utils/aosp: Update script and Dockerfile to work with any host user uid/gid

This commit introduces the "docker_entrypoint" script that will create
a user with uid/gid matching given `USER_ID` and `GROUP_ID` (or default to
`1000` if not provided).

Fixes #9

This approach works around missing docker feature discussed in
docker/docker#7198 and allow to have executable in the docker container
manipulating files in the shared volume owned by the `USER_ID:GROUP_ID`

The utility script `aosp` has also been updated to automatically
set `USER_ID` and `GROUP_ID` to the value matching the current user
by invoking "docker run" with

```
-e USER_ID=$(id -u) -e GROUP_ID=$(id -g)
```

Finally, the output has also been updated to be more verbose. For example:

```
$ AOSP_VOL=/home/jcfr/Projects/aosp-root/ aosp id
aosp: Checking if /home/jcfr/Projects/aosp-root/aosp exists
aosp: Checking if /home/jcfr/Projects/aosp-root/aosp exists - ok
aosp: Checking if /home/jcfr/Projects/aosp-root/ccache exists
aosp: Checking if /home/jcfr/Projects/aosp-root/ccache exists - ok

docker_entrypoint: Creating user UID/GID [1000/1000]
docker_entrypoint: Creating user UID/GID [1000/1000] - done
docker_entrypoint: Copying .gitconfig and .ssh/config to new user home
docker_entrypoint: Copying .gitconfig and .ssh/config to new user home - done
docker_entrypoint: Creating /tmp/ccache and /asop directory
docker_entrypoint: Creating /tmp/ccache and /asop directory - done

uid=1000(aosp) gid=1000(aosp) groups=1000(aosp)
```

Dockerfile

@@ -43,14 +43,8 @@ RUN curl -O http://mirrors.kernel.org/ubuntu/pool/universe/o/openjdk-8/openjdk-8
     apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
 # All builds will be done by user aosp
-RUN groupadd -r aosp && useradd --create-home -g aosp aosp
-COPY gitconfig /home/aosp/.gitconfig
-COPY ssh_config /home/aosp/.ssh/config
-RUN chown aosp:aosp /home/aosp/.gitconfig && \
-  chown aosp:aosp -R /home/aosp/.ssh
-
-RUN mkdir -p /tmp/ccache /aosp && \
-  chown aosp:aosp /tmp/ccache /aosp
+COPY gitconfig /root/.gitconfig
+COPY ssh_config /root/.ssh/config
 
 # The persistent data will be in these two directories, everything else is
 # considered to be ephemeral
@@ -61,5 +55,7 @@ ENV USE_CCACHE 1
 ENV CCACHE_DIR /tmp/ccache
 
 # Work in the build directory, repo is expected to be init'd here
-USER aosp
 WORKDIR /aosp
+
+COPY utils/docker_entrypoint.sh /root/docker_entrypoint.sh
+ENTRYPOINT ["/root/docker_entrypoint.sh"]

utils/aosp

@@ -22,7 +22,7 @@ AOSP_VOL_CCACHE=${AOSP_VOL_CCACHE%/} # Trim trailing slash if needed
 # Convenience function
 function aosp_create_dir_if_needed {
   directory=$1
-  msg="Checking if $directory exists"
+  msg="aosp: Checking if $directory exists"
   echo "$msg"
   if [ ! -d "$directory" ]; then
     echo "$msg - unexistent"
@@ -37,12 +37,15 @@ function aosp_create_dir_if_needed {
 aosp_create_dir_if_needed $AOSP_VOL_AOSP
 aosp_create_dir_if_needed $AOSP_VOL_CCACHE
 
+# Set uid and gid to match host current user
+AOSP_HOST_ID_ARGS="-e USER_ID=$(id -u) -e GROUP_ID=$(id -g)"
+
 if [ -n "$SSH_AUTH_SOCK" ]; then
     SSH_AUTH_ARGS="-v $SSH_AUTH_SOCK:/tmp/ssh_auth -e SSH_AUTH_SOCK=/tmp/ssh_auth"
 fi
 
 echo ""
 
-docker run $AOSP_ARGS $SSH_AUTH_ARGS $AOSP_EXTRA_ARGS \
+docker run $AOSP_ARGS $AOSP_HOST_ID_ARGS $SSH_AUTH_ARGS $AOSP_EXTRA_ARGS \
     -v "$AOSP_VOL_AOSP:/aosp" -v "$AOSP_VOL_CCACHE:/tmp/ccache" \
     $AOSP_IMAGE $@

utils/docker_entrypoint.sh

@@ -0,0 +1,43 @@
+#!/bin/bash
+set -e
+
+# This script designed to be used a docker ENTRYPOINT "workaround" missing docker
+# feature discussed in docker/docker#7198, allow to have executable in the docker
+# container manipulating files in the shared volume owned by the USER_ID:GROUP_ID.
+#
+# It creates a user named `aosp` with selected USER_ID and GROUP_ID (or
+# 1000 if not specified).
+
+# Example:
+#
+#  docker run -ti -e USER_ID=$(id -u) -e GROUP_ID=$(id -g) imagename bash
+#
+
+# Reasonable defaults if no USER_ID/GROUP_ID environment variables are set.
+if [ -z ${USER_ID+x} ]; then USER_ID=1000; fi
+if [ -z ${GROUP_ID+x} ]; then GROUP_ID=1000; fi
+
+msg="docker_entrypoint: Creating user UID/GID [$USER_ID/$GROUP_ID]" && echo $msg
+groupadd -g $GROUP_ID -r aosp && \
+useradd -u $USER_ID --create-home -r -g aosp aosp
+echo "$msg - done"
+
+msg="docker_entrypoint: Copying .gitconfig and .ssh/config to new user home" && echo $msg
+cp /root/.gitconfig /home/aosp/.gitconfig && \
+chown aosp:aosp /home/aosp/.gitconfig && \
+mkdir -p /home/aosp/.ssh && \
+cp /root/.ssh/config /home/aosp/.ssh/config && \
+chown aosp:aosp -R /home/aosp/.ssh &&
+echo "$msg - done"
+
+msg="docker_entrypoint: Creating /tmp/ccache and /asop directory" && echo $msg
+mkdir -p /tmp/ccache /aosp
+chown aosp:aosp /tmp/ccache /aosp
+echo "$msg - done"
+
+echo ""
+
+
+# Execute command as `aosp` user
+export HOME=/home/aosp
+exec sudo -u aosp "$@"