i have creted a docker volume with such command
docker run -ti --rm -v TestVolume1:/testvolume1 ubuntu
then i created a file there, called TestFile.txt and added text to it
Also i have a simple "Hello world" .net core app with Dockerfile
FROM mcr.microsoft.com/dotnet/aspnet:6.0
COPY bin/Release/net6.0/publish/ ShareFileTestInstance1/
WORKDIR /ShareFileTestInstance1
ENTRYPOINT ["dotnet", "ShareFileTestInstance1.dll"]
I published it using
dotnet publish -c Release
then ran
docker build -t counter-image -f Dockerfile .
And finally executed
docker run -it --rm --name=counter-container counter-image -v TestVolume1:/testvolume1 ubuntu
to run my app with a docker volume
So what i want to achive to access a file which is in a volume("TestFile.txt" in my case) from a code in the container.
for example
Console.WriteLine(File.Exists("WHAT FILE PATH HAS TO BE HERE") ? "File exists." : "File does not exist.");
Is it also possible to combine all this stuff in a Dockerfile? I want to add one more container next and connect to the volume to save data there.
The parameters for docker run can be either for docker or for the program running in the docker container. Parameters for docker go before the image name and parameters for the program in the container go after the image name.
The volume mapping is a parameter for docker, so it should go before the image name. So instead of
docker run -it --rm --name=counter-container counter-image -v TestVolume1:/testvolume1 ubuntu
you should do
docker run -it --rm --name=counter-container -v TestVolume1:/testvolume1 counter-image
When you do that, your file should be accessible for your program at /testvolume1/TestFile.txt.
It's not possible to do the mapping in the Dockerfile as you ask. Mappings may vary from docker host to docker host, so they need to be specified at run-time.
Related
I am facing an issue where after runnig the container and using bind mount to mount the directory on host to container I am not able to see new files created in host machine inside container.Below is my project structure.
The python code creates a file inside the container which should be available inside the host machine too however this does happen when I start the container with below command. However updates to python code and html is available inside the container.
sudo docker container run -p 5000:5000 --name flaskapp --volume feedback1:/app/feedback/ --volume /home/deepak/PycharmProjects/NewDockerProject/sampleapp:/app flask_image
However after starting the container using below command, everything seems to work fine. I can see all the files from container to host and vice versa(new created , edited).I git this command from docker in the month of lunches book.
sudo docker container run --mount type=bind,source=/home/deepak/PycharmProjects/NewDockerProject/sampleapp,target=/app -p 5000:5000 --name flaskapp
Below is the content of my dockerfile
FROM python:3.8-alpine
WORKDIR /app
COPY ./requirements.txt .
RUN pip install -r requirements.txt
COPY . .
CMD ["python","main.py"]
Could someone please help me in figuring out the difference between the two commands ? I am using ubuntu. Thank you
In my case i got working volumes using following docker run args (but i am running without --mount type=bind):
docker run -it ... -v mysql_data:/var/lib/mysql -v storage:/usr/shared/app_storage
where:
mysql_data is a volume name
/var/lib/mysql path inside container machine
you could list volumes as:
docker volume ls
and inspect them to see where it points on your system (usually /var/lib/docker/volumes/{volume_nanme}/_data):
docker volume inspect mysql_data
to create volume use following command:
docker volume create {volume_name}
I have created a customised-docker image which runs some code after creating a container.
But I want to attach a config file at the time of deployment and our config file is saved on the local machine.
docker run -d -ti -v /home/logs/:/home/logs/ --name "ContainerName" "ImageName" /bin/bash
I want to attach file at the place of volume.
How can I attach a config file to the container at runtime?
the docker run options doesnt really let you mess with the image. for that you have the Dockerfile - so you can build an inage of your own, or in this case- kinda like extending the base one:
on your project root directory:
copy the logs you need to sit inside your project (so the dockerfile can access them)
create a Dockerfile:
#Dockerfile
FROM <image_name>
COPY ./logs /home/logs
build your own image: ( you can also push it to a repo)
docker build . -t <new_image_name>
run the container:
docker run -d -ti --name "ContainerName" <new_image_name> /bin/bash
I can't copy the file from the host into the container using the Dockerfile, because i'm simply not allowed to, as mentioned in Docker Documentation:
The path must be inside the context of the build; you cannot
COPY ../something /something, because the first step of a docker build
is to send the context directory (and subdirectories) to the docker
daemon.
