1# Server Configuration
2
3Core server settings for Gordon.
4
5## Configuration
6
7```toml
8[server]
9port = 8088                              # HTTP proxy port
10registry_port = 5000                     # Container registry port
11tls_port = 8443                          # HTTPS listener port (0 = disabled)
12# tls_cert_file = ""                       # Optional: PEM certificate for static TLS
13# tls_key_file = ""                        # Optional: PEM key for static TLS
14# force_https_redirect = false             # Redirect all HTTP traffic to HTTPS
15gordon_domain = "gordon.mydomain.com"    # Gordon domain (required)
16# data_dir = "~/.gordon"                 # Data storage directory (default)
17max_blob_chunk_size = "95MB"             # Max registry blob upload chunk
18max_blob_size = "1GB"                    # Max cumulative registry blob/layer upload
19```
20
21## Options
22
23| Option | Type | Default | Description |
24|--------|------|---------|-------------|
25| `port` | int | `8088` | HTTP proxy port for routing traffic to containers |
26| `registry_port` | int | `5000` | Docker registry port for image push/pull |
27| `tls_port` | int | `8443` | HTTPS listener port with internal CA. Set to `0` to disable TLS entirely |
28| `tls_cert_file` | string | `""` | Path to PEM certificate file. When set (with `tls_key_file`), this cert is served for matching SNI domains; unmatched domains fall through to the internal CA |
29| `tls_key_file` | string | `""` | Path to PEM private key file. Must be set together with `tls_cert_file` |
30| `force_https_redirect` | bool | `false` | Redirect all HTTP requests to the HTTPS port. For direct-access setups without a TLS-terminating proxy |
31| `gordon_domain` | string | **required** | Domain for Gordon (registry + admin API) |
32| `registry_domain` | string | - | Deprecated migration key. Set `gordon_domain` instead. |
33| `data_dir` | string | `~/.gordon` | Directory for registry data, logs, and env files |
34| `max_proxy_body_size` | string | `"512MB"` | Maximum request body size for proxied requests |
35| `max_blob_chunk_size` | string | `"95MB"` | Maximum request body size for a single registry blob upload chunk |
36| `max_blob_size` | string | `"1GB"` | Maximum cumulative size for one registry blob/layer upload |
37| `registry_allowed_ips` | []string | `[]` | IPs or CIDR ranges allowed to access the registry (empty = allow all) |
38| `proxy_allowed_ips` | []string | `[]` | IPs or CIDR ranges allowed to reach the proxy (empty = allow all) |
39| `registry_listen_address` | string | `""` | Bind address for registry (empty = all interfaces) |
40
41## Port Configuration
42
43### Proxy Port
44
45The `port` setting controls where Gordon listens for HTTP traffic:
46
47```toml
48[server]
49port = 8080  # Use 8080 for rootless containers with port forwarding
50```
51
52For rootless containers, you'll typically use a high port and configure firewall port forwarding:
53
54```bash
55# Forward port 80 to 8080
56sudo firewall-cmd --permanent --add-forward-port=port=80:proto=tcp:toport=8080
57```
58
59### Internal CA and TLS
60
61Gordon includes an internal certificate authority that issues on-demand TLS certificates for proxied domains. The HTTPS listener is enabled by default on `tls_port` (8443).
62
63```toml
64[server]
65tls_port = 8443   # Default. Set to 0 to disable TLS entirely.
66```
67
68With TLS enabled:
69- Gordon runs an internal CA (root + intermediate) stored in `{data_dir}/pki/`
70- Leaf certificates are issued on-demand per domain (SNI-based) and cached in memory
71- The intermediate CA auto-renews before expiry
72- An onboarding page at `https://<gordon-host>:<tls_port>/.well-known/gordon/` lets clients download the root CA certificate
73- The root CA is stable across restarts (generated once, persisted to disk)
74
75#### Custom certificates
76
77To use your own certificate (e.g. from Tailscale, Let's Encrypt, or a corporate CA) alongside the internal CA:
78
79```toml
80[server]
81tls_cert_file = "/etc/gordon/tls/cert.pem"
82tls_key_file = "/etc/gordon/tls/key.pem"
83```
84
85The static certificate is served for SNI-matching domains (including wildcards). All other domains get on-demand certs from the internal CA.
