Connect to docker container as user other than root

Question

BY default when you run   docker run -it  myimage     OR  docker attach  mycontainer   you connect to the terminal as root user  but I would like to connect as a different user   Is this possible

User · Answer

My solution      bin bash user cmds       GID   id -g  USER  UID   id -u  USER  RUN SCRIPT   mktemp -p   pwd     cat  lt  lt  EOF addgroup --gid  GID  USER useradd --no-create-home --home  cmd --gid  GID --uid  UID   USER cd  cmd runuser -l  USER -c    user cmds   EOF    gt   RUN SCRIPT  trap  rm -rf  RUN SCRIPT  EXIT  docker run -v   pwd   cmd --rm my-docker-image  bash  cmd   basename   RUN SCRIPT      This allows the user to run arbitrary commands using the tools provides by my-docker-image   Note how the user s current working directory is volume mounted to   cmd inside the container   I am using this workflow to allow my dev-team to cross-compile C C   code for the arm64 target  whose bsp I maintain  the my-docker-image contains the cross-compiler  sysroot  make  cmake  etc    With this a user can simply do something like   cd  path to target software cross compile sh  mkdir build  cd build  cmake      make    Where cross compile sh is the script shown above   The addgroup useradd machinery allows user-ownership of any files directories created by the build   While this works for us   It seems sort of hacky   I m open to alternative implementations

User · Answer

You can run a shell in a running docker container using a command like   docker exec -it --user root  lt container id gt   bin bash

User · Answer

This solved my use case that is   quot Compile webpack stuff in nodejs container on Windows running Docker Desktop with WSL2 and have the built assets under your currently logged in user  quot  docker run -u 1000 -v  quot  PWD quot   build -w  build node 10 23  bin sh -c  npm install  amp  amp  npm run build   Based on the answer by eigenfield  Thank you  Also this material helped me understand what is going on

User · Answer

The only way I am able to make it work is by   docker run -it -e USER  USER -v  etc passwd  etc passwd -v  pwd   siem mono bash su - magnus   So I have to both specify  USER environment variable as well a point the  etc passwd file  In this way  I can compile in  siem folder and retain ownership of files there not as root

User · Answer

You can specify USER in the Dockerfile  All subsequent actions will be performed using that account  You can specify USER one line before the CMD or ENTRYPOINT if you only want to use that user when launching a container  and not when building the image   When you start a container from the resulting image  you will attach as the specified user

User · Answer

For docker run   Simply add the option --user  lt user gt  to change to another user when you start the docker container   docker run -it --user nobody busybox   For docker attach or docker exec   Since the command is used to attach execute into the existing process  therefore it uses the current user there directly    docker run -it busybox    CTRL-P Q to quit docker attach  lt container id gt     then you have root user     id uid 0 root  gid 0 root  groups 10 wheel   docker run -it --user nobody busybox   CTRL-P Q to quit docker attach  lt container id gt        id uid 99 nobody  gid 99 nogroup    If you really want to attach to the user you want to have  then    start with that user run --user  lt user gt  or mention it in your Dockerfile using USER change the user using  su

User · Answer

For docker-compose  In the docker-compose yml   version   3  services      app          image              user    UID -0        In  env   UID 1000

User · Answer

As an updated answer from 2020  --user   -u option is Username or UID  format   lt name uid gt    lt group gid gt     Then  it works for me like this  docker exec -it -u root root container  bin bash  Reference  https   docs docker com engine reference commandline exec

User · Answer

Execute command as www-data user  docker exec -t --user www-data container bash -c  ls -la

[docker] Connect to docker container as user other than root

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