feat: Allow configuring the tracing log output format (#275)

Cargo.toml

@@ -35,7 +35,7 @@ dotenvy = "0.15.5"
 
 # Tracing
 tracing = { workspace = true }
-tracing-subscriber = { version = "0.3.17", features = ["env-filter"] }
+tracing-subscriber = { version = "0.3.17", features = ["env-filter", "json"] }
 opentelemetry-semantic-conventions = "0.15.0"
 opentelemetry = { version = "0.23.0", features = ["trace", "metrics", "logs"], optional = true }
 opentelemetry_sdk = { version = "0.23.0", features = ["tokio", "rt-tokio", "metrics", "logs", "trace"], optional = true }

config/development.toml

@@ -1,3 +1,6 @@
+[tracing]
+format = "pretty"
+
 [auth.jwt]
 secret = "secret-dev"
 

config/test.toml

@@ -1,3 +1,6 @@
+[tracing]
+format = "pretty"
+
 [auth.jwt]
 secret = "secret-test"
 

examples/full/config/development.toml

@@ -1,3 +1,6 @@
+[tracing]
+format = "pretty"
+
 [auth.jwt]
 secret = "secret-dev"
 

examples/full/config/test.toml

@@ -1,3 +1,6 @@
+[tracing]
+format = "pretty"
+
 [auth.jwt]
 secret = "secret-test"
 

src/config/snapshots/roadster__config__app_config__tests__test.snap

@@ -137,6 +137,7 @@ required-claims = []
 
 [tracing]
 level = 'debug'
+format = 'compact'
 trace-propagation = true
 
 [database]

src/config/tracing/default.toml

@@ -1,2 +1,3 @@
 [tracing]
+format = "compact"
 trace-propagation = true

src/config/tracing/mod.rs

@@ -2,6 +2,7 @@
 use crate::util::serde_util::default_true;
 use config::{FileFormat, FileSourceString};
 use serde_derive::{Deserialize, Serialize};
+use strum_macros::{EnumString, IntoStaticStr};
 #[cfg(feature = "otel")]
 use url::Url;
 use validator::Validate;
@@ -16,6 +17,9 @@ pub fn default_config() -> config::File<FileSourceString, FileFormat> {
 pub struct Tracing {
     pub level: String,
 
+    /// The format to use when printing traces to logs.
+    pub format: Format,
+
     /// The name of the service to use for the OpenTelemetry `service.name` field. If not provided,
     /// will use the [`App::name`][crate::config::app_config::App] config value, translated to `snake_case`.
     #[cfg(feature = "otel")]
@@ -31,6 +35,17 @@ pub struct Tracing {
     pub otlp_endpoint: Option<Url>,
 }
 
+#[derive(Debug, Clone, Eq, PartialEq, Serialize, Deserialize, EnumString, IntoStaticStr)]
+#[serde(rename_all = "kebab-case")]
+#[strum(serialize_all = "kebab-case")]
+#[non_exhaustive]
+pub enum Format {
+    None,
+    Pretty,
+    Compact,
+    Json,
+}
+
 // To simplify testing, these are only run when all of the config fields are available
 #[cfg(all(test, feature = "otel"))]
 mod deserialize_tests {
@@ -49,28 +64,32 @@ mod deserialize_tests {
     #[case(
         r#"
         level = "debug"
+        format = "compact"
         "#
     )]
     #[case(
         r#"
         level = "info"
+        format = "json"
         service-name = "foo"
         "#
     )]
     #[case(
         r#"
         level = "error"
+        format = "pretty"
         trace-propagation = false
         "#
     )]
     #[case(
         r#"
         level = "debug"
+        format = "none"
         otlp-endpoint = "https://example.com:1234"
         "#
     )]
     #[cfg_attr(coverage_nightly, coverage(off))]
-    fn sidekiq(_case: TestCase, #[case] config: &str) {
+    fn tracing(_case: TestCase, #[case] config: &str) {
         let tracing: Tracing = toml::from_str(config).unwrap();
 
         assert_toml_snapshot!(tracing);

src/config/tracing/snapshots/roadster__config__tracing__deserialize_tests__sidekiq@case_1.snap → src/config/tracing/snapshots/roadster__config__tracing__deserialize_tests__tracing@case_1.snap

