I have Dockerfile as shown here.
A script in the entrypoint creates a directory and places few artifacts.
# from base image
FROM ......
RUN mkdir -p /home/myuser
RUN groupadd -g 999 myuser &&\
useradd -r -u 999 -g myuser myuser
ENV HOME=/home/myuser
ENV APP_HOME=/home/myuser/workspace
RUN mkdir $APP_HOME
WORKDIR $APP_HOME
RUN chown -R myuser:myuser $APP_HOME
USER myuser
ENTRYPOINT ......
I start a container for the above image as shown here
sudo docker run -v ${WORKSPACE}/output:/home/myuser/workspace/output image
I could not get the artifacts in the host machine. ${WORKSPACE}/output created with permission drwxr_xr_x
What is the process to get the container files into the host machine?
Additional Info:
My host username is kit
container user is myuser
container works perfectly fine - at the time of creating output file it throws an error that Permission denied
I tried to give full permission drwxrwxrwx to ${WORKSPACE}/output. then i could see the output files.
The permission denied error is because you are running a container with uid 999, but trying to write to a host directory that is owned by uid 1000 and only configured to allow writes by the user. You can:
chmod the directory to allow anyone to write (not recommended, but quick and easy)
update your image to match the uid/gid of your user on the host
switch to using a named volume
use an entrypoint to align the container uid/gid to that of a volume mount before starting your app
I go into a bit more detail on these in my slides here. There are also some speaker notes in there (I believe either P or S will bring them up).
Related
I am trying to build a Kafka-Connect image in Docker:
FROM confluentinc/cp-kafka-connect
RUN confluent-hub install --no-prompt wepay/kafka-connect-bigquery:1.6.1
RUN confluent-hub install --no-prompt confluentinc/connect-transforms:latest
RUN mkdir -p /usr/share/landoop-plugins
COPY kafka-connect-redis-1.2.2-2.1.0-all.jar /usr/share/landoop-plugins/
but it runs as appuser
Step 4/4 : RUN id
---> Running in d2094f6336a7
uid=1000(appuser) gid=1000(appuser) groups=1000(appuser)
so if I want for example
RUN mkdir -p /usr/share/landoop-plugins
it stops because of root privilages:
mkdir: cannot create directory '/usr/share/landoop-plugins': Permission denied
The command '/bin/sh -c mkdir -p /usr/share/landoop-plugins' returned a non-zero code: 1
I can add USER root at the beginning of Dockerfile:
Step 3/15 : RUN id
---> Running in 6255e2e7ff81
uid=0(root) gid=0(root) groups=0(root)
but then if I ran the container, I am logged as appuser which causes problems with permissions:
[appuser#connect ~]$.
Actually, in source image
confluentinc/cp-kafka-connect:6.0.0
there is a layer USER appuser so my question is how can I build my image as root and then login as root and do not use appuser user. I've tried and USER root does not help.
Is it somehow connected with groups?
groups
gignac sudo docker
I tried docker build and sudo docker build as well
I do something similar, when I need to create my own plugin to Kafka Connect but I don't exactly do it as root.
Simply I put my jars in a place I have permission to write and just configure the plugins Environment Setting
something like this:
FROM confluentinc/cp-kafka-connect:5.5.2
ENV CONNECT_PLUGIN_PATH='/usr/share/java,/usr/share/confluent-hub-components'
COPY converter/* /usr/share/java/kafka-serde-tools/
COPY format/* /usr/share/java/kafka-connect-storage-common/
would this not work?
For installing packages and troubleshooting, we would require root user. Using version 5.5.3 does the trick wherein the APPUSER is not created and root is loaded by default.
The version can be verified by
http://localhost:8083/connectors
which provides the version details.
Seems like a basic issue but couldnt find any answers so far ..
When using ADD / COPY in Dockerfile and running the image on linux, the default file permission of the file copied in the image is 644. The onwner of this file seems to be as 'root'
However, when running the image, a non-root user starts the container and any file thus copied with 644 permission cannot execute this copied/added file and if the file is executed at ENTRYPOINT it fails to start with permission denied error.
I read in one of the posts that COPY/ADD after Docker 1.17.0+ allows chown but in my case i dont know who will be the non-root user starting so i cannot set the permission as that user.