I'm also unable to do so from inside jenkins job, because the job commands run inside the shell of the docker container, there is not way to talk to the parent(which is the jenkins host).
This jenkins plugin could have been a life saver, but as mentioned in the first section: distribution of this plugin has been suspended due to unresolved security vulnerabilities.
This is how I copy files from host to docker image using Dockerfile
I have a folder called tomcat
Inside that, I have a tar file and Dockerfile
Commands to do the whole process just for understanding
$ pwd
/home/user/Documents/dockerfiles/tomcat/
$ ls
apache-tomcat-7.0.84.tar.gz Dockerfile
Sample Docker file:
FROM ubuntu_docker
COPY apache-tomcat-7.0.84.tar.gz /home/test/
...
Docker commands:
$ docker build -it testserver .
$ docker run -itd --name test1 testserver
$ docker exec -it bash
Now you are inside docker container
# ls
apache-tomcat-7.0.84.tar.gz
As you can see I am able to copy apache-tomcat-7.0.84.tar.gz from host to Docker container.
Notice the Docker Documentation first line which you have shared
The path must be inside the context of the build;
So as long as the path is reachable during build you can copy.
Another way of doing this would be using volume
docker run -itd -v $(pwd)/somefolder:/home/test --name test1 testserver
Notice -v parameter
You are telling Docker to mount Current_Directory/somefolder to Docker's path at /home/test
Once the container is up and running you can simply copy any file to $(pwd)/somefolder and it will get copied
inside container at /home/test
Please bear with me as I learn my way around docker. I'm using v1.11.1
I am making a Dockerfile and would like to specify that a folder of the container should be persisted, this should only be persisted per user (computer running the container). I originally thought that including:
VOLUME /path/to/dir/to/persist
would be enough, but when I start my container with docker run -t -i myimage:latest bash and manually add files in then exit I expect to be able to find my files again. But when I run the image again (as per above) the added files are no longer there.
I've read around but answers seem either outdated in regards to the use of VOLUMES, or suggest things I would rather not do, which is:
I don't want to use -v in the run command
I would rather not make a volume container (seems like overkill for my one tiny folder)
What is it that I'm doing wrong? Any help would be greatly appreciated.
Cheers guys.
Update: I can persist data using a named volume ie: docker run -v name:/path/to/persist -t -i myimage:latest bash But building with a Dockerfile that contains VOLUME name:/path/to/persist does not work.
What is not very obvious is that you are creating a brand new container every time you do a "docker run". Each new container would then have a fresh volume.
So your data is being persisted, but you're not reading the data from the container you wrote it to.
Example to illustrate the problem
Sample Dockerfile
FROM ubuntu
VOLUME /data
built as normal
$ docker build . -t myimage
Sending build context to Docker daemon 2.048 kB
Step 1 : FROM ubuntu
---> bd3d4369aebc
Step 2 : VOLUME /data
---> Running in db84d80841de
---> 7c94335543b8
Now run it twice
$ docker run -ti myimage echo hello world
$ docker run -ti myimage echo hello world
And take a look at the volumes
$ docker volume ls
DRIVER VOLUME NAME
local 078820609d31f814cd5704cf419c3f579af30672411c476c4972a4aad3a3916c
local cad0604d02467a02f2148a77992b1429bb655dba8137351d392b77a25f30192b
The "docker rm" command has a special "-v" option that will cleanup any volumes associated with containers.
$ docker rm -v $(docker ps -qa)
How to use a data container
Using the same docker image, built in the previous example create a container whose sole purpose is to persist data via it's volume
$ docker create --name mydata myimage
Launch another container that saves some data into the "/data" volume
$ docker run -it --rm --volumes-from mydata myimage bash
root#a1227abdc212:/# echo hello world > /data/helloworld.txt
root#a1227abdc212:/# exit
Launch a second container that retrieves the data
$ docker run -it --rm --volumes-from mydata myimage cat /data/helloworld.txt
hello world
Cleanup, simply remove the container and specify the "-v" option to ensure its volume is cleaned up.
$ docker rm -v mydata
Notes:
The "volumes-from" parameter means all data is saved into the underlying volume associated with the "mydata" container
When running the containers the "rm" option will ensure they are automatically removed, useful for once-off containers.
