[Solved] Given this Dockerfile snippet:FROM python:3.12-slim WORKDIR /app COPY requirements.txt .... EXPOSE 5000 CMD ["flask", "run", "--host=0.0.0.0"]What happens when you run the container? | Flask

Flask - Deployment

Given this Dockerfile snippet:

FROM python:3.12-slim
WORKDIR /app
COPY requirements.txt .
RUN pip install -r requirements.txt
COPY . .
EXPOSE 5000
CMD ["flask", "run", "--host=0.0.0.0"]

What happens when you run the container?

AContainer fails because requirements.txt is missing

BFlask app runs but listens only on localhost inside the container

CFlask app runs but port 5000 is not accessible outside the container

DFlask app runs and listens on all network interfaces at port 5000

Step-by-Step Solution

Solution:

Step 1: Analyze CMD and EXPOSE instructions
The CMD runs Flask with --host=0.0.0.0, making it listen on all interfaces. EXPOSE 5000 declares port 5000 for external access.
Step 2: Understand container networking
Because Flask listens on 0.0.0.0 and port 5000 is exposed, the app is accessible from outside the container on port 5000.
Final Answer:
Flask app runs and listens on all network interfaces at port 5000 -> Option D
Quick Check:
CMD host=0.0.0.0 + EXPOSE 5000 = accessible app [OK]

Quick Trick: Use --host=0.0.0.0 to expose Flask outside container [OK]

Common Mistakes:

MISTAKES

Assuming Flask listens only on localhost by default
Thinking EXPOSE opens ports automatically without CMD
Confusing container internal ports with host ports

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More Flask Quizzes

Given this Dockerfile snippet:

Step 1: Analyze CMD and EXPOSE instructions

Step 2: Understand container networking

Final Answer:

Quick Check:

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