aws_utils_lambda

AWS Lambda utilities for Rust, providing a simplified interface for AWS Lambda operations.

Features

• Easy client creation with automatic credential handling
• Lambda function invocation with comprehensive parameter support
• Error handling with custom error types
• Re-exports aws_sdk_lambda for direct access to AWS SDK types

Installation

Add this to your Cargo.toml:

[dependencies]
aws_utils_lambda = "0.1.0"

Usage

Creating a Lambda Client

use aws_utils_lambda;

#[tokio::main]
async fn main() {
    // Create client with default timeout configuration
    let client = aws_utils_lambda::make_client_with_timeout_default(None).await;
    
    // Create client with custom endpoint (e.g., for LocalStack)
    let client = aws_utils_lambda::make_client_with_timeout_default(Some("http://localhost:4566".to_string())).await;
}

The client uses the AWS SDK's default credential chain for authentication:

• Environment variables if set
• ECS task role (for Fargate/ECS)
• EC2 instance profile
• AWS credentials file
• Other configured credential providers

Timeout Configuration

use aws_utils_lambda::{make_client, make_client_with_timeout, make_client_with_timeout_default};
use std::time::Duration;

#[tokio::main]
async fn main() {
    // Use default timeout settings (recommended)
    let client = make_client_with_timeout_default(None).await;
    
    // Use custom timeout settings
    let client = make_client_with_timeout(
        None, // endpoint_url
        Some(Duration::from_secs(3100)), // connect_timeout
        Some(Duration::from_secs(60)),   // operation_timeout
        Some(Duration::from_secs(55)),   // operation_attempt_timeout
        Some(Duration::from_secs(50)),   // read_timeout
    ).await;
    
    // Use legacy client without timeout configuration
    let client = make_client(None, None, None).await;
}

Logging AWS Communication

make_client accepts an optional [SharedInterceptor]. By passing an interceptor that implements aws_sdk_lambda::config::Intercept, you can run custom logic — such as logging — every time the client communicates with AWS.

The interceptor below logs each request, response, and operation result. It uses the tracing crate, which is also what the AWS SDK uses internally.

use aws_utils_lambda::make_client;
use aws_sdk_lambda::config::{
    ConfigBag, Intercept, RuntimeComponents, SharedInterceptor,
    interceptors::{
        AfterDeserializationInterceptorContextRef, BeforeDeserializationInterceptorContextRef,
        BeforeTransmitInterceptorContextRef,
    },
};

type BoxError = Box<dyn std::error::Error + Send + Sync + 'static>;

#[derive(Debug, Clone)]
struct LoggingInterceptor;

impl Intercept for LoggingInterceptor {
    fn name(&self) -> &'static str {
        "LambdaLoggingInterceptor"
    }

    // Called just before each HTTP request is sent (once per retry attempt).
    fn read_before_transmit(
        &self,
        context: &BeforeTransmitInterceptorContextRef<'_>,
        _runtime_components: &RuntimeComponents,
        _cfg: &mut ConfigBag,
    ) -> Result<(), BoxError> {
        let request = context.request();
        tracing::info!(
            method = %request.method(),
            uri = %request.uri(),
            "Lambda -> AWS request"
        );
        Ok(())
    }

    // Called right after each HTTP response is received.
    fn read_before_deserialization(
        &self,
        context: &BeforeDeserializationInterceptorContextRef<'_>,
        _runtime_components: &RuntimeComponents,
        _cfg: &mut ConfigBag,
    ) -> Result<(), BoxError> {
        let response = context.response();
        tracing::info!(status = %response.status(), "AWS -> Lambda response");
        Ok(())
    }

    // Called once when the operation completes (after retries), with success or error.
    fn read_after_deserialization(
        &self,
        context: &AfterDeserializationInterceptorContextRef<'_>,
        _runtime_components: &RuntimeComponents,
        _cfg: &mut ConfigBag,
    ) -> Result<(), BoxError> {
        match context.output_or_error() {
            Ok(_) => tracing::info!("Lambda operation succeeded"),
            Err(err) => tracing::warn!(error = %err, "Lambda operation failed"),
        }
        Ok(())
    }
}

# async fn run() {
// Pass the interceptor as the third argument.
let client = make_client(None, None, Some(SharedInterceptor::new(LoggingInterceptor))).await;
# }

tracing does not emit anything until a subscriber is initialized. Set one up once in your application (for example with tracing-subscriber) and control verbosity with RUST_LOG:

// Add `tracing-subscriber` to your dependencies.
tracing_subscriber::fmt()
    .with_env_filter(
        tracing_subscriber::EnvFilter::try_from_default_env()
            .unwrap_or_else(|_| "info".into()),
    )
    .init();

Example output (RUST_LOG=info):

INFO LambdaLoggingInterceptor: Lambda -> AWS request method=POST uri=https://lambda.ap-northeast-1.amazonaws.com/
INFO LambdaLoggingInterceptor: AWS -> Lambda response status=200
INFO LambdaLoggingInterceptor: Lambda operation succeeded

Invoking Lambda Functions

use aws_utils_lambda::{lambda, aws_sdk_lambda::types::{InvocationType, LogType}};
use aws_sdk_lambda::primitives::Blob;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = aws_utils_lambda::make_client_with_timeout_default(None).await;
    
    // Simple invocation
    let result = lambda::invoke(
        &client,
        Some("my-function"),
        None,  // client_context
        None,  // invocation_type (defaults to RequestResponse)
        None,  // log_type
        Some(Blob::new(r#"{"key": "value"}"#)),
        None,  // qualifier
    ).await?;
    
    // Async invocation
    let result = lambda::invoke(
        &client,
        Some("my-function"),
        None,
        Some(InvocationType::Event),
        Some(LogType::Tail),
        Some(Blob::new(r#"{"key": "value"}"#)),
        Some("$LATEST"),
    ).await?;
    
    Ok(())
}

Error Handling

The crate provides custom error types that wrap AWS SDK errors:

use aws_utils_lambda::error::Error;

match lambda::invoke(&client, Some("my-function"), None, None, None, None, None).await {
    Ok(output) => {
        // Handle successful response
    }
    Err(Error::AwsSdk(e)) => {
        // Handle AWS SDK errors
    }
    Err(Error::BuildError(e)) => {
        // Handle build errors
    }
    Err(Error::ValidationError(msg)) => {
        // Handle validation errors
    }
}

API Reference

Client Creation Functions

• make_client_with_timeout_default(endpoint_url: Option<String>) - Creates a Lambda client with default timeout settings
• make_client_with_timeout(endpoint_url, connect_timeout, operation_timeout, operation_attempt_timeout, read_timeout) - Creates a Lambda client with custom timeout settings
• make_client(endpoint_url: Option<String>, timeout_config: Option<TimeoutConfig>, interceptor: Option<SharedInterceptor>) - Creates a Lambda client with optional custom endpoint, timeout configuration, and interceptor (e.g. for logging)

Lambda Functions

• lambda::invoke(client, function_name, client_context, invocation_type, log_type, payload, qualifier) - Invokes a Lambda function with comprehensive parameter support

Re-exports

The crate re-exports aws_sdk_lambda for direct access to AWS SDK types:

use aws_utils_lambda::aws_sdk_lambda::{types::InvocationType, primitives::Blob};

License

This project is licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.