document settings crate (#271)

actix-settings/examples/actix.rs

@@ -62,7 +62,7 @@ async fn main() -> std::io::Result<()> {
     .await
 }
 
-/// Initialize the logging infrastructure
+/// Initialize the logging infrastructure.
 fn init_logger(settings: &Settings) {
     if !settings.actix.enable_log {
         return;

actix-settings/src/defaults.toml

@@ -21,19 +21,19 @@ num-workers = "default"
 # Takes a string value: Either "default", or an integer N > 0 e.g. "6".
 backlog = "default"
 
-# Sets the maximum per-worker number of concurrent connections. All socket listeners
+# Sets the per-worker maximum number of concurrent connections. All socket listeners
 # will stop accepting connections when this limit is reached for each worker.
 # By default max connections is set to a 25k.
 # Takes a string value: Either "default", or an integer N > 0 e.g. "6".
 max-connections = "default"
 
-# Sets the maximum per-worker concurrent connection establish process. All listeners
+# Sets the per-worker maximum concurrent connection establish process. All listeners
 # will stop accepting connections when this limit is reached. It can be used to limit
 # the global TLS CPU usage. By default max connections is set to a 256.
 # Takes a string value: Either "default", or an integer N > 0 e.g. "6".
 max-connection-rate = "default"
 
-# Set server keep-alive setting. By default keep alive is set to 5 seconds.
+# Set server keep-alive preference. By default keep alive is set to 5 seconds.
 # Takes a string value: Either "default", "disabled", "os",
 # or a string of the format "N seconds" where N is an integer > 0 e.g. "6 seconds".
 keep-alive = "default"

actix-settings/src/error.rs

@@ -2,12 +2,20 @@ use std::{env::VarError, io, num::ParseIntError, path::PathBuf, str::ParseBoolEr
 
 use toml::de::Error as TomlError;
 
+/// Convenience type alias for `Result<T, AtError>`.
 pub type AtResult<T> = std::result::Result<T, AtError>;
 
-#[derive(Clone, Debug)]
+/// Errors that can be returned from methods in this crate.
+#[derive(Debug, Clone)]
 pub enum AtError {
+    /// Environment variable does not exists or is invalid.
     EnvVarError(VarError),
+
+    /// File already exists on disk.
     FileExists(PathBuf),
+
+    /// Invalid value.
+    #[allow(missing_docs)]
     InvalidValue {
         expected: &'static str,
         got: String,
@@ -15,10 +23,20 @@ pub enum AtError {
         line: u32,
         column: u32,
     },
+
+    /// I/O error.
     IoError(ioe::IoError),
+
+    /// Value is not a boolean.
     ParseBoolError(ParseBoolError),
+
+    /// Value is not an integer.
     ParseIntError(ParseIntError),
+
+    /// Value is not an address.
     ParseAddressError(String),
+
+    /// Error deserializing as TOML.
     TomlError(TomlError),
 }
 

