rws_http/server_config/mod.rs
1//! Typed server configuration.
2//!
3//! [`ServerConfig`] holds all per-instance configuration fields as typed Rust
4//! values. It replaces point-of-use `env::var("RWS_CONFIG_*")` calls with a
5//! struct that can be:
6//!
7//! - Built from environment variables once at startup: [`ServerConfig::from_env()`]
8//! - Constructed directly in tests without touching the environment:
9//! [`ServerConfig::default()`] / struct update syntax
10//! - Passed to [`App::with_config`] to create a fully isolated application
11//! instance — essential for parallel tests and embedded multi-tenant use
12//!
13//! # Test isolation example
14//!
15//! ```rust,ignore
16//! use rust_web_server::app::App;
17//! use rust_web_server::server_config::ServerConfig;
18//! use rust_web_server::test_client::TestClient;
19//!
20//! // No env writes, no lock needed.
21//! let app = App::with_config(ServerConfig {
22//! cors_allow_all: false,
23//! cors_allow_origins: "https://example.com".to_string(),
24//! ..ServerConfig::default()
25//! });
26//! let client = TestClient::new(app);
27//! let res = client.get("/").send();
28//! ```
29
30
31use std::sync::atomic::{AtomicU64, Ordering};
32use std::sync::{Arc, RwLock};
33
34use crate::entry_point::Config;
35
36/// Bumped whenever `RWS_CONFIG_*` variables change (see [`invalidate`]).
37static GENERATION: AtomicU64 = AtomicU64::new(1);
38
39/// The snapshot [`ServerConfig::current`] hands out, with the generation it
40/// was built at.
41static CURRENT: RwLock<Option<(u64, Arc<ServerConfig>)>> = RwLock::new(None);
42
43/// Mark the cached [`ServerConfig::current`] snapshot stale: the next call
44/// re-reads the environment. Called by everything in the crate that writes
45/// `RWS_CONFIG_*` variables (config file, command line, defaults,
46/// `config_reload::reload`); call it yourself after `std::env::set_var` of
47/// a setting that should take effect immediately.
48pub fn invalidate() {
49 GENERATION.fetch_add(1, Ordering::SeqCst);
50}
51
52/// Default `Content-Security-Policy` header value. Mirrors
53/// `Header::_CONTENT_SECURITY_POLICY_VALUE_DEFAULT` without creating a
54/// circular import (`server_config` ← `header` ← `cors` ← `server_config`).
55const CSP_DEFAULT: &str = "default-src 'self'";
56/// Default `Cache-Control` for static files: cache, but revalidate.
57#[doc(hidden)]
58pub const STATIC_CACHE_CONTROL_DEFAULT: &str = "no-cache";
59
60/// All runtime-configurable settings for one server instance.
61///
62/// Fields map 1-to-1 to `RWS_CONFIG_*` environment variable names documented
63/// in [`Config`]. Default values match the environment-variable defaults.
64///
65/// Construct via [`ServerConfig::from_env()`] at startup or
66/// [`ServerConfig::default()`] in tests.
67#[derive(Clone, Debug, PartialEq)]
68pub struct ServerConfig {
69 // ── CORS ─────────────────────────────────────────────────────────────────
70 /// `RWS_CONFIG_CORS_ALLOW_ALL` — when `true`, all cross-origin requests are
71 /// reflected back as allowed (echo the `Origin` header). Overrides all
72 /// other CORS fields. Default: `true`.
73 pub cors_allow_all: bool,
74 /// `RWS_CONFIG_CORS_ALLOW_ORIGINS` — comma-separated list of allowed
75 /// origins when `cors_allow_all` is `false`. Default: `""` (none).
76 pub cors_allow_origins: String,
77 /// `RWS_CONFIG_CORS_ALLOW_CREDENTIALS` — value for the
78 /// `Access-Control-Allow-Credentials` response header. Default: `""`.
79 pub cors_allow_credentials: String,
80 /// `RWS_CONFIG_CORS_ALLOW_METHODS` — value for
81 /// `Access-Control-Allow-Methods`. Default: `""`.
82 pub cors_allow_methods: String,
83 /// `RWS_CONFIG_CORS_ALLOW_HEADERS` — value for
84 /// `Access-Control-Allow-Headers`. Default: `""`.
85 pub cors_allow_headers: String,
86 /// `RWS_CONFIG_CORS_EXPOSE_HEADERS` — value for
87 /// `Access-Control-Expose-Headers`. Default: `""`.
88 pub cors_expose_headers: String,
89 /// `RWS_CONFIG_CORS_MAX_AGE` — value for `Access-Control-Max-Age`.
90 /// Default: `"86400"`.
