Add /log page that displays server log

This will eventually be behind an authorization guard so that only I
have access, but it's useful to have for monitoring and testing out
turbo streams.

.gitignore

@@ -1,2 +1,3 @@
 /target
+/logs
 .env

Cargo.lock

@@ -260,6 +260,7 @@ dependencies = [
  "feed-rs",
  "maud",
  "notify",
+ "once_cell",
  "reqwest",
  "serde",
  "serde_with",
@@ -270,6 +271,7 @@ dependencies = [
  "tower-http",
  "tower-livereload",
  "tracing",
+ "tracing-appender",
  "tracing-subscriber",
  "validator",
 ]
@@ -2139,6 +2141,17 @@ dependencies = [
  "tracing-core",
 ]
 
+[[package]]
+name = "tracing-appender"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09d48f71a791638519505cefafe162606f706c25592e4bde4d97600c0195312e"
+dependencies = [
+ "crossbeam-channel",
+ "time 0.3.21",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "tracing-attributes"
 version = "0.1.24"

Cargo.toml

@@ -19,6 +19,7 @@ dotenvy = "0.15"
 feed-rs = "1.3"
 maud = { version = "0.25", features = ["axum"] }
 notify = "6"
+once_cell = "1.17"
 reqwest = { version = "0.11", features = ["json"] }
 serde = { version = "1", features = ["derive"] }
 serde_with = "3"
@@ -35,5 +36,6 @@ tower = "0.4"
 tower-livereload = "0.7"
 tower-http = { version = "0.4", features = ["trace"] }
 tracing = "0.1"
+tracing-appender = "0.2"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 validator = { version = "0.16", features = ["derive"] }

