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Developing and Deploying with SAM CLI

Learn about Developing and Deploying with SAM CLI as part of Serverless Architecture with AWS Lambda

Table of Contents

Developing and Deploying with AWS SAM CLI

The AWS Serverless Application Model (SAM) Command Line Interface (CLI) is a powerful tool that simplifies the development, testing, and deployment of serverless applications on AWS. It provides a consistent workflow for building applications that leverage AWS Lambda, API Gateway, DynamoDB, and other AWS services.

What is SAM CLI?

SAM CLI is an open-source framework for building serverless applications. It extends AWS CloudFormation to provide shorthand syntax to define functions, APIs, databases, and event source mappings. With SAM CLI, you can define your serverless application's infrastructure as code, making it repeatable and manageable.

SAM CLI streamlines serverless development by providing local testing and simplified deployment.

SAM CLI allows you to build, test, and debug your serverless applications locally before deploying them to AWS. This significantly speeds up the development cycle and reduces the risk of deployment errors.

The core functionality of SAM CLI revolves around its ability to simulate AWS Lambda and API Gateway environments on your local machine. This means you can write your Lambda function code, define your application's resources using a SAM template, and then use SAM CLI commands to build, invoke, and test your functions locally. Once you're satisfied with the local testing, SAM CLI can package your application and deploy it to your AWS account using CloudFormation, ensuring a consistent and repeatable deployment process.

Key SAM CLI Commands and Workflow

The typical workflow with SAM CLI involves several key commands:

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1. Initialize Project (`sam init`)

This command bootstraps a new serverless application project. You can choose from various runtime templates (e.g., Python, Node.js, Java) and project structures. It creates a

code
template.yaml
file, which defines your serverless resources, and a sample Lambda function.

2. Build Application (`sam build`)

The

code
sam build
command compiles your application code and dependencies. It reads your
code
template.yaml
file, identifies the Lambda functions, and prepares them for local execution or deployment. This step ensures that all necessary libraries and packages are included.

3. Test Locally (`sam local invoke`, `sam local start-api`)

SAM CLI provides commands to invoke your Lambda functions locally with sample event data (

code
sam local invoke
) or to run a local API Gateway endpoint that simulates your application (
code
sam local start-api
). This allows for rapid iteration and debugging without deploying to AWS.

Local testing is crucial for catching bugs early and ensuring your Lambda functions behave as expected before going live.

4. Package and Deploy (`sam package`, `sam deploy`)

The

code
sam package
command packages your application code and dependencies into a deployable artifact (e.g., a ZIP file) and uploads it to an S3 bucket. The
code
sam deploy
command then takes this artifact and the
code
template.yaml
file to create or update your serverless application in AWS using CloudFormation. You can automate deployments using CI/CD pipelines.

Benefits of Using SAM CLI

FeatureBenefit
Local Development & TestingFaster iteration, reduced debugging time, offline development.
Infrastructure as CodeRepeatable deployments, version control, easier management of resources.
Simplified DeploymentAutomates packaging and CloudFormation deployment, reducing manual effort.
Cost EfficiencyCatching errors locally prevents unnecessary AWS resource usage and costs.
Integration with AWS ServicesSeamlessly works with Lambda, API Gateway, DynamoDB, and more.

Advanced SAM CLI Features

SAM CLI also supports features like local debugging with IDE integration, custom build methods, and integration with AWS X-Ray for tracing.

What is the primary purpose of the sam build command?

To compile application code and dependencies, preparing them for local execution or deployment.

Which SAM CLI command simulates a local API Gateway endpoint for your serverless application?

sam local start-api

Learning Resources

AWS SAM CLI Documentation(documentation)

The official AWS documentation for installing and getting started with the SAM CLI, covering its core commands and concepts.

AWS SAM CLI GitHub Repository(documentation)

Explore the source code, report issues, and contribute to the AWS SAM CLI project. This is a great resource for understanding its inner workings.

Building Serverless Applications with AWS SAM(blog)

An introductory blog post from AWS that walks through the basics of building serverless applications using SAM and SAM CLI.

Local Debugging with AWS SAM CLI(documentation)

Learn how to set up and use local debugging capabilities with SAM CLI, integrating with popular IDEs like VS Code and PyCharm.

AWS SAM Templates(documentation)

Understand the structure and syntax of SAM templates, which are essential for defining your serverless application's resources.

AWS Lambda Developer Guide(documentation)

The comprehensive guide to AWS Lambda, providing details on function configuration, event sources, and best practices relevant to SAM development.

Serverless Patterns with AWS SAM(video)

A video tutorial demonstrating common serverless patterns and how to implement them using AWS SAM CLI.

AWS SAM CLI: Local Testing and Debugging(video)

A practical video guide focusing on the local testing and debugging features of the AWS SAM CLI.

Deploying Serverless Applications with SAM(blog)

An announcement and explanation of the `sam deploy` command, detailing how it simplifies the deployment process to AWS.

Serverless Application Model (SAM) - Wikipedia(wikipedia)

An overview of the AWS Serverless Application Model, providing context and a general understanding of its role in serverless development.