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AWS Lambda

A. Lambda:Function

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  • lambda initially was FaaS. Now serverless : provision code/function
  • lambda@edge - globally service. 👈
  • author: us-east-1
  • replicated to edge location from author.
  • invoke:
  • by services(eg: s3 trigger lambda)
  • by SDK/CLI
    • --invocation-type Event for making async call from cli
  • Avoid using recursive code, never have a Lambda function call itself 👈 👈
  • can create vpce (PrivateLink)

1. Scaling

  • auto-scale with load(parallel Lambdas,max- 1000`)
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2. Network ⭕️

  • default: run in aws owned VPC (has public internet access)
  • run inside our VPC-1 and subnet
  • attach ENI to lambda
    • ENI has SG
    • define ingress/egress.
  • deployed in private subnet --> don't have internet access
  • deployed in public subnet (igw attached)
    • still don't have internet access by-default 👈 👈
  • Get internet access with NAT
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    • deploy lambda in private subnet
    • update rtb, to route traffic 0.0.0.0.\0 traffic to NAT gateway
    • this is the only way.

3. Pricing

  • cost-efficient
  • no of call: First 1M free, then 20cent/million req
  • cpu usage: First 400K GB-second free, then $1/600K GB-second

4. Security

  • Attach IAM role with fine grain access to lambda. eg:
  • cw:log-group
  • sqs:poll (event source mapping)
  • ...
  • lambda resource based policy
  • who can invoke the Lambda function and under what conditions
  • eg: allow S3 bucket:

5. programming things 📚

5.-1. create function:

5.0. Basic

  • compute-time /timeout:
  • 0 - 15 min
  • or, 0 - 900 sec

  • default : 3 seconds

  • handler : file.method (eg: l_function.l_handler(event,context))

  • context - metadata about the Lambda function execution environment.
    • re-use for multiple invocation.
    • great for DB connection, Http client, etc
    • cold start: first call will have latency to init context.
  • event - contains the input data for the Lambda function.

  • sample: 03_lambda-dva-03-context+event.md

  • language/runtime :

  • node, py, java, Golang, C#/Ruby, Custom Runtime - rust/golang
  • java 11 or above : performance is 10x (free) - SnapStart feature 👈

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  • build pkg size :

  • 50 MB compressed
  • 250 MB code+dependency

5.1 resource

  • RAM : 128 MB -10 GB
    • implicitly improves network as well
    • implicitly add more CPU credit.
  • disk
    • /tmp- ephemeral storage :
    • space for writing temp files.
    • no shared.
    • 512 MD to 10 GB
    • if needed permanent space, use:
    • s3,
    • EFS : very fast (if running inside our vpc-1) 👈
    • can be shared among lambda/s
    • programmatically encrypt /tmp using KMS keys. generate ir first.
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5.2. ENV var

  • 4 KB
  • can encrypt them as well 👈
  • sample py code: 
    import os;
os.getenv("ENV_VAR_1")

5.3. Monitor ⭕️

  • inbuilt metric
  • iterator-age: can check stream iterator/offset/sequence 👈
  • concurrent-execution
  • Throttle
  • Async delivery failure
  • ...
  • log-group : /aws/lambda/lambda-1/
  • traces 👈
  • Enable Active Tracing, to run the X-Ray daemon
  • add this to Lambda-role : AWSXRayDaemonWriteAccess
  • Environment variables to communicate with X-Ray
    • _X_AMZN_TRACE_ID: contains the tracing header
    • AWS_XRAY_CONTEXT_MISSING: by default, LOG_ERROR
    • AWS_XRAY_DAEMON_ADDRESS: the X-Ray Daemon IP_ADDRESS:PORT
  • Use AWS X-Ray SDK in Code
    • use these env var and write trace.

5.4. lambda layer

img_1.png - 5 layer max - 250 MB total - aws-sdk dependency : no need to pkg in zip. :)

5.5. Lambda Container Image

  • run docker image in lambda Function
  • base image : lambda runtime API
  • eg: FROM amazon/aws-lambda-nodejs:12
  • to run javacode, provides JVM runtime.
  • similar provide container-d runtime.
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5.6. Concurrency

  • set reservedConcurrency
  • max/default = 1000 (can be increased on request)

  • combined for all function/s together. 👈

    • function-1 has 500 invocation
    • function-2 has 500 invocation
    • function-3 will get retry first and then give ThrottleError (429)

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  • retry:
  • for sync invocation - 2 times

  • for a-sync invocation:

    • retry attempt exponentially increases from 1 second - 5 minutes
    • max 6 hrs

  • provisioned concurrency

  • configure it to have warm start, else cold-start.

5.7 CodeGuru (java/py)

  • developer tool powered by machine learning (ML)
  • Identifies performance bottlenecks
  • Offers recommendations to optimize CPU and memory usage, helping to reduce costs
  • Enforces coding standards and recommends fixes for anti-patterns

  • Detects common security vulnerabilities

  • When activated, Lambda adds:

  • CodeGuruProfiler layer to function
  • Env vars to your function
  • AmazonCodeGuruProfilerAgentAccess policy to your function

5.8 version and alias

  • publish function to create version 1,2... immutable
  • arn:aws:lambda:us-east-1:123456789012:function:function-1:alias/version
  • current version : $LATEST - mutable (edit code)
  • create alias to point one specfic version
  • alias1 --> version 1,2...
  • alias1 --> ❌ --> alias-2
  • weight alias (canary model)
    • alias1 (1-2-M)
    • 90% --> v1
    • 10% --> v2
  • eg:
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5.9 integration with codeDeploy

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5.10 Function URL

  • expose function-1:version-1/alias with Dedicated HTTP(S) endpoint.
  • https://<url-id>.lambda-url..on.aws (dual-stack IPv4 & IPv6)
  • Access your function URL through the public Internet only
  • Doesn’t support PrivateLink / vpce 👈
  • security:
  • Supports Resource-based Policies
  • CORS configurations
  • set Throttle. eg: seservedConcurrency=10
  • AuthType== NONE (allow public and unauthenticated access)
  • AuthType== AWS_IAM
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B. integration with other services :green_circle:

  • lambda trigger patterns: 👈
  • Event source mapping
  • Synchronous
  • A-synchronous

  • details: 03_lambda-dva-02-trigger.md for details

  • all common eg:

  • API-gateway (REST) >> lambda
  • ALB >> target-group-1:lambda ⭕️
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  • S3:objectcreate,etc >> lambda ⭕️
  • CW:log-event||loggroup-subscription-filter >> lambda (log-processing)
  • DynamoDB-streams >> lambda
  • SQS/SNS:consumer > Consumer/Subscriber > lambda/s ⭕️
  • KDS:consumer >> Lambda/s
  • web-client-req --> CloudFront ( lambda@Edge :customize req+some processing ) --> origin
  • IAM:cognito >> Lambda
  • other services's event >> eventBridge(EventRule/cron scheduler) >> Lambda 👈
    • codePipeline's in-built event, say e1 > eventBridge(bus) > EventRule-1 (capture e1) > lambda-1 (process)
    • ...
    • generic pattern :)
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C. Architecture example

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D. extra

1. limit summary

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