86
87#### Public ACME certificates
88
89Gordon can obtain public certificates through Let's Encrypt-compatible ACME when `[tls.acme]` is enabled. The HTTPS listener must also be enabled (`server.tls_port > 0`).
90
91```toml
92[server]
93tls_port = 8443
94
95[dns]
96resolvers = ["1.1.1.1:53", "8.8.8.8:53"]
97propagation_timeout = "5m"
98polling_interval = "5s"
99
100[tls.acme]
101enabled = true
102email = "admin@example.com"
103challenge = "auto"       # auto, http-01, or cloudflare-dns-01
104obtain_batch_size = 1    # maximum new certificate orders per reconcile run
105```
106
107Challenge behavior:
108- `http-01` serves `/.well-known/acme-challenge/<token>` on the HTTP proxy port.
109- `cloudflare-dns-01` uses a Cloudflare API token from `pass`, `GORDON_CLOUDFLARE_API_TOKEN_FILE`, or `GORDON_CLOUDFLARE_API_TOKEN`.
110- `auto` selects Cloudflare DNS-01 when a token is available, otherwise falls back to HTTP-01.
111
112HTTP-01 requires public access to port 80 for each hostname being validated. If you use Cloudflare in DNS-only/gray-cloud mode, your firewall/NAT must allow direct public traffic to Gordon's HTTP proxy port. A firewall rule that only allows Cloudflare source IPs on port 80 is compatible with orange-cloud proxying, but it blocks gray-cloud HTTP-01 validation; use DNS-01 or temporarily open port 80 for direct validation.
113
114Gordon limits new ACME certificate orders to `obtain_batch_size` per reconcile run (default `1`) so enabling ACME on an existing multi-route server does not burst through every route and hit Let's Encrypt rate limits. Later reloads, restarts, or other explicit reconcile runs continue issuing remaining certificates.
115
116If the initial ACME reconcile fails (e.g. due to a transient network error or misconfiguration), Gordon logs the failure but still starts the renewal loop for already cached certificates. Operators should fix the underlying error and restart/reload Gordon to trigger a new obtain attempt for missing certificates.
117
118For Cloudflare Full/Strict, Cloudflare terminates browser TLS at the edge and connects to Gordon over HTTPS. A public ACME certificate served by Gordon is the preferred origin certificate because Cloudflare Strict can validate it without custom origin trust. Cloudflare Flexible mode (HTTPS at the edge, HTTP to Gordon) is not end-to-end HTTPS.
119
120Static certificates have priority, then public ACME certificates, then Gordon's internal CA fallback. Gordon uses the `go-acme/lego` ACME client, including its DNS-provider support for Cloudflare DNS-01.
121
122DNS-01 uses the Cloudflare API to create TXT records, then checks public DNS visibility through `[dns].resolvers`. These resolvers are recursive resolvers (for example Cloudflare DNS or Google DNS), not the authoritative DNS provider. A domain can be hosted at Cloudflare while Gordon verifies propagation through Google DNS.
123
124The defaults avoid relying on host-local DNS. This matters on hosts using Tailscale MagicDNS, split-horizon corporate DNS, or Pi-hole, where `/etc/resolv.conf` may not reflect public DNS visibility as Let's Encrypt sees it.
125
126Because Gordon's ACME challenge mode is global, `cloudflare-dns-01` requires a Cloudflare token that can read zones and edit DNS records for every zone used by configured HTTPS routes. If that is not desirable, use `http-01` until Gordon supports per-route or per-zone challenge policy.
127
128#### Direct HTTP Onboarding
129
130When `tls_port` is non-zero, direct HTTP clients (those not arriving through a trusted proxy) are restricted to CA onboarding paths only:
131
132- `/.well-known/gordon/`, `/.well-known/gordon/ca`, `/.well-known/gordon/ca.crt`, `/.well-known/gordon/ca.mobileconfig` — serve the onboarding page and CA certificate downloads
133- `/.well-known/acme-challenge/*` — serves ACME HTTP-01 challenges when public ACME HTTP-01 is enabled, otherwise returns `404 Not Found`
134- All other paths return `403 Forbidden`
135
136This lets new clients discover and trust the internal CA over plain HTTP without exposing the full application. Trusted proxy traffic (e.g. from Cloudflare) continues through the normal HTTP proxy path unaffected.
