I am new to docker and I have a problem when it comes to shipping data containers. Ok, usually we ship images and users can start as may containers from this image as the want, right?
Now I want to ship some data too - so I have made a data container so:
docker create -v /dbdata --name dbdata phusion/baseimage
Next I simply started a bash and inserted some data into my data container
docker run --volumes-from dbdata -i -t phusion/baseimage /bin/bash
echo "foo" > /dbdata/bar.txt
exit
Now I want to allow my team members to use the same data (offline), so I would like to "send" my data container to them. Therefore I have used
docker export dbdata > /tmp/cool_data.tar
But when I re import this with
cat /tmp/data.tar | sudo docker import - dbdata2
I can not use this "container" because it seems to be an image
docker run --volumes-from dbdata2 -i -t phusion/baseimage /bin/bash
FATA[0000] Error response from daemon: Container dbdata2 not found. Impossible to mount its volumes
How do I export and import data containers correctly?
You can't export and import data in volumes like this - volumes are simply not included in export/import.
You don't need to do this however - just zip or tar the directories the volumes are mapped to and send to your colleagues. They can then make their own data containers using those files.
You may also want to look at flocker, which can help you migrate containers and data.
You need to make a container out of this image first. Run this:
docker create -v /dbdata --name dbdata2 dbdata2
For more details, check out Creating and mounting Data Volume Containers
I'm having good luck with the following Dockerfile:
from scratch
ADD install_theGreatSoftwarePkg /install
VOLUME /install
Then I do a build and create:
docker build -t greatSoftwareInstallImage .
docker create -t --name=greatSoftwareMedia greatSoftwareInstallImage /bin/true
Related
I did a docker pull and can list the image that's downloaded. I want to see the contents of this image. Did a search on the net but no straight answer.
If the image contains a shell, you can run an interactive shell container using that image and explore whatever content that image has. If sh is not available, the busybox ash shell might be.
For instance:
docker run -it image_name sh
Or following for images with an entrypoint
docker run -it --entrypoint sh image_name
Or if you want to see how the image was built, meaning the steps in its Dockerfile, you can:
docker image history --no-trunc image_name > image_history
The steps will be logged into the image_history file.
You should not start a container just to see the image contents. For instance, you might want to look for malicious content, not run it. Use "create" instead of "run";
docker create --name="tmp_$$" image:tag
docker export tmp_$$ | tar t
docker rm tmp_$$
The accepted answer here is problematic, because there is no guarantee that an image will have any sort of interactive shell. For example, the drone/drone image contains on a single command /drone, and it has an ENTRYPOINT as well, so this will fail:
$ docker run -it drone/drone sh
FATA[0000] DRONE_HOST is not properly configured
And this will fail:
$ docker run --rm -it --entrypoint sh drone/drone
docker: Error response from daemon: oci runtime error: container_linux.go:247: starting container process caused "exec: \"sh\": executable file not found in $PATH".
This is not an uncommon configuration; many minimal images contain only the binaries necessary to support the target service. Fortunately, there are mechanisms for exploring an image filesystem that do not depend on the contents of the image. The easiest is probably the docker export command, which will export a container filesystem as a tar archive. So, start a container (it does not matter if it fails or not):
$ docker run -it drone/drone sh
FATA[0000] DRONE_HOST is not properly configured
Then use docker export to export the filesystem to tar:
$ docker export $(docker ps -lq) | tar tf -
The docker ps -lq there means "give me the id of the most recent docker container". You could replace that with an explicit container name or id.
docker save nginx > nginx.tar
tar -xvf nginx.tar
Following files are present:
manifest.json – Describes filesystem layers and name of json file that has the Container properties.
.json – Container properties
– Each “layerid” directory contains json file describing layer property and filesystem associated with that layer. Docker stores Container images as layers to optimize storage space by reusing layers across images.
https://sreeninet.wordpress.com/2016/06/11/looking-inside-container-images/
OR
you can use dive to view the image content interactively with TUI
https://github.com/wagoodman/dive
EXPLORING DOCKER IMAGE!
Figure out what kind of shell is in there bash or sh...
Inspect the image first: docker inspect name-of-container-or-image
Look for entrypoint or cmd in the JSON return.
Then do: docker run --rm -it --entrypoint=/bin/bash name-of-image
once inside do: ls -lsa or any other shell command like: cd ..
The -it stands for interactive... and TTY. The --rm stands for remove container after run.
If there are no common tools like ls or bash present and you have access to the Dockerfile simple add the common tool as a layer.
example (alpine Linux):
RUN apk add --no-cache bash
And when you don't have access to the Dockerfile then just copy/extract the files from a newly created container and look through them:
docker create <image> # returns container ID the container is never started.
docker cp <container ID>:<source_path> <destination_path>
docker rm <container ID>
cd <destination_path> && ls -lsah
To list the detailed content of an image you have to run docker run --rm image/name ls -alR where --rm means remove as soon as exits form a container.