@@ -1,6 +1,7 @@
 ---
-source: src/config/tracing.rs
+source: src/config/tracing/mod.rs
 expression: tracing
 ---
 level = 'debug'
+format = 'compact'
 trace-propagation = true

src/config/tracing/snapshots/roadster__config__tracing__deserialize_tests__sidekiq@case_2.snap → src/config/tracing/snapshots/roadster__config__tracing__deserialize_tests__tracing@case_2.snap

@@ -1,7 +1,8 @@
 ---
-source: src/config/tracing.rs
+source: src/config/tracing/mod.rs
 expression: tracing
 ---
 level = 'info'
+format = 'json'
 service-name = 'foo'
 trace-propagation = true

src/config/tracing/snapshots/roadster__config__tracing__deserialize_tests__sidekiq@case_3.snap → src/config/tracing/snapshots/roadster__config__tracing__deserialize_tests__tracing@case_3.snap

@@ -1,6 +1,7 @@
 ---
-source: src/config/tracing.rs
+source: src/config/tracing/mod.rs
 expression: tracing
 ---
 level = 'error'
+format = 'pretty'
 trace-propagation = false

src/config/tracing/snapshots/roadster__config__tracing__deserialize_tests__sidekiq@case_4.snap → src/config/tracing/snapshots/roadster__config__tracing__deserialize_tests__tracing@case_4.snap

@@ -1,7 +1,8 @@
 ---
-source: src/config/tracing.rs
+source: src/config/tracing/mod.rs
 expression: tracing
 ---
 level = 'debug'
+format = 'none'
 trace-propagation = true
 otlp-endpoint = 'https://example.com:1234/'

src/tracing/mod.rs

@@ -21,6 +21,7 @@ use tracing_subscriber::util::SubscriberInitExt;
 use tracing_subscriber::EnvFilter;
 
 use crate::config::app_config::AppConfig;
+use crate::config::tracing::Format;
 use crate::error::RoadsterResult;
 
 // Todo: make this configurable
@@ -30,7 +31,42 @@ pub fn init_tracing(
     metadata: &AppMetadata,
 ) -> RoadsterResult<()> {
     // Stdout Layer
-    let stdout_layer = tracing_subscriber::fmt::layer();
+    // Each format results in a different type, so we can't use a `match` on the format enum.
+    // Instead, we need to create an optional layer of each type, and add all of them to the
+    // registry -- if a layer is `None`, it won't actually be added.
+    let compact_log_layer = if matches!(config.tracing.format, Format::Compact) {
+        Some(tracing_subscriber::fmt::layer().compact())
+    } else {
+        None
+    };
+    let pretty_log_layer = if matches!(config.tracing.format, Format::Pretty) {
+        Some(tracing_subscriber::fmt::layer().pretty())
+    } else {
+        None
+    };
+    let json_log_layer = if matches!(config.tracing.format, Format::Json) {
+        Some(tracing_subscriber::fmt::layer().json())
+    } else {
+        None
+    };
+    match config.tracing.format {
+        Format::None => {
+            assert!(
+                pretty_log_layer.is_none()
+                    && compact_log_layer.is_none()
+                    && json_log_layer.is_none()
+            )
+        }
+        Format::Pretty => {
+            assert!(pretty_log_layer.is_some())
+        }
+        Format::Compact => {
+            assert!(compact_log_layer.is_some())
+        }
+        Format::Json => {
+            assert!(json_log_layer.is_some())
+        }
+    }
 
     #[cfg(feature = "otel")]
     if config.tracing.trace_propagation {
@@ -104,7 +140,9 @@ pub fn init_tracing(
 
     let registry = tracing_subscriber::Registry::default()
         .with(env_filter)
-        .with(stdout_layer);
+        .with(compact_log_layer)
+        .with(pretty_log_layer)
+        .with(json_log_layer);
 
     #[cfg(feature = "otel")]
     let registry = { registry.with(oltp_traces_layer).with(otlp_metrics_layer) };