Where is the mount point of an external volume located on a windows 10 host machine when using docker compose v3? e.g. The host path for mydata when the top-level volumes key is set as follows:
volumes:
mydata:
external: true
-
@FiberOptic as here for example: stackoverflow.com/a/42244742/594323ramiwi– ramiwi2017-11-22 22:32:20 +00:00Commented Nov 22, 2017 at 22:32
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3 Answers
I found out that external volume is just a volume that has been created outside of Docker Compose and it is still located inside docker's vm:
C:\Users\Public\Documents\Hyper-V\Virtual Hard Disks\MobyLinuxVM.vhdx in my case.
For sharing data between my host and the containers I can define standard volumes inside the compose services and specify my preferred host directory there, or use local persist plugin
("Create named local volumes that persist in the location(s) you want").
Comments
Using external makes docker search for a folder named what you called it - in your case mydata.
If this folder doesn't exist there will be no mount and no error will be raised.
https://docs.docker.com/compose/compose-file/compose-file-v3/#external
You can also use the inspect to see the exact location:
Docker inspect -f "{{json. Mounts}}" container_name | jq.
https://container-solutions.com/understanding-volumes-docker/
4 Comments
ramiwi
The docs (linked) says mydata is a volume name, not a file name, and external volumes does not have a path configuration key (to point to a target directory).
ramiwi
Where did you read this? And the inspect option was already suggested by Fiber Optic, I will try it.
smac89
Your answer is wrong. If the external volume doesn't exist, an error is thrown
crowne
This answer may have been true for a legacy version of docker-compose but now should be deleted.
If you mean the internal path used by Docker, try to inspect an existing one:
docker volume inspect my-vol.
It will show where the data is stored.
5 Comments
Fiber Optic
Did you inspect it?
ramiwi
I`m getting an error trying to create external volume (ERROR: Volume data declared as external, but could not be found). stackoverflow.com/questions/47479767/…
Fiber Optic
As said in the 2nd post, create an external volume before trying to "link" it.
ramiwi
Inspect gives me a guest path - "Mountpoint": "/var/lib/docker/volumes/data/_data" but I dont see the host windows path there
szabozoltan
It works for me fine, with the data named volume: docker volume inspect data
[ { "CreatedAt": "2020-05-27T08:38:01Z", "Driver": "local", "Labels": {}, "Mountpoint": "/var/lib/docker/volumes/data/_data", "Name": "data", "Options": null, "Scope": "local" } ] There is a /var/lib/docker/volumes/metadata.db, which should contain the further information... :-)