[AWS] Lab: CloudFormation and SAM to deploy a Serverless fuction

Task Breakdown

1. Install the AWS SAM CLI on your local machine
2. Create an S3 bucket
3. Use `sam package` to package our code and save it in S3
4. Use `sam deploy` to deploy a Lambda function using CloudFormation

Install SAM CLI

Guide

Create an S3 bucket

Make user your IAM user has access to S3

aws iam get-user

Then find the user in IAM to make sure it has 

`AmazonS3FullAccess`

Create an S3 bucket

aws s3 mb s3://<bucket-name> --region us-esat-1

Resource files:

Lambda.yml

AWSTemplateFormatVersion: "2010-09-09"
Transform: AWS::Serverless-2016-10-31
Resources:
  TestFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: index.handler
      Runtime: nodejs12.x
      Environment:
        Variables:
          S3_BUCKET: <YOUR_BUCKET_NAME>

index.js

exports.handler = (event, context, callback) => {
    // TODO implement
    const response = {
        statusCode: 200,
        body: JSON.stringify('Hello Cloud Gurus, This Lambda Function was deployed using SAM!')
    };
    callback(null, response);
};

SAM package

Make sure put those two files in the same folder and run cmd:

sam package --template-file ./Lambda.yml --output-template-file sam-template.yml --s3-bucket <YOUR_BUCKET_NAME> 

Replacae <Your_BUCKET_NAME>.

That cmd will package our code and output `sam-template.yml` file in our folder.

SAM deploy

Now it's time to deploy:

sam deploy --template-file sam-template.yml --stack-name <STACK_NAME> --capabilities CAPABILITY_IAM

Make sure you have permission to deploy the CloudFormation. If you have AdminAccess then it is fine. Otherwise, you need to give `EC2, CloudFormation, S3, Lambda, IAM full access`.

 

Lambda

Last, you can go to Lambda, find newly create lambda, run the test, to make sure, SAM has deploy a Lmabda by using CloudFormation.

Summary

If you want to deploy a serverless function, you can use SAM CLI.

1. It create bucket on S3 and save the CloudFormation template
2. sam package & sam deploy cmds.