I have a Dockerfile based on apache/nifi:1.12.1 and want to expand it like this:
FROM apache/nifi:1.12.1
RUN mkdir -p /opt/nifi/nifi-current/conf/flow
Thing is that the folder isn't created when I'm building the image from Linux distros like Ubuntu and CentOS. Build succeeds, I run it with docker run -it -d --rm --name nifi nifi-test but when I enter the container through docker exec there's no flow dir.
Strange thing is, that the flow dir is being created normally when I'm building the image through Windows and Docker Desktop. I can't understand why is this happening.
I've tried things such as USER nifi or RUN chown ... but still...
For your convenience, this is the base image:
https://github.com/apache/nifi/blob/rel/nifi-1.12.1/nifi-docker/dockerhub/Dockerfile
Take a look at this as well:
This is what looks like at the CLI
Thanks in advance.
By taking a look at the dockerfile provided you can see the following volume definition
Then if you run
docker image inspect apache/nifi:1.12.1
As a result, when you execute the RUN command to create a folder under the conf directory it succeeds
BUT when you run the container the volumes are mounted and as a result they overwrite everything that is under the mountpoint /opt/nifi/nifi-current/conf
In your case the flow directory.
You can test this by editing your Dockerfile
FROM apache/nifi:1.12.1
# this will be overriden, by volumes
RUN mkdir -p /opt/nifi/nifi-current/conf/flow
# this will be available in the container environment
RUN mkdir -p /opt/nifi/nifi-current/flow
To tackle this you could
clone the Dockerfile of the image you use as base one (the one in
FROM) and remove the VOLUME directive manually. Then build it and
use in your FROM as base one.
You could try to avoid adding directories under the mount points specified in the Dockerfile
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.
I am new to docker, I'm dynamically creating a file which is in docker container and want to copy that local machine at the same time, please let me know how it is possible through volumes.
For now, I have to use the below command again and again to check the file data :
docker cp source destination
How it can be done through volumes, the file format will be in .csv or .xlsx? I mean what should I write the command in docker files so that it can copy the file
What you need is volume. You have to add your current directory as a volume to the docker container when you first create the container so that they are the same folder. By doing this, you'll be able to sync the files in that folder automatically. But I'm assuming you're using docker for development environment.
This is how I run my container.
docker run -d -it --name {container_name} --volume $PWD:{directory_in_container} --entrypoint /bin/bash {image_name}
In addition to your run command, you have to add --volume $PWD:{directory_in_container} to your run script.
If you have a problem again, just add more detail to your question.
Things you can add might be your Dockerfile, and how you first run your container.
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.
My question is related to this question on copying files from containers to hosts; I have a Dockerfile that fetches dependencies, compiles a build artifact from source, and runs an executable. I also want to copy the build artifact (in my case it's a .zip produced by sbt dist in '../target/`, but I think this question also applies to jars, binaries, etc.
docker cp works on containers, not images; do I need to start a container just to get a file out of it? In a script, I tried running /bin/bash in interactive mode in the background, copying the file out, and then killing the container, but this seems kludgey. Is there a better way?
On the other hand, I would like to avoid unpacking a .tar file after running docker save $IMAGENAME just to get one file out (but that seems like the simplest, if slowest, option right now).
I would use docker volumes, e.g.:
docker run -v hostdir:out $IMAGENAME /bin/cp/../blah.zip /out
but I'm running boot2docker in OSX and I don't know how to directly write to my mac host filesystem (read-write volumes are mounting inside my boot2docker VM, which means I can't easily share a script to extract blah.zip from an image with others. Thoughts?
To copy a file from an image, create a temporary container, copy the file from it and then delete it:
id=$(docker create image-name)
docker cp $id:path - > local-tar-file
docker rm -v $id
Unfortunately there doesn't seem to be a way to copy files directly from Docker images. You need to create a container first and then copy the file from the container.
