Tech-Reader.blog

  The Secret Life of JavaScript: The Rejection # JavaScript # AsyncAwait # ErrorHandling # Webdev Why async errors bypass try/catch, and how to fix them. Timothy felt invincible. He had learned the mechanics of Stack Unwinding. He had placed a strategic  try/catch  boundary at the top of his application. He was a master of disaster recovery. Then, he wrote a new network request. function loadDashboard () { try { // Initiating a background network request fetch ( ' /api/corrupted-data ' ); console . log ( " Dashboard loading... " ); } catch ( error ) { console . error ( " Safe Landing: " , error . message ); } } loadDashboard (); Timothy ran the code. The console printed  Dashboard loading... . Two seconds later, a massive red error filled the screen:  UnhandledPromiseRejection: Failed to fetch . Timothy stared at the screen. The application had crashed. "But... I put it inside a  try/catch ,...

  The Secret Life of AWS: Cross-Network Communication (VPC Peering) # AWS # VPC # Peering # CloudArchitecture Connecting isolated environments without touching the public internet. Part 43 of The Secret Life of AWS Timothy was staring at a connection timeout error. Following Margaret's advice from the previous week, he had fully embraced network isolation. When he was tasked with building a new "Inventory" microservice, he created a brand new Virtual Private Cloud (VPC) for it, completely separate from the "Checkout" VPC. Now, the Inventory service needed to query the Checkout database. "They are in two different VPCs," Timothy explained to Margaret. "I can't connect them. I was thinking of attaching a NAT Gateway to the Inventory VPC and routing the traffic over the public internet to the Checkout VPC's public endpoint... but we just made the database private." "Exactly," Margaret said. "We did not isolate the database...

  AWS Under Real Load: Event Notification Fan-Out Storms in Amazon S3 # AWS # S3 # Serverless # CloudOps A production-grade diagnostic and prevention guide for cascading compute bursts and system instability caused by high-volume S3 event notifications. Problem A system that relies on S3 event notifications begins experiencing: Sudden Lambda concurrency spikes Increased SQS queue depth Rising processing latency Downstream timeouts Unexpected cost surges No visible S3 errors PUT and DELETE operations succeed. But the compute layer destabilizes. The storage tier looks healthy. The event-driven tier is overwhelmed. Clarifying the Issue S3 Event Notifications trigger downstream services for object events such as: s3:ObjectCreated:* s3:ObjectRemoved:* s3:ObjectRestore:* Under light traffic, this works seamlessly. Under heavy object churn, each object operation generates an event. High ingestion rates or mass deletes create: One object → one event 10,000 objects → 10,000 events 1 million...

  The Secret Life of AWS: Network Isolation (VPC & Security Groups) # AWS # VPC # Security # DevOps Why your database shouldn't have a public IP address. Part 42 of The Secret Life of AWS Timothy was proud of his new microservice. He had successfully connected his serverless application to an Amazon RDS PostgreSQL database. "The latency is great," Timothy told Margaret, bringing up his dashboard. "I can query the database directly from my local machine using pgAdmin, and the application connects perfectly." Margaret leaned in and looked at the connection string on his screen. Host: checkout-db.c3x...us-east-1.rds.amazonaws.com She opened the AWS Console, navigated to the RDS instance, and checked the network settings. Publicly Accessible: Yes Security Group Inbound Rules:   PostgreSQL (5432) | Source: 0.0.0.0/0 Margaret sighed. "Timothy, your database is sitting on the public internet." "I know," Timothy said. "I had to set it to ...