /certificate/renew` | get a new certificate now, in the background (202); follow it with `GET /certificate` |

### Users, tokens, audit

| | |
|---|---|
| `POST /auth/login`, `POST /auth/logout`, `GET /auth/whoami` | `whoami` has `token_id` when the caller uses a token |
| `POST /me/password` | `{"current", "password"}` |
| `GET /me/tokens`, `POST /me/tokens` | `{"name", "role", "grants", "expires_in"}`; the answer's `secret` is shown once |
| `GET /tokens`, `DELETE /tokens/{id}` | all tokens (administrators), revoke |
| `POST /tokens/{id}/rotate` | a new secret: `{"grace": "1h", "expires_in": "90d", "no_expiry": false}`, all optional; answers with `secret` and `previous_secret_valid_until` |
| `GET`, `POST /users`; `PATCH`, `DELETE /users/{id}` | administrators; `{"username", "password", "admin", "role", "grants", "disabled", "comment"}` |
| `GET`, `POST /users/{id}/tokens` | |
| `GET /audit[?user=&action=&result=&q=&before=&limit=]` | |