Add support for JSON log output.

Cargo.lock

@@ -4534,6 +4534,16 @@ dependencies = [
  "tracing-core",
 ]
 
+[[package]]
+name = "tracing-serde"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bc6b213177105856957181934e4920de57730fc69bf42c37ee5bb664d406d9e1"
+dependencies = [
+ "serde",
+ "tracing-core",
+]
+
 [[package]]
 name = "tracing-subscriber"
 version = "0.3.17"
@@ -4541,11 +4551,14 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "30a651bc37f915e81f087d86e62a18eec5f79550c7faff886f7090b4ea757c77"
 dependencies = [
  "nu-ansi-term",
+ "serde",
+ "serde_json",
  "sharded-slab",
  "smallvec",
  "thread_local",
  "tracing-core",
  "tracing-log",
+ "tracing-serde",
 ]
 
 [[package]]

chirpstack/Cargo.toml

@@ -42,6 +42,7 @@ tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = [
 	"fmt",
 	"ansi",
+	"json",
 ], default-features = true }
 
 # ChirpStack API definitions

chirpstack/src/cmd/configfile.rs

@@ -4,6 +4,23 @@ use super::super::config;
 
 pub fn run() {
     let template = r#"
+# Logging configuration
+[logging]
+
+  # Log level.
+  #
+  # Valid options are:
+  #   * TRACE
+  #   * DEBUG
+  #   * INFO
+  #   * WARN
+  #   * ERROR
+  #   * OFF
+  level="{{ logging.level }}"
+
+  # Log as JSON.
+  json={{ logging.json }}
+
 # PostgreSQL configuration.
 [postgresql]
 

chirpstack/src/config.rs

@@ -37,12 +37,14 @@ pub struct Configuration {
 #[serde(default)]
 pub struct Logging {
     pub level: String,
+    pub json: bool,
 }
 
 impl Default for Logging {
     fn default() -> Self {
         Logging {
             level: "info".into(),
+            json: false,
         }
     }
 }

chirpstack/src/main.rs

@@ -92,10 +92,17 @@ async fn main() -> Result<()> {
         ("lrwn", Level::from_str(&conf.logging.level).unwrap()),
     ]);
 
-    tracing_subscriber::registry()
+    if conf.logging.json {
-        .with(tracing_subscriber::fmt::layer())
+        tracing_subscriber::registry()
-        .with(filter)
+            .with(tracing_subscriber::fmt::layer().json())
-        .init();
+            .with(filter)
+            .init();
+    } else {
+        tracing_subscriber::registry()
+            .with(tracing_subscriber::fmt::layer())
+            .with(filter)
+            .init();
+    }
 
     if let Some(Commands::Configfile {}) = &cli.command {
         cmd::configfile::run();