Implement instance info endpoint (JSON, YAML, TXT)

Cargo.lock

@@ -679,6 +679,7 @@ dependencies = [
  "sealed_test",
  "serde",
  "serde_json",
+ "serde_yaml",
  "time",
  "tokio",
  "toml",
@@ -774,6 +775,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "num_threads"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2819ce041d2ee131036f4fc9d6ae7ae125a3a40e97ba64d04fe799ad9dabbb44"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "once_cell"
 version = "1.16.0"
@@ -1158,6 +1168,19 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serde_yaml"
+version = "0.9.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "92b5b431e8907b50339b51223b97d102db8d987ced36f6e4d03621db9316c834"
+dependencies = [
+ "indexmap",
+ "itoa",
+ "ryu",
+ "serde",
+ "unsafe-libyaml",
+]
+
 [[package]]
 name = "sha2"
 version = "0.10.6"
@@ -1267,6 +1290,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a561bf4617eebd33bca6434b988f39ed798e527f51a1e797d0ee4f61c0a38376"
 dependencies = [
  "itoa",
+ "libc",
+ "num_threads",
  "serde",
  "time-core",
  "time-macros",
@@ -1435,6 +1460,12 @@ dependencies = [
  "tinyvec",
 ]
 
+[[package]]
+name = "unsafe-libyaml"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bc7ed8ba44ca06be78ea1ad2c3682a43349126c8818054231ee6f4748012aed2"
+
 [[package]]
 name = "untrusted"
 version = "0.7.1"

Cargo.toml

@@ -21,13 +21,14 @@ percent-encoding = "2.2.0"
 route-recognizer = "0.3.1"
 serde_json = "1.0.87"
 tokio = { version = "1.21.2", features = ["full"] }
-time = "0.3.17"
+time = { version = "0.3.17", features = ["local-offset"] }
 url = "2.3.1"
 rust-embed = { version = "6.4.2", features = ["include-exclude"] }
 libflate = "1.2.0"
 brotli = { version = "3.3.4", features = ["std"] }
 toml = "0.5.9"
 once_cell = "1.16.0"
+serde_yaml = "0.9.16"
 
 [dev-dependencies]
 lipsum = "0.8.2"

build.rs

@@ -0,0 +1,6 @@
+use std::process::Command;
+fn main() {
+	let output = Command::new("git").args(["rev-parse", "HEAD"]).output().unwrap();
+	let git_hash = String::from_utf8(output.stdout).unwrap();
+	println!("cargo:rustc-env=GIT_HASH={git_hash}");
+}

src/config.rs

@@ -1,4 +1,5 @@
 use once_cell::sync::Lazy;
+use serde::{Deserialize, Serialize};
 use std::{env::var, fs::read_to_string};
 
 // Waiting for https://github.com/rust-lang/rust/issues/74465 to land, so we
@@ -6,44 +7,47 @@ use std::{env::var, fs::read_to_string};
 //
 // This is the local static that is initialized at runtime (technically at
 // first request) and contains the instance settings.
-static CONFIG: Lazy<Config> = Lazy::new(Config::load);
+pub(crate) static CONFIG: Lazy<Config> = Lazy::new(Config::load);
 
 /// Stores the configuration parsed from the environment variables and the
 /// config file. `Config::Default()` contains None for each setting.
-#[derive(Default, serde::Deserialize)]
+/// When adding more config settings, add it to `Config::load`,
+/// `get_setting_from_config`, both below, as well as
+/// instance_info::InstanceInfo.to_string(), README.md and app.json.
+#[derive(Default, Serialize, Deserialize, Clone)]
 pub struct Config {
 	#[serde(rename = "LIBREDDIT_SFW_ONLY")]
-	sfw_only: Option<String>,
+	pub(crate) sfw_only: Option<String>,
 
 	#[serde(rename = "LIBREDDIT_DEFAULT_THEME")]
-	default_theme: Option<String>,
+	pub(crate) default_theme: Option<String>,
 
