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‎.env.example‎

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AWS_REGION=us-east-1
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AWS_ACCESS_KEY_ID=your_access_key_here
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AWS_SECRET_ACCESS_KEY=your_secret_key_here
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SQS_QUEUE_URL=https://sqs.us-east-1.amazonaws.com/YOUR_ACCOUNT_ID/task-queue
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SQS_DLQ_URL=https://sqs.us-east-1.amazonaws.com/YOUR_ACCOUNT_ID/task-queue-dlq
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DYNAMODB_TABLE=tasks
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WORKER_COUNT=5
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PORT=8080

‎.github/workflows/ci.yml‎

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name: CI/CD Pipeline
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on:
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push:
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branches: [main, develop]
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pull_request:
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branches: [main]
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jobs:
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# ---- Lint & Test ----
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test:
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name: Test
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runs-on: ubuntu-latest
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steps:
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- name: Checkout code
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uses: actions/checkout@v4
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- name: Set up Go
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uses: actions/setup-go@v5
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with:
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go-version: '1.22'
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- name: Cache Go modules
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uses: actions/cache@v4
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with:
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path: ~/go/pkg/mod
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key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
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restore-keys: ${{ runner.os }}-go-
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- name: Download dependencies
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run: go mod download
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- name: Vet (static analysis)
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run: go vet ./...
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- name: Build
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run: go build ./...
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- name: Run tests with race detector
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run: go test ./... -v -race -coverprofile=coverage.out
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- name: Upload coverage report
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uses: codecov/codecov-action@v4
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with:
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file: ./coverage.out
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fail_ci_if_error: false
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# ---- Docker Build ----
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docker:
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name: Docker Build
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needs: test
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runs-on: ubuntu-latest
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steps:
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- name: Checkout code
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uses: actions/checkout@v4
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- name: Build Docker image
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run: |
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docker build -t task-queue-engine:${{ github.sha }} .
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docker build -t task-queue-engine:latest .
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- name: Smoke test — container starts and responds to health check
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run: |
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docker run -d --name tqe-test \
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-e SQS_QUEUE_URL=mock \
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-e SQS_DLQ_URL=mock \
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-p 8080:8080 \
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task-queue-engine:latest || true
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sleep 3
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docker logs tqe-test || true

‎.gitignore‎

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# Binaries
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task-queue-api
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*.exe
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# Environment variables — NEVER commit this
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.env
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# Go build cache
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/vendor/
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# IDE
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.vscode/
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.idea/
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*.swp
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# OS
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.DS_Store
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Thumbs.db

‎Dockerfile‎

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# ---- Build Stage ----
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FROM golang:1.22-alpine AS builder
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WORKDIR /app
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# Download dependencies first (cached layer — only re-runs if go.mod changes)
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COPY go.mod go.sum ./
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RUN go mod download
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# Copy source and build a statically linked binary
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COPY . .
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RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-w -s" -o /task-queue-api ./cmd/api
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# ---- Runtime Stage ----
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# Use minimal alpine image — final image is ~15MB instead of ~800MB
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FROM alpine:3.19
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RUN apk --no-cache add ca-certificates tzdata
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WORKDIR /app
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COPY --from=builder /task-queue-api .
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EXPOSE 8080
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# Run as non-root user for security
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RUN adduser -D -g '' appuser
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USER appuser
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CMD ["./task-queue-api"]

