Mastering Deployments

Getting code to the server is easy. Getting it there safely without users noticing is the hard part. A Cloud Architect must know which strategy to use for which risk level.

1. Rolling Update (The Standard)

Update one server at a time. If you have 10 servers, you update #1, then #2... Pros: No extra cost. Cons: No instant rollback—you have to roll back one-by-one too.

2. Blue-Green (The Safe Choice)

Run two full copies of production. Switch the Load Balancer instantly. Pros: Zero downtime, near-instant rollback. Cons: Double the server cost while both are running.

3. Canary (The Advanced Choice)

Send only 5% of users to the new version. Monitor metrics. If 5% is happy, go to 100%. Pros: Finds "Sneaky bugs" that only show up under load without breaking it for everyone.

4. Interview Mastery

Q: "What is 'Dark Launching' and how does it differ from Canary?"

Architect Answer: "**Dark Launching** is when you deploy the new code but keep it hidden from the user (often via **Feature Flags**). The service might be processing data in the background, but the UI doesn't show it yet. **Canary** is a traffic-splitting method at the network level. You use Dark Launching to test backend performance and Canary to test user acceptance."