I was using Docker in the old way, with a volume container:
docker run -d --name jenkins-data jenkins:tag echo "data-only container for Jenkins"
But now I changed to the new way by creating a named volume:
docker volume create --name my-jenkins-volume
I bound this new volume to a new Jenkins container.
The only thing I've left is a folder in which I have the /var/jenkins_home of my previous jenkins container. (by using docker cp)
Now I want to fill my new named volume with the content of that folder.
Can I just copy the content of that folder to /var/lib/jenkins/volume/my-jenkins-volume/_data?
You can certainly copy data directly into /var/lib/docker/volumes/my-jenkins-volume/_data, but by doing this you are:
Relying on physical access to the docker host. This technique won't work if you're interacting with a remote docker api.
Relying on a particular aspect of the volume implementation would could change in the future, breaking any processes you have that rely on it.
I think you are better off relying on things you can accomplish using the docker api, via the command line client. The easiest solution is probably just to use a helper container, something like:
docker run -v my-jenkins-volume:/data --name helper busybox true
docker cp . helper:/data
docker rm helper
You don't need to start some container to add data to already existing named volume, just create a container and copy data there:
docker container create --name temp -v my-jenkins-volume:/data busybox
docker cp . temp:/data
docker rm temp
You can reduce the accepted answer to one line using, e.g.
docker run --rm -v `pwd`:/src -v my-jenkins-volume:/data busybox cp -r /src /data
Here are steps for copying contents of ~/data to docker volume named my-vol
Step 1. Attach the volume to a "temporary" container. For that run in terminal this command :
docker run --rm -it --name alpine --mount type=volume,source=my-vol,target=/data alpine
Step 2. Copy contents of ~/data into my-vol . For that run this commands in new terminal window :
cd ~/data
docker cp . alpine:/data
This will copy contents of ~/data into my-vol volume. After copy exit the temporary container.
You can add this BASH function to your .bashrc to copy files to a existing Docker volume without running a container
# Usage: copy-to-docker-volume SRC_PATH DEST_VOLUME_NAME [DEST_PATH]
copy-to-docker-volume() {
SRC_PATH=$1
DEST_VOLUME_NAME=$2
DEST_PATH="${3:-}"
# create smallest Docker image possible
echo -e 'FROM scratch\nLABEL empty=""' | docker build -t empty -
# create temporary container to be able to mount volume
CONTAINER_ID=$(docker container create -v my-volume:/data empty cmd)
# copy files to volume
docker cp "${SRC_PATH}" "${CONTAINER_ID}":"/data/${DEST_PATH}"
# remove temporary container
docker rm "${CONTAINER_ID}"
}
Example
# create volume as destination
docker volume create my-volume
# create directory to copy
mkdir my-dir
echo "hello file1" > my-dir/my-file-1
# copy directory to volume
copy-to-docker-volume my-dir my-volume
# list directory on volume
docker run --rm -it -v my-volume:/data busybox ls -la /data/my-dir
# show file content on volume
docker run --rm -it -v my-volume:/data busybox cat /data/my-dir/my-file-1
# create another file to copy
echo "hello file2" > my-file-2
# copy file to directory on volume
copy-to-docker-volume my-file-2 my-volume my-dir
# list (updated) directory on volume
docker run --rm -it -v my-volume:/data busybox ls -la /data/my-dir
# check volume content
docker run --rm -it -v my-volume:/data busybox cat /data/my-dir/my-file-2
If you don't want to create a docker and you can access as privileged user to , simply do (on Linux systems):
docker volume create my_named_volume
sudo cp -p . /var/lib/docker/volumes/my_named_volume/_data/
Furthermore, it also allows you to access data in docker runtime or also with docker containers stopped.
If you don't want to create a temp helper container on windows docker desktop (backed by wsl2) then
copy the files to below location
\\wsl$\docker-desktop-data\version-pack-data\community\docker\volumes\my-volume\_data
here my-volume is the name of your named volume. browse the above path from address bar in your file explorer. This is a internal network created by wsl in windows.
Note: it might be better to use docker API like mentioned by larsks, but I have not faced any issues on windows.
Similarly on linux files can be copied to
/var/lib/docker/volumes/my-volume/_data/