actix-settings/src/lib.rs

@@ -1,9 +1,68 @@
 //! Easily manage Actix Web's settings from a TOML file and environment variables.
+//!
+//! To get started add a [`Settings::parse_toml("./Server.toml")`](Settings::parse_toml) call to the
+//! top of your main function. This will create a template file with descriptions of all the
+//! configurable settings. You can change or remove anything in that file and it will be picked up
+//! the next time you run your application.
+//!
+//! Overriding parts of the file can be done from values using [`Settings::override_field`] or from
+//! the environment using [`Settings::override_field_with_env_var`].
+//!
+//! # Examples
+//!
+//! See examples folder on GitHub for complete example.
+//!
+//! ```ignore
+//! # use actix_web::{
+//! #     get,
+//! #     middleware::{Compress, Condition, Logger},
+//! #     web, App, HttpServer,
+//! # };
+//! use actix_settings::{ApplySettings as _, Mode, Settings};
+//!
+//! #[actix_web::main]
+//! async fn main() -> std::io::Result<()> {
+//!     let mut settings = Settings::parse_toml("./Server.toml")
+//!         .expect("Failed to parse `Settings` from Server.toml");
+//!
+//!     // If the environment variable `$APPLICATION__HOSTS` is set,
+//!     // have its value override the `settings.actix.hosts` setting:
+//!     Settings::override_field_with_env_var(&mut settings.actix.hosts, "APPLICATION__HOSTS")?;
+//!
+//!     init_logger(&settings);
+//!
+//!     HttpServer::new({
+//!         // clone settings into each worker thread
+//!         let settings = settings.clone();
+//!
+//!         move || {
+//!             App::new()
+//!                 // Include this `.wrap()` call for compression settings to take effect
+//!                 .wrap(Condition::new(
+//!                     settings.actix.enable_compression,
+//!                     Compress::default(),
+//!                 ))
+//!
+//!                 // add request logger
+//!                 .wrap(Logger::default())
+//!
+//!                 // make `Settings` available to handlers
+//!                 .app_data(web::Data::new(settings.clone()))
+//!
+//!                 // add request handlers as normal
+//!                 .service(index)
+//!         }
+//!     })
+//!     // apply the `Settings` to Actix Web's `HttpServer`
+//!     .apply_settings(&settings)
+//!     .run()
+//!     .await
+//! }
+//! ```
 
 #![forbid(unsafe_code)]
 #![deny(rust_2018_idioms, nonstandard_style)]
-#![warn(future_incompatible, missing_debug_implementations)]
-// #![warn(missing_docs)]
+#![warn(future_incompatible, missing_docs, missing_debug_implementations)]
 #![doc(html_logo_url = "https://actix.rs/img/logo.png")]
 #![doc(html_favicon_url = "https://actix.rs/favicon.ico")]
 
@@ -37,15 +96,21 @@ pub use self::settings::{
     NumWorkers, Timeout, Tls,
 };
 
+/// Wrapper for server and application-specific settings.
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Deserialize)]
 #[serde(bound = "A: Deserialize<'de>")]
 pub struct BasicSettings<A> {
+    /// Actix Web server settings.
     pub actix: ActixSettings,
+
+    /// Application-specific settings.
     pub application: A,
 }
 
+/// Convenience type alias for [`BasicSettings`] with no defined application-specific settings.
 pub type Settings = BasicSettings<NoSettings>;
 
+/// Marker type representing no defined application-specific settings.
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Deserialize)]
 #[non_exhaustive]
 pub struct NoSettings {/* NOTE: turning this into a unit struct will cause deserialization failures. */}
@@ -54,14 +119,16 @@ impl<A> BasicSettings<A>
 where
     A: de::DeserializeOwned,
 {
-    /// NOTE **DO NOT** mess with the ordering of the tables in this template.
-    ///      Especially the `[application]` table needs to be last in order
-    ///      for some tests to keep working.
+    // NOTE **DO NOT** mess with the ordering of the tables in the default template.
+    //      Especially the `[application]` table needs to be last in order
+    //      for some tests to keep working.
+    /// Default settings file contents.
     pub(crate) const DEFAULT_TOML_TEMPLATE: &'static str = include_str!("./defaults.toml");
 
-    /// Parse an instance of `Self` from a `TOML` file located at `filepath`.
-    /// If the file doesn't exist, it is generated from the default `TOML`
-    /// template, after which the newly generated file is read in and parsed.
+    /// Parse an instance of `Self` from a TOML file located at `filepath`.
+    ///
+    /// If the file doesn't exist, it is generated from the default TOML template, after which the
+    /// newly generated file is read in and parsed.
     pub fn parse_toml<P>(filepath: P) -> AtResult<Self>
     where
         P: AsRef<Path>,
@@ -73,43 +140,62 @@ where
         }
 
         let mut f = File::open(filepath)?;
+        // TODO: don't bail on metadata fail
         let mut contents = String::with_capacity(f.metadata()?.len() as usize);
         f.read_to_string(&mut contents)?;
 