If you want to list the files in an image without starting a container :
docker create --name listfiles <image name>
docker export listfiles | tar -t
docker rm listfiles
We can try a simpler one as follows:
docker image inspect image_id
This worked in Docker version:
DockerVersion": "18.05.0-ce"
if you want to check the image contents without running it you can do this:
$ sudo bash
...
$ cd /var/lib/docker # default path in most installations
$ find . -iname a_file_inside_the_image.ext
... (will find the base path here)
This works fine with the current default BTRFS storage driver.
Oneliner, no docker run (based on responses above)
IMAGE=your_image docker create --name filelist $IMAGE command && docker export filelist | tar tf - | tree --fromfile . && docker rm filelist
Same, but report tree structure to result.txt
IMAGE=your_image docker create --name filelist $IMAGE command && docker export filelist | tar tf - | tree --noreport --fromfile . | tee result.txt && docker rm filelist
I tried this tool - https://github.com/wagoodman/dive
I found it quite helpful to explore the content of the docker image.
Perhaps this is nota very straight forward approach but this one worked for me.
I had an ECR Repo (Amazon Container Service Repository) whose code i wanted to see.
First we need to save the repo you want to access as a tar file. In my case the command went like - docker save .dkr.ecr.us-east-1.amazonaws.com/<name_of_repo>:image-tag > saved-repo.tar
UNTAR the file using the command - tar -xvf saved-repo.tar. You could see many folders and files
Now try to find the file which contain the code you are looking for (if you know some part of the code)
Command for searching the file - grep -iRl "string you want to search" ./
This will make you reach the file. It can happen that even that file is tarred, so untar it using the command mentioned in step 2.
If you dont know the code you are searching for, you will need to go through all the files that you got after step 2 and this can be bit tiring.
All the Best !
There is a free open source tool called Anchore-CLI that you can use to scan container images. This command will allow you to list all files in a container image
anchore-cli image content myrepo/app:latest files
https://anchore.com/opensource/
EDIT: not available from anchore.com anymore, It's a python program you can install from https://github.com/anchore/anchore-cli
With Docker EE for Windows (17.06.2-ee-6 on Hyper-V Server 2016) all contents of Windows Containers can be examined at C:\ProgramData\docker\windowsfilter\ path of the host OS.
No special mounting needed.
Folder prefix can be found by container id from docker ps -a output.
I did a docker pull and can list the image that's downloaded. I want to see the contents of this image. Did a search on the net but no straight answer.
If the image contains a shell, you can run an interactive shell container using that image and explore whatever content that image has. If sh is not available, the busybox ash shell might be.
For instance:
docker run -it image_name sh
Or following for images with an entrypoint
docker run -it --entrypoint sh image_name
Or if you want to see how the image was built, meaning the steps in its Dockerfile, you can:
docker image history --no-trunc image_name > image_history
The steps will be logged into the image_history file.
You should not start a container just to see the image contents. For instance, you might want to look for malicious content, not run it. Use "create" instead of "run";
docker create --name="tmp_$$" image:tag
docker export tmp_$$ | tar t
docker rm tmp_$$
The accepted answer here is problematic, because there is no guarantee that an image will have any sort of interactive shell. For example, the drone/drone image contains on a single command /drone, and it has an ENTRYPOINT as well, so this will fail:
$ docker run -it drone/drone sh
FATA[0000] DRONE_HOST is not properly configured
And this will fail:
$ docker run --rm -it --entrypoint sh drone/drone
docker: Error response from daemon: oci runtime error: container_linux.go:247: starting container process caused "exec: \"sh\": executable file not found in $PATH".
This is not an uncommon configuration; many minimal images contain only the binaries necessary to support the target service. Fortunately, there are mechanisms for exploring an image filesystem that do not depend on the contents of the image. The easiest is probably the docker export command, which will export a container filesystem as a tar archive. So, start a container (it does not matter if it fails or not):
$ docker run -it drone/drone sh
FATA[0000] DRONE_HOST is not properly configured
Then use docker export to export the filesystem to tar:
$ docker export $(docker ps -lq) | tar tf -
The docker ps -lq there means "give me the id of the most recent docker container". You could replace that with an explicit container name or id.
docker save nginx > nginx.tar
tar -xvf nginx.tar
Following files are present:
manifest.json – Describes filesystem layers and name of json file that has the Container properties.
