feat(vlog): Report observability config, flush, and shutdown

core/lib/config/Cargo.toml

@@ -16,6 +16,7 @@ zksync_crypto_primitives.workspace = true
 zksync_consensus_utils.workspace = true
 zksync_concurrency.workspace = true
 zksync_vlog = { workspace = true, optional = true }
+tracing = { workspace = true, optional = true }
 
 url.workspace = true
 anyhow.workspace = true
@@ -25,4 +26,4 @@ serde = { workspace = true, features = ["derive"] }
 
 [features]
 default = []
-observability_ext = ["zksync_vlog"]
+observability_ext = ["zksync_vlog", "tracing"]

core/lib/config/src/observability_ext.rs

@@ -16,6 +16,9 @@ impl ObservabilityConfig {
             .with_sentry(sentry)
             .with_opentelemetry(opentelemetry)
             .build();
+
+        tracing::info!("Installed observability stack with the following configuration: {self:?}");
+
         Ok(guard)
     }
 }

core/lib/vlog/src/lib.rs

@@ -42,6 +42,7 @@ impl ObservabilityGuard {
 
         if let Some(sentry_guard) = &self.sentry_guard {
             sentry_guard.flush(Some(FLUSH_TIMEOUT));
+            tracing::info!("Sentry events are flushed");
         }
 
         if let Some(provider) = &self.otlp_tracing_provider {
@@ -50,6 +51,7 @@ impl ObservabilityGuard {
                     tracing::warn!("Flushing the spans failed: {err:?}");
                 }
             }
+            tracing::info!("Spans are flushed");
         }
 
         if let Some(provider) = &self.otlp_logging_provider {
@@ -58,6 +60,7 @@ impl ObservabilityGuard {
                     tracing::warn!("Flushing the logs failed: {err:?}");
                 }
             }
+            tracing::info!("Logs are flushed");
         }
     }
 
@@ -70,15 +73,20 @@ impl ObservabilityGuard {
         // `take` here and below ensures that we don't have any access to the deinitialized resources.
         if let Some(sentry_guard) = self.sentry_guard.take() {
             sentry_guard.close(Some(SHUTDOWN_TIMEOUT));
+            tracing::info!("Sentry client is shut down");
         }
         if let Some(provider) = self.otlp_tracing_provider.take() {
             if let Err(err) = provider.shutdown() {
                 tracing::warn!("Shutting down the OTLP tracing provider failed: {err:?}");
+            } else {
+                tracing::info!("OTLP tracing provider is shut down");
             }
         }
         if let Some(provider) = self.otlp_logging_provider.take() {
             if let Err(err) = provider.shutdown() {
                 tracing::warn!("Shutting down the OTLP logs provider failed: {err:?}");
+            } else {
+                tracing::info!("OTLP logs provider is shut down");
             }
         }
     }