Chapter 4.5

+ Add in logging
+ Move logging functions to new telemetry.rs file

Cargo.lock

@@ -787,6 +787,16 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "gethostname"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c1ebd34e35c46e00bb73e81363248d627782724609fe1b6396f553f68fe3862e"
+dependencies = [
+ "libc",
+ "winapi",
+]
+
 [[package]]
 name = "getrandom"
 version = "0.2.10"
@@ -1154,9 +1164,22 @@ dependencies = [
  "serde",
  "sqlx",
  "tokio",
+ "tracing",
+ "tracing-bunyan-formatter",
+ "tracing-log 0.1.4",
+ "tracing-subscriber",
  "uuid",
 ]
 
+[[package]]
+name = "matchers"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8263075bb86c5a1b1427b5ae862e8889656f126e9f77c484496e8b47cf5c5558"
+dependencies = [
+ "regex-automata 0.1.10",
+]
+
 [[package]]
 name = "md-5"
 version = "0.10.5"
@@ -1245,6 +1268,16 @@ dependencies = [
  "minimal-lexical",
 ]
 
+[[package]]
+name = "nu-ansi-term"
+version = "0.46.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77a8165726e8236064dbb45459242600304b42a5ea24ee2948e18e023bf7ba84"
+dependencies = [
+ "overload",
+ "winapi",
+]
+
 [[package]]
 name = "num-bigint-dig"
 version = "0.8.4"
@@ -1361,6 +1394,12 @@ dependencies = [
  "vcpkg",
 ]
 
+[[package]]
+name = "overload"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b15813163c1d831bf4a13c3610c05c0d03b39feb07f7e09fa234dac9b15aaf39"
+
 [[package]]
 name = "parking_lot"
 version = "0.12.1"
@@ -1521,8 +1560,17 @@ checksum = "12de2eff854e5fa4b1295edd650e227e9d8fb0c9e90b12e7f36d6a6811791a29"
 dependencies = [
  "aho-corasick",
  "memchr",
- "regex-automata",
+ "regex-automata 0.3.7",
- "regex-syntax",
+ "regex-syntax 0.7.5",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c230d73fb8d8c1b9c0b3135c5142a8acee3a0558fb8db5cf1cb65f8d7862132"
+dependencies = [
+ "regex-syntax 0.6.29",
 ]
 
 [[package]]
@@ -1533,9 +1581,15 @@ checksum = "49530408a136e16e5b486e883fbb6ba058e8e4e8ae6621a77b048b314336e629"
 dependencies = [
  "aho-corasick",
  "memchr",
- "regex-syntax",
+ "regex-syntax 0.7.5",
 ]
 
+[[package]]
+name = "regex-syntax"
+version = "0.6.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f162c6dd7b008981e4d40210aca20b4bd0f9b60ca9271061b07f78537722f2e1"
+
 [[package]]
 name = "regex-syntax"
 version = "0.7.5"
@@ -1812,6 +1866,15 @@ dependencies = [
  "digest",
 ]
 
+[[package]]
+name = "sharded-slab"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f40ca3c46823713e0d4209592e8d6e826aa57e928f09752619fc696c499637f6"
+dependencies = [
+ "lazy_static",
+]
+
 [[package]]
 name = "signal-hook-registry"
 version = "1.4.1"
@@ -2181,6 +2244,16 @@ dependencies = [
  "syn 2.0.32",
 ]
 
+[[package]]
+name = "thread_local"
+version = "1.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b9ef9bad013ada3808854ceac7b46812a6465ba368859a37e2100283d2d719c"
+dependencies = [
+ "cfg-if",
+ "once_cell",
+]
+
 [[package]]
 name = "time"
 version = "0.3.28"
@@ -2319,6 +2392,24 @@ dependencies = [
  "syn 2.0.32",
 ]
 
+[[package]]
+name = "tracing-bunyan-formatter"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b5c266b9ac83dedf0e0385ad78514949e6d89491269e7065bee51d2bb8ec7373"
+dependencies = [
+ "ahash",
+ "gethostname",
+ "log",
+ "serde",
+ "serde_json",
+ "time",
+ "tracing",
+ "tracing-core",
+ "tracing-log 0.1.4",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "tracing-core"
 version = "0.1.31"
@@ -2326,6 +2417,47 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0955b8137a1df6f1a2e9a37d8a6656291ff0297c1a97c24e0d8425fe2312f79a"
 dependencies = [
  "once_cell",
+ "valuable",
+]
+
+[[package]]
+name = "tracing-log"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f751112709b4e791d8ce53e32c4ed2d353565a795ce84da2285393f41557bdf2"
+dependencies = [
+ "log",
+ "once_cell",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-log"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee855f1f400bd0e5c02d150ae5de3840039a3f54b025156404e34c23c03f47c3"
+dependencies = [
+ "log",
+ "once_cell",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-subscriber"
+version = "0.3.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ad0f048c97dbd9faa9b7df56362b8ebcaa52adb06b498c050d2f4e32f90a7a8b"
+dependencies = [
+ "matchers",
+ "nu-ansi-term",
+ "once_cell",
+ "regex",
+ "sharded-slab",
+ "smallvec",
+ "thread_local",
+ "tracing",
+ "tracing-core",
+ "tracing-log 0.2.0",
 ]
 
