Use once_cell instead of lazy_static for tracing. Use custom sinks instead of filters to disable logging.

Cargo.lock

@@ -1291,9 +1291,9 @@ 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"
@@ -2651,8 +2651,8 @@ dependencies = [
  "claim",
  "config",
  "fake",
- "lazy_static",
  "linkify",
+ "once_cell",
  "quickcheck",
  "quickcheck_macros",
  "rand 0.8.3",

Cargo.toml

@@ -33,7 +33,7 @@ rand = { version = "0.8", features=["std_rng"] }
 sha2 = { version = "0.9" }
 
 [dev-dependencies]
-lazy_static = "1.4.0"
+once_cell = "1.7.2"
 claim = "0.4.0"
 quickcheck = "0.9.2"
 quickcheck_macros = "0.9.1"

src/main.rs

@@ -4,7 +4,7 @@ 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/api/helpers.rs

@@ -1,3 +1,4 @@
+use once_cell::sync::Lazy;
 use sqlx::{Connection, Executor, PgConnection, PgPool};
 use uuid::Uuid;
 use wiremock::MockServer;
@@ -5,14 +6,18 @@ use zero2prod::configuration::{get_configuration, DatabaseSettings};
 use zero2prod::startup::{get_connection_pool, Application};
 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,
@@ -64,7 +69,7 @@ impl TestApp {
 }
 
 pub async fn spawn_app() -> TestApp {
-    lazy_static::initialize(&TRACING);
+    Lazy::force(&TRACING);
 
     // Launch a mock server to stand in for Postmark's API
     let email_server = MockServer::start().await;