AWS has over 200 services and they announce new ones every re:Invent like they are trying to break a record. The vastness is paralyzing if you let it be. Do not let it be. For Rails, you need about 15 services, and you can learn them in order of how often you will actually touch them.
The core stack: EC2 or ECS for compute, RDS for Postgres, ElastiCache for Redis, S3 for file storage, CloudFront for CDN, SES for email, SQS for background job queues when Sidekiq with Redis is not enough. That covers 90% of what a Rails application needs in production. ALB for load balancing, Route 53 for DNS, ACM for SSL certificates, CloudWatch for basic monitoring. IAM for permissions, which you will hate and which will save you from security disasters.
The remaining 185+ services exist for good reasons, but those reasons are probably not your reasons right now. Do not learn Lambda because it is trendy. Do not learn DynamoDB because a blog post said it scales better than Postgres. Learn services when you have a problem they solve, not because they appear on an architecture diagram you saw at a conference.
The Solutions Architect mindset is essentially the software architect mindset applied to infrastructure. You are designing systems with trade-offs: cost vs performance, availability vs consistency, managed vs self-hosted. An integrator's mindset fits perfectly here because cloud architecture is fundamentally about understanding how dozens of services connect and interact. It is systems thinking applied to infrastructure, and if that is how your brain works, this module will feel like home.
One honest warning: AWS billing is where good intentions go to die. A forgotten NAT gateway costs $30/month. An undeleted EBS snapshot accumulates quietly. Set up billing alerts on day one, set a budget, and review it weekly. The free tier is generous but its boundaries are poorly documented. Do not learn this lesson the hard way.