[Solved] Consider this Dockerfile snippet:FROM openjdk:17-jdk-slim COPY target/app.jar /app.jar EXPOSE 8080 ENTRYPOINT ["java", "-jar", "/app.... | Spring Boot

Spring Boot - Docker and Deployment

Consider this Dockerfile snippet:

FROM openjdk:17-jdk-slim
COPY target/app.jar /app.jar
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "/app.jar"]

What is the expected behavior when you start a container from this image?

AThe app starts but listens on a random port

BThe container starts but immediately exits without running the app

CThe container fails to build due to missing jar file

DThe Spring Boot app starts and listens on port 8080 inside the container

Step-by-Step Solution

Solution:

Step 1: Analyze ENTRYPOINT
The ENTRYPOINT runs java -jar /app.jar, which starts the Spring Boot application.
Step 2: Check EXPOSE
Port 8080 is exposed, matching the default Spring Boot port.
Step 3: Confirm COPY
The jar is copied correctly to /app.jar.
Final Answer:
The Spring Boot app starts and listens on port 8080 inside the container -> Option D
Quick Check:
ENTRYPOINT runs app, EXPOSE matches app port [OK]

Quick Trick: ENTRYPOINT runs app; EXPOSE declares port [OK]

Common Mistakes:

Master "Docker and Deployment" in Spring Boot

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Consider this Dockerfile snippet: