Add flattened JSON log format support

.schema/pgdog.schema.json

@@ -1255,6 +1255,11 @@
           "description": "Structured JSON logs suitable for ECS/Datadog ingestion.",
           "type": "string",
           "const": "json"
+        },
+        {
+          "description": "Structured JSON logs with event fields flattened into the root object.",
+          "type": "string",
+          "const": "json_flattened"
         }
       ]
     },

example.pgdog.toml

@@ -138,6 +138,7 @@ openmetrics_namespace = "pgdog_"
 # Available options:
 # - text
 # - json
+# - json_flattened
 log_format = "text"
 # Log filter directives using the same syntax as RUST_LOG.
 #

pgdog-config/src/general.rs

@@ -28,13 +28,16 @@ pub enum LogFormat {
     Text,
     /// Structured JSON logs suitable for ECS/Datadog ingestion.
     Json,
+    /// Structured JSON logs with event fields flattened into the root object.
+    JsonFlattened,
 }
 
 impl fmt::Display for LogFormat {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             Self::Text => f.write_str("text"),
             Self::Json => f.write_str("json"),
+            Self::JsonFlattened => f.write_str("json_flattened"),
         }
     }
 }
@@ -46,6 +49,7 @@ impl FromStr for LogFormat {
         match s.to_ascii_lowercase().as_str() {
             "text" => Ok(Self::Text),
             "json" => Ok(Self::Json),
+            "json_flattened" => Ok(Self::JsonFlattened),
             _ => Err(()),
         }
     }
@@ -1635,6 +1639,9 @@ mod tests {
         assert_eq!(General::log_format(), LogFormat::Json);
         assert_eq!(General::log_level(), "pgdog=debug,info");
 
+        env::set_var("PGDOG_LOG_FORMAT", "json_flattened");
+        assert_eq!(General::log_format(), LogFormat::JsonFlattened);
+
         env::remove_var("PGDOG_LOG_FORMAT");
         env::remove_var("RUST_LOG");
 

pgdog/src/lib.rs

@@ -173,10 +173,11 @@ fn init_logger(general: Option<&General>) {
 
     let throttle = throttle_handle().clone();
 
-    match general
+    let log_format = general
         .map(|general| general.log_format)
-        .unwrap_or_default()
-    {
+        .unwrap_or_default();
+
+    match log_format {
         LogFormat::Text => {
             let format = fmt::layer()
                 .with_ansi(std::io::stderr().is_terminal())
@@ -191,14 +192,18 @@ fn init_logger(general: Option<&General>) {
                 .with(filter)
                 .try_init();
         }
-        LogFormat::Json => {
+        LogFormat::Json | LogFormat::JsonFlattened => {
             let format = fmt::layer()
                 .json()
                 .with_ansi(false)
                 .with_writer(std::io::stderr)
                 .with_file(false)
                 .with_current_span(false)
                 .with_span_list(false);
+            let format = match log_format {
+                LogFormat::JsonFlattened => format.flatten_event(true),
+                _ => format,
+            };
             #[cfg(not(debug_assertions))]
             let format = format.with_target(false);
             let format = format.with_filter(throttle);

pgdog/src/plugin/mod.rs

@@ -108,7 +108,10 @@ pub fn load(config: &Config) -> Result<(), libloading::Error> {
 
             let pd_config = PdConfig {
                 log_level: PdStr::from(config.general.log_level.as_str()),
-                log_json: if config.general.log_format == LogFormat::Json {
+                log_json: if matches!(
+                    config.general.log_format,
+                    LogFormat::Json | LogFormat::JsonFlattened
+                ) {
                     1
                 } else {
                     0