 	#[serde(rename = "LIBREDDIT_DEFAULT_FRONT_PAGE")]
-	default_front_page: Option<String>,
+	pub(crate) default_front_page: Option<String>,
 
 	#[serde(rename = "LIBREDDIT_DEFAULT_LAYOUT")]
-	default_layout: Option<String>,
+	pub(crate) default_layout: Option<String>,
 
 	#[serde(rename = "LIBREDDIT_DEFAULT_WIDE")]
-	default_wide: Option<String>,
+	pub(crate) default_wide: Option<String>,
 
 	#[serde(rename = "LIBREDDIT_DEFAULT_COMMENT_SORT")]
-	default_comment_sort: Option<String>,
+	pub(crate) default_comment_sort: Option<String>,
 
 	#[serde(rename = "LIBREDDIT_DEFAULT_POST_SORT")]
-	default_post_sort: Option<String>,
+	pub(crate) default_post_sort: Option<String>,
 
 	#[serde(rename = "LIBREDDIT_DEFAULT_SHOW_NSFW")]
-	default_show_nsfw: Option<String>,
+	pub(crate) default_show_nsfw: Option<String>,
 
 	#[serde(rename = "LIBREDDIT_DEFAULT_BLUR_NSFW")]
-	default_blur_nsfw: Option<String>,
+	pub(crate) default_blur_nsfw: Option<String>,
 
 	#[serde(rename = "LIBREDDIT_DEFAULT_USE_HLS")]
-	default_use_hls: Option<String>,
+	pub(crate) default_use_hls: Option<String>,
 
 	#[serde(rename = "LIBREDDIT_DEFAULT_HIDE_HLS_NOTIFICATION")]
-	default_hide_hls_notification: Option<String>,
+	pub(crate) default_hide_hls_notification: Option<String>,
 }
 