91 pub cors_max_age: String,
92
93 // ── Security headers ──────────────────────────────────────────────────────
94 /// `RWS_CONFIG_CSP` — `Content-Security-Policy` header value. An empty
95 /// string suppresses the header. Unset: `default-src 'self'` when
96 /// [`security_headers`](Self::security_headers) is on, otherwise no header
97 /// (18.0.0; was always `default-src 'self'`).
98 pub csp: String,
99 /// `RWS_CONFIG_SECURITY_HEADERS` — send `X-Frame-Options: SAMEORIGIN`,
100 /// `Referrer-Policy` and `Permissions-Policy` on every response (and the
101 /// default CSP, unless `RWS_CONFIG_CSP` is set). Off by default (18.0.0;
102 /// was always on): nginx sends none of them, and over HTTP/2 every header
103 /// costs HPACK work. `X-Content-Type-Options: nosniff` is always sent.
104 pub security_headers: bool,
105 /// `RWS_CONFIG_NANOS_HEADERS` — send `Date-Unix-Epoch-Nanos` and, for
106 /// static files, `Last-Modified-Unix-Epoch-Nanos`. Off by default (18.0.0;
107 /// was always on): they change on every response, so HTTP/2 can't index
108 /// them, and `Date`/`Last-Modified` carry the same information to the second.
109 pub nanos_headers: bool,
110 /// `RWS_CONFIG_CLIENT_HINTS` — send `Accept-CH`, `Critical-CH` and the
111 /// client hints in `Vary` on every response. Off by default (18.0.0; was
112 /// always on): ~700 bytes per response, and `Critical-CH` makes Chromium
113 /// retry a request that came without the hints.
114 pub client_hints: bool,
115 /// `RWS_CONFIG_STATIC_CACHE_CONTROL` — `Cache-Control` for static files
116 /// (other responses keep `no-store, …`). Default `"no-cache"` (18.0.0; was
117 /// `no-store, …`): browsers keep the file and revalidate it with
118 /// `If-None-Match` / `If-Modified-Since` (a 304). An empty value keeps
119 /// the `no-store` default for static files too.
120 pub static_cache_control: String,
121 /// `RWS_CONFIG_ERROR_FORMAT` — `"text"` sends rws-made errors as plain
122 /// text (`502 Bad Gateway`) as before 18.17.0; anything else (default
123 /// `"problem"`) sends RFC 9457 `application/problem+json`.
124 pub error_format_text: bool,
125 /// `RWS_CONFIG_PROXY_STATUS` — when proxied responses carry
126 /// `Proxy-Status` (RFC 9209): `"always"` (default), `"errors"`, `"off"`.
127 pub proxy_status: String,
128 /// `RWS_CONFIG_PROXY_NAME` — this hop's name in `Proxy-Status` (and
129 /// `Cache-Status`). Default `"rws"`.
130 pub proxy_name: String,
131 /// `RWS_CONFIG_PROXY_STATUS_NEXT_HOP` — add the backend address
132 /// (`next-hop`) and failure text (`details`). Default `false`.
133 pub proxy_status_next_hop: bool,
134 /// `RWS_CONFIG_CACHE_STATUS` — `CacheLayer` responses carry
135 /// `Cache-Status` (RFC 9211). Default `true`.
136 pub cache_status: bool,
137 /// `RWS_CONFIG_FORWARDED_HEADER` — proxied requests carry RFC 7239
138 /// `Forwarded` beside `X-Forwarded-*`. Default on; `"off"` leaves it out.
139 pub forwarded_header: bool,
140 /// `trusted_proxies` (18.24.0): peers whose `X-Forwarded-*` and
141 /// `Forwarded` headers are passed on; from anyone else they are
142 /// replaced.
143 pub trusted_proxies: crate::ip_filter::TrustedProxies,
144 /// `RWS_CONFIG_CLIENT_IP` (18.27.0): `"forwarded"` (default) takes the
145 /// client's address from a trusted proxy's `X-Forwarded-For`
146 /// (`ip_filter::client_ip`); `"peer"` always uses the TCP peer.
147 pub client_ip_forwarded: bool,
148 /// `RWS_CONFIG_METRICS_ALLOW` (18.27.0): clients `GET /metrics` answers
149 /// (the client as `ip_filter::client_ip` sees it); anyone else gets a
150 /// `404`. Default loopback and the private ranges, where scrapers sit;
151 /// `*` everyone (before 18.27), `none` no one.
152 pub metrics_allow: crate::ip_filter::TrustedProxies,
153 /// `RWS_CONFIG_SHUTDOWN_DELAY_SECS` (18.27.0): on SIGTERM, `/readyz`
154 /// answers `503` at once but connections are still accepted this long
155 /// before draining, so a load balancer takes the pod out first. Default 5.
