Tweak non-root user logic

.devcontainer/Dockerfile

@@ -8,11 +8,11 @@ FROM node:10
 # Avoid warnings by switching to noninteractive
 ENV DEBIAN_FRONTEND=noninteractive
 
-# The node image comes with a base non-root 'node' user, so the alternate
-# user here is primarily for Linux scenarios where you need to match your local
-# user UID/GID. See https://aka.ms/vscode-remote/containers/non-root-user.
-ARG USERNAME=vscode
-ARG USER_UID=1001
+# The node image comes with a base non-root 'node' user which this Dockerfile
+# gives sudo access. Hoewver, for Linux, this user's GID/UID must match your local
+# user UID/GID to avoid permission issues with bind mounts. Update USER_UID / USER_GID 
+# if yours is not 1000. See https://aka.ms/vscode-remote/containers/non-root-user.
+ARG USER_UID=1000
 ARG USER_GID=$USER_UID
 
 # Configure apt and install packages
@@ -37,13 +37,12 @@ RUN apt-get update \
     && npm install -g eslint \
     #
     # Create a non-root user to use if preferred - see https://aka.ms/vscode-remote/containers/non-root-user.
-    && if [ "$USER_GID" != "1000" ]; then groupadd --gid $USER_GID $USERNAME; fi \
-    && if [ "$USER_UID" != "1000" ]; then useradd -s /bin/bash --uid $USER_UID --gid $USER_GID -m $USERNAME; fi \
+    && if [ "$USER_GID" != "1000" ]; then groupmod node --gid $USER_GID; fi \
+    && if [ "$USER_UID" != "1000" ]; then usermod --uid $USER_UID node; fi \
     # [Optional] Add sudo support for non-root users
     && apt-get install -y sudo \
-    && if [ "$USER_UID" != "1000" ]; then echo $USERNAME ALL=\(root\) NOPASSWD:ALL > /etc/sudoers.d/$USERNAME; fi \
     && echo node ALL=\(root\) NOPASSWD:ALL > /etc/sudoers.d/node \
-    && chmod 0440 /etc/sudoers.d/$USERNAME \
+    && chmod 0440 /etc/sudoers.d/node \
     #
     # Clean up
     && apt-get autoremove -y \