.json – Container properties
– Each “layerid” directory contains json file describing layer property and filesystem associated with that layer. Docker stores Container images as layers to optimize storage space by reusing layers across images.
https://sreeninet.wordpress.com/2016/06/11/looking-inside-container-images/
OR
you can use dive to view the image content interactively with TUI
https://github.com/wagoodman/dive
EXPLORING DOCKER IMAGE!
Figure out what kind of shell is in there bash or sh...
Inspect the image first: docker inspect name-of-container-or-image
Look for entrypoint or cmd in the JSON return.
Then do: docker run --rm -it --entrypoint=/bin/bash name-of-image
once inside do: ls -lsa or any other shell command like: cd ..
The -it stands for interactive... and TTY. The --rm stands for remove container after run.
If there are no common tools like ls or bash present and you have access to the Dockerfile simple add the common tool as a layer.
example (alpine Linux):
RUN apk add --no-cache bash
And when you don't have access to the Dockerfile then just copy/extract the files from a newly created container and look through them:
docker create <image> # returns container ID the container is never started.
docker cp <container ID>:<source_path> <destination_path>
docker rm <container ID>
cd <destination_path> && ls -lsah
To list the detailed content of an image you have to run docker run --rm image/name ls -alR where --rm means remove as soon as exits form a container.
If you want to list the files in an image without starting a container :
docker create --name listfiles <image name>
docker export listfiles | tar -t
docker rm listfiles
We can try a simpler one as follows:
docker image inspect image_id
This worked in Docker version:
DockerVersion": "18.05.0-ce"
if you want to check the image contents without running it you can do this:
$ sudo bash
...
$ cd /var/lib/docker # default path in most installations
$ find . -iname a_file_inside_the_image.ext
... (will find the base path here)
This works fine with the current default BTRFS storage driver.
Oneliner, no docker run (based on responses above)
IMAGE=your_image docker create --name filelist $IMAGE command && docker export filelist | tar tf - | tree --fromfile . && docker rm filelist
Same, but report tree structure to result.txt
IMAGE=your_image docker create --name filelist $IMAGE command && docker export filelist | tar tf - | tree --noreport --fromfile . | tee result.txt && docker rm filelist
I tried this tool - https://github.com/wagoodman/dive
I found it quite helpful to explore the content of the docker image.
Perhaps this is nota very straight forward approach but this one worked for me.
I had an ECR Repo (Amazon Container Service Repository) whose code i wanted to see.
First we need to save the repo you want to access as a tar file. In my case the command went like - docker save .dkr.ecr.us-east-1.amazonaws.com/<name_of_repo>:image-tag > saved-repo.tar
UNTAR the file using the command - tar -xvf saved-repo.tar. You could see many folders and files
Now try to find the file which contain the code you are looking for (if you know some part of the code)
Command for searching the file - grep -iRl "string you want to search" ./
This will make you reach the file. It can happen that even that file is tarred, so untar it using the command mentioned in step 2.
If you dont know the code you are searching for, you will need to go through all the files that you got after step 2 and this can be bit tiring.
All the Best !
There is a free open source tool called Anchore-CLI that you can use to scan container images. This command will allow you to list all files in a container image
anchore-cli image content myrepo/app:latest files
https://anchore.com/opensource/
EDIT: not available from anchore.com anymore, It's a python program you can install from https://github.com/anchore/anchore-cli
With Docker EE for Windows (17.06.2-ee-6 on Hyper-V Server 2016) all contents of Windows Containers can be examined at C:\ProgramData\docker\windowsfilter\ path of the host OS.
No special mounting needed.
Folder prefix can be found by container id from docker ps -a output.
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 have been trying to setup a graph database using orientdb. So I tried using volumes by the following command
docker run -d -p 2424:2424 -p 2480:2480 -v config:/orientdb/config -v database:/orientdb/databases -v backup:/orientdb/backup -e ORIENTDB_ROOT_PASSWORD=mypasswdhere orientdb:latest
My prime motive behind using volumes was to store data in database after I kill the container.
But I used this command frequently to start the server.
Now it has hogged my disk space so I guess it creates a new copy each time this command is executed.
Can someone indicate a correct way to use existing volumes to use stored data in docker and to clean up the redundant data recreated by frequent execution of this command?
You can create named volumes with docker volume create
$ docker volume create --name hello
$ docker run -d -v hello:/world busybox ls /world
That way, only one volume in /var/lib/docker/volumes will be used each time you launch that container.
See also "Mount a shared-storage volume as a data volume".
In the meantime, to remove dangling volumes:
docker volume ls -qf "dangling=true" | xargs docker volume rm
As far as I understand, you aren't re-using the container, instead you start a new one each time.
After the first run, you can stop and the restart it with docker stop/start commands.
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.