137
138On HTTPS, onboarding paths are served only on `server.gordon_domain`; app hosts can use their own routes without Gordon intercepting them. If `gordon_domain` is empty, HTTPS onboarding paths are not served at all to avoid intercepting app hosts.
139
140#### HTTP to HTTPS redirect
141
142When clients connect directly (no Cloudflare or reverse proxy in front), enable `force_https_redirect` to redirect all HTTP traffic to the HTTPS port. Direct HTTP onboarding paths are still served even with this flag enabled.
143
144```toml
145[server]
146force_https_redirect = true
147```
148
149When `proxy_allowed_ips` is configured, non-proxy clients are redirected automatically even without this flag — trusted proxy IPs pass through to serve Cloudflare-proxied traffic.
150
151#### Disabling TLS
152
153For setups where TLS is handled entirely by an external proxy (Cloudflare, nginx, etc.):
154
155```toml
156[server]
157tls_port = 0   # No HTTPS listener, no internal CA generated
158```
159
160#### Firewall port forwarding
161
162For rootless user services, forward 443 to the high port at the firewall:
163
164```bash
165# Forward 443 -> 8443
166sudo firewall-cmd --permanent --add-forward-port=port=443:proto=tcp:toport=8443
167sudo firewall-cmd --reload
168```
169
170With firewalld and Tailscale:
171
172```bash
173# Verify tailscale0 is in trusted zone
174sudo firewall-cmd --get-zone-of-interface=tailscale0
175
176# If needed, place tailscale0 in trusted
177sudo firewall-cmd --permanent --zone=trusted --add-interface=tailscale0
178sudo firewall-cmd --reload
179
180# Forward 443 -> 8443 permanently (IPv4 + IPv6)
181sudo firewall-cmd --permanent --zone=trusted --add-rich-rule='rule family=ipv4 forward-port port=443 protocol=tcp to-port=8443'
182sudo firewall-cmd --permanent --zone=trusted --add-rich-rule='rule family=ipv6 forward-port port=443 protocol=tcp to-port=8443'
183sudo firewall-cmd --reload
184```
185
186### Registry Port
187
188The `registry_port` setting controls where Gordon accepts image pushes:
189
190```toml
191[server]
192registry_port = 5000
193```
194
195Docker/Podman clients push to this port:
196
197```bash
198docker push registry.mydomain.com:5000/myapp:latest
199```
200
201If the registry is served over plain HTTP (no TLS), clients must be configured to allow insecure access. See [Troubleshooting: insecure registry](../reference/troubleshooting.md#server-gave-http-response-to-https-client) for Docker and Podman instructions.
202
203## Gordon Domain
204
205The `gordon_domain` is required and must match your DNS configuration:
206
207```toml
208[server]
209gordon_domain = "gordon.mydomain.com"
210```
211
212This domain is used for:
213- Docker login and image push/pull operations
214- Admin API access (`/admin/*` endpoints)
215- CLI remote targeting (`gordon routes --remote https://gordon.mydomain.com`)
216- Authentication endpoints (`/auth/*`)
217
218> **Warning:** If you are upgrading an older config, copy `server.registry_domain` to `server.gordon_domain` before restarting.
219
220Without this migration, a Host/remote-target mismatch can break routing or remote CLI token exchange.
221
222When requests arrive on the proxy port with this domain as the Host header, Gordon routes them to the backend services (registry and admin API).
223
224Security note:
225- Direct access to `/admin/*` on `registry_port` is blocked for non-loopback clients.
226- Admin API traffic should go through the main proxy listener (`server.port`/`server.tls_port`).
227
228> **Note:** `registry_domain` is a deprecated migration key; use `gordon_domain` for new and upgraded configs.