‎README.md‎

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# Task Queue Engine
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A production-grade distributed task queue system built with **Go** and **AWS**, designed for reliable asynchronous job processing at scale.
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[![CI/CD](https://github.com/manohar6317/task-queue-engine/actions/workflows/ci.yml/badge.svg)](https://github.com/manohar6317/task-queue-engine/actions)
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![Go Version](https://img.shields.io/badge/go-1.22-blue)
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![AWS](https://img.shields.io/badge/AWS-SQS%20%7C%20DynamoDB-orange)
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---
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## Architecture
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```
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┌─────────────────────────────────────────┐
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│ Task Queue Engine │
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│ │
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Client │ ┌──────────────┐ │
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│ │ │ HTTP API │ │
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│ POST /tasks │ │ (Go server) │ │
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├────────────────────►│ └──────┬───────┘ │
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│ │ │ 1. Save task │
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│ GET /tasks/{id} │ ▼ │
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├────────────────────►│ ┌──────────────┐ 2. Enqueue │
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│ │ │ DynamoDB │◄──────────────────┐ │
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│ GET /metrics │ │ (task store)│ │ │
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└────────────────────►│ └──────────────┘ │ │
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│ ┌───────────┴──┴────┐
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│ │ AWS SQS │
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│ │ ┌─────────────┐ │
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│ │ │ Main Queue │ │
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│ │ └──────┬──────┘ │
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│ │ │ │
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│ │ (after 3 fails) │
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│ │ ┌──────▼──────┐ │
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│ │ │ Dead Letter│ │
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│ │ │ Queue │ │
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│ │ └─────────────┘ │
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│ └────────┬──────────┘
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│ │ 3. Poll (long-polling)
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│ ┌──────────────────────────────────────────┐
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│ │ Worker Pool (5 goroutines) │
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│ │ ┌────────┐ ┌────────┐ ┌────────┐ │
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│ │ │Worker 0│ │Worker 1│ │Worker N│ ... │
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│ │ └────────┘ └────────┘ └────────┘ │
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│ │ 4. Process task concurrently │
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│ │ 5. Update status in DynamoDB │
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│ │ 6. Delete message from SQS │
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│ └──────────────────────────────────────────┘
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└─────────────────────────────────────────────┘
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```
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---
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## Features
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- **Concurrent Workers** — configurable pool of goroutines, each polling SQS independently
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- **Reliable Delivery** — SQS visibility timeout prevents duplicate processing during failures
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- **Auto Retry** — failed tasks are retried up to 3 times before moving to the Dead Letter Queue
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- **Dead Letter Queue** — unprocessable messages are isolated for investigation without blocking the main queue
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- **Task Persistence** — every task's full lifecycle is tracked in DynamoDB with timestamps
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- **Real-time Metrics** — `/metrics` endpoint exposes queue depth, active workers, and task counts
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- **Graceful Shutdown** — handles SIGINT/SIGTERM by draining in-flight tasks before exiting
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- **Dockerized** — multi-stage build produces a ~15MB production image
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- **CI/CD** — GitHub Actions pipeline runs lint, tests (with race detector), and Docker build on every push
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---
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## Tech Stack
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| Layer | Technology |
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|---|---|
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| Language | Go 1.22 |
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| Message Queue | AWS SQS |
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| Database | AWS DynamoDB |
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| Containerization | Docker (multi-stage) |
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| CI/CD | GitHub Actions |
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| Cloud | AWS (free tier compatible) |
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---
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## Project Structure
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```
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task-queue-engine/
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├── cmd/
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│ └── api/
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│ └── main.go # Entry point — wires up all components
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├── internal/
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│ ├── api/
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│ │ └── handler.go # HTTP handlers (submit, status, metrics, health)
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│ ├── models/
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│ │ └── task.go # Task domain model and request/response types
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│ ├── queue/
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│ │ └── sqs.go # SQS enqueue / dequeue / delete operations
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│ ├── store/
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│ │ └── dynamodb.go # DynamoDB CRUD and status queries
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│ └── worker/
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│ └── worker.go # Concurrent worker pool with retry logic
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├── config/
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│ └── config.go # Environment-based configuration loader
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├── .github/
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│ └── workflows/
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│ └── ci.yml # CI/CD pipeline (lint → test → docker build)
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├── setup-aws.sh # One-time AWS resource provisioning script
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├── Dockerfile # Multi-stage Docker build
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├── docker-compose.yml # Local development environment
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└── go.mod
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```
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---
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## Getting Started
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### Prerequisites
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- [Go 1.22+](https://go.dev/dl/)
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- [AWS CLI](https://docs.aws.amazon.com/cli/latest/userguide/install-cliv2.html) configured (`aws configure`)
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- [Docker](https://docs.docker.com/get-docker/) (optional)
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- AWS account (free tier works)
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### 1. Clone the repository
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```bash
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git clone https://github.com/manohar6317/task-queue-engine.git
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cd task-queue-engine
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```
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### 2. Provision AWS resources
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```bash
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chmod +x setup-aws.sh
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./setup-aws.sh
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```
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This creates:
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- SQS main queue with a 30s visibility timeout
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- SQS Dead Letter Queue with a 3-retry redrive policy
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- DynamoDB `tasks` table with a GSI on `status`
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Copy the output values into a `.env` file.
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### 3. Configure environment
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```bash
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cp .env.example .env
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# Edit .env with the values from setup-aws.sh output
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```
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```env
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AWS_REGION=us-east-1
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AWS_ACCESS_KEY_ID=your_access_key
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AWS_SECRET_ACCESS_KEY=your_secret_key
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SQS_QUEUE_URL=https://sqs.us-east-1.amazonaws.com/123456789/task-queue
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SQS_DLQ_URL=https://sqs.us-east-1.amazonaws.com/123456789/task-queue-dlq
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DYNAMODB_TABLE=tasks
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WORKER_COUNT=5
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PORT=8080
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```
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### 4. Run locally
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```bash
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# Option A: directly with Go
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source .env
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go run ./cmd/api
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# Option B: with Docker
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docker-compose up --build
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```
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---
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## API Reference
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### Submit a Task
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```http
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POST /tasks
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Content-Type: application/json
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{
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"type": "email",
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"payload": "user@example.com"
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}
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```
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**Response:**
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```json
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{
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"id": "550e8400-e29b-41d4-a716-446655440000",
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"type": "email",
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"payload": "user@example.com",
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"status": "PENDING",
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"retry_count": 0,
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"created_at": "2024-01-15T10:30:00Z",
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"updated_at": "2024-01-15T10:30:00Z"
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}
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```
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### Check Task Status
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```http
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GET /tasks/{id}
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```
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**Possible status values:** `PENDING` → `PROCESSING` → `COMPLETED` or `FAILED`
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### Get System Metrics
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```http
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GET /metrics
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```
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```json
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{
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"total_tasks": 1500,
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"pending_tasks": 23,
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"completed_tasks": 1460,
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"failed_tasks": 17,
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"active_workers": 4,
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"queue_depth": 23
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}
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```
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### Health Check
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```http
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GET /health
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```
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---
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## Supported Task Types
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| Type | Description |
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|---|---|
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| `email` | Sends an email notification |
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| `image-resize` | Resizes an uploaded image |
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| `data-export` | Exports a data set to CSV/JSON |
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To add a new task type, add a case to `executeTask()` in `internal/worker/worker.go`.
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---
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## Key Design Decisions
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**Why SQS over a database queue?**
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SQS provides at-least-once delivery guarantees, built-in visibility timeouts, and native dead-letter queue support — without managing a separate queue infrastructure.
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**Why DynamoDB?**
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Serverless, pay-per-request pricing, and predictable single-digit millisecond latency make it ideal for task status lookups. The GSI on `status` enables O(1) metric aggregation.
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**Why goroutines over threads?**
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Go goroutines are extremely lightweight (~2KB stack vs ~1MB per OS thread). Running 5–50 concurrent workers is trivial in Go.
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**Why long polling?**
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SQS long polling (20s) reduces empty receive calls by ~99% compared to short polling, lowering both latency and AWS costs.
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---
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## License
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MIT

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