Docker - mount directory's owner and group

Question

I ran a docker container with binding a host directory to a container directory, but the permissions for the container directory and its files are given differently depending on the hosts.

docker run -w /vlc-android -v $(pwd)/vlc-android:/vlc-android --rm vlc-android:latest bash -c "ls -ld /vlc-android"

result on Mac OS 10.14.6 (Docker desktop version 2.1.0.3)

drwxr-xr-x 2 videolan videolan 64 Sep 27 04:34 /vlc-android

result on Ubuntu server 18.04.3

drwxr-xr-x 2 root root 4096 Sep 27 06:11 /vlc-android

I'm trying to build the VLC player android app. from the source code via a docker image of the vlc-android build environment or below...

FROM debian:stretch-20190506

MAINTAINER VideoLAN roots <roots@videolan.org>

ENV IMAGE_DATE=201907171600

ENV ANDROID_NDK="/sdk/android-ndk" \
    ANDROID_SDK="/sdk/android-sdk-linux"

# If someone wants to use VideoLAN docker images on a local machine and does
# not want to be disturbed by the videolan user, we should not take an uid/gid
# in the user range of main distributions, which means:
# - Debian based: <1000
# - RPM based: <500 (CentOS, RedHat, etc.)
ARG VIDEOLAN_CI_UID=499

RUN addgroup --quiet --gid ${VIDEOLAN_CI_UID} videolan && \
    adduser --quiet --uid ${VIDEOLAN_CI_UID} --ingroup videolan videolan && \
    echo "videolan:videolan" | chpasswd && \
    apt-get update && \
    apt-get install --no-install-suggests --no-install-recommends -y \
    openjdk-8-jdk-headless ca-certificates autoconf m4 automake ant autopoint bison \
    flex build-essential libtool libtool-bin patch pkg-config ragel subversion \
    git rpm2cpio libwebkitgtk-1.0-0 yasm ragel g++ protobuf-compiler gettext \
    libgsm1-dev wget expect unzip python python3 locales libltdl-dev curl && \
    echo "deb http://ftp.debian.org/debian stretch-backports main" > /etc/apt/sources.list.d/stretch-backports.list && \
    apt-get update && apt-get -y -t stretch-backports install cmake && \
    rm -f /etc/apt/sources.list.d/stretch-backports.list && \
    echo "deb http://deb.debian.org/debian testing main" > /etc/apt/sources.list.d/testing.list && \
    apt-get update && apt-get -y -t testing --no-install-suggests --no-install-recommends install automake && \
    rm -f /etc/apt/sources.list.d/testing.list && \
    apt-get clean -y && rm -rf /var/lib/apt/lists/* && \
    localedef -i en_US -c -f UTF-8 -A /usr/share/locale/locale.alias en_US.UTF-8 && \
    echo "export ANDROID_NDK=${ANDROID_NDK}" >> /etc/profile.d/vlc_env.sh && \
    echo "export ANDROID_SDK=${ANDROID_SDK}" >> /etc/profile.d/vlc_env.sh && \
    mkdir sdk && cd sdk && \
    wget -q https://dl.google.com/android/repository/android-ndk-r18b-linux-x86_64.zip && \
    ANDROID_NDK_SHA256=4f61cbe4bbf6406aa5ef2ae871def78010eed6271af72de83f8bd0b07a9fd3fd && \
    echo $ANDROID_NDK_SHA256 android-ndk-r18b-linux-x86_64.zip | sha256sum -c && \
    unzip android-ndk-r18b-linux-x86_64.zip && \
    rm -f android-ndk-r18b-linux-x86_64.zip && \
    ln -s android-ndk-r18b android-ndk && \
    mkdir android-sdk-linux && \
    cd android-sdk-linux && \
    mkdir "licenses" && \
    echo "24333f8a63b6825ea9c5514f83c2829b004d1fee" > "licenses/android-sdk-license" && \
    echo "d56f5187479451eabf01fb78af6dfcb131a6481e" >> "licenses/android-sdk-license" && \
    wget -q https://dl.google.com/android/repository/sdk-tools-linux-3859397.zip && \
    SDK_TOOLS_SHA256=444e22ce8ca0f67353bda4b85175ed3731cae3ffa695ca18119cbacef1c1bea0 && \
    echo $SDK_TOOLS_SHA256 sdk-tools-linux-3859397.zip | sha256sum -c && \
    unzip sdk-tools-linux-3859397.zip && \
    rm -f sdk-tools-linux-3859397.zip && \
    tools/bin/sdkmanager "build-tools;26.0.1" "platform-tools" "platforms;android-26" && \
    chown -R videolan /sdk

ENV LANG en_US.UTF-8
USER videolan

RUN git config --global user.name "VLC Android" && \
    git config --global user.email buildbot@videolan.org

and built it like below

docker build -t vlc-android .

I want the user id "videolan" is the owner id of the container directory "/vlc-android" and all files under it in the container run on Ubuntu server 18.04.3, like "result on Mac OS 10.14.6 (Docker desktop version 2.1.0.3)".

How can I do?

Answer 1

When you mount a volume on linux, the resulting folder in the docker container will get the same rights as the folder on the host. If the folder on the host is owned by root, then it'll be owned by root also inside the docker container.

To fix your problem, you have to change the owner of the $(pwd)/vlc-android to match the user id used in the container (according to the Dockerfile you attached in your question, the UID is 499).

Try to execute this:

sudo chown 499 -R $(pwd)/vlc-android

then restart the container.

---

EDIT:

Another solution would be, if you're able to rebuild the docker image on the ubuntu server, to regenerate the image to use the folder owner id instead of 499.

You simply have to fetch the folder owner ID (try to avoid the root user):

id $username

and regenerate the docker image using the following command:

USER_ID=1000
docker build \
    -t my_new_vlc_androing_thingy \
    --build-arg VIDEOLAN_CI_UID=${USER_ID} \
    .

and run it with:

docker run --rm \
    -w /vlc-android \
    -v $(pwd)/vlc-android:/vlc-android \
    my_new_vlc_androing_thingy \
    bash -c "ls -ld /vlc-android"