I also saw another work around to ADD/COPY files to a different location and use RUN to copy them from the temp location to actual folder like what am doing below. But this approach doesnt work as the final image doesnt have the files in /otp/scm
#Installing Bitbucket and setting variables
WORKDIR /tmp
ADD atlassian-bitbucket-${BITBUCKET_VERSION}.tar.gz .
COPY bbconfigupdater.sh .
#Copying Entrypoint script which will get executed when container starts
WORKDIR /tmp
COPY entrypoint.sh .
RUN ls -lrth /tmp
WORKDIR /opt/scm
RUN pwd && cp /tmp/bbconfigupdater.sh /opt/scm \
&& cp /tmp/entrypoint.sh /opt/scm \
&& cp -r /tmp/atlassian-bitbucket-${BITBUCKET_VERSION} /opt/scm \
&& chgrp -R 0 /opt/ \
&& chmod -R 755 /opt/ \
&& chgrp -R 0 /scm/bitbucket \
&& chmod -R 755 /scm/bitbucket \
&& ls -lrth /opt/scm && ls -lrth /scmdata
Any help is appreciated to figure out how i can get my entrypoint script copied to the desired path with execute permissions set.
The default file permission is whatever the file permission is in your build context from where you copy the file. If you control the source, then it's best to fix the permissions there to avoid a copy-on-write operation. Otherwise, if you cannot guarantee the system building the image will have the execute bit set on the files, a chmod after the copy operation will fix the permission. E.g.
COPY entrypoint.sh .
RUN chmod +x entrypoint.sh
A better option with newer versions of docker (and which didn't exist when this answer was first posted) is to use the --chmod flag (the permissions must be specified in octal at last check):
COPY --chmod=0755 entrypoint.sh .
You do not need to know who will run the container. The user inside the container is typically configured by the image creator (using USER) and doesn't depend on the user running the container from the docker host. When the user runs the container, they send a request to the docker API which does not track the calling user id.
The only time I've seen the host user matter is if you have a host volume and want to avoid permission issues. If that's your scenario, I often start the entrypoint as root, run a script called fix-perms to align the container uid with the host volume uid, and then run gosu to switch from root back to the container user.
A --chmod flag was added to ADD and COPY instructions in Docker CE 20.10. So you can now do.
COPY --chmod=0755 entrypoint.sh .
To be able to use it you need to enable BuildKit.
# enable buildkit for docker
DOCKER_BUILDKIT=1
# enable buildkit for docker-compose
COMPOSE_DOCKER_CLI_BUILD=1
Note: It seems to not be documented at this time, see this issue.
I have a dockerfile with a user created so it is not running as root(best pratice)
FROM microsoft/dotnet:sdk AS build-env
WORKDIR /app
# Copy csproj and restore as distinct layers
COPY *.csproj ./
RUN dotnet restore
# Copy everything else and build
COPY . ./
RUN dotnet publish -c Release -o out
# Build runtime image
FROM microsoft/dotnet:aspnetcore-runtime
RUN groupadd -g 1001 appuser && useradd -r -u 1001 -g appuser appuser
USER appuser
WORKDIR /app
COPY --from=build-env /app/out .
ENTRYPOINT ["dotnet", "ConsoleApp32.dll"]
I build the image and run the container:
docker build -f Dockerfile1 -t myappimage .
docker run -d --name myapp myappimage
And then check it running:
ps aux | grep dotnet
21569 1001 0:00 dotnet ConsoleApp32.dll
So running as uid 1001.
I then check host for this user:
cut -d: -f1 /etc/passwd
root
bin
daemon
adm
lp
sync
shutdown
halt
mail
news
uucp
operator
man
postmaster
cron
ftp
sshd
at
squid
xfs
games
postgres
cyrus
vpopmail
ntp
smmsp
guest
nobody
dockremap
No sign of appuser. My understanding(which may be wrong) is we are using a shared Kernel and user should be in list.
I also looked up uid
getent passwd 1001
Which returned no result.
Can someone explain this, as I dont understand how a process is running on host as a uid of 1001 and there is no associated user
The user ID is shared with the host: it’s 1001. The name of that user comes from looking it up in the /etc/passwd file. Since the host and container have different filesystem spaces, they have different passwd files; the kernel doesn’t know anything about a user’s name.
The corresponding FAQ: it doesn’t matter if you have users named pat on both the host and in the container; if their numeric user IDs don’t match up, and you’re on Linux, and you’re trying to share content with docker run -v, one user won’t be able to access the other’s files.
I'm trying a simple workflow without success and it take me a loooooot of time to test many solutions on SO and github. Permission for named folder and more generaly permissions volume in docker is a nightmare link1 link2 imho.
So i restart from scratch, trying to create a simple proof of concept for my use case.
I want this general workflow :
user on windows and/or linux build the Dockerfile
user run the container (if possible not as root)
the container launch a crontab which run a script writing in the data volume each minute
users (on linux or windows) get the results from the data volume (not root) because permissions are correctly mapped
I use supercronic because it runs crontab in container without root permission.
The Dockerfile :
FROM artemklevtsov/r-alpine:latest as baseImage
RUN mkdir -p /usr/local/src/myscript/
RUN mkdir -p /usr/local/src/myscript/result
COPY . /usr/local/src/myscript/
WORKDIR /usr/local/src/myscript/
RUN echo http://nl.alpinelinux.org/alpine/edge/testing >> /etc/apk/repositories
RUN apk --no-cache add busybox-suid curl
ENV SUPERCRONIC_URL=https://github.com/aptible/supercronic/releases/download/v0.1.$
SUPERCRONIC=supercronic-linux-amd64 \
SUPERCRONIC_SHA1SUM=9aeb41e00cc7b71d30d33c57a2333f2c2581a201
RUN curl -fsSLO "$SUPERCRONIC_URL" \
&& echo "${SUPERCRONIC_SHA1SUM} ${SUPERCRONIC}" | sha1sum -c - \
&& chmod +x "$SUPERCRONIC" \
&& mv "$SUPERCRONIC" "/usr/local/bin/${SUPERCRONIC}" \
&& ln -s "/usr/local/bin/${SUPERCRONIC}" /usr/local/bin/supercronic
CMD ["supercronic", "crontab"]
The crontab file :
* * * * * sh /usr/local/src/myscript/run.sh > /proc/1/fd/1 2>&1
The run.sh script
#!/bin/bash
name=$(date '+%Y-%m-%d-%s')
echo "some data for the file" >> ./result/fileName$name
The commands :
# create the volume for result, uid/gid option are not possible for windows
docker volume create --name myTestVolume
docker run --mount type=volume,source=myTestVolume,destination=/usr/local/src/myscript/result test
docker run --rm -v myTestVolume:/alpine_data -v $(pwd)/local_backup:/alpine_backup alpine:latest tar cvf /alpine_backup/scrap_data_"$(date '+%y-%m-%d')".tar /alpine_data
When i do this the result folder local_backup and files it contains has root:root permissions, so user who launch this container cannot access the files.
Is there a solution which works, which permits windows/linux/mac users who launch the same script to access easily the files into volume without problem of permissions ?
EDIT 1 :
The strategy first described here only work with binded volume, and not named volume. We use an entrypoint.sh to chown uid/gid of folders of container based on information given by docker run.
I copy paste the modified Dockerfile :
FROM artemklevtsov/r-alpine:latest as baseImage
RUN mkdir -p /usr/local/src/myscript/
RUN mkdir -p /usr/local/src/myscript/result
COPY . /usr/local/src/myscript/
ENTRYPOINT [ "/usr/local/src/myscript/entrypoint.sh" ]
WORKDIR /usr/local/src/myscript/
RUN echo http://nl.alpinelinux.org/alpine/edge/testing >> /etc/apk/repositories
RUN apk --no-cache add busybox-suid curl su-exec
ENV SUPERCRONIC_URL=https://github.com/aptible/supercronic/releases/download/v0.1.$
SUPERCRONIC=supercronic-linux-amd64 \
SUPERCRONIC_SHA1SUM=9aeb41e00cc7b71d30d33c57a2333f2c2581a201
RUN curl -fsSLO "$SUPERCRONIC_URL" \
&& echo "${SUPERCRONIC_SHA1SUM} ${SUPERCRONIC}" | sha1sum -c - \
&& chmod +x "$SUPERCRONIC" \
&& mv "$SUPERCRONIC" "/usr/local/bin/${SUPERCRONIC}" \
&& ln -s "/usr/local/bin/${SUPERCRONIC}" /usr/local/bin/supercronic
CMD ["supercronic", "crontab"]
The entrypoint.sh
#!/bin/sh
set -e
addgroup -g $GID scrap && adduser -s /bin/sh -D -G scrap -u $UID scrap
if [ "$(whoami)" == "root" ]; then
chown -R scrap:scrap /usr/local/src/myscript/
chown --dereference scrap "/proc/$$/fd/1" "/proc/$$/fd/2" || :
exec su-exec scrap "$#"
fi
The procedure to build,launch, export:
docker build . --tag=test
docker run -e UID=1000 -e GID=1000 --mount type=volume,source=myTestVolume,destination=/usr/local/src/myscript/result test
docker run --rm -v myTestVolume:/alpine_data -v $(pwd)/local_backup:/alpine_backup alpine:latest tar cvf /alpine_backup/scrap_data_"$(date '+%y-%m-%d')".tar /alpine_data
EDIT 2 :
For Windows, using docker toolbox and binded volume, i found the answer on SO. I use the c:/Users/MyUsers folder for binding, it's more simple.
