Improve handling when run using root user (#1572)

Allow for the image to be run with the root user if desired, however
change to requiring setting of a variable to allow it to continue as it
may change ownership of files unexpectedly.

Additionally ensure that the workdir passed to docker matches the target
mount path used, in case the realpath to ${PWD} resolves to be different
to it's value resulting in the starting workdir being somewhere
different to the current path on the host.

Fixes: #1442

docs/installation.markdown

@@ -86,7 +86,7 @@ docker run -i --rm \
   -v /var/run/libvirt/:/var/run/libvirt/ \
   -v ~/.vagrant.d:/.vagrant.d \
   -v $(realpath "${PWD}"):${PWD} \
-  -w $(realpath "${PWD}") \
+  -w "${PWD}" \
   --network host \
   vagrantlibvirt/vagrant-libvirt:latest \
     vagrant status
@@ -100,7 +100,7 @@ vagrant(){
     -v /var/run/libvirt/:/var/run/libvirt/ \
     -v ~/.vagrant.d:/.vagrant.d \
     -v $(realpath "${PWD}"):${PWD} \
-    -w $(realpath "${PWD}") \
+    -w "${PWD}" \
     --network host \
     vagrantlibvirt/vagrant-libvirt:latest \
       vagrant $@
@@ -126,7 +126,7 @@ vagrant(){
     -v /var/run/libvirt/:/var/run/libvirt/ \
     -v ~/.vagrant.d:/.vagrant.d \
     -v $(realpath "${PWD}"):${PWD} \
-    -w $(realpath "${PWD}") \
+    -w "${PWD}" \
     --network host \
     --entrypoint /bin/bash \
     --security-opt label=disable \

entrypoint.sh

@@ -53,9 +53,18 @@ USER_UID=${USER_UID:-$(stat -c %u ${path})} || exit 3
 USER_GID=${USER_GID:-$(stat -c %g ${path})} || exit 3
 if [[ ${USER_UID} -eq 0 ]]
 then
-    if [[ -z "${IGNORE_RUN_AS_ROOT:-}" ]]
+    if [[ "${IGNORE_RUN_AS_ROOT:-0}" == "0" ]]
     then
-        echo "WARNING! Running as root, if this breaks, you get to keep both pieces"
+        echo "ERROR! Running as root, this usually means there has been a mistake" \
+            "in how the image has been launched."
+        echo "If this is actually intended, please pass '-e IGNORE_RUN_AS_ROOT=1'" \
+            "via the docker run command to allow execution as root."
+        echo
+        echo "Used '${path}' to determine uid/gid, typically starting looking for the" \
+            "file '$(pwd)/Vagrantfile' or if there is a Vagrantfile in the parent directory" \
+            "otherwise fall back to owner/group of'$(pwd)'"
+
+        exit 2
     fi
 else
     vdir_uid=$(stat -c %u ${vdir})
@@ -104,9 +113,12 @@ then
     ${USERCMD} --shell /bin/bash -u ${USER_UID} -g ${USER_GID} -o -c "" -m ${USER} >/dev/null 2>&1 || exit 3
 fi
 
-# make sure the directories can be written to by vagrant otherwise will
-# get a start up error
-find "${VAGRANT_HOME}" -maxdepth 1 ! -exec chown -h ${USER}:${GROUP} {} \+
+if [[ "${USER_UID}" != "0" ]]
+then
+    # make sure the directories can be written to by vagrant otherwise will
+    # get a start up error
+    find "${VAGRANT_HOME}" -maxdepth 1 ! -exec chown -h ${USER}:${GROUP} {} \+
+fi
 
 LIBVIRT_SOCK=/var/run/libvirt/libvirt-sock
 if [[ ! -S ${LIBVIRT_SOCK} ]]
@@ -121,7 +133,7 @@ then
 else
     LIBVIRT_GID=$(stat -c %g ${LIBVIRT_SOCK})
     # only do this if the host uses a non-root group for libvirt
-    if [[ ${LIBVIRT_GID} -ne 0 ]]
+    if [[ "${USER_UID}" != "0" ]] && [[ ${LIBVIRT_GID} -ne 0 ]]
     then
         if getent group libvirt >/dev/null
         then
@@ -138,7 +150,17 @@ fi
 if [[ $# -eq 0 ]]
 then
     # if no command provided
-    exec gosu ${USER} vagrant help >&3
+    if [[ "${USER_UID}" != "0" ]]
+    then
+        exec gosu ${USER} vagrant help >&3
+    else
+        exec vagrant help >&3
+    fi
 fi
 
-exec gosu ${USER} "$@" >&3
+if [[ "${USER_UID}" != "0" ]]
+then
+    exec gosu ${USER} "$@" >&3
+else
+    exec "$@" >&3
+fi