🚦 ECS Deployment Circuit Breaker with Serverless Fargate

Stop Bad Deployments Before They Break Your App

Deployments are exciting—until they fail in production. 😅 That’s where Amazon ECS Deployment Circuit Breaker comes in.
Think of it as a safety switch: it catches failed deployments early, rolls back automatically, and keeps your app running smoothly.

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💡 Why You Should Care

Here’s what the circuit breaker does for you:

• 🔄 Auto Rollback – Bad deploy? ECS flips back to the last good version.
• ⏱ Less Downtime – Faulty tasks get stopped before they impact users.
• 🛡 Safety Net – ECS continuously checks health and cancels bad rollouts.
• 😴 Sleep Easy – No more 3 AM firefights over broken deployments.

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⚙️ How It Works

ECS tracks deployment failures in two stages:

1️⃣ Task Startup

• ✅ Success: At least one task reaches RUNNING → move to health checks.
• ❌ Failure: Multiple tasks fail to start → deployment may be marked as FAILED.

2️⃣ Health Checks

• ✅ Success: At least one task passes ELB, Cloud Map, or container health checks.
• ❌ Failure: Health check failures exceed threshold → deployment fails → rollback triggered.

Failure Threshold Example:

Desired Task Count	Threshold (min 3, max 200)
1	3
25	13
400	200
800	200 (capped)

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🚀 Setup with Serverless + Fargate

Enable circuit breaker in your serverless.yml:

cloudFormationResource:
  service:
    DeploymentConfiguration:
      DeploymentCircuitBreaker:
        Enable: true
        Rollback: true

Done ✅ — your service now has a safety net.

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🧪 Test It Out

1. Deploy a simple Express app:

const express = require('express');
const app = express();
app.get('/', (_, res) => res.send('Health Check!'));
app.listen(3000, () => console.log(`Running on :3000`));

1. Build & push Docker image.
2. Simulate a bad deploy by forcing an error in Dockerfile:

CMD ["EXIT", "2"]

👉 ECS rolls back automatically, saving your users.

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🎯 The Takeaway

The ECS Deployment Circuit Breaker is a simple switch with a huge payoff:

• Fewer outages
• Automatic rollbacks
• Stress-free deployments

If you’re using Fargate + Serverless, flipping it on is a no-brainer.