229
230## Data Directory
231
232The `data_dir` setting controls where Gordon stores data:
233
234```toml
235[server]
236data_dir = "~/.gordon"  # Default for user installations
237```
238
239### Directory Structure
240
241```
242~/.gordon/
243├── registry/           # Container images and manifests
244│   ├── blobs/
245│   └── manifests/
246├── env/                # Environment files per domain
247│   ├── app_mydomain_com.env
248│   └── api_mydomain_com.env
249├── logs/               # Application and container logs
250│   ├── gordon.log
251│   ├── proxy.log
252│   └── containers/
253└── secrets/            # Secrets (unsafe backend only)
254```
255
256### Permissions
257
258 Gordon creates directories with secure permissions:
259 - Directories: `0700` (owner only)
260 - Files: `0600` (owner only)
261
262 ## Maximum Proxy Body Size
263
264 The `max_proxy_body_size` setting limits the size of request bodies that Gordon will forward to backend containers:
265
266 ```toml
267 [server]
268 max_proxy_body_size = "512MB"  # Default
269 ```
270
271 **Purpose:** Prevents resource exhaustion attacks from extremely large uploads through the proxy.
272
273 **Supported units:** B, KB, MB, GB, TB (case-insensitive, decimal/1024-based)
274
275 **Examples:**
276 ```toml
277 max_proxy_body_size = "100MB"   # Stricter limit
278 max_proxy_body_size = "1GB"     # Allow larger uploads
279 max_proxy_body_size = "0"       # No limit (not recommended)
280 ```
281
282 **Behavior:**
283 - When a request exceeds the limit, Gordon returns `413 Request Entity Too Large`
284 - The limit is applied before the request reaches the backend container
285 - Uploads in progress are terminated when the limit is exceeded
286
287 **Use cases:**
288 - File upload services: increase to `1GB` or higher
289 - CI/CD artifact uploads: adjust based on your largest artifacts
290 - Tight security: reduce to `100MB` or lower
291 - Default (512MB): suitable for most applications
292
293 > **Warning:** Setting this to `0` (no limit) allows unlimited upload sizes, which can lead to disk exhaustion and DoS vulnerabilities. Always set a reasonable limit for production deployments.
294
295## Maximum Registry Blob Chunk Size
296
297The `max_blob_chunk_size` setting limits the size of a single blob upload request to the registry (`PATCH`/`PUT` under `/v2/*/blobs/uploads/*`):
298
299```toml
300[server]
301max_blob_chunk_size = "95MB"  # Default
302```
303
304**Purpose:** Prevents excessive memory usage during blob uploads while allowing large real-world image layers.
305
306**Supported units:** B, KB, MB, GB, TB (case-insensitive, decimal/1024-based)
307
308**Examples:**
309
310```toml
311max_blob_chunk_size = "256MB"  # Stricter limit
312max_blob_chunk_size = "1GB"    # Allow larger layers
313```
314
315**Behavior:**
316- When a blob chunk exceeds the limit, Gordon returns `413 Request Entity Too Large`
317- Gordon CLI uploads image layers in 50MB chunks by default, and this setting caps the maximum chunk accepted per request
318- Keep this below Cloudflare's 100MB per-request limit when operating behind Cloudflare; the default (`95MB`) is fine
319- Increase it only if you expect larger direct registry uploads from other clients
320
321## Maximum Registry Blob Size
322
323The `max_blob_size` setting limits the cumulative size of one blob/layer upload across all chunks:
324
325```toml
326[server]
327max_blob_size = "1GB"  # Default
328```
329
330**Purpose:** Prevents disk exhaustion from multi-chunk uploads where each individual chunk is below `max_blob_chunk_size` but the total blob grows without bound.
331
332**Behavior:**
333- Gordon tracks the current upload size and rejects appends that would exceed the limit.
334- Rejected uploads return an OCI-compatible `413` size error.
335- Failed uploads are cleaned up so temporary blob data does not accumulate indefinitely.
336
337## Registry IP Allowlist
338
339The `registry_allowed_ips` setting restricts registry access to specific IPs or IP ranges. Accepts both CIDR notation (`100.64.0.0/10`) and individual IPs (`203.0.113.50`). When set, only requests from listed addresses (plus localhost) can reach registry and auth endpoints. An empty list allows all traffic (default).
