Named volumes
- Docker & Kubernetes course
- Beginner
- Lesson 50/82
- 4 min
Learn to create named volumes with docker volume create.
Named volume
A named volume can be created explicitly or is created automatically on first use. When an empty volume is mounted at a container directory, the contents of that directory in the image are copied into the volume:
docker volume create web-icerik
docker run -d --name web -v web-icerik:/usr/share/nginx/html nginx
# the volume now contains nginx's default index.htmlSharing and anonymous volumes
The same volume can be mounted into several containers; one writes, another reads. If only a container path is given in the form -v /path, an anonymous volume with a random name is created; these are hard to track, so named volumes are preferred:
docker run -d --name yazici -v loglar:/var/log/app api:1.0
docker run --rm -v loglar:/data:ro alpine tail /data/app.log # :ro read-only
docker run -d -v /data redis # anonymous volume: 8f3c1a…Practice A shared volume
Write three commands: create the loglar volume; start a container named api from api:1.0 in the background mounting this volume at /var/log/app; in an alpine container deleted when done, mount the volume read-only at /data and run ls /data.
Starter code
# buraya yazSample solution
docker volume create loglar
docker run -d --name api -v loglar:/var/log/app api:1.0
docker run --rm -v loglar:/data:ro alpine ls /dataExpected output
loglar 4d5e6f708192 app.log
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What happens if the volume name given with -v doesn't exist?
- The container doesn't start
- Docker creates it automatically Correct answer
- It errors
- It is interpreted as a bind mount
Explanation: If the name doesn't start with /, it counts as a named volume.
2 Mount the volume read-only.
docker run --rm -v loglar:/data____ alpine ls /datadocker run --rm -v loglar:/data:ro alpine ls /dataExplanation: ro. :ro prevents writing.
3 Match.
| Term | Meaning |
|---|---|
docker volume create |
Creates a volume |
-v ad:/yol |
Named volume |
-v /yol |
Anonymous volume |
:ro |
Read-only |