In this article, I will show you how to build a microservice with AWS Lambda and API Gateway.
What are AWS Lambda and API Gateway
AWS Lambda lets you run your code without provisioning or managing any servers. This gives you a completely serverless architecture with little to no effort on maintenance.
Amazon API Gateway is a fully managed service for managing your APIs. In order for your Lambda to run, it will need a trigger event. AWS allows you to attach multiple different event sources, like SQS, DynamoDB Streams, but in this article, I will focus on API Gateway.
By setting API Gateway as the event source, Lambda can receive your API input and send the output back to API Gateway.
What is AWS CloudFormation?
AWS CloudFormation allows you to create your infrastructure as code. And by deploying your CloudFormation script, AWS will automatically provision all resources specified. This script will serve as the single source of truth for your cloud environment.
Let’s Get Started
LambdaFunction creates a Lambda function called SampleLambda with a memory size of 128 mb and a timeout of 10 seconds.
LambdaFunction: Type: AWS::Lambda::Function Properties: Code: S3Bucket: <BUCKET_NAME> S3Key: <BUCKET_KEY> Description: Sample Lambda FunctionName: SampleLambda Handler: main MemorySize: 128 Role: !GetAtt LambdaFunctionRole.Arn Runtime: go1.x Timeout: 10
LambdaFunctionRole creates a Lambda IAM role called SampleLambdaRole. This gives your Lambda permissions to perform certain actions. The role below allows your Lambda to perform X-Ray PutTraceSegments and PutTelemetryRecords.
LambdaFunctionRole: Type: AWS::IAM::Role Properties: RoleName: SampleLambdaRole AssumeRolePolicyDocument: Version: '2012-10-17' Statement: - Effect: Allow Action: sts:AssumeRole Principal: Service: - lambda.amazonaws.com Path: '/' Policies: - PolicyName: XRayPolicy PolicyDocument: Version: '2012-10-17' Statement: - Effect: Allow Action: - xray:PutTraceSegments - xray:PutTelemetryRecords Resource: '*'
Api creates an API Gateway from a Swagger/OpenAPI file. By doing so, you can document your API at the same time. One limitation is that you will need to upload your Swagger file to S3 before deploying CloudFormation.
ApiAccount allows you to attach a CloudWatch role to your API Gateway.
ApiStage creates an API stage and
ApiDeployment deploys your API stage.
Api: Type: AWS::ApiGateway::RestApi Properties: Name: SampleAPIGateway Description: Sample API Gateway EndpointConfiguration: Types: - REGIONAL Body: Fn::Transform: Name: AWS::Include Parameters: Location: !Sub s3://swagger.yaml
ApiAccount: Type: AWS::ApiGateway::Account Properties: CloudWatchRoleArn: !GetAtt CloudWatchRole.Arn
CloudWatchRole: Type: AWS::IAM::Role Properties: AssumeRolePolicyDocument: Version: '2012-10-17' Statement: - Effect: Allow Action: sts:AssumeRole Principal: Service: - apigateway.amazonaws.com Path: '/' ManagedPolicyArns: - 'arn:aws:iam::aws:policy/service-role/AmazonAPIGatewayPushToCloudWatchLogs'
ApiStage: Type: 'AWS::ApiGateway::Stage' DependsOn: - ApiAccount Properties: DeploymentId: !Ref ApiDeployment MethodSettings: - DataTraceEnabled: true HttpMethod: '*' LoggingLevel: INFO ResourcePath: /* RestApiId: !Ref Api StageName: !Ref StageParameter
ApiDeployment: Type: AWS::ApiGateway::Deployment Properties: RestApiId: !Ref Api
Congratulations! You now have a CloudFormation script ready to deploy.
But before you can deploy, you will need to run the
package command. This will transform your Swagger file and add it to packaged-template.yaml.
$ aws cloudformation package --template-file template.yaml --s3-prefix $BUCKET_KEY --s3-bucket $BUCKET_NAME --output-template-file packaged-template.yaml
Next, run the
deploy command to deploy the Lambda and API Gateway to your AWS account.
$ aws cloudformation deploy --template-file packaged-template.yaml --stack-name sample-stack --capabilities CAPABILITY_NAMED_IAM
Hope this article helped build a microservice with AWS Lambda and API Gateway using CloudFormation.
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