feat(logs): support json formatter

Author: sigilioso

Cargo.lock

@@ -20,7 +20,7 @@ regex = "1.11.1"
 mockall = "0.13.1"
 clap = "4.5.31"
 nix = "0.30.0"
-tracing-subscriber = "0.3.19"
+tracing-subscriber = { version = "0.3.19", features = [ "json" ] }
 tracing-test = "0.2.5"
 assert_cmd = "2.0.16"
 assert_matches = "1.5.0"

Cargo.toml

@@ -2338,6 +2338,12 @@ Distributed under the following license(s):
 
 * MIT
 
+## tracing-serde <https://crates.io/crates/tracing-serde>
+
+Distributed under the following license(s):
+
+* MIT
+
 ## tracing-subscriber <https://crates.io/crates/tracing-subscriber>
 
 Distributed under the following license(s):

THIRD_PARTY_NOTICES.md

@@ -508,6 +508,7 @@ agents: {}
                     target: true,
                     timestamp: TimestampFormat("%Y".to_string()),
                     ansi_colors: false,
+                    formatter: Default::default(),
                 },
                 ..Default::default()
             }

agent-control/src/agent_control/config.rs

@@ -15,6 +15,22 @@ impl Default for TimestampFormat {
     }
 }
 
+/// Represents the supported logging formatters
+#[derive(Debug, Deserialize, PartialEq, Clone)]
+#[serde(rename_all = "snake_case")]
+pub enum Formatter {
+    /// Human-readable single-line logs
+    Default,
+    /// Newline delimited JSON logs
+    Json,
+}
+
+impl Default for Formatter {
+    fn default() -> Self {
+        Self::Default
+    }
+}
+
 /// Defines the format to be used for logging, including target and timestamp.
 ///
 /// # Fields:
@@ -29,4 +45,60 @@ pub struct LoggingFormat {
     pub(crate) timestamp: TimestampFormat,
     #[serde(default)]
     pub(crate) ansi_colors: bool,
+    #[serde(default)]
+    pub(crate) formatter: Formatter,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use rstest::rstest;
+    use serde_yaml;
+
+    #[rstest]
+    #[case::with_defaults(
+        r#"
+        target: false
+        "#,
+        LoggingFormat {
+            target: false,
+            timestamp: TimestampFormat::default(),
+            ansi_colors: false,
+            formatter: Formatter::Default,
+        }
+    )]
+    #[case::with_custom_values(
+        r#"
+        target: true
+        timestamp: "custom_format"
+        ansi_colors: true
+        formatter: json
+        "#,
+        LoggingFormat {
+            target: true,
+            timestamp: TimestampFormat("custom_format".to_string()),
+            ansi_colors: true,
+            formatter: Formatter::Json,
+        }
+    )]
+    #[case::with_partial_values(
+        r#"
+        target: true
+        "#,
+        LoggingFormat {
+            target: true,
+            timestamp: TimestampFormat::default(),
+            ansi_colors: false,
+            formatter: Formatter::Default,
+        }
+    )]
+    fn test_logging_format_deserialization(
+        #[case] yaml_data: &str,
+        #[case] expected_logging_format: LoggingFormat,
+    ) {
+        let logging_format: LoggingFormat = serde_yaml::from_str(yaml_data).unwrap();
+
+        assert_eq!(logging_format, expected_logging_format);
+    }
 }

agent-control/src/instrumentation/config/logs/format.rs

@@ -1,4 +1,5 @@
 use crate::instrumentation::config::logs::config::{LoggingConfig, LoggingConfigError};
+use crate::instrumentation::config::logs::format::Formatter;
 use crate::instrumentation::tracing::{LayerBox, TracingGuard};
 use std::path::PathBuf;
 use tracing_appender::non_blocking::WorkerGuard;
@@ -28,13 +29,21 @@ pub fn file(
         .map(|(file_writer, guard)| {
             let layer = tracing_subscriber::fmt::layer()
                 .with_writer(file_writer)
-                .with_ansi(false) // Disable colors for file
                 .with_span_events(config.fmt_span_events())
                 .with_target(target)
-                .with_timer(ChronoLocal::new(timestamp_fmt.clone()))
-                .fmt_fields(PrettyFields::new())
-                .with_filter(config.filter()?)
-                .boxed();
+                .with_timer(ChronoLocal::new(timestamp_fmt.clone()));
+            let layer = match config.format.formatter {
+                Formatter::Default => layer
+                    .with_ansi(false) // Disable colors for file
+                    .fmt_fields(PrettyFields::new())
+                    .with_filter(config.filter()?)
+                    .boxed(),
+                Formatter::Json => layer
+                    .json()
+                    .flatten_event(true)
+                    .with_filter(config.filter()?)
+                    .boxed(),
+            };
             Ok((layer, guard))
         })
         .transpose()

agent-control/src/instrumentation/tracing_layers/file.rs

@@ -1,4 +1,5 @@
 use crate::instrumentation::config::logs::config::{LoggingConfig, LoggingConfigError};
+use crate::instrumentation::config::logs::format::Formatter;
 use crate::instrumentation::tracing::LayerBox;
 use tracing_subscriber::Layer;
 use tracing_subscriber::fmt::format::PrettyFields;
@@ -11,12 +12,21 @@ pub fn stdout(config: &LoggingConfig) -> Result<LayerBox, LoggingConfigError> {
 
     let layer = tracing_subscriber::fmt::layer()
         .with_writer(std::io::stdout)
-        .with_ansi(config.format.ansi_colors)
         .with_target(target)
         .with_span_events(config.fmt_span_events())
-        .with_timer(ChronoLocal::new(timestamp_fmt))
-        .fmt_fields(PrettyFields::new())
-        .with_filter(config.filter()?)
-        .boxed();
+        .with_timer(ChronoLocal::new(timestamp_fmt));
+
+    let layer = match config.format.formatter {
+        Formatter::Default => layer
+            .with_ansi(config.format.ansi_colors)
+            .fmt_fields(PrettyFields::new())
+            .with_filter(config.filter()?)
+            .boxed(),
+        Formatter::Json => layer
+            .json()
+            .flatten_event(true)
+            .with_filter(config.filter()?)
+            .boxed(),
+    };
     Ok(layer)
 }

agent-control/src/instrumentation/tracing_layers/stdout.rs

@@ -30,7 +30,6 @@ use tempfile::tempdir;
 #[test]
 fn onhost_opamp_agent_control_local_effective_config() {
     // Given a agent-control without agents and opamp configured.
-
     let opamp_server = FakeServer::start_new();
 
     let local_dir = tempdir().expect("failed to create local temp dir");

agent-control/tests/on_host/scenarios/opamp.rs

@@ -34,6 +34,7 @@ log:
     target: true # Defaults to false, includes extra information for debugging purposes
     timestamp: "%Y-%m-%dT%H:%M%S" # Defaults to "%Y-%m-%dT%H:%M%S", details in <https://docs.rs/chrono/0.4.40/chrono/format/strftime/index.html#fn7>
     ansi_colors: true # Defaults to false, set up ansi-colors in the stdout logs output.
+    formatter: json # Defaults to "default". It accepts "json" (newline delimited JSON logs) or "default" (human-readable, single-line logs)
   level: debug # Defines the log level, defaults to "info".
   insecure_fine_grained_level: debug # Enables logs for external dependencies and sets its level. This cannot be considered secure since external dependencies may leek secrets. If this is set the 'level' field does not apply.
   file: