Docker

Nov 5, 2022

• Software engineering
• Docker

• Use docker multi stage build

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FROM maven:3.6.3-openjdk-11-slim as builder

WORKDIR /app
COPY pom.xml .
# Use this optimization to cache the local dependencies. Works as long as the POM doesn't change
RUN mvn dependency:go-offline

COPY src/ /app/src/
RUN mvn package

# Use AdoptOpenJDK for base image.
FROM adoptopenjdk/openjdk11:jre-11.0.8_10-alpine

# Copy the jar to the production image from the builder stage.
COPY --from=builder /app/target/*.jar /app.jar

# Run the web service on container startup.
CMD ["java", "-jar", "/app.jar"]

• docker container ls lists all running containers
• docker container ls -a lists all containers
• docker container prune add -f or –force to not prompt for confirmation
• docker images lists all images that are present locally
• docker image rm IMAGE_ID to remove an image
• docker image prune add -f or –force to not prompt for confirmation
• docker system df shows disk usage and size of ‘Build Cache’

You can run an interactive shell container using that image and explore whatever content that image has. For instance:

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docker run -it image_name sh

Or the following for images with an entrypoint:

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docker run -it --entrypoint sh image_name

Or, if you want to see how the image was build, meaning the steps in its Dockerfile, you can:

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docker image history --no-trunc image_name > image_history

The steps will be logged into the image_history file.

• Load Docker Image from tar file

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docker load -i application-image.tar 

• Inspect image

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docker inspect application