docker volume

Containers are thrown away, data shouldn't be: create a volume, mount it with -v, and see it survive docker rm.

>_ Try it: a simulated Linux, right herenothing runs on your computer

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Examples

docker volume create db-data a volume for the database
docker run -d --name db -e POSTGRES_PASSWORD=secret -v db-data:/var/lib/postgresql/data postgres the database keeps its files in it
docker volume ls there it is
docker volume inspect db-data where Docker keeps it
docker rm -f db delete the container…
docker volume ls …the volume (and the data) is still there

How it works

Files written inside a container disappear with it. A volume is storage Docker keeps outside the container: mount it with -v NAME:/path and whatever is written there stays.

That is how databases run in Docker: delete and recreate the container (a new version, new settings) and mount the same volume — the data is still there.

Syntax

docker volume create|ls|inspect|rm [NAME]  ·  docker run -v NAME:PATH IMAGE

Options

Option	What it does
`create NAME`	create a named volume
`-v NAME:PATH`	mount it into a container at PATH
`ls`	list volumes
`inspect NAME`	details, like where it lives on the host
`rm NAME`	delete it (only when no container uses it)

Good to know

docker run -v db-data:/path creates the volume by itself if it doesn't exist yet.
With a folder path instead of a name (-v ./site:/usr/share/nginx/html) you mount a folder of your own machine — a bind mount.