156 pub shutdown_delay_secs: u64,
157 /// `RWS_CONFIG_EARLY_HINTS_HTTP1` — also send `103 Early Hints` to
158 /// HTTP/1.1 clients. Default `false`: browsers use them only over HTTP/2
159 /// and HTTP/3, and some old HTTP/1.1 clients mishandle extra `1xx`
160 /// responses (18.12.0).
161 pub early_hints_http1: bool,
162 /// `RWS_CONFIG_COMPRESSION_DICTIONARIES` — URL patterns (`/js/app.*.js`,
163 /// comma-separated) of static files used as compression dictionaries:
164 /// later versions go out as `dcz` / `dcb` deltas against the one the
165 /// browser has (18.12.0). Empty by default.
166 pub compression_dictionaries: Vec<String>,
167 /// `RWS_CONFIG_DIRECTORY_LISTING` — list a directory that has no
168 /// `index.html`. Default `true`; `false` answers 404 instead (18.8.4).
169 pub directory_listing: bool,
170
171 // ── Server internals ──────────────────────────────────────────────────────
172 /// `RWS_CONFIG_LOG_FORMAT` — `"json"` or `"combined"`. Default: `"json"`.
173 pub log_format: String,
174 /// `RWS_CONFIG_REQUEST_ALLOCATION_SIZE_IN_BYTES` — bytes allocated for
175 /// incoming request parsing. Default: `10000`.
176 pub request_allocation_size: i64,
177}
178
179impl Default for ServerConfig {
180 fn default() -> Self {
181 Self {
182 cors_allow_all: Config::RWS_CONFIG_CORS_ALLOW_ALL_DEFAULT_VALUE
183 .eq_ignore_ascii_case("true"),
184 cors_allow_origins: Config::RWS_CONFIG_CORS_ALLOW_ORIGINS_DEFAULT_VALUE.to_string(),
185 cors_allow_credentials: Config::RWS_CONFIG_CORS_ALLOW_CREDENTIALS_DEFAULT_VALUE
186 .to_string(),
187 cors_allow_methods: Config::RWS_CONFIG_CORS_ALLOW_METHODS_DEFAULT_VALUE.to_string(),
188 cors_allow_headers: Config::RWS_CONFIG_CORS_ALLOW_HEADERS_DEFAULT_VALUE.to_string(),
189 cors_expose_headers: Config::RWS_CONFIG_CORS_EXPOSE_HEADERS_DEFAULT_VALUE.to_string(),
190 cors_max_age: Config::RWS_CONFIG_CORS_MAX_AGE_DEFAULT_VALUE.to_string(),
191 csp: String::new(),
192 security_headers: false,
193 nanos_headers: false,
194 client_hints: false,
195 static_cache_control: STATIC_CACHE_CONTROL_DEFAULT.to_string(),
196 error_format_text: false,
197 proxy_status: "always".to_string(),
198 proxy_name: "rws".to_string(),
199 proxy_status_next_hop: false,
200 cache_status: true,
201 forwarded_header: true,
202 trusted_proxies: crate::ip_filter::TrustedProxies::parse("").expect("the default parses"),
203 client_ip_forwarded: true,
204 metrics_allow: crate::ip_filter::TrustedProxies::parse("").expect("the default parses"),
205 shutdown_delay_secs: 5,
206 early_hints_http1: false,
207 compression_dictionaries: Vec::new(),
208 directory_listing: true,
209 log_format: Config::RWS_CONFIG_LOG_FORMAT_DEFAULT_VALUE.to_string(),
210 request_allocation_size: *Config::RWS_DEFAULT_REQUEST_ALLOCATION_SIZE_IN_BYTES,
211 }
212 }
213}
214
215impl ServerConfig {
216 /// Build a `ServerConfig` by reading all `RWS_CONFIG_*` environment
217 /// variables. Missing variables fall back to their default values.
218 ///
219 /// Each call reads every variable — the environment lock is taken once
220 /// per variable — so per-request code uses [`ServerConfig::current`].