 impl Config {

src/instance_info.rs

@@ -0,0 +1,108 @@
+use hyper::{http::Error, Body, Request, Response};
+use once_cell::sync::Lazy;
+use serde::{Deserialize, Serialize};
+use time::OffsetDateTime;
+
+use crate::{
+	config::{Config, CONFIG},
+	server::RequestExt,
+};
+
+// This is the local static that is intialized at runtime (technically at
+// the first request *to the instance-info endpoint) and contains the data
+// retrieved from the instance-info endpoint.
+pub(crate) static INSTANCE_INFO: Lazy<InstanceInfo> = Lazy::new(InstanceInfo::new);
+
+/// Handles instance info endpoint
+pub async fn instance_info(req: Request<Body>) -> Result<Response<Body>, String> {
+	let extension = req.param("extension").unwrap_or("json".into());
+	let response = match extension.as_str() {
+		"yaml" => info_yaml(),
+		"txt" => info_txt(),
+		"json" | _ => info_json(),
+	};
+	response.map_err(|err| format!("{err}"))
+}
+
+fn info_json() -> Result<Response<Body>, Error> {
+	let body = serde_json::to_string(&*INSTANCE_INFO).unwrap_or("Error serializing JSON.".into());
+	Response::builder().status(200).header("content-type", "application/json").body(body.into())
+}
+
+fn info_yaml() -> Result<Response<Body>, Error> {
+	let body = serde_yaml::to_string(&*INSTANCE_INFO).unwrap_or("Error serializing YAML.".into());
+	// https://github.com/ietf-wg-httpapi/mediatypes/blob/main/draft-ietf-httpapi-yaml-mediatypes.md
+	Response::builder().status(200).header("content-type", "application/yaml").body(body.into())
+}
+
+fn info_txt() -> Result<Response<Body>, Error> {
+	Response::builder()
+		.status(200)
+		.header("content-type", "text/plain")
+		.body((INSTANCE_INFO.to_string()).into())
+}
+
+#[derive(Serialize, Deserialize, Default)]
+pub(crate) struct InstanceInfo {
+	crate_version: String,
+	git_commit: String,
+	deploy_date: String,
+	compile_mode: String,
+	deploy_unix_ts: i64,
+	config: Config,
+}
+
+impl InstanceInfo {
+	pub fn new() -> Self {
+		Self {
+			crate_version: env!("CARGO_PKG_VERSION").to_string(),
+			git_commit: env!("GIT_HASH").to_string(),
+			deploy_date: OffsetDateTime::now_local().unwrap_or_else(|_| OffsetDateTime::now_utc()).to_string(),
+			#[cfg(debug_assertions)]
+			compile_mode: "Debug".into(),
+			#[cfg(not(debug_assertions))]
+			compile_mode: "Release".into(),
+			deploy_unix_ts: OffsetDateTime::now_local().unwrap_or_else(|_| OffsetDateTime::now_utc()).unix_timestamp(),
+			config: CONFIG.clone(),
+		}
+	}
+}
+impl ToString for InstanceInfo {
+	fn to_string(&self) -> String {
+		format!(
+			"Crate version: {}\n
+                Git commit: {}\n
+                Deploy date: {}\n
+                Deploy timestamp: {}\n
+                Compile mode: {}\n
+                Config:\n
+                    SFW only: {:?}\n
+                    Default theme: {:?}\n
+                    Default front page: {:?}\n
+                    Default layout: {:?}\n
+                    Default wide: {:?}\n
+                    Default comment sort: {:?}\n
+                    Default post sort: {:?}\n
+                    Default show NSFW: {:?}\n
+                    Default blur NSFW: {:?}\n
+                    Default use HLS: {:?}\n
+                    Default hide HLS notification: {:?}\n",
+			self.crate_version,
+			self.git_commit,
+			self.deploy_date,
+			self.deploy_unix_ts,
+			self.compile_mode,
+			self.config.sfw_only,
+			self.config.default_theme,
+			self.config.default_front_page,
+			self.config.default_layout,
+			self.config.default_wide,
+			self.config.default_comment_sort,
+			self.config.default_post_sort,
+			self.config.default_show_nsfw,
+			self.config.default_blur_nsfw,
+			self.config.default_use_hls,
+			self.config.default_hide_hls_notification
+		)
+	}
+}

src/main.rs

@@ -5,6 +5,7 @@
 // Reference local files
 mod config;
 mod duplicates;
+mod instance_info;
 mod post;
 mod search;
 mod settings;
@@ -20,6 +21,7 @@ use hyper::{header::HeaderValue, Body, Request, Response};
 
 mod client;
 use client::{canonical_path, proxy};
+use once_cell::sync::Lazy;
 use server::RequestExt;
 use utils::{error, redirect, ThemeAssets};
 
@@ -156,6 +158,13 @@ async fn main() {
 	// Begin constructing a server
 	let mut app = server::Server::new();
 
+	// Force evaluation of statics. In instance_info case, we need to evaluate
+	// the timestamp so deploy date is accurate - in config case, we need to 
+	// evaluate the configuration to avoid paying penalty at first request.
+
+	Lazy::force(&config::CONFIG);
+	Lazy::force(&instance_info::INSTANCE_INFO);
+
 	// Define default headers (added to all responses)
 	app.default_headers = headers! {
 		"Referrer-Policy" => "no-referrer",
@@ -283,6 +292,10 @@ async fn main() {
 	// Handle about pages
 	app.at("/about").get(|req| error(req, "About pages aren't added yet".to_string()).boxed());
 
+	// Instance info page
+	app.at("/instance-info").get(|r| instance_info::instance_info(r).boxed());
+	app.at("/instance-info.:extension").get(|r| instance_info::instance_info(r).boxed());
+
 	app.at("/:id").get(|req: Request<Body>| {
 		Box::pin(async move {
 			match req.param("id").as_deref() {