However, if your image contains a cat command (and it will do in many cases), you can do it with a single command:
docker run --rm --entrypoint cat yourimage /path/to/file > path/to/destination
If your image doesn't contain cat, simply create a container and use the docker cp command as suggested in Igor's answer.
docker cp $(docker create --name tc registry.example.com/ansible-base:latest):/home/ansible/.ssh/id_rsa ./hacked_ssh_key && docker rm tc
wanted to supply a one line solution based on pure docker functionality (no bash needed)
edit: container does not even has to be run in this solution
edit2: thanks to #Jonathan Dumaine for --rm so the container will be removed after, i just never tried, because it sounded illogical to copy something from somewhere which has been already removed by the previous command, but i tried it and it works
edit3: due the comments we found out --rm is not working as expected, it does not remove the container because it never runs, so I added functionality to delete the created container afterwards(--name tc=temporary-container)
edit 4: this error appeared, seems like a bug in docker, because t is in a-z and this did not happen a few months before.
Error response from daemon: Invalid container name (t), only [a-zA-Z0-9][a-zA-Z0-9_.-] are allowed
A much faster option is to copy the file from running container to a mounted volume:
docker run -v $PWD:/opt/mount --rm --entrypoint cp image:version /data/libraries.tgz /opt/mount/libraries.tgz
real 0m0.446s
** VS **
docker run --rm --entrypoint cat image:version /data/libraries.tgz > libraries.tgz
real 0m9.014s
Parent comment already showed how to use cat. You could also use tar in a similar fashion:
docker run yourimage tar -c -C /my/directory subfolder | tar x
Another (short) answer to this problem:
docker run -v $PWD:/opt/mount --rm -ti image:version bash -c "cp /source/file /opt/mount/"
Update - as noted by #Elytscha Smith this only works if your image has bash built in
Not a direct answer to the question details, but in general, once you pulled an image, the image is stored on your system and so are all its files. Depending on the storage driver of the local Docker installation, these files can usually be found in /var/lib/docker/overlay2 (requires root access). overlay2 should be the most common storage driver nowadays, but the path may differ.
The layers associated with an image can be found using $ docker inspect image IMAGE_NAME:TAG, look for a GraphDriver attribute.
At least in my local environment, the following also works to quickly see all layers associated with an image:
docker inspect image IMAGE_NAME:TAG | jq ".[0].GraphDriver.Data"
In one of these diff directories, the wanted file can be found.
So in theory, there's no need to create a temporary container. Ofc this solution is pretty inconvenient.
First pull docker image using docker pull
docker pull <IMG>:<TAG>
Then, create a container using docker create command and store the container id is a variable
img_id=$(docker create <IMG>:<TAG>)
Now, run the docker cp command to copy folders and files from docker container to host
docker cp $img_id:/path/in/container /path/in/host
Once the files/folders are moved, delete the container using docker rm
docker rm -v $img_id
You essentially had the best solution already. Have the container copy out the files for you, and then remove itself when it's complete.
This will copy the files from /inside/container/ to your machine at /path/to/hostdir/.
docker run --rm -v /path/to/hostdir:/mnt/out "$IMAGENAME" /bin/cp -r /inside/container/ /mnt/out/
Update - here's a better version without the tar file:
$id = & docker create image-name
docker cp ${id}:path .
docker rm -v $id
Old answer
PowerShell variant of Igor Bukanov's answer:
$id = & docker create image-name
docker cp ${id}:path - > local-file.tar
docker rm -v $id
I am using boot2docker on MacOS. I can assure you that scripts based on "docker cp" are portable. Because any command is relayed inside boot2docker but then the binary stream is relayed back to the docker command line client running on your mac. So write operations from the docker client are executed inside the server and written back to the executing client instance!
I am sharing a backup script for docker volumes with any docker container I provide and my backup scripts are tested both on linux and MacOS with boot2docker. The backups can be easily exchanged between platforms. Basically I am executing the following command inside my script:
docker run --name=bckp_for_volume --rm --volumes-from jenkins_jenkins_1 -v /Users/github/jenkins/backups:/backup busybox tar cf /backup/JenkinsBackup-2015-07-09-14-26-15.tar /jenkins
Runs a new busybox container and mounts the volume of my jenkins container with the name jenkins_jenkins_1. The whole volume is written to the file backups/JenkinsBackup-2015-07-09-14-26-15.tar
I have already moved archives between the linux container and my mac container without any adjustments to the backup or restore script. If this is what you want you find the whole script an tutorial here: blacklabelops/jenkins
You could bind a local path on the host to a path on the container, and then cp the desired file(s) to that path at the end of your script.
$ docker run -d \
-it \
--name devtest \
--mount type=bind,source="$(pwd)"/target,target=/app \
nginx:latest
Then there is no need to copy afterwards.