Caching

In this training, you will learn how to write Dockerfiles which will decrease build time due to using caches.

Navigate to the folder 13_caching from CLI, before you get started.

cd /workspaces/container-fundamentals/13_caching

Inspect the Dockerfile and the server.js file

cat Dockerfile
cat server.js

Build and run the docker image

docker build -t webserver:1.0.0 .
docker run -it -d --rm --name my-webserver -p 80:80 webserver:1.0.0

Visit the site via the external IP of your VM on port 80 via http

Remove the container

docker rm -f my-webserver 

Re-build the docker image

docker build -t webserver:1.0.0 .

Note that all layers are taken from the cache.

Adapt the application and re-build the docker image

Change the message to something different in the file server.js

docker build -t webserver:1.0.0 .
docker run -it -d --rm --name my-webserver -p 80:80 webserver:1.0.0

Visit the site via the external IP of your VM on port 80 via http Note that all layers starting from the RUN npm install layer are not taken from the cache. On bigger projects, this can increase your build times significantly.

Remove the container

docker rm -f my-webserver 

Fix the Dockerfile

• Change the content of the Dockerfile to this

FROM node:12
WORKDIR /app
COPY package.json .
RUN npm install
COPY server.js .
ENTRYPOINT [ "npm" ]
CMD [ "start" ]

• Do the initial build

docker build -t webserver:2.0.0 .

• Re-build the docker image

Change the message to something different in the file server.js.

docker build -t webserver:2.0.0 .
docker run -it -d --rm --name my-webserver -p 80:80 webserver:2.0.0

Visit the site via the external IP of your VM on port 80 via http Note the layers which are taken from the cache.

Cleanup

# Remove all the containers
docker rm -f $(docker ps -qa)

# Remove all the images
docker rmi -f $(docker images -qa)