Add sudo permission (without password ) to user by command line

I'm creating a docker file from ubuntu:bionic image.

I want an ubuntu user with sudo privileges.

This is my Dockerfile

FROM ubuntu:bionic

ENV DEBIAN_FRONTEND noninteractive

# Get the basic stuff
RUN apt-get update && \
    apt-get -y upgrade && \
    apt-get install -y \
    sudo

# Create ubuntu user with sudo privileges
RUN useradd -ms /bin/bash ubuntu && \
    usermod -aG sudo ubuntu

# Set as default user
USER ubuntu
WORKDIR /home/ubuntu

ENV DEBIAN_FRONTEND teletype

CMD ["/bin/bash"]

But with this aproach I need to write the password of ubuntu user.

There is a way to add NOPASSWD clausule to sudo group in sudoers file by command line?

Solution

First, you are not suggested to use sudo in docker. You could well design your behavior using USER + gosu.

But, if you insist for some uncontrolled reason, just add next line after you setup normal user:

RUN echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers

So for your scenario, the workable one is:

FROM ubuntu:bionic

ENV DEBIAN_FRONTEND noninteractive

# Get the basic stuff
RUN apt-get update && \
    apt-get -y upgrade && \
    apt-get install -y \
    sudo

# Create ubuntu user with sudo privileges
RUN useradd -ms /bin/bash ubuntu && \
    usermod -aG sudo ubuntu
# New added for disable sudo password
RUN echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers

# Set as default user
USER ubuntu
WORKDIR /home/ubuntu

ENV DEBIAN_FRONTEND teletype

CMD ["/bin/bash"]

Test the effect:

$ docker build -t abc:1 .
Sending build context to Docker daemon  2.048kB
Step 1/9 : FROM ubuntu:bionic
......
Successfully built b3aa0793765f
Successfully tagged abc:1

$ docker run --rm abc:1 cat /etc/sudoers
cat: /etc/sudoers: Permission denied

$ docker run --rm abc:1 sudo cat /etc/sudoers
#
# This file MUST be edited with the 'visudo' command as root.
#
# Please consider adding local content in /etc/sudoers.d/ instead of
# directly modifying this file.
#
# See the man page for details on how to write a sudoers file.
#
Defaults        env_reset
......
#includedir /etc/sudoers.d
%sudo ALL=(ALL) NOPASSWD:ALL

You could see with sudo, we could already execute a root-needed command.