test: Add test to confirm programmatic config wins over env in BatchConfig (#2781)

Author: cijothomas

opentelemetry-sdk/src/logs/batch_log_processor.rs

@@ -614,6 +614,8 @@ impl Default for BatchConfigBuilder {
     /// * `OTEL_BLRP_SCHEDULE_DELAY`
     /// * `OTEL_BLRP_MAX_EXPORT_BATCH_SIZE`
     /// * `OTEL_BLRP_EXPORT_TIMEOUT`
+    ///
+    /// Note: Programmatic configuration overrides any value set via the environment variable.
     fn default() -> Self {
         BatchConfigBuilder {
             max_queue_size: OTEL_BLRP_MAX_QUEUE_SIZE_DEFAULT,
@@ -630,7 +632,11 @@ impl BatchConfigBuilder {
     /// Set max_queue_size for [`BatchConfigBuilder`].
     /// It's the maximum queue size to buffer logs for delayed processing.
     /// If the queue gets full it will drop the logs.
-    /// The default value of is 2048.
+    /// The default value is 2048.
+    ///
+    /// Corresponding environment variable: `OTEL_BLRP_MAX_QUEUE_SIZE`.
+    ///
+    /// Note: Programmatically setting this will override any value set via the environment variable.
     pub fn with_max_queue_size(mut self, max_queue_size: usize) -> Self {
         self.max_queue_size = max_queue_size;
         self
@@ -639,6 +645,10 @@ impl BatchConfigBuilder {
     /// Set scheduled_delay for [`BatchConfigBuilder`].
     /// It's the delay interval in milliseconds between two consecutive processing of batches.
     /// The default value is 1000 milliseconds.
+    ///
+    /// Corresponding environment variable: `OTEL_BLRP_SCHEDULE_DELAY`.
+    ///
+    /// Note: Programmatically setting this will override any value set via the environment variable.
     pub fn with_scheduled_delay(mut self, scheduled_delay: Duration) -> Self {
         self.scheduled_delay = scheduled_delay;
         self
@@ -647,6 +657,10 @@ impl BatchConfigBuilder {
     /// Set max_export_timeout for [`BatchConfigBuilder`].
     /// It's the maximum duration to export a batch of data.
     /// The default value is 30000 milliseconds.
+    ///
+    /// Corresponding environment variable: `OTEL_BLRP_EXPORT_TIMEOUT`.
+    ///
+    /// Note: Programmatically setting this will override any value set via the environment variable.
     #[cfg(feature = "experimental_logs_batch_log_processor_with_async_runtime")]
     pub fn with_max_export_timeout(mut self, max_export_timeout: Duration) -> Self {
         self.max_export_timeout = max_export_timeout;
@@ -658,6 +672,10 @@ impl BatchConfigBuilder {
     /// more than one batch worth of logs then it processes multiple batches
     /// of logs one batch after the other without any delay.
     /// The default value is 512.
+    ///
+    /// Corresponding environment variable: `OTEL_BLRP_MAX_EXPORT_BATCH_SIZE`.
+    ///
+    /// Note: Programmatically setting this will override any value set via the environment variable.
     pub fn with_max_export_batch_size(mut self, max_export_batch_size: usize) -> Self {
         self.max_export_batch_size = max_export_batch_size;
         self
@@ -774,6 +792,27 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_code_based_config_overrides_env_vars() {
+        let env_vars = vec![
+            (OTEL_BLRP_SCHEDULE_DELAY, Some("2000")),
+            (OTEL_BLRP_MAX_QUEUE_SIZE, Some("4096")),
+            (OTEL_BLRP_MAX_EXPORT_BATCH_SIZE, Some("1024")),
+        ];
+
+        temp_env::with_vars(env_vars, || {
+            let config = BatchConfigBuilder::default()
+                .with_max_queue_size(2048)
+                .with_scheduled_delay(Duration::from_millis(1000))
+                .with_max_export_batch_size(512)
+                .build();
+
+            assert_eq!(config.scheduled_delay, Duration::from_millis(1000));
+            assert_eq!(config.max_queue_size, 2048);
+            assert_eq!(config.max_export_batch_size, 512);
+        });
+    }
+
     #[test]
     fn test_batch_config_configurable_by_env_vars() {
         let env_vars = vec![

opentelemetry-sdk/src/logs/logger_provider.rs

@@ -200,15 +200,22 @@ impl LoggerProviderBuilder {
         LoggerProviderBuilder { processors, ..self }
     }
 
-    /// Adds a [BatchLogProcessor] with the configured exporter to the pipeline.
+    /// Adds a [BatchLogProcessor] with the configured exporter to the pipeline,
+    /// using the default [super::BatchConfig].
+    ///
+    /// The following environment variables can be used to configure the batching configuration:
+    ///
+    /// * `OTEL_BLRP_SCHEDULE_DELAY` - Corresponds to `with_scheduled_delay`.
+    /// * `OTEL_BLRP_MAX_QUEUE_SIZE` - Corresponds to `with_max_queue_size`.
+    /// * `OTEL_BLRP_MAX_EXPORT_BATCH_SIZE` - Corresponds to `with_max_export_batch_size`.
     ///
     /// # Arguments
     ///
-    /// * `exporter` - The exporter to be used by the BatchLogProcessor.
+    /// * `exporter` - The exporter to be used by the `BatchLogProcessor`.
     ///
     /// # Returns
     ///
-    /// A new `Builder` instance with the BatchLogProcessor added to the pipeline.
+    /// A new `LoggerProviderBuilder` instance with the `BatchLogProcessor` added to the pipeline.
     ///
     /// Processors are invoked in the order they are added.
     pub fn with_batch_exporter<T: LogExporter + 'static>(self, exporter: T) -> Self {