Q: A legacy monolithic application is tightly coupled to a single master database. You want to break it into microservices, but they all still query the massive 10TB monolithic database. What is this anti-pattern called, and how do you migrate away from it?
The anti-pattern is an Integration Database. It ruins the benefits of microservices because the database becomes a massive single point o...
#General DevOps #General DevOps — Scenario-Based Interview Questions #L3 #DevOps #SRE #Architecture
🎙️ Candidate Opening & Architectural Context
""When an interviewer asks about this scenario, I explain how we balanced incident response with long-term prevention. The interviewer is testing: Integration Database anti-pattern, Strangler Fig pattern, database per service.. I structure my answer around systematic triage first, root cause analysis second, and permanent remediation third.""
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🛠️ Production Runbook & Step-by-Step Resolution
1️⃣
Initial Diagnostics & Root Cause Analysis
The anti-pattern is an Integration Database. It ruins the benefits of microservices because the database becomes a massive single point of failure; a schema change by Service A breaks Service B, and scaling the DB becomes near impossible.
- Identify a small, bounded context (e.g., User Profiles) in the monolith.
- Build the new
UserProfileServiceand give it its own entirely separate, small database. - Keep them in sync during migration using Change Data Capture (CDC, like Debezium) streaming from the monolith DB to the new DB.
2️⃣
Remediation & Permanent Safeguards
The migration approach is the Strangler Fig Pattern combined with Database per Service:
- Update the API Gateway to route
/userstraffic to the new microservice. - Once stable, sever the sync and delete the tables from the monolithic database. Repeat for all domains until the monolith is "strangled."
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Pro-Tip: Identify a small, bounded context (e.g., User Profiles) in the monolith.."
⚡ 60-Second Elevator Pitch Talking Points
- Identify a small, bounded context (e.g., User Profiles) in the monolith.
- Build the new UserProfileService and give it its own entirely separate, small database.
- Keep them in sync during migration using Change Data Capture (CDC, like Debezium) streaming from ...
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