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AWS Lambda

Development with AWS Services

Event-driven, serverless compute that runs code without provisioning servers.

Core concepts

▸Max execution timeout: 15 minutes.
▸Memory: 128 MB – 10,240 MB; CPU scales proportionally with memory.
▸/tmp ephemeral storage: up to 10,240 MB, persists only for the life of the execution environment.
▸Deployment package limits: 50 MB zipped (direct upload), 250 MB unzipped, 10 GB for container images.

▸Reserved concurrency: caps AND guarantees a max number of concurrent executions for a function.
▸Provisioned concurrency: pre-initializes environments to eliminate cold starts for predictable load.
▸Unreserved account concurrency is shared across all functions without reserved concurrency.

▸Versions are immutable snapshots of code + config; $LATEST is always mutable.
▸Aliases are mutable pointers to a version, and can split traffic by weight between two versions.
▸CodeDeploy automates canary/linear traffic shifting between versions via an alias, with alarm-based rollback.

▸Synchronous invocations: API Gateway, ALB, direct SDK calls — caller waits for a response.
▸Asynchronous invocations: S3 events, SNS — Lambda retries automatically and can send failures to a DLQ or Lambda Destination.
▸Poll-based (event source mapping): SQS, Kinesis, DynamoDB Streams — Lambda service polls on your behalf.
▸Lambda Destinations route async/stream success or failure results to SQS, SNS, EventBridge, or another Lambda — richer than a DLQ.