Q: What is the difference between CMD and ENTRYPOINT?
ENTRYPOINT defines the main command that always runs. CMD provides default arguments. If ENTRYPOINT is ["nginx"] and CMD is ["-g", "daemo...
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🎙️ Candidate Opening & Architectural Context
""In an interview, I explain how we diagnosed container runtime failures without guessing. When addressing this question, I walk the interviewer through our production incident runbook: isolating the blast radius, checking diagnostic logs and metrics, and applying a safe fix.""
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🛠️ Production Runbook & Step-by-Step Resolution
1️⃣
Production Solution & Architecture
ENTRYPOINT defines the main command that always runs. CMD provides default arguments. If ENTRYPOINT is ["nginx"] and CMD is ["-g", "daemon off;"], running docker run myimage -t would execute nginx -t (CMD replaced by args). If only CMD: docker run myimage bash runs bash instead. Best practice: use ENTRYPOINT for the executable, CMD for default arguments.
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Pro-Tip: ENTRYPOINT defines the main command that always runs. CMD provides default arguments. If ENTRYPOINT is ["nginx"] and CMD is ["-g",."
⚡ 60-Second Elevator Pitch Talking Points
- Immediate Triage: ENTRYPOINT defines the main command that always runs. CMD provides default arguments. If ENTRYP
- Run targeted verification commands before modifying configuration.
- Automate permanent guardrails (CI check, alerts, IaC policy) to prevent recurrence.
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