         Ok(toml::from_str::<Self>(&contents)?)
     }
 
-    /// Parse an instance of `Self` straight from the default `TOML` template.
+    /// Parse an instance of `Self` straight from the default TOML template.
+    // TODO: make infallible
+    // TODO: consider "template" rename
     pub fn from_default_template() -> AtResult<Self> {
         Self::from_template(Self::DEFAULT_TOML_TEMPLATE)
     }
 
-    /// Parse an instance of `Self` straight from the default `TOML` template.
+    /// Parse an instance of `Self` straight from the default TOML template.
+    // TODO: consider "template" rename
     pub fn from_template(template: &str) -> AtResult<Self> {
         Ok(toml::from_str(template)?)
     }
 
-    /// Write the default `TOML` template to a new file, to be located
-    /// at `filepath`.  Return a `Error::FileExists(_)` error if a
-    /// file already exists at that location.
+    /// Writes the default TOML template to a new file, located at `filepath`.
+    ///
+    /// # Errors
+    /// Returns a [`FileExists`](crate::AtError::FileExists) error if a file already exists at that
+    /// location.
     pub fn write_toml_file<P>(filepath: P) -> AtResult<()>
     where
         P: AsRef<Path>,
     {
         let filepath = filepath.as_ref();
-        let contents = Self::DEFAULT_TOML_TEMPLATE.trim();
 
         if filepath.exists() {
             return Err(AtError::FileExists(filepath.to_path_buf()));
         }
 
         let mut file = File::create(filepath)?;
-        file.write_all(contents.as_bytes())?;
+        file.write_all(Self::DEFAULT_TOML_TEMPLATE.trim().as_bytes())?;
         file.flush()?;
 
         Ok(())
     }
 
+    /// Attempts to parse `value` and override the referenced `field`.
+    ///
+    /// # Examples
+    /// ```
+    /// use actix_settings::{Settings, Mode};
+    ///
+    /// # fn inner() -> actix_settings::AtResult<()> {
+    /// let mut settings = Settings::from_default_template()?;
+    /// assert_eq!(settings.actix.mode, Mode::Development);
+    ///
+    /// Settings::override_field(&mut settings.actix.mode, "production")?;
+    /// assert_eq!(settings.actix.mode, Mode::Production);
+    /// # Ok(()) }
+    /// ```
     pub fn override_field<F, V>(field: &mut F, value: V) -> AtResult<()>
     where
         F: Parse,
@@ -119,6 +205,22 @@ where
         Ok(())
     }
 
+    /// Attempts to read an environment variable, parse it, and override the referenced `field`.
+    ///
+    /// # Examples
+    /// ```
+    /// use actix_settings::{Settings, Mode};
+    ///
+    /// std::env::set_var("OVERRIDE__MODE", "production");
+    ///
+    /// # fn inner() -> actix_settings::AtResult<()> {
+    /// let mut settings = Settings::from_default_template()?;
+    /// assert_eq!(settings.actix.mode, Mode::Development);
+    ///
+    /// Settings::override_field_with_env_var(&mut settings.actix.mode, "OVERRIDE__MODE")?;
+    /// assert_eq!(settings.actix.mode, Mode::Production);
+    /// # Ok(()) }
+    /// ```
     pub fn override_field_with_env_var<F, N>(field: &mut F, var_name: N) -> AtResult<()>
     where
         F: Parse,
@@ -132,6 +234,7 @@ where
     }
 }
 
+/// Extension trait for applying parsed settings to the server object.
 pub trait ApplySettings {
     /// Apply a [`BasicSettings`] value to `self`.
     ///
@@ -200,9 +303,9 @@ where
         self = match settings.actix.client_timeout {
             Timeout::Default => self,
             Timeout::Milliseconds(n) => {
-                self.client_disconnect_timeout(Duration::from_millis(n as u64))
+                self.client_request_timeout(Duration::from_millis(n as u64))
             }
-            Timeout::Seconds(n) => self.client_disconnect_timeout(Duration::from_secs(n as u64)),
+            Timeout::Seconds(n) => self.client_request_timeout(Duration::from_secs(n as u64)),
         };
 
         self = match settings.actix.client_shutdown {

actix-settings/src/parse.rs

@@ -2,7 +2,9 @@ use std::{path::PathBuf, str::FromStr};
 
 use crate::AtError;
 
