Q: Explain the difference between COPY and ADD in a Dockerfile.
COPY: copies files from build context to image. Simple and explicit. ADD: same as COPY but also supports URLs and auto-extracts tar archi...
#Docker #Docker #L2 #Containers #Linux
🎙️ Candidate Opening & Architectural Context
""Container stability relies on clean signal handling (SIGTERM vs SIGKILL) and immutable image tagging. 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
COPY: copies files from build context to image. Simple and explicit. ADD: same as COPY but also supports URLs and auto-extracts tar archives. Prefer COPY — ADD's extra features make behavior less predictable. Use ADD only when you specifically need tar extraction.
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Pro-Tip: COPY: copies files from build context to image. Simple and explicit. ADD: same as COPY but also supports URLs and auto-extracts ta."
⚡ 60-Second Elevator Pitch Talking Points
- Immediate Triage: COPY: copies files from build context to image. Simple and explicit. ADD: same as COPY but also
- Run targeted verification commands before modifying configuration.
- Automate permanent guardrails (CI check, alerts, IaC policy) to prevent recurrence.
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