Migrating from Heroku to AWS: lessons learned

Leading the migration from Heroku to AWS at Heard was one of the most challenging infrastructure projects I've managed. We cut costs by 20% and improved uptime from 97.5% to 99.9%, but the journey was complex.

Why Migrate?

Heroku was great for getting started, but as we scaled:

• Costs grew faster than revenue
• Limited control over infrastructure
• Performance bottlenecks
• Compliance requirements needed more control

The Migration Strategy

We used a phased approach:

1. Assessment: Inventory all services and dependencies
2. Parallel Run: Run both environments simultaneously
3. Gradual Cutover: Move services one by one
4. Optimization: Tune AWS services for cost and performance

Key Decisions

ECS vs EC2: Chose ECS for container orchestration RDS vs Self-Managed: RDS for managed Postgres CloudFront: For CDN and caching Terraform: Infrastructure as code

Challenges

• Database migration was the hardest part
• DNS cutover timing
• Team training on AWS services
• Monitoring and alerting setup

Results

• 20% cost reduction
• 99.9% uptime (up from 97.5%)
• Better performance and scalability
• More control over infrastructure

Lessons

1. Plan for 2x the time you think you need
2. Test migrations thoroughly in staging
3. Have rollback plans for every step
4. Communicate progress regularly
5. Invest in monitoring from day one

"A successful migration is one where users don't notice it happened."