Lambda is a FaaS (Function as a service) product where you can upload your code and create functions. Functions are invoked by events and can be executed for up to 15 minutes.
Features
- Lambda is a serverless computing platform, which you can run code without managing server
- Lambda is highly available, fault-tolerant, and scalable – scales out (not up) automatically-.
- Functions are stateless – each run is clean.
- Execution Role is assumed by Lambda and temporary security credentials are available via STS.
- You can specify the Environment variables, which can be retrieved through the event object.
- Lambda is charged based on the run duration – the minimum billing duration is 100ms.
- Functions can trigger other functions. The architecture can be complicated. AWS X-ray can debug the function.
Lambda Function Configurations
- You can import code to Lambda in 3 ways:
- Uploading a zip file, uploading a file from S3, and editing inline code
- Supported Languages
- Node.js, .Net Core (C#/PowerShell), Java, Python, Ruby, and Go.
- Handler
- Memory Allocation: CPU scales with memory.
- Permission
Running a Lambda from Scratch
- Implement the logic in a supported programming language.
- Create a function, which has a unique name in a region in your account.
- Need to select the proper runtime to run the function.
- Proper permissions are needed: run the Lambda function, access CloudWatch’s log, and any necessary permission to access other services if required.
Invoking Lambda Functions
Lambda functions are triggered by events.
Events
- API Gateway – used to expose HTTP endpoint
- S3 file uploads
- CloudWatch scheduled events
- DynamoDB Streams change
- Direct Invocations using SDK or CLI
Synchronous Invokes
- Elastic Load Balancing (Application Load Balancer)
- Amazon Cognito
- Amazon Lex
- Amazon Alexa
- Amazon API Gateway
- Amazon CloudFront (Lambda@Edge)
- Amazon Kinesis Data Firehose
Asynchronous Invokes
- Amazon Simple Storage Service (S3)
- Amazon Simple Notification Service (SNS)
- Amazon Simple Email Service (SES)
- AWS CloudFormation
- Amazon CloudWatch Logs
- Amazon CloudWatch Events
- AWS CodeCommit
- AWS Config
Poll-Based Invokes
Lambda will poll the following services, retrieve data, and invoke functions.
- Amazon Kinesis
- Amazon SQS
- Amazon DynamoDB Streams