221 pub fn from_env() -> Self {
222 let read = |key: &str| std::env::var(key).unwrap_or_default();
223 Self {
224 cors_allow_all: read(Config::RWS_CONFIG_CORS_ALLOW_ALL)
225 .eq_ignore_ascii_case("true"),
226 cors_allow_origins: read(Config::RWS_CONFIG_CORS_ALLOW_ORIGINS),
227 cors_allow_credentials: read(Config::RWS_CONFIG_CORS_ALLOW_CREDENTIALS),
228 cors_allow_methods: read(Config::RWS_CONFIG_CORS_ALLOW_METHODS),
229 cors_allow_headers: read(Config::RWS_CONFIG_CORS_ALLOW_HEADERS),
230 cors_expose_headers: read(Config::RWS_CONFIG_CORS_EXPOSE_HEADERS),
231 cors_max_age: read(Config::RWS_CONFIG_CORS_MAX_AGE),
232 csp: std::env::var("RWS_CONFIG_CSP").unwrap_or_else(|_| {
233 if read("RWS_CONFIG_SECURITY_HEADERS").eq_ignore_ascii_case("true") {
234 CSP_DEFAULT.to_string()
235 } else {
236 String::new()
237 }
238 }),
239 security_headers: read("RWS_CONFIG_SECURITY_HEADERS").eq_ignore_ascii_case("true"),
240 nanos_headers: read("RWS_CONFIG_NANOS_HEADERS").eq_ignore_ascii_case("true"),
241 client_hints: read("RWS_CONFIG_CLIENT_HINTS").eq_ignore_ascii_case("true"),
242 static_cache_control: std::env::var("RWS_CONFIG_STATIC_CACHE_CONTROL")
243 .unwrap_or_else(|_| STATIC_CACHE_CONTROL_DEFAULT.to_string()),
244 error_format_text: read("RWS_CONFIG_ERROR_FORMAT").trim().eq_ignore_ascii_case("text"),
245 proxy_status: match read("RWS_CONFIG_PROXY_STATUS").trim().to_ascii_lowercase().as_str() {
246 "off" | "false" | "none" => "off".to_string(),
247 "errors" => "errors".to_string(),
248 _ => "always".to_string(),
249 },
250 proxy_name: Some(read("RWS_CONFIG_PROXY_NAME").trim().to_string()).filter(|n| !n.is_empty()).unwrap_or_else(|| "rws".to_string()),
251 proxy_status_next_hop: read("RWS_CONFIG_PROXY_STATUS_NEXT_HOP").eq_ignore_ascii_case("true"),
252 cache_status: !read("RWS_CONFIG_CACHE_STATUS").trim().eq_ignore_ascii_case("false"),
253 forwarded_header: !matches!(read("RWS_CONFIG_FORWARDED_HEADER").trim().to_ascii_lowercase().as_str(), "off" | "false" | "none"),
254 // A bad list is reported by `rws --check`; here it falls back to
255 // the default rather than trusting everyone.
256 trusted_proxies: crate::ip_filter::TrustedProxies::parse(&read("RWS_CONFIG_TRUSTED_PROXIES"))
257 .unwrap_or_else(|_| crate::ip_filter::TrustedProxies::parse("").expect("the default parses")),
258 client_ip_forwarded: !read("RWS_CONFIG_CLIENT_IP").trim().eq_ignore_ascii_case("peer"),
259 metrics_allow: crate::ip_filter::TrustedProxies::parse(&read("RWS_CONFIG_METRICS_ALLOW"))
260 .unwrap_or_else(|_| crate::ip_filter::TrustedProxies::parse("").expect("the default parses")),
261 shutdown_delay_secs: read("RWS_CONFIG_SHUTDOWN_DELAY_SECS").trim().parse().unwrap_or(5),
262 early_hints_http1: read("RWS_CONFIG_EARLY_HINTS_HTTP1").eq_ignore_ascii_case("true"),
263 compression_dictionaries: read("RWS_CONFIG_COMPRESSION_DICTIONARIES")
264 .split(',')
265 .map(|p| p.trim().to_string())
266 .filter(|p| p.starts_with('/') && crate::early_hints::valid(p))
267 .collect(),
268 directory_listing: !read("RWS_CONFIG_DIRECTORY_LISTING").eq_ignore_ascii_case("false"),
269 log_format: read(Config::RWS_CONFIG_LOG_FORMAT),
270 request_allocation_size: std::env::var(
271 Config::RWS_CONFIG_REQUEST_ALLOCATION_SIZE_IN_BYTES,
272 )
273 .ok()
274 .and_then(|v| v.parse().ok())
275 .unwrap_or(*Config::RWS_DEFAULT_REQUEST_ALLOCATION_SIZE_IN_BYTES),
276 }
277 }
278
279 /// The configuration from the environment, read once and shared: an
280 /// atomic load and an `Arc` clone per call instead of ten `getenv`s.
281 /// Rebuilt after [`invalidate`] — which `config_reload::reload()` (SIGHUP,
282 /// `POST /admin/config/reload`) and every config writer in the crate call,
283 /// so hot reload still takes effect on the next request.
284 pub fn current() -> Arc<ServerConfig> {
285 let generation = GENERATION.load(Ordering::SeqCst);
286 if let Some((built_at, config)) = CURRENT.read().unwrap_or_else(|e| e.into_inner()).as_ref() {
287 if *built_at == generation {
288 return Arc::clone(config);
289 }
290 }
291 // Built from the generation read *before* the environment: a change
292 // during the rebuild leaves the cache stale, not wrong.
293 let fresh = Arc::new(ServerConfig::from_env());
294 *CURRENT.write().unwrap_or_else(|e| e.into_inner()) = Some((generation, Arc::clone(&fresh)));
295 fresh
296 }
297}