docker storage

for the best wisdom - https://docs.docker.com/engine/storage/ beautifully written docs by docker team!

docker storage - volumes, bind mounts

what was the challenge?

• docker containers are ephemeral, which means the data in the containers get destroyed when the containers get destroyed!
• so if you are running an application that stores some critical data, you might lose it if the container stops running due to any reason, this is a very big issue.
• To solve this docker provides persistent storage for containers using 3 storage mount options - volume mounts, bind mounts, tmpfs mounts and named pipes!
• no matter which mount you choose the data looks the same from inside the container!

difference between volume & bind mounts

• bind mounts are a way using which you can bind a local container directory to a host directory running the container such that any change in either reflects in the other.
• a volume on the other hand could be anything for ex an ec2 instance, a folder in the host fileserver, or any cloud storage outside the host!
• a volume is much more flexible than bind mounts as:
  • volumes are easier to backup and scale than bind mounts
  • volumes can be managed using docker-cli or docker-api directly
  • a volume can be shared by multiple containers
  • a volume can be used for high performance I/O

always go with a volume storage over bind mount unless you have a specific usecase where bind mount is better!

docker volume commands

# create a docker volume
docker volume create <volume-name>
 
# list all volumes
docker volume ls
 
# delete a docker volume
docker volume rm <volume-name>
 
# to inspect a volume 
docker volume inspect <volume-name>
 
# mount a volume to docker container
docker run -d --name container --mount type=volume,src=aniket,dst=/app nginx:latest
 

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