Fix mapping of uids

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.7
+FROM eugenmayer/unison:unox
 
 # Add community repos.
 RUN echo "http://dl-2.alpinelinux.org/alpine/edge/community" >> /etc/apk/repositories; \
@@ -9,10 +9,27 @@ RUN echo "http://dl-2.alpinelinux.org/alpine/edge/community" >> /etc/apk/reposit
 # Install packages.
 RUN apk add --no-cache \
 	tini \
-	unison
+	unison \
+	sudo \
+	ruby
+
+RUN set -xe \
+	&& addgroup -g 82 -S www-data \
+	&& addgroup -S sudo \
+	&& adduser -u 82 -D -S -G www-data www-data \
+	&& echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers \
+	&& adduser www-data sudo \
+	&& echo "PS1='\w\$ '" >> /home/www-data/.bashrc;
 
 COPY docker-entrypoint.sh /docker-entrypoint.sh
 
+ENV UNISON_DIR=/unison
+
+USER root
+RUN set -xe \
+	&& mkdir -p /volume \
+	&& mkdir -p /host
+
 ENTRYPOINT ["/docker-entrypoint.sh"]
 
 CMD [ \

docker-entrypoint.sh

@@ -1,9 +1,77 @@
 #!/bin/sh
 set -e
 
+APP_VOLUME=${APP_VOLUME:-/volume}
+HOST_VOLUME=${HOST_VOLUME:-/host}
+OWNER_UID=${OWNER_UID:-0}
+GROUP_ID=${GROUP_ID:-0}
+
 # Allow setting maximum iNotify
-if [ ! -z $MAXIMUM_INOTIFY_WATCHES ]; then
-  echo fs.inotify.max_user_watches=$MAXIMUM_INOTIFY_WATCHES | tee -a /etc/sysctl.conf && sysctl -p
+if [ ! -z ${MAXIMUM_INOTIFY_WATCHES} ]; then
+  echo fs.inotify.max_user_watches=${MAXIMUM_INOTIFY_WATCHES} | tee -a /etc/sysctl.conf && sysctl -p
+fi
+
+# if the user did not set anything particular to use, we use root
+# since this means, no special user has been created on the target container
+# thus it is most probably root to run the daemon and thats a good default then
+if [ -z ${OWNER_UID} ];then
+   OWNER_UID=0
+fi
+
+if [ ! -z ${GROUP_ID} ]; then
+  # If gid doesn't exist on the system
+  if ! cut -d: -f3 /etc/group | grep -q $GROUP_ID; then
+     echo "no group has gid $GROUP_ID"
+     groupadd -g ${GROUP_ID} dockersync
+  fi
+else
+  GROUP_ID=0
+fi
+
+# if the user with the uid does not exist, create it, otherwise reuse it
+if ! cut -d: -f3 /etc/passwd | grep -q ${OWNER_UID}; then
+  echo "Creating user with uid ${OWNER_UID}"
+
+  # If user doesn't exist on the system
+  useradd -u ${OWNER_UID} -g ${GROUP_ID} dockersync -m
+else
+  if [ ${OWNER_UID} == 0 ]; then
+    # in case it is root, we need a special treatment
+    echo "user with uid ${OWNER_UID} already exist and its root"
+  else
+    # we actually rename the user to unison, since we do not care about
+    # the username on the sync container, it will be matched to whatever the target container uses for this uid
+    # on the target container anyway, no matter how our user is name here
+    echo "User with uid ${OWNER_UID} already exists"
+    existing_user_with_uid=$(awk -F: "/:$OWNER_UID:/{print \$1}" /etc/passwd)
+    OWNER=`getent passwd "${OWNER_UID}" | cut -d: -f1`
+    GROUP=`getent group "${GROUP_ID}" | cut -d: -f1`
+    mkdir -p /home/${OWNER}
+    usermod -u ${OWNER_UID} -g ${GROUP_ID} ${OWNER}
+    usermod --home /home/${OWNER} ${OWNER}
+    chown -R ${OWNER} /home/${OWNER}
+    chgrp -R ${GROUP} /home/${OWNER}
+   fi
+fi
+
+export OWNER_HOMEDIR=`getent passwd $OWNER_UID | cut -f6 -d:`
+# OWNER should actually be dockersync in all cases the user did not match a system user
+export OWNER=`getent passwd "${OWNER_UID}" | cut -d: -f1`
+export GROUP=`getent group "${GROUP_ID}" | cut -d: -f1`
+chown -R ${OWNER} ${APP_VOLUME}
+chgrp -R ${GROUP} ${APP_VOLUME}
+
+if [ ! -f /tmp/initial_sync_finished ]; then
+	echo "doing initial sync with unison"
+	# we use ruby due to http://mywiki.wooledge.org/BashFAQ/050
+	time ruby -e '`unison #{ENV["UNISON_ARGS"]} #{ENV["UNISON_PREFER"]} #{ENV["UNISON_EXCLUDES"]} -numericids -auto -batch /host /volume`'
+	#time cp -au  $HOST_VOLUME/.  $APP_VOLUME
+	echo "chown ing file to uid ${OWNER_UID}"
+	chown -R ${OWNER_UID} ${APP_VOLUME}
+	touch /tmp/initial_sync_finished
+	echo "initial sync done using unison" >> /tmp/unison.log
+else
+	echo "skipping initial copy with unison"
 fi
 
 # If the first argument passed in looks like a flag