Dockerfile: Adds gosu support

Currently is not possible to use a different user id as one
used when the container is created.

| id -u
| # 10060
| docker run --rm -u $(id -u) ...

This will enter in the container with a different user as the default
one created and configured. Now inside the container the user id from
the host machine, 10060 in this case, not exist:

| # I have no name!@2e9103210ce0:/$
| whoami
| # whoami: cannot find name for user ID 10060
| # I have no name!
| id -u builder
| # 1000

To user the default user account with the same id for user and group
we can use gosu with an entrypoint.
Launching docker with the environment argument UID and GID fixes
this issue.

| echo "$(id -u)/$(id -g)"
| # 10060/100
| docker run --rm --env UID=$(id -u) --env GID=$(id -g) ...

And on the container we have the same:

| # builder@20f4393ec053:/$
| whoami
| # builder
| echo "$(id -u)/$(id -g)"
| # 10060/100

Signed-off-by: Jose Quaresma <[email protected]>

Dockerfile

@@ -56,7 +56,7 @@ RUN apt-get update \
 		make patch repo sudo texinfo vim-tiny wget whiptail libelf-dev git-lfs screen \
 		socket corkscrew curl xz-utils tcl libtinfo5 device-tree-compiler python3-pip python3-dev \
 		tmux libncurses-dev vim zstd lz4 liblz4-tool libc6-dev-i386 \
-		awscli docker-compose \
+		awscli docker-compose gosu \
 	&& ln -s /usr/bin/python3 /usr/bin/python \
 	&& pip3 --no-cache-dir install expandvars jsonFormatter \
 	&& apt-get autoremove -y \
@@ -72,8 +72,14 @@ RUN useradd -c $DEV_USER_NAME \
 		-s /bin/bash \
 		$DEV_USER
 
+# Add entrypoint to run gosu
+COPY entrypoint /
+ENTRYPOINT ["/entrypoint"]
+
 # Add default password for the SDK user (useful with sudo)
-RUN echo $DEV_USER:$DEV_USER_PASSWD | chpasswd
+# and replace entrypoint with dev user name
+RUN echo $DEV_USER:$DEV_USER_PASSWD | chpasswd && \
+	sed "s/@@DOCKER_USER@@/$DEV_USER/g" -i /entrypoint
 
 # Initialize development environment for $DEV_USER.
 RUN sudo -u $DEV_USER -H git config --global credential.helper 'cache --timeout=3600'

entrypoint

@@ -0,0 +1,45 @@
+#!/bin/sh
+
+: '
+MIT License
+
+Copyright (c) 2022 Foundries.io
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+'
+
+set -e
+set -u
+
+: "${UID:=0}"
+: "${GID:=${UID}}"
+
+if [ "$#" = 0 ]; then
+        set -- "$(command -v bash 2>/dev/null || command -v sh)" -l
+fi
+
+if [ "$UID" != 0 ]; then
+        usermod -u "$UID" "@@DOCKER_USER@@" 2>/dev/null && {
+                groupmod -g "$GID" "@@DOCKER_USER@@" 2>/dev/null ||
+                usermod -a -G "$GID" "@@DOCKER_USER@@"
+        }
+        set -- gosu "${UID}:${GID}" "${@}"
+fi
+
+exec "$@"