Add tracing

Cargo.toml

@@ -10,3 +10,5 @@ lambda_runtime = "0.8.1"
 serde = "1.0.164"
 serde_json = "1.0.97"
 tokio = "1.28.2"
+tracing = { version = "0.1.37", features = ["log"] }
+tracing-subscriber = { version = "0.3.17", features = ["fmt", "env-filter"] }

readme.md

@@ -9,3 +9,5 @@ Tested with Rust 1.73.0, Terraform 1.6.3.
 
 * [The Rust Lambda runtime](https://github.com/awslabs/aws-lambda-rust-runtime)
 * [Cargo Lambda](https://www.cargo-lambda.info/)
+* [tracing documentation](https://docs.rs/tracing/latest/tracing/)
+* [Lambda logging in Rust](https://docs.aws.amazon.com/lambda/latest/dg/rust-logging.html)

src/main.rs

@@ -19,8 +19,10 @@ fn say_hello(name: Option<&str>) -> HelloResponse {
 // Wrapper for our core function
 // Its role is to extract the relevant info from the incoming event, and convert the
 // response to json.
+#[tracing::instrument()]
 async fn run_lambda(event: LambdaEvent<Value>) -> Result<Value, Error> {
-    let (event, _context) = event.into_parts();
+    let (event, context) = event.into_parts();
+    tracing::info!(event = ?event, context = ?context);
 
     let name = event["name"].as_str();
     let result = say_hello(name);
@@ -30,6 +32,11 @@ async fn run_lambda(event: LambdaEvent<Value>) -> Result<Value, Error> {
 
 #[tokio::main]
 async fn main() -> Result<(), Error> {
+    tracing_subscriber::fmt()
+        .with_max_level(tracing::Level::INFO)
+        .with_ansi(false) // no colors as they look messed up in Cloudwatch
+        .init();
+
     lambda_runtime::run(service_fn(run_lambda)).await
 }