340
341```toml
342[server]
343registry_allowed_ips = [
344  "100.64.0.0/10",   # Tailscale CGNAT range
345  "203.0.113.50",    # single IP (treated as /32)
346]
347```
348
349**Behavior:**
350- Single IPs are automatically converted to `/32` (IPv4) or `/128` (IPv6)
351- Denied requests receive `403 Forbidden`
352- Localhost (`127.0.0.0/8`, `::1`) is always allowed so Gordon can pull from its own registry
353- Respects `trusted_proxies` for accurate client IP extraction behind reverse proxies
354- Applied before rate limiting and authentication
355- Changes require a Gordon server restart; not picked up by config hot-reload
356
357**Use cases:**
358- Restrict registry to Tailscale network: `["100.64.0.0/10"]`
359- Restrict to private subnets: `["10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16"]`
360- Allow a specific CI server: `["100.64.0.0/10", "203.0.113.50"]`
361
362Via environment variable:
363
364```bash
365GORDON_SERVER_REGISTRY_ALLOWED_IPS=100.64.0.0/10
366```
367
368## Proxy Origin IP Allowlist
369
370The `proxy_allowed_ips` setting restricts which IPs can reach the proxy server. This prevents direct-to-origin attacks that bypass CDN protections (e.g. Cloudflare WAF, DDoS mitigation). When set, only connections from listed CIDRs (plus localhost) are accepted.
371
372```toml
373[server]
374# Only accept proxy traffic from Cloudflare edge IPs
375proxy_allowed_ips = [
376  "173.245.48.0/20", "103.21.244.0/22", "103.22.200.0/22",
377  "103.31.4.0/22", "141.101.64.0/18", "108.162.192.0/18",
378  "190.93.240.0/20", "188.114.96.0/20", "197.234.240.0/22",
379  "198.41.128.0/17", "162.158.0.0/15", "104.16.0.0/13",
380  "104.24.0.0/14", "172.64.0.0/13", "131.0.72.0/22",
381]
382```
383
384**Behavior:**
385- Checks the direct connection IP (`RemoteAddr`), not `X-Forwarded-For`
386- Localhost is always allowed
387- Denied requests receive `403 Forbidden`
388- An empty list allows all traffic (default)
389
390**Important:** Cloudflare publishes their IP ranges at [cloudflare.com/ips](https://www.cloudflare.com/ips/). Keep your allowlist updated when Cloudflare adds new ranges.
391
392## Registry Listen Address
393
394The `registry_listen_address` controls which interface the registry server binds to. By default it binds to all interfaces. Set to `127.0.0.1` to restrict registry access to localhost only, preventing containers from reaching the registry via the Docker bridge gateway.
395
396```toml
397[server]
398registry_listen_address = "127.0.0.1"  # Loopback only
399```
400
401## HSTS
402
403HSTS headers are sent automatically on the HTTPS listener (when `r.TLS != nil`). When Gordon runs behind a TLS-terminating proxy (Cloudflare, Tailscale) and only receives plain HTTP, HSTS is not sent — the edge proxy is expected to handle it.
404
405## Examples
406
407### Development Configuration
408
409```toml
410[server]
411port = 8080
412registry_port = 5000
413gordon_domain = "gordon.local"
414data_dir = "./dev-data"
415```
416
417### Production Configuration
418
419```toml
420[server]
421port = 8080
422registry_port = 5000
423gordon_domain = "gordon.company.com"
424data_dir = "/var/lib/gordon"
425```
426
427### Rootless Container Setup
428
429```toml
430[server]
431port = 8080      # High port for rootless
432registry_port = 5000
433gordon_domain = "gordon.mydomain.com"
434```
435
436With firewall port forwarding:
437```bash
438sudo firewall-cmd --permanent --add-forward-port=port=80:proto=tcp:toport=8080
439sudo firewall-cmd --reload
440```
441
442## Related
443
444- [Configuration Overview](./index.md)
445- [Installation Guide](../installation.md)
446- [Routes Configuration](./routes.md)