+/// A specialized `FromStr` trait that returns [`AtError`] errors
 pub trait Parse: Sized {
+    /// Parse `Self` from `string`.
     fn parse(string: &str) -> Result<Self, AtError>;
 }
 

actix-settings/src/settings/address.rs

@@ -37,9 +37,13 @@ static ADDR_LIST_REGEX: Lazy<Regex> = Lazy::new(|| {
     .expect("Failed to compile regex: ADDRS_REGEX")
 });
 
+/// A host/port pair for the server to bind to.
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Deserialize)]
 pub struct Address {
+    /// Host part of address.
     pub host: String,
+
+    /// Port part of address.
     pub port: u16,
 }
 

actix-settings/src/settings/backlog.rs

@@ -4,9 +4,20 @@ use serde::de;
 
 use crate::{AtError, AtResult, Parse};
 
+/// The maximum number of pending connections.
+///
+/// This refers to the number of clients that can be waiting to be served. Exceeding this number
+/// results in the client getting an error when attempting to connect. It should only affect servers
+/// under significant load.
+///
+/// Generally set in the 64–2048 range. The default value is 2048. Takes a string value: Either
+/// "default", or an integer N > 0 e.g. "6".
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum Backlog {
+    /// The default number of connections. See struct docs.
     Default,
+
+    /// A specific number of connections.
     Manual(usize),
 }
 

actix-settings/src/settings/keep_alive.rs

@@ -6,11 +6,24 @@ use serde::de;
 
 use crate::{AtError, AtResult, Parse};
 
+/// The server keep-alive preference.
+///
+/// By default keep alive is set to 5 seconds. Takes a string value: Either "default", "disabled",
+/// "os", or a string of the format "N seconds" where N is an integer > 0 e.g. "6 seconds".
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum KeepAlive {
+    /// The default keep-alive as defined by Actix Web.
     Default,
+
+    /// Disable keep-alive.
     Disabled,
+
+    /// Let the OS determine keep-alive duration.
+    ///
+    /// Note: this is usually quite long.
     Os,
+
+    /// A specific keep-alive duration (in seconds).
     Seconds(usize),
 }
 

actix-settings/src/settings/max_connection_rate.rs

@@ -4,9 +4,17 @@ use serde::de;
 
 use crate::{AtError, AtResult, Parse};
 
+/// The maximum per-worker concurrent TLS connection limit.
+///
+/// All listeners will stop accepting connections when this limit is reached. It can be used to
+/// limit the global TLS CPU usage. By default max connections is set to a 256. Takes a string
+/// value: Either "default", or an integer N > 0 e.g. "6".
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum MaxConnectionRate {
+    /// The default connection limit. See struct docs.
     Default,
+
+    /// A specific connection limit.
     Manual(usize),
 }
 

actix-settings/src/settings/max_connections.rs

@@ -4,9 +4,17 @@ use serde::de;
 
 use crate::{AtError, AtResult, Parse};
 
+/// The maximum per-worker number of concurrent connections.
+///
+/// All socket listeners will stop accepting connections when this limit is reached for each worker.
+/// By default max connections is set to a 25k. Takes a string value: Either "default", or an
+/// integer N > 0 e.g. "6".
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum MaxConnections {
+    /// The default number of connections. See struct docs.
     Default,
+
+    /// A specific number of connections.
     Manual(usize),
 }
 

