I have made a data container in Docker with the directory /tmp:
sudo docker create -v /tmp --name datacontainer ubuntu
I will add another directory to this existing data container like /opt.
How can i do this?
You cannot add a new data volume to an existing (created or running) container.
With docker 1.9+, you would use instead docker volume create:
docker volume create --name my-tmp
docker volume create --name my-opt
Then you can mount those volumes to any container you want (when you run those containers, not when they are already running)
docker run -d -P \
-v my-tmp:/tmp \
-v my-opt:/opt \
--name mycontainer myimage
Related
I run a docker container of nginx with the following: docker container run -d --name nginx3 -p 85:80 -v $(pwd):/usr/share/nginx/html nginx , then when I add files in the container volume (/usr/share/nginx/html) they are also added locally on the $pwd folder.
But when I remove the container, image, and volume with docker rm -vf $(docker ps -aq) && docker rmi -f $(docker images -aq) && docker volume prune the files on my local $pwd folder are still there.. why were they not deleted when I removed the volume?
That's because docker volume prune delete the docker volumes and not the mounted volumes from the host.
If you define a volume with docker volume create nginx_volume and then use
docker container run -d --name nginx3 -p 85:80 -v nginx_volume:/usr/share/nginx/html nginx
the volume will be deleted
You are not using a docker volume, you are using a bind mount. This was not that clear with the -v syntax, that's why docker recommends the new --mount syntax for new users:
This creates a bind mount from the host OS. Docker is not owner of it and therefore not deleting the folder if you unmount the binding.
docker run -d \
-it \
--name devtest \
--mount type=bind,source="$(pwd)"/target,target=/app \
nginx:latest
Further reading
This creates a docker volume, which is managed by docker. And therefore all volume-commands can be applied:
docker run -d \
--name devtest \
--mount source=myvol2,target=/app \
nginx:latest
Further reading
I want to know how to start a Docker container with a named volume. I've tried this
docker run -it --name container1 -v path:path --name volumename image bin/bash
But the container was also named "volumename"
How can I resolve this issue?
First of all, if you don't have an existing image then you have to create one by using:
docker volume create --name [volume name]
For instance:
docker volume create --name namedvolume
If you did this you can check if it has been created. Just type:
docker volume ls
You did all right, if it shows your created volume.
Last step:
docker run -v [volume name]:[container directory]
With a directory:
docker run -it --name container -v data-volume:/data image /bin/bash
I have Docker installed in top of a CentOS system.
I tried to use volume but each new container is deleting (or hidding) the content of the folder to share.
My volume is always empty after a Docker run.
In order to create my containers, I use
docker run -dit --name $CONTAINER_NAME -p $PORT:8080 \
-v $VOLUME_PATH:/opt/conf/ \
$IMAGE_NAME
I aim at sharing a folder from the host between few Docker containers (to READ) AND I want also to write into this folder from the host.
What is an elegant way to do that ?
One solution is to use Data Volume Containers.
First, create a data volume container
docker run -d --name <data-volume-name> -v /<data-volume-name> ubuntu
You can add any data you want in this container.
Create your containers that will share by using the option volume-from
Let's create container foo and container bar using the shared datacontainer :
docker run -it --name foo --volumes-from=<data-volume-name> ubuntu
docker run -it --name bar --volumes-from=<data-volume-name> centos
Enjoy yourself
Each container in my example is mapped to the root folder.
From either bar or foo you can see /, in the filesytem.
You can also use volume field.
Create a volume
docker volume create --name <volume-name>
Create containers foo and bar that witl be mapped to the volume
docker run -dit --name foo -v test-volume:/path/in/container/ <image-name>
docker run -dit --name bar -v test-volume:/path/in/container/ <image-name>
Each container that will write in the volume will be visible by other.
I have a test data which I build as a Docker image (docker build with copy to /db/data) and pushed to docker hub.
I want to run a db instance that will use that data.
I would expect to be able to:
run a "docker create" and create a container from image and map it to a volume (maybe named volume) which will practically will copy the data to that volume.
run a "docker run" with volumes-from and map that data from first container to the second.
When I tried it out I always see that in the second directory there is a folder mapping but I can't reach any pre-populated data from the data-container.
--volumes-from will add "Volume" from a docker container to another.
In your case you created an image that contains your data, you didnt create a volume that contains your data.
Docker is currently supporting the following:
a host bind mount that is listed as a bind mount in both services
a named volume that is used by both services
volumes_from another service
for example if you have your data in /my/data on docker host you can use the following:
sudo docker run -d --name firstcontainer -v /my/data:/db/data <image name>
sudo docker run -d --name secondcontainer -v /my/data:/db/data <image name>
If you want to use named volumes follow these steps:
create the named volume
sudo docker volume create <volumename>
Mount it to a transitional container and copy your data in it with docker cp
sudo docker cp /path/to/your/file <containername>:/destination/path
Mount your named volume on multiple containers.
sudo docker run -d --name firstcontainer -v <volumename>:/db/data <image name>
sudo docker run -d --name secondcontainer -v <volumename>:/db/data <image name>
I need to setup one container volume use to multiple container.
for example:
Container 1(web app1): volume path -v /var/www/html/
Container 2 (web app2): volume path -v /var/www/html/
Container 3(Commaon Files): volume path -v /var/www/html/
I need to setup Container-3 Common file use other two Containers.
How can I Achive this.
You should name your volumes so you can mount them by name instead of by container. So:
docker run -d --name web1 -v web1-html:/var/www/html web-img
docker run -d --name web2 -v web2-html:/var/www/html web-img
docker run -d --name common -v web1-html:/var/www/web1/html \
-v web2-html:/var/www/web2/html your-img
With the volumes created today from your two web apps, you'll see them listed with a guid under docker volume ls. By giving them a name, you can easily reused those volumes in other containers.