docker run --name test -d -e UID=1000 -e GID=1000 --mount type=bind,source=/c/Users/myusers/localbackup,destination=/usr/local/src/myscript/result dockertest --name rflightscraps
Result of investigation
crontab run with scrap user [OK]
UID/GID of local user are mapped to container user scrap [OK]
Exported data continue to be root [NOT OK].
Windows / Linux [HALF OK]
If i use bind volume and not a named volume, it works. But this is not the desired behavior, how can i use the named volume with correct permission on Win/Linux ...
Let me divide the answer into two parts Linux Part and Docker part. You need to understand both in order to solve this problem.
Linux Part
It is easy to run cronjobs as user other than root in Linux.
This can be achieved by creating a user in docker container with the same UID as of that in the host machine and copying the crontab file as /var/spool/cron/crontabs/user_name.
From man crontab
crontab is the program used to install, deinstall or list the
tables used to drive the cron(8) daemon in Vixie Cron. Each user can
have their own crontab, and though these are files in
/var/spool/cron/crontabs, they are not intended to be edited directly.
Since Linux identifies users by User Id, inside docker the UID will be bound to the newly created user whereas in host machine the same will be binded with host user.
So, You don't have any permission issue as the files is owned by the host_user. Now you would have understood why I mentioned creating user with same UID as of that in host machine.
Docker Part
Docker considers all the directories(or layers) to be UNION FILE SYSTEM. Whenever you build an image each instruction creates a layer and the layer is marked as read-only. This is the reason Docker containers doesn't persist data. So you have to explicitly tell docker that some directories need to persist data by using VOLUME keyword.
You can run containers without mentioning volume explicitly. If you do so, docker daemon considers them to be UFS and resets the permissions.
In order to preserve the changes to a file/directory including ownership. The respective file should be declared as Volume in Dockerfile.
From UNION FILE SYSTEM
Indeed, when a container has booted, it is moved into memory, and the boot filesystem is unmounted to free up the RAM used by the initrd disk image. So far this looks pretty much like a typical Linux virtualization stack. Indeed, Docker next layers a root filesystem, rootfs, on top of the boot filesystem. This rootfs can be one or more operating systems (e.g., a Debian or Ubuntu filesystem).
Docker calls each of these filesystems images. Images can be layered on top of one another. The image below is called the parent image and you can traverse each layer until you reach the bottom of the image stack where the final image is called the base image. Finally, when a container is launched from an image, Docker mounts a read-write filesystem on top of any layers below. This is where whatever processes we want our Docker container to run will execute. When Docker first starts a container, the initial read-write layer is empty. As changes occur, they are applied to this layer; for example, if you want to change a file, then that file will be copied from the read-only layer below into the read-write layer. The read-only version of the file will still exist but is now hidden underneath the copy.
Example:
Let us assume that we have a user called host_user. The UID of host_user is 1000. Now we are going to create a user called docker_user in Docker container. So I'll assign him UID as 1000. Now whatever files that are owned by docker_user in Docker container is also owned by host_user if those files are accessible by host_user from host(i.e through volumes).
Now you can share the binded directory with others without any permission issues. You can even give 777 permission on the corresponding directory which allows others to edit the data. Else, You can leave 755 permissions which allows others to copy but only the owner to edit the data.
I've declared the directory to persist changes as a volume. This preserves all changes. Be careful as once you declare a directory as volume further changes made to that directory while building the will be ignored as those changes will be in separate layers. Hence do all your changes in the directory and then declare it as volume.
Here is the Docker file.
