Docker Volumes

Dockerfile

FROM node:alpine

WORKDIR /app

RUN echo "hello" > hello-world.txt

script.sh

# Build the image
docker build -t test-volume-shizzle .

# Creates a new container with an id that has a volume attached
docker create -v /app --name container-id-10 test-volume-shizzle /bin/true

# If you started with a clean docker env you should have 1 volume now
docker volume ls

# On mac you can also attach to the docker vm tty
screen ~/Library/Containers/com.docker.docker/Data/vms/0/tty

# And then, you should also see that volume here. It should show the same id!
ls -ltrh /var/lib/docker/volumes

# Start a new container with volumes from the container named earlier (container-id-10)
# you should be able to see the file with cat /app/hello-world.txt
docker run -it --volumes-from container-id-10 ubuntu bash

# Lets exit and clean up everything
docker rm $(docker ps -aq)
docker rmi $(docker images -aq)

# That volume should still be there
docker volume ls

# The file should be 6 bytes, and docker system df claims that the size used by volumes is 6B
docker system df

# Let's create a few more
docker create -v /app --name container-id-11 test-volume-shizzle /bin/true
docker create -v /app --name container-id-12 test-volume-shizzle /bin/true
docker create -v /app --name container-id-13 test-volume-shizzle /bin/true
docker create -v /app --name container-id-14 test-volume-shizzle /bin/true
docker create -v /app --name container-id-15 test-volume-shizzle /bin/true

# The amount of volumes taken up should now be 36B
docker system df

# Let's clean up again, docker will tell it cleaned up 36B of volumes
docker rm $(docker ps -aq)
docker rmi $(docker images -aq)
docker volume prune

# This shows that each volume created from a container contains
# all the files and folders behind that given folder. In this case /app.