README.md

@@ -34,6 +34,7 @@ PORT=3000
 DATABASE_URL=postgresql://crawlnicle:<password>@localhost/crawlnicle
 DATABASE_MAX_CONNECTIONS=5
 TITLE=crawlnicle
+MAX_MEM_LOG_SIZE=1000000
 ```
 
 4. Install

src/config.rs

@@ -7,6 +7,7 @@ pub struct Config {
     pub host: String,
     pub port: u16,
     pub title: String,
+    pub max_mem_log_size: usize,
 }
 
 impl Config {
@@ -16,6 +17,7 @@ impl Config {
         let host = std::env::var("HOST").context("HOST not set")?;
         let port = std::env::var("PORT").context("PORT not set")?.parse()?;
         let title = std::env::var("TITLE").context("TITLE not set")?;
+        let max_mem_log_size = std::env::var("MAX_MEM_LOG_SIZE").context("MAX_MEM_LOG_SIZE not set")?.parse()?;
 
         Ok(Config {
             database_url,
@@ -23,6 +25,7 @@ impl Config {
             host,
             port,
             title,
+            max_mem_log_size,
         })
     }
 }

src/handlers/log.rs

@@ -0,0 +1,13 @@
+use axum::response::Response;
+use maud::html;
+
+use crate::error::Result;
+use crate::partials::layout::Layout;
+use crate::log::MEM_LOG;
+
+pub async fn get(layout: Layout) -> Result<Response> {
+    let mem_buf = MEM_LOG.lock().unwrap();
+    Ok(layout.render(html! {
+        pre { (std::str::from_utf8(mem_buf.as_slices().0).unwrap()) }
+    }))
+}

src/handlers/mod.rs

@@ -2,3 +2,4 @@ pub mod api;
 pub mod entry;
 pub mod home;
 pub mod feeds;
+pub mod log;

src/lib.rs

@@ -2,6 +2,7 @@ pub mod config;
 pub mod error;
 pub mod handlers;
 pub mod jobs;
+pub mod log;
 pub mod models;
 pub mod partials;
 pub mod state;

src/log.rs

@@ -0,0 +1,94 @@
+use std::sync::Mutex;
+use std::{io::Write, collections::VecDeque};
+
+use anyhow::Result;
+use once_cell::sync::Lazy;
+use tracing_appender::non_blocking::WorkerGuard;
+use tracing_subscriber::prelude::*;
+use tracing_subscriber::{fmt::format, EnvFilter};
+
+use crate::config::Config;
+
+/// A shared in-memory buffer to store log bytes
+pub static MEM_LOG: Lazy<Mutex<VecDeque<u8>>> = Lazy::new(|| Mutex::new(VecDeque::new()));
+
+/// A `Writer` to a shared static in-memory buffer that stores bytes up until `max` bytes, at which 
+/// point it will truncate the buffer from the front up to the first newline byte `\n` within the 
+/// size limit.
+///
+/// This is useful for storing the last emitted log lines of an application in-memory without 
+/// needing to worry about the memory growing infinitely large.
+///
+/// `LimitedInMemoryBuffer` does not guarantee that the memory usage is less than `max`. 
+/// VecDeque`'s capacity may exceed `max` and it will only check and truncate the size of the 
+/// internal buffer *before* writing to it. It will continue to write, even if the size of the line 
+/// to write will make the buffer exceed `max`.
+struct LimitedInMemoryBuffer {
+    pub buf: &'static Mutex<VecDeque<u8>>,
+    max: usize,
+}
+
+impl LimitedInMemoryBuffer {
+    fn new(buf: &'static Mutex<VecDeque<u8>>, max: usize) -> Self {
+        Self {
+            buf,
+            max,
+        }
+    }
+
+    /// Truncate the buffer to max bytes plus bytes before the closest newline starting from the 
+    /// front
+    fn truncate(&mut self) {
+        let mut buf = self.buf.lock().unwrap();
+        let len = buf.len();
+        if len > self.max {
+            drop(buf.drain(..len - self.max));
+            let mut i = 0;
+            while i < buf.len() {
+                if buf[i] == b'\n' {
+                    break;
+                }
+                i += 1;
+            }
+            drop(buf.drain(..i));
+        }
+    }
+}
+
+impl Write for LimitedInMemoryBuffer {
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+        // if self.buf is too big, truncate it to the closest newline starting from the front
+        self.truncate();
+        let mut mem_buf = self.buf.lock().unwrap();
+        mem_buf.write(buf)
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        let mut buf = self.buf.lock().unwrap();
+        buf.flush()
+    }
+}
+
+pub fn init_tracing(config: &Config) -> Result<(WorkerGuard, WorkerGuard)> {
+    let fmt_layer = tracing_subscriber::fmt::layer();
+    let filter_layer = EnvFilter::from_default_env();
+    let file_appender = tracing_appender::rolling::hourly("./logs", "log");
+    let (file_writer, file_writer_guard) = tracing_appender::non_blocking(file_appender);
+    let mem_writer = LimitedInMemoryBuffer::new(&MEM_LOG, config.max_mem_log_size);
+    let (mem_writer, mem_writer_guard) = tracing_appender::non_blocking(mem_writer);
+    let file_writer_layer = tracing_subscriber::fmt::layer()
+        .with_writer(file_writer)
+        .with_ansi(false)
+        .fmt_fields(format::PrettyFields::new().with_ansi(false));
+    let mem_writer_layer = tracing_subscriber::fmt::layer()
+        .with_writer(mem_writer)
+        .with_ansi(false)
+        .fmt_fields(format::PrettyFields::new().with_ansi(false));
+    tracing_subscriber::registry()
+        .with(filter_layer)
+        .with(fmt_layer)
+        .with(file_writer_layer)
+        .with(mem_writer_layer)
+        .init();
+    Ok((file_writer_guard, mem_writer_guard))
+}

src/main.rs

@@ -9,21 +9,22 @@ use dotenvy::dotenv;
 use notify::Watcher;
 use sqlx::postgres::PgPoolOptions;
 use tower::ServiceBuilder;
-use tower_livereload::LiveReloadLayer;
 use tower_http::trace::TraceLayer;
+use tower_livereload::LiveReloadLayer;
 use tracing::debug;
 
-use lib::config;
+use lib::config::Config;
 use lib::handlers;
 use lib::state::AppState;
+use lib::log::init_tracing;
 
 #[tokio::main]
 async fn main() -> Result<()> {
     dotenv().ok();
 
-    let config = config::Config::new()?;
+    let config = Config::new()?;
 
-    tracing_subscriber::fmt::init();
+    let _guards = init_tracing(&config)?;
 
     let pool = PgPoolOptions::new()
         .max_connections(config.database_max_connections)
@@ -43,10 +44,8 @@ async fn main() -> Result<()> {
         .route("/", get(handlers::home::get))
         .route("/feeds", get(handlers::feeds::get))
         .route("/entry/:id", get(handlers::entry::get))
-        .with_state(AppState {
-            pool,
-            config,
-        })
+        .route("/log", get(handlers::log::get))
+        .with_state(AppState { pool, config })
         .layer(ServiceBuilder::new().layer(TraceLayer::new_for_http()));
 
     #[cfg(debug_assertions)]
@@ -54,7 +53,10 @@ async fn main() -> Result<()> {
         let livereload = LiveReloadLayer::new();
         let reloader = livereload.reloader();
         let mut watcher = notify::recommended_watcher(move |_| reloader.reload())?;
-        watcher.watch(Path::new("target/debug/crawlnicle"), notify::RecursiveMode::Recursive)?;
+        watcher.watch(
+            Path::new("target/debug/crawlnicle"),
+            notify::RecursiveMode::Recursive,
+        )?;
         app = app.layer(livereload);
     }
 

src/partials/header.rs

@@ -7,6 +7,7 @@ pub fn header() -> Markup {
                 h1 { a href="/" data-turbo-frame="main" { "crawlnicle" } }
                 ul {
                     li { a href="/feeds" data-turbo-frame="main" { "feeds" } }
+                    li { a href="/log" data-turbo-frame="main" { "log" } }
                 }
             }
         }