FROM alpine:latest
ARG ID=1000
#UID as arg so we can also pass custom user_id
ARG CRON_USER=docker_user
#same goes for username
COPY crontab /var/spool/cron/crontabs/$CRON_USER
RUN adduser -g "Custom Cron User" -DH -u $ID $CRON_USER && \
chmod 0600 /var/spool/cron/crontabs/$CRON_USER && \
mkdir /temp && \
chown -R $ID:$ID /temp && \
chmod 777 /temp
VOLUME /temp
#Specify the dir to be preserved as Volume else docker considers it as Union File System
ENTRYPOINT ["crond", "-f", "-l", "2"]
Here is the crontab
* * * * * /usr/bin/whoami >> /temp/cron.log
Building the image
docker build . -t test
Create new volume
docker volume create --name myTestVolume
Run with Data volume
docker run --rm --name test -d -v myTestVolume:/usr/local/src/myscript/result test:latest
Whenever you mount myTestVolume to other container you can see the
data under /usr/local/src/myscript/result is owned by UID 1000
if no user exist with that UID in that container or the username of
corresponding UID.
Run with Bind volume
docker run --rm --name test - -dv $PWD:/usr/local/src/myscript/result test:latest
When you do an ls -al /home/host_user/temp You will see that file called cron.log is created and is owned by **host_user**.
The same will be owned by docker_user in docker container when you do an ls -al /temp. The contents of cron.log will be docker_user.
So, Your effective Dockerfile should be
FROM artemklevtsov/r-alpine:latest as baseImage
ARG ID=1000
ARG CRON_USER=docker_user
RUN adduser -g "Custom Cron User" -DH -u $ID $CRON_USER && \
chmod 0600 /var/spool/cron/crontabs/$CRON_USER && \
echo http://nl.alpinelinux.org/alpine/edge/testing >> /etc/apk/repositories && \
apk --no-cache add busybox-suid curl && \
mkdir -p /usr/local/src/myscript/result && \
chown -R $ID:$ID /usr/local/src/myscript/result && \
chmod 777 /usr/local/src/myscript/result
COPY crontab /var/spool/cron/crontabs/$CRON_USER
COPY . /usr/local/src/myscript/
VOLUME /usr/local/src/myscript/result
#This preserves chown and chmod changes.
WORKDIR /usr/local/src/myscript/
ENTRYPOINT ["crond", "-f", "-l", "2"]
Now whenever you attach a Data/bind volume to /usr/local/src/myscript/result it will be owned by user having UID 1000 and the same is persistent across all the containers whichever has mounted the same volume with their corresponding user with 1000 as file owners.
Please Note: I've given 777 permissions in order to share with every one. You can skip that step in your Dockerfle based on your convinence.
References:
Crontab manual.
User identiier - Wiki.
User ID Definition.
About storage drivers.
UNION FILE SYSTEM.
This question already has answers here:
Share files between host system and docker container using specific UID
(4 answers)
Closed 7 years ago.
I'm using Docker (1.3.1) to build RPMs inside a container:
docker run -v /home/matt/build:/build build-rpm /build/build-pkg.sh
This works fine (my user is in the docker group, so I don't need to sudo) and drops a completed .rpm file in the current directory. The problem is that the file is created as owned by root.
How can I arrange it so that the file is created owned by the same user as I run docker with?
You could try to create (in the Dockerfile of a custom image) a user and set it as the one used by the container
RUN adduser --system --group --shell /bin/sh auser \
&& mkdir /home/auser/bin
USER auser
Then check if a docker run -v /home/matt/build:/build build-rpm mounts the shared folder in /build as auser.
Another option mentioned in issue 2259:
If you chown the volume (on the host side) before bind-mounting it, it will work.
In that case, you could do:
mkdir /tmp/www
chown 101:101 /tmp/www
docker run -v /tmp/www:/var/www ubuntu stat -c "%U %G" /var/www
(Assuming that 101:101 is the UID:GID of the www-data user in your container.)
Docker runs as root and has no idea what your user is inside its virtual environment (even if you're in the sudoers group). But you can create a non-root user while building your docker image that can be called whatever you like.
# create a non-root user named tester,
# give them the password "tester" put them in the sudo group
RUN useradd -d /home/tester -m -s /bin/bash tester && echo "tester:tester" | chpasswd && adduser tester sudo
# start working in the "tester" home directory
WORKDIR /home/tester
COPY ./src
# Make the files owned by tester
RUN chown -R tester:tester /home/tester
# Switch to your new user in the docker image
USER tester