Authentication token manipulation error when trying to change use password in dockerfile

Question

I am trying to change a password for a user I am creating during the run of a dockerfile:

RUN groupadd --system ${UNAME} --gid ${UID} && \
    useradd --uid ${UID} --system --gid ${UNAME} --home-dir /home/${UNAME} --create-home --comment "Docker image user" ${UNAME} && \
    chown -R ${UNAME}:${UNAME} /home/${UNAME} && \
    usermod -aG sudo ${UNAME}

RUN echo '${UNAME}:password' | chpasswd

The second RUN command fails with

Authentication token manipulation error chpasswd: (line 1, user
${UNAME}) password not changed ```

Doing the very same like so, does work:

RUN useradd pi && \
    mkdir -p /home/pi && \
    chown pi /home/pi && \
    echo 'pi:password' | chpasswd

I don't understand the difference. I just want to give ${UNAME} a constant password password.

Answer 1

working for me now:

use a single RUN command for less docker images.

RUN groupadd --system ${UNAME} --gid ${UID}
RUN useradd --uid ${UID} --system --gid ${UNAME} --home-dir /home/${UNAME} --create-home --comment "Docker image user" ${UNAME}
RUN chown -R ${UNAME}:${UNAME} /home/${UNAME}
RUN usermod -aG sudo ${UNAME}
RUN echo "${UNAME}  ALL=(ALL) ALL" | sudo tee /etc/sudoers.d/permissions
RUN echo ${UNAME}:password | chpasswd

Notice the added line RUN echo "${UNAME} ALL=(ALL) ALL" | sudo tee /etc/sudoers.d/permissions