Improve Developer Workflow with ECS Multi-Service Deployment Using AppConfig and GitHub Actions

In this build session, we deploy a full 3-tier application on ECS with a Vue.js frontend, Flask backend, and MySQL database. Instead of hardcoding everything, we use AWS AppConfig to let developers control deployments and influence running applications without touching infrastructure code. We build a two-workflow pattern: first workflow builds images and publishes configuration to AppConfig, then a second dispatchable workflow lets teams deploy by simply choosing their application profile and environment. 🧱 What We're Building ➜ Vue.js frontend serving the UI ➜ Flask (FastAPI) backend with REST API ➜ MySQL database for persistence ➜ All three tiers running on ECS (Fargate + EC2 launch types) behind an ALB ➜ Service Connect for internal service discovery ➜ Secrets Manager for database credentials ➜ ECR for container image storage ➜ AppConfig for deployment configuration and feature flags ➜ Two-stage GitHub Actions workflow: build → publish → deploy docker build → ECR push → AppConfig publish → workflow dispatch → ECS deployment 🔍 What We Covered ✅ Why self-managed services make sense for non-prod environments to save cost ✅ Building a 3-tier application with Vue.js, FastAPI, and MySQL ✅ Containerizing each tier with production-ready Dockerfiles ✅ Using ECS Service Connect for service-to-service communication ✅ Storing database credentials in Secrets Manager and injecting them into ECS tasks ✅ Building and pushing multi-service images to ECR with change detection ✅ Introducing AWS AppConfig as a deployment configuration store ✅ Publishing deployment manifests to AppConfig with image tags and environment variables ✅ Smart merging of environment variables to preserve manual feature flags ✅ Creating a dispatchable workflow that deploys from AppConfig ✅ Letting developers choose application ID, profile ID, and environment to deploy ✅ Updating ECS task definitions with new images and environment variables from AppConfig ✅ Waiting for service stability and verifying deployment health ✅ Testing the full application stack through the ALB 🧩 Why This Matters ➜ AppConfig decouples deployment configuration from infrastructure code ➜ Developers can influence running applications without modifying Terraform or workflows ➜ The two-workflow pattern separates build concerns from deployment concerns ➜ Smart environment variable merging preserves manual feature flags ➜ Service Connect simplifies service discovery without hardcoding endpoints ➜ Secrets Manager keeps credentials out of code and environment variables ➜ Teams can deploy specific versions by choosing AppConfig profiles ➜ Self-managed MySQL in non-prod saves cost compared to RDS Grab the source code here https://github.com/brainyl/brainyl_do... — Build with Brainyl