- A Cloud Guru
Adding Metadata and Labels
For the last six months, the Acme Anvil Corporation has been migrating some of their bare-metal infrastructure to Docker containers. After the initial implementation, you mention to the team that labels can be used for storing metadata about images and containers. This is useful for keeping track of image and container attributes like the build date and application version. Your team thinks this is a great idea, and you’ve been tasked with creating a quick demo to show how useful labels can be. You created a small weather app a few months ago while learning Node.js, and it’s perfect for a quick demo. On your Docker workstation, you will create a Dockerfile that contains four labels: the maintainer, build date, application name, and application version. You will then build the image and push it to Docker Hub. On your Docker server, you will create a new container using the `weather-app` image. Once the container is running, you will update the branch of your application, rebuild the image, and push the changes to Docker Hub. On the Docker server, Watchtower will update the running container with the new version of the image.
Table of Contents
Create a Dockerfile
Create a Dockerfile using the following instructions:
FROM node LABEL maintainer="EMAIL_ADDRESS" ARG BUILD_VERSION ARG BUILD_DATE ARG APPLICATION_NAME LABEL org.label-schema.build-date=$BUILD_DATE LABEL org.label-schema.application=$APPLICATION_NAME LABEL org.label-schema.version=$BUILD_VERSION RUN mkdir -p /var/node ADD weather-app/ /var/node/ WORKDIR /var/node RUN npm install EXPOSE 3000 CMD ./bin/www
Build the Docker Image
Build the Docker image using the following parameters:
docker build -t <USERNAME>/weather-app --build-arg BUILD_DATE=$(date -u +'%Y-%m-%dT%H:%M:%SZ') --build-arg APPLICATION_NAME=weather-app --build-arg BUILD_VERSION=v1.0 -f Dockerfile .
Push the Image to Docker Hub
weather-appimage to Docker Hub.
docker push <USERNAME>/weather-app
Create the `weather-app` Container
docker run -d --name demo-app -p 80:3000 --restart always <USERNAME>/weather-app
Check Out Version v1.1 of the Weather App
weather-appdirectory, check out version v1.1 of the weather app.
cd weather-app git checkout v1.1 cd ../
Rebuild the `weather-app` Image
Rebuild and push the
docker build -t <USERNAME>/weather-app --build-arg BUILD_DATE=$(date -u +'%Y-%m-%dT%H:%M:%SZ') / --build-arg APPLICATION_NAME=weather-app --build-arg BUILD_VERSION=v1.1 -f Dockerfile . docker push <USERNAME>/weather-app
What's a lab?
Hands-on Labs are real environments created by industry experts to help you learn. These environments help you gain knowledge and experience, practice without compromising your system, test without risk, destroy without fear, and let you learn from your mistakes. Hands-on Labs: practice your skills before delivering in the real world.