CODEWITHSUNDEEP
dockerdocker-volume
loonyuni
loonyuni

Reputation: 1483

How to create docker volume device/host path

I believe there is an easy way to copy files into a docker volume that has already been mounted to a container.

docker cp /tmp/my_data/. my_container:/my_data as referenced by How to copy multiple files into a docker data volume

But, how does one create a named volume using docker volume create --name my-volume that already has files in it? I have read that it's not a good idea to cp files into the {{.Mountpoint}}.

I'm new to docker and all of it's nuancies, so apologies if my fundamental understanding of volumes is incorrect.

Upvotes: 36

Views: 83324

Answers (3)

Cheikh HAIBALA
Cheikh HAIBALA

Reputation: 125

To bind volumes between container and host machine. The most easy way is to use volume mounting. With which we can setup your container before starting it, (its images, ports, ..etc)

To build the container from an image: docker-compose build To start the container : docker-compose up

Volumes key in the docker-compose file is used to set the binding. which means when we update the content of volumes in the container it will persist even after stopping the container.

We can bind volumes from a local dir or from a named docker volume see the exmple below

We can use COPY or ADD in your Dockerfile to make the content of your local diroctory available in the docker container.

read docs here

version: "3.2"
services:
  web:
    image: nginx:alpine
    ports:
      - "80:80"
    volumes:
      - type: volume
        source: mydata
        target: /data
        volume:
          nocopy: true
      - type: bind
        source: ./static
        target: /opt/app/static

    networks:
      webnet:

    volumes:

Upvotes: -1

Jinna Baalu
Jinna Baalu

Reputation: 7839

Approach #1 - COPY

To copy the file from the host to the container

docker cp /path/of/the/file <Container_ID>:/path/of/he/container/folder

Issue with the above approch is, it will not persists the volume or file or dir, as you remove the container it will be lost. This is suggested only for temporary pupose.

Approach #2 - Volume Mounting

Mouting the volume from the host to container

Step1: Create the volume with the custom path

docker volume create --name my_test_volume --opt type=none --opt device=/home/jinna/Jinna_Balu/Test_volume --opt o=bind

Step2 : Mount to the container or swarm service

docker run -d \
  --name devtest \
  --mount source=my_test_volume,target=/app \
  nginx:1.11.8-alpine

We can do both of the above steps with below .yaml files

version: '3'
services:
  nginx:
    image: nginx:1.11.8-alpine
    ports:
      - "8081:80"
    volumes:
      - my_test_volume:/usr/share/app
volumes:
  my_test_volume:
    driver: local
    driver_opts:
       o: bind
       type: none
       device: /home/jinna/Jinna_Balu/Test_volume

RUN the above yml with docker-compose

docker-compose up -d

NOTE: create the folder path before you do docker-compose.

Good practice to have files mouted to maintain the persistency.

Upvotes: 78

Saito Kazuo
Saito Kazuo

Reputation: 135

create a volume.

$ docker volume ls | grep my-volume
$ docker run -it --rm -d --name tmp -v my-volume:/mnt alpine
$ docker volume ls | grep my-volume
local               my-volume
$ docker exec tmp ls -l /mnt
total 0
$

Copy a file to a container.

$ docker cp . tmp:/mnt
$ docker exec tmp ls -l /mnt
total 4
-rw-r--r--    1 501      50              93 Apr 20 22:53 Dockerfile
$ ls
Dockerfile
$

clean up.

$ docker rm -f tmp
tmp
$

check.

$ docker run --rm -v my-volume:/mnt alpine ls /mnt
Dockerfile
$

Upvotes: -1

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