build: Dockerfile: mod "new user to avoid using root" to support UID=0

Extend "create new user to avoid using root" copypasta to support being run as root
(ARG UID=0).

When running build.sh directly on a cirrus CI runner, we are running as root.

Author: SomberNight

contrib/android/Dockerfile

@@ -174,17 +174,16 @@ RUN apt -y update -qq \
 
 # create new user to avoid using root; but with sudo access and no password for convenience.
 ARG UID=1000
-ENV USER="user"
-ENV HOME_DIR="/home/${USER}"
+RUN if [ "$UID" != "0" ] ; then useradd --uid $UID --create-home --shell /bin/bash "user" ; fi
+RUN usermod -append --groups sudo $(id -nu $UID || echo "user")
+RUN echo "%sudo ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
+RUN HOME_DIR=$(getent passwd $UID | cut -d: -f6)
 ENV WORK_DIR="${HOME_DIR}/wspace" \
     PATH="${HOME_DIR}/.local/bin:${PATH}"
-RUN useradd --uid $UID --create-home --shell /bin/bash ${USER}
-RUN usermod -append --groups sudo ${USER}
-RUN echo "%sudo ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
 WORKDIR ${WORK_DIR}
-RUN chown --recursive ${USER} ${WORK_DIR} ${ANDROID_SDK_HOME}
-RUN chown ${USER} /opt
-USER ${USER}
+RUN chown --recursive ${UID} ${WORK_DIR} ${ANDROID_SDK_HOME}
+RUN chown ${UID} /opt
+USER ${UID}
 
 # venv, VIRTUAL_ENV is used by buildozer to indicate a venv environment
 ENV VIRTUAL_ENV=/opt/venv

contrib/build-linux/appimage/Dockerfile

@@ -75,13 +75,12 @@ RUN apt-get update -q && \
 
 # create new user to avoid using root; but with sudo access and no password for convenience.
 ARG UID=1000
-ENV USER="user"
-ENV HOME_DIR="/home/${USER}"
+RUN if [ "$UID" != "0" ] ; then useradd --uid $UID --create-home --shell /bin/bash "user" ; fi
+RUN usermod -append --groups sudo $(id -nu $UID || echo "user")
+RUN echo "%sudo ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
+RUN HOME_DIR=$(getent passwd $UID | cut -d: -f6)
 ENV WORK_DIR="${HOME_DIR}/wspace" \
     PATH="${HOME_DIR}/.local/bin:${PATH}"
-RUN useradd --uid $UID --create-home --shell /bin/bash ${USER}
-RUN usermod -append --groups sudo ${USER}
-RUN echo "%sudo ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
 WORKDIR ${WORK_DIR}
-RUN chown --recursive ${USER} ${WORK_DIR}
-USER ${USER}
+RUN chown --recursive ${UID} ${WORK_DIR}
+USER ${UID}

contrib/build-linux/sdist/Dockerfile

@@ -18,13 +18,12 @@ RUN apt-get update -q && \
 
 # create new user to avoid using root; but with sudo access and no password for convenience.
 ARG UID=1000
-ENV USER="user"
-ENV HOME_DIR="/home/${USER}"
+RUN if [ "$UID" != "0" ] ; then useradd --uid $UID --create-home --shell /bin/bash "user" ; fi
+RUN usermod -append --groups sudo $(id -nu $UID || echo "user")
+RUN echo "%sudo ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
+RUN HOME_DIR=$(getent passwd $UID | cut -d: -f6)
 ENV WORK_DIR="${HOME_DIR}/wspace" \
     PATH="${HOME_DIR}/.local/bin:${PATH}"
-RUN useradd --uid $UID --create-home --shell /bin/bash ${USER}
-RUN usermod -append --groups sudo ${USER}
-RUN echo "%sudo ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
 WORKDIR ${WORK_DIR}
-RUN chown --recursive ${USER} ${WORK_DIR}
-USER ${USER}
+RUN chown --recursive ${UID} ${WORK_DIR}
+USER ${UID}

contrib/build-wine/Dockerfile

@@ -58,16 +58,15 @@ RUN DEBIAN_CODENAME=$(lsb_release --codename --short) && \
 
 # create new user to avoid using root; but with sudo access and no password for convenience.
 ARG UID=1000
-ENV USER="user"
-ENV HOME_DIR="/home/${USER}"
+RUN if [ "$UID" != "0" ] ; then useradd --uid $UID --create-home --shell /bin/bash "user" ; fi
+RUN usermod -append --groups sudo $(id -nu $UID || echo "user")
+RUN echo "%sudo ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
+RUN HOME_DIR=$(getent passwd $UID | cut -d: -f6)
 ENV WORK_DIR="${HOME_DIR}/wspace" \
     PATH="${HOME_DIR}/.local/bin:${PATH}"
-RUN useradd --uid $UID --create-home --shell /bin/bash ${USER}
-RUN usermod -append --groups sudo ${USER}
-RUN echo "%sudo ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
 WORKDIR ${WORK_DIR}
-RUN chown --recursive ${USER} ${WORK_DIR}
-RUN chown ${USER} /opt
-USER ${USER}
+RUN chown --recursive ${UID} ${WORK_DIR}
+RUN chown ${UID} /opt
+USER ${UID}
 
 RUN mkdir --parents "/opt/wine64/drive_c/electrum"