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Managing Multiple AWS Accounts with CLI Profiles: A Practical Guide

Running work and personal AWS accounts from the same machine is a common reality for engineers — and without a proper profile strategy, you risk deploying personal side projects into your company's production account, or worse, billing your employer for your weekend experiments. TL;DR Step Action File Modified 1 Add named credentials ~/.aws/credentials 2 Add named config (region, output) ~/.aws/config 3 Use --profile flag per command CLI invocation 4 (Optional) Set AWS_PROFILE env var Shell session How AWS CLI Profile Resolution Works The AWS CLI uses a layered credential resolution chain. Named profiles are stored across two files: ~/.aws/credentials (access keys) and ~/.aws/config (region, output format, and advanced settings). The default profile is used when no profile is explicitly specified. Every other named profile must be referenced explicitly — either via the --profile flag or t...
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Scaling Reads with RDS Read Replicas: Architecture, Load Distribution & Multi-AZ Comparison

Your application's read traffic has outpaced your primary RDS instance — SELECT queries are piling up, latency is climbing, and vertical scaling is hitting diminishing returns. This is a classic read-heavy workload problem, and RDS Read Replicas are the purpose-built solution. But engineers frequently conflate Read Replicas with Multi-AZ deployments — they look similar on the surface but solve fundamentally different problems. TL;DR Dimension Read Replica Multi-AZ Primary Purpose Scale read throughput High availability / failover Replication Type Asynchronous Synchronous Replica is Queryable? Yes — has its own endpoint No — standby is passive Failover Target? Manual promotion required Automatic failover Cross-Region Support Yes No (same region, different AZ) Use Case Reporting, analytics, read scaling Production HA, DR within region The Core Problem: Read-Heavy Workloads A single RDS ...
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Security Group vs. Network ACL: Stateful vs. Stateless Traffic Filtering in AWS VPC

When designing network security in AWS VPC, engineers routinely confuse Security Groups and Network ACLs — both filter traffic, but they operate at fundamentally different layers, with different state-tracking behaviors that can cause subtle, hard-to-debug connectivity failures if misunderstood. TL;DR — Quick Comparison Attribute Security Group (SG) Network ACL (NACL) Applies To ENI (instance/resource level) Subnet level State ✅ Stateful ❌ Stateless Rule Direction Inbound & Outbound (return traffic auto-allowed) Inbound & Outbound rules evaluated independently Rule Type Allow only (implicit deny) Allow & Deny (explicit) Rule Evaluation All rules evaluated together Rules evaluated in numbered order (lowest first) Default Beh...
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How to Draw Support and Resistance Lines on Charts

Why Support and Resistance Lines Are the Foundation of Every Trade Support and resistance lines are the most fundamental tools for identifying where price stops and reverses on any chart — and mastering them can transform how you read the market forever. Whether you're trading stocks, crypto, or forex, these invisible walls and floors shape every price move you see. Miss them, and you're trading blind. Spot them correctly, and you'll know exactly where the crowd is watching — and where the real money is positioned. The Core Concept: Floors, Ceilings, and the Crowd's Memory Think of price action like a bouncing ball inside a room. The floor is your support level — a price zone where buyers consistently step in and stop the price from falling further. The ceiling is your resistance level — a price zone where sellers overwhelm buyers and push the price back down. Support : A price level where demand is strong enough to halt ...
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