 [[package]]
@@ -2411,6 +2543,12 @@ dependencies = [
  "getrandom",
 ]
 
+[[package]]
+name = "valuable"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "830b7e5d4d90034032940e4ace0d9a9a057e7a45cd94e6c007832e39edb82f6d"
+
 [[package]]
 name = "vcpkg"
 version = "0.2.15"

Cargo.toml

@@ -17,6 +17,10 @@ serde = { version = "1", features = ["derive"] }
 config = { version = "0.13", default-features = false, features = ["yaml"] }
 uuid = { version = "1", features = ["v4"] }
 chrono = { version = "0.4.22", default-features = false, features = ["clock"] }
+tracing = { version = "0.1", features = ["log"] }
+tracing-subscriber = { version = "0.3", features = ["registry", "env-filter"] }
+tracing-bunyan-formatter = "0.3"
+tracing-log = "0.1"
 
 [dependencies.sqlx]
 version = "0.7"

src/lib.rs

@@ -1,3 +1,4 @@
 pub mod configuration;
 pub mod routes;
 pub mod startup;
+pub mod telemetry;

src/main.rs

@@ -1,10 +1,14 @@
 use mail_app::configuration::get_configuration;
 use mail_app::startup::run;
-use sqlx::PgPool;
+use mail_app::telemetry::{get_subscriber, init_subscriber};
+use sqlx::postgres::PgPool;
 use std::net::TcpListener;
 
 #[tokio::main]
 async fn main() -> Result<(), std::io::Error> {
+    let subscriber = get_subscriber("mail_app".into(), "info".into());
+    init_subscriber(subscriber);
+
     let configuration = get_configuration().expect("Failed to read configuration");
     let connection_pool = PgPool::connect(&configuration.database.connection_string())
         .await

src/routes/subscriptions.rs

@@ -1,6 +1,7 @@
 use actix_web::{web, HttpResponse};
 use chrono::Utc;
 use sqlx::PgPool;
+use tracing::Instrument;
 use uuid::Uuid;
 
 #[derive(serde::Deserialize)]
@@ -10,6 +11,16 @@ pub struct FormData {
 }
 
 pub async fn subscribe(form: web::Form<FormData>, pool: web::Data<PgPool>) -> HttpResponse {
+    let request_id = Uuid::new_v4();
+    let request_span = tracing::info_span!(
+        "Adding a new subscriber.",
+        %request_id,
+        subscriber_email = %form.email,
+        subscriber_name = %form.name
+    );
+
+    let _request_span_guard = request_span.enter();
+    let query_span = tracing::info_span!("Saving new subscriber details to database");
     match sqlx::query!(
         r#"
         INSERT INTO subscriptions (id, email, name, subscribed_at)
@@ -21,11 +32,12 @@ pub async fn subscribe(form: web::Form<FormData>, pool: web::Data<PgPool>) -> Ht
         Utc::now()
     )
     .execute(pool.get_ref())
+    .instrument(query_span)
     .await
     {
         Ok(_) => HttpResponse::Ok().finish(),
         Err(e) => {
-            println!("Failed to execute query: {}", e);
+            tracing::error!("Failed to execute query: {:?}", e);
             HttpResponse::InternalServerError().finish()
         }
     }

src/startup.rs

@@ -1,5 +1,6 @@
 use crate::routes::{health_check, subscribe};
 use actix_web::dev::Server;
+use actix_web::middleware::Logger;
 use actix_web::{web, App, HttpServer};
 use sqlx::PgPool;
 use std::net::TcpListener;
@@ -8,6 +9,7 @@ pub fn run(listener: TcpListener, db_pool: PgPool) -> Result<Server, std::io::Er
     let connection = web::Data::new(db_pool);
     let server = HttpServer::new(move || {
         App::new()
+            .wrap(Logger::default())
             .route("/health_check", web::get().to(health_check))
             .route("/subscriptions", web::post().to(subscribe))
             .app_data(connection.clone())

src/telemetry.rs

@@ -0,0 +1,19 @@
+use tracing::{subscriber::set_global_default, Subscriber};
+use tracing_bunyan_formatter::{BunyanFormattingLayer, JsonStorageLayer};
+use tracing_log::LogTracer;
+use tracing_subscriber::{layer::SubscriberExt, EnvFilter, Registry};
+
+pub fn get_subscriber(name: String, env_filter: String) -> impl Subscriber + Send + Sync {
+    let env_filter =
+        EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new(env_filter));
+    let formatting_layer = BunyanFormattingLayer::new(name, std::io::stdout);
+    Registry::default()
+        .with(env_filter)
+        .with(JsonStorageLayer)
+        .with(formatting_layer)
+}
+
+pub fn init_subscriber(subscriber: impl Subscriber + Send + Sync) {
+    LogTracer::init().expect("Failed to set logger.");
+    set_global_default(subscriber).expect("Failed to set subscriber.");
+}