Update to use once_cell instead of lazy_static.

Use a custom sink instead of different log levels to silence logs in tests.

Cargo.lock

@@ -1172,9 +1172,9 @@ dependencies = [
 
 [[package]]
 name = "once_cell"
-version = "1.5.2"
+version = "1.7.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "13bd41f508810a131401606d54ac32a467c97172d74ba7662562ebba5ad07fa0"
+checksum = "af8b08b04175473088b46763e51ee54da5f9a164bc162f615b91bc179dbf15a3"
 
 [[package]]
 name = "opaque-debug"
@@ -2508,7 +2508,7 @@ dependencies = [
  "actix-web",
  "chrono",
  "config",
- "lazy_static",
+ "once_cell",
  "reqwest",
  "serde",
  "sqlx",

Cargo.toml

@@ -28,6 +28,6 @@ tracing-actix-web = "0.3.0-beta.2"
 
 [dev-dependencies]
 reqwest = { version = "0.11", features = ["json"] }
-lazy_static = "1.4.0"
 actix-rt = "2"
 tokio = "1"
+once_cell = "1.7.2"

src/main.rs

@@ -6,7 +6,7 @@ use zero2prod::telemetry::{get_subscriber, init_subscriber};
 
 #[actix_web::main]
 async fn main() -> std::io::Result<()> {
-    let subscriber = get_subscriber("zero2prod".into(), "info".into());
+    let subscriber = get_subscriber("zero2prod".into(), "info".into(), std::io::stdout);
     init_subscriber(subscriber);
 
     let configuration = get_configuration().expect("Failed to read configuration.");

src/telemetry.rs

@@ -2,6 +2,7 @@ use tracing::subscriber::set_global_default;
 use tracing::Subscriber;
 use tracing_bunyan_formatter::{BunyanFormattingLayer, JsonStorageLayer};
 use tracing_log::LogTracer;
+use tracing_subscriber::fmt::MakeWriter;
 use tracing_subscriber::{layer::SubscriberExt, EnvFilter, Registry};
 
 /// Compose multiple layers into a `tracing`'s subscriber.
@@ -10,10 +11,14 @@ use tracing_subscriber::{layer::SubscriberExt, EnvFilter, Registry};
 ///
 /// We are using `impl Subscriber` as return type to avoid having to spell out the actual
 /// type of the returned subscriber, which is indeed quite complex.
-pub fn get_subscriber(name: String, env_filter: String) -> impl Subscriber + Sync + Send {
+pub fn get_subscriber(
+    name: String,
+    env_filter: String,
+    sink: impl MakeWriter + Send + Sync + 'static,
+) -> impl Subscriber + Sync + Send {
     let env_filter =
         EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new(env_filter));
-    let formatting_layer = BunyanFormattingLayer::new(name, std::io::stdout);
+    let formatting_layer = BunyanFormattingLayer::new(name, sink);
     Registry::default()
         .with(env_filter)
         .with(JsonStorageLayer)

tests/health_check.rs

@@ -1,3 +1,4 @@
+use once_cell::sync::Lazy;
 use sqlx::{Connection, Executor, PgConnection, PgPool};
 use std::net::TcpListener;
 use uuid::Uuid;
@@ -5,14 +6,18 @@ use zero2prod::configuration::{get_configuration, DatabaseSettings};
 use zero2prod::startup::run;
 use zero2prod::telemetry::{get_subscriber, init_subscriber};
 
-// Ensure that the `tracing` stack is only initialised once using `lazy_static`
-lazy_static::lazy_static! {
-    static ref TRACING: () = {
-        let filter = if std::env::var("TEST_LOG").is_ok() { "debug" } else { "" };
-        let subscriber = get_subscriber("test".into(), filter.into());
+// Ensure that the `tracing` stack is only initialised once using `once_cell`
+static TRACING: Lazy<()> = Lazy::new(|| {
+    let default_filter_level = "info".to_string();
+    let subscriber_name = "test".to_string();
+    if std::env::var("TEST_LOG").is_ok() {
+        let subscriber = get_subscriber(subscriber_name, default_filter_level, std::io::stdout);
+        init_subscriber(subscriber);
+    } else {
+        let subscriber = get_subscriber(subscriber_name, default_filter_level, std::io::sink);
         init_subscriber(subscriber);
     };
-}
+});
 
 pub struct TestApp {
     pub address: String,
@@ -22,7 +27,7 @@ pub struct TestApp {
 async fn spawn_app() -> TestApp {
     // The first time `initialize` is invoked the code in `TRACING` is executed.
     // All other invocations will instead skip execution.
-    lazy_static::initialize(&TRACING);
+    Lazy::force(&TRACING);
 
     let listener = TcpListener::bind("127.0.0.1:0").expect("Failed to bind random port");
     // We retrieve the port assigned to us by the OS