SW BBANG

You have a DynamoDB table and you need to react to every write — inserts, updates, deletes — without polling or building a change-detection layer yourself. DynamoDB Streams with Lambda as an event source is the standard pattern for this, but the wiring has enough moving parts that it's easy to get the IAM wrong, pick the wrong stream view type, or misconfigure the event source mapping and wonder why your function never fires. TL;DR: DynamoDB Streams + Lambda Event Source Mapping Step What You're Doing Key Decision 1 Enable Streams on the table Choose StreamViewType (NEW_IMAGE is the most common) 2 Grant Lambda permission to read the stream Attach AWSLambdaDynamoDBExecutionRole or equivalent custom policy 3 Create the Event Source Mapping Set StartingPosition, BatchSize, and bisect-on-error behavior 4 Validate end-to-end Write a test item, check CloudWatch Logs for invocation How DynamoDB Str...

When a company outgrows a single AWS account — dev workloads sharing blast radius with production, billing impossible to attribute, security policies applied inconsistently — the answer is almost always AWS Organizations. Setting up separate accounts for dev, staging, and production sounds straightforward, but the real value comes from understanding how Organizational Units, Service Control Policies, and consolidated billing interact before you start moving resources. TL;DR: AWS Organizations Multi-Account Setup Concern AWS Organizations Feature Scope Centralized billing Consolidated billing (automatic) Organization root Environment isolation Separate accounts per env Account level Policy guardrails Service Control Policies (SCPs) OU or account level Account provisioning AWS Organizations API / Control Tower Management account Cross-account access IAM roles with trust policies Member account Ho...

You have a content pipeline — articles, blog posts, documentation — and you want to ship an audio version without standing up a separate TTS infrastructure. Amazon Polly lets you call a single API, get back an MP3 stream, and pipe it directly to S3. The tricky part is understanding which voice options are available for non-English languages like Korean, and how the neural vs. standard engine selection affects both quality and cost. TL;DR: Amazon Polly Text-to-Speech Pipeline Step Action Key Decision 1 Choose engine (Neural vs. Standard) Neural sounds better; not all voices support it 2 Select voice ID for target language Korean: Seoyeon (Neural supported) 3 Call SynthesizeSpeech or StartSpeechSynthesisTask Short text → SynthesizeSpeech; long text → async task 4 Write audio stream to S3 Use PutObject or let Polly write directly via async task How Amazon Polly Text-to-Speech Works Polly exposes two s...

You have a production S3 bucket and want a live backup copy in the same AWS region — not for disaster recovery across regions, but for data redundancy, compliance isolation, or log aggregation into a single bucket. Same-Region Replication (SRR) handles exactly this, but the IAM role configuration is where most engineers get stuck. A misconfigured replication role fails silently: the replication rule shows as 'Enabled' in the console, but objects never appear in the destination bucket. TL;DR: S3 Same-Region Replication Setup Step What You Do Common Mistake 1. Enable versioning Both source and destination buckets Forgetting the destination bucket 2. Create IAM role Trust policy for S3, permissions to read source and write destination Missing s3:ReplicateObject on destination 3. Configure replication rule Attach role, set destination bucket, define scope Role ARN typo causes silent failure 4. KMS (i...

You've got an S3 bucket filling up with user-uploaded photos, and someone asks: 'Can we auto-tag these with what's actually in them?' That's exactly the problem Amazon Rekognition's DetectLabels API solves — and wiring it to a Lambda function triggered by S3 uploads is the most common production pattern for this use case. TL;DR: Amazon Rekognition DetectLabels via Lambda Step What Happens 1. Image uploaded to S3 S3 event notification triggers Lambda 2. Lambda invokes DetectLabels Passes S3 bucket + object key to Rekognition 3. Rekognition returns labels JSON array with label names and confidence scores 4. Lambda stores results Write tags to DynamoDB, S3 metadata, or downstream system How Amazon Rekognition DetectLabels Works DetectLabels analyzes an image and returns a list of labels — objects, scenes, concepts, and activities detected in the image — each with a confidence ...