Root password inside a Docker container

Question

I m using a Docker image which was built using the USER command to use a non-root user called dev  Inside a container  I m  dev   but I want to edit the  etc hosts file   So I need to be root  I m trying the su command  but I m asked to enter the root password   What s the default root user s password inside a Docker container

User · Answer

You can SSH in to docker container as root by using

docker exec -it --user root <container_id> /bin/bash

Then change root password using this

passwd root

Make sure sudo is installed check by entering

sudo

if it is not installed install it

apt-get install sudo

If you want to give sudo permissions for user dev you can add user dev to sudo group

usermod -aG sudo dev

Now you'll be able to run sudo level commands from your dev user while inside the container or else you can switch to root inside the container by using the password you set earlier.

To test it login as user dev and list the contents of root directory which is normally only accessible to the root user.

sudo ls -la /root

Enter password for dev

If your user is in the proper group and you entered the password correctly, the command that you issued with sudo should run with root privileges.

User · Answer

Get a shell of your running container and change the root pass  docker exec -it  lt MyContainer gt  bash  root MyContainer    passwd Enter new UNIX password   Retype new UNIX password

User · Answer

You can log into the Docker container using the root user  ID   0  instead of the provided default user when you use the -u option  E g  docker exec -u 0 -it mycontainer bash   root  id   0  is the default user within a container  The image developer can create additional users  Those users are accessible by name  When passing a numeric ID  the user does not have to exist in the container   from Docker documentation Update  Of course you can also use the Docker management command for containers to run this  docker container exec -u 0 -it mycontainer bash

User · Answer

I had exactly this problem of not being able to su to root because I was running in the container as an unprivileged user   But I didn t want to rebuild a new image as the previous answers suggest   Instead I have found that I could access the container as root using  nsenter   see  https   github com jpetazzo nsenter  First determine the PID of your container on the host   docker inspect --format    State Pid    lt container name or ID gt    Then use nsenter to enter the container as root  nsenter --target  lt PID gt  --mount --uts --ipc --net --pid

User · Answer

To create change a root password in a running container  docker exec -itu root  containerName  passwd

User · Answer

I d suggest a better solution is to give the --add-host NAME IP argument to docker run when starting the container  That will update the  etc hosts  file without any need to become root   Otherwise  you can override the the USER setting by giving the -u USER flag to docker run  I would advise against this however  as you shouldn t really be changing things in a running container  Instead  make your changes in a Dockerfile and build a new image

User · Answer

docker exec -u 0 -it containername bash

User · Answer

The password is  ubuntu  for the  ubuntu  user  at least in docker for ubuntu  14 04 03    NB   ubuntu  is created after the startup of the container so  if you just do this    docker run -i -t --entrypoint  bin bash  ubuntu        You ll get the root prompt directly  From there you can force the password change of root  commit the container and optionally tag it  with -f  to ubuntu latest like this     root ec384466fbbb    passwd Enter new UNIX password  Retype new UNIX password  passwd  password updated successfully root ec384466fbbb    exit    docker commit ec3844 5d3c03e7d6d861ce519fe33b184cd477b8ad03247ffe19b2a57d3f0992d71bca  docker tag -f 5d3c ubuntu latest   You must rebuild your eventual dependencies on ubuntu latest

User · Answer

try the following command to get the root access     sudo -i

User · Answer

When you start the container  you will be root but you won t know what root s pw is  To set it to something you know simply use  passwd root   Snapshot commit the container to save your actions

User · Answer

You can use the USER root command in your Dockerfile

User · Answer

By default docker containers run as the root user   If you are still using the container you can use exit command to get back to root  default user  user instead of running the container again   Example -   dev 6c4c86bccf93     ls  dev 6c4c86bccf93     other-commands    dev 6c4c86bccf93     exit  root 6c4c86bccf93     ls

User · Answer

There are a couple of ways to do it   To run the Docker overriding the USER setting  docker exec -u 0 -it containerName bash    or docker exec -u root -it --workdir    lt containerName gt  bash   Make necessary file permissions  etc   during the image build in the Docker file  If all the packages are available in your Linux image  chpasswdin the dockerfile before the USER utility    For complete reference  http   muralitechblog com root-password-of-a-docker-container

User · Answer

In some cases you need to be able to do things like that under a user with sudo  e g  the application running in the container provides a shell to users   Simply add this into you Dockerfile   RUN apt-get update           If necessary RUN apt-get install sudo     If your base image does not contain sudo  RUN useradd -m -N -s  bin bash -u 1000 -p   1 miTOHCYy K c4Yw edukWJ7z9rbpTZ0  user  amp  amp        usermod -aG sudo user    Grant sudo to the user USER user   Now under the default image user user you will be able to sudo with the password set on line 3   See how to generate password hash for useradd here or here

User · Answer

I am able to get it working with the below command   root gitnew   docker exec -it --user   username    containername   bin bash

User · Answer

Eventually  I decided to rebuild my Docker images  so that I change the root password by something I will know   RUN echo  root Docker     chpasswd   or  RUN echo  Docker     passwd --stdin root

[docker] Root password inside a Docker container

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