actix-settings/src/settings/mod.rs

@@ -24,17 +24,42 @@ pub use self::tls::Tls;
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Deserialize)]
 #[serde(rename_all = "kebab-case")]
 pub struct ActixSettings {
+    /// List of addresses for the server to bind to.
     pub hosts: Vec<Address>,
-    pub mode: mode::Mode,
+
+    /// Marker of intended deployment environment.
+    pub mode: Mode,
+
+    /// True if the [`Compress`](actix_web::middleware::Compress) middleware should be enabled.
     pub enable_compression: bool,
+
+    /// True if the [`Logger`](actix_web::middleware::Logger) middleware should be enabled.
     pub enable_log: bool,
+
+    /// The number of workers that the server should start.
     pub num_workers: NumWorkers,
+
+    /// The maximum number of pending connections.
     pub backlog: Backlog,
+
+    /// The per-worker maximum number of concurrent connections.
     pub max_connections: MaxConnections,
+
+    /// The per-worker maximum concurrent TLS connection limit.
     pub max_connection_rate: MaxConnectionRate,
+
+    /// Server keep-alive preference.
     pub keep_alive: KeepAlive,
+
+    /// Timeout duration for reading client request header.
     pub client_timeout: Timeout,
+
+    /// Timeout duration for connection shutdown.
     pub client_shutdown: Timeout,
+
+    /// Timeout duration for graceful worker shutdown.
     pub shutdown_timeout: Timeout,
+
+    /// TLS (HTTPS) configuration.
     pub tls: Tls,
 }

actix-settings/src/settings/mode.rs

@@ -2,10 +2,14 @@ use serde::Deserialize;
 
 use crate::{AtResult, Parse};
 
+/// Marker of intended deployment environment.
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Deserialize)]
 #[serde(rename_all = "lowercase")]
 pub enum Mode {
+    /// Marks development environment.
     Development,
+
+    /// Marks production environment.
     Production,
 }
 

actix-settings/src/settings/num_workers.rs

@@ -4,9 +4,16 @@ use serde::de;
 
 use crate::{AtError, AtResult, Parse};
 
+/// The number of workers that the server should start.
+///
+/// By default the number of available logical cpu cores is used. Takes a string value: Either
+/// "default", or an integer N > 0 e.g. "6".
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum NumWorkers {
+    /// The default number of workers. See struct docs.
     Default,
+
+    /// A specific number of workers.
     Manual(usize),
 }
 

actix-settings/src/settings/timeout.rs

@@ -6,10 +6,16 @@ use serde::de;
 
 use crate::{AtError, AtResult, Parse};
 
+/// A timeout duration in milliseconds or seconds.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum Timeout {
+    /// The default timeout. Depends on context.
     Default,
+
+    /// Timeout in milliseconds.
     Milliseconds(usize),
+
+    /// Timeout in seconds.
     Seconds(usize),
 }
 
@@ -34,18 +40,22 @@ impl Parse for Timeout {
                 })
             }
         }
+
         match string {
             "default" => Ok(Timeout::Default),
+
             string if !FMT.is_match(string) => invalid_value!(string),
+
             string => match (DIGITS.find(string), UNIT.find(string)) {
-                (None, _) => invalid_value!(string),
-                (_, None) => invalid_value!(string),
-                (Some(dmatch), Some(umatch)) => {
-                    let digits = &string[dmatch.start()..dmatch.end()];
-                    let unit = &string[umatch.start()..umatch.end()];
+                (None, _) | (_, None) => invalid_value!(string),
+
+                (Some(digits), Some(unit)) => {
+                    let digits = &string[digits.range()];
+                    let unit = &string[unit.range()];
+
                     match (digits.parse(), unit) {
-                        (Ok(v), "milliseconds") => Ok(Timeout::Milliseconds(v)),
-                        (Ok(v), "seconds") => Ok(Timeout::Seconds(v)),
+                        (Ok(n), "milliseconds") => Ok(Timeout::Milliseconds(n)),
+                        (Ok(n), "seconds") => Ok(Timeout::Seconds(n)),
                         _ => invalid_value!(string),
                     }
                 }

actix-settings/src/settings/tls.rs

@@ -2,10 +2,17 @@ use std::path::PathBuf;
 
 use serde::Deserialize;
 
+/// TLS (HTTPS) configuration.
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Deserialize)]
 #[serde(rename_all = "kebab-case")]
+#[doc(alias = "ssl", alias = "https")]
 pub struct Tls {
+    /// Tru if accepting TLS connections should be enabled.
     pub enabled: bool,
+
+    /// Path to certificate `.pem` file.
     pub certificate: PathBuf,
+
+    /// Path to private key `.pem` file.
     pub private_key: PathBuf,
 }