añadiendo permisos sobre la carpeta docker a ver si asi..

Dockerfile

@@ -47,7 +47,9 @@ ARG GID=1000
 ENV HOME /home/$USER
 ENV ENV_PREFIX $HOME/env
 
+RUN echo "---> Ensure group"
 RUN if ! getent group $GID; then addgroup --gid $GID $USER; fi
+RUN echo "---> Ensure user"
 RUN if ! id -u %USER > /dev/null 2>&1; then \
 	adduser --disabled-password \
 	--gecos "Non-root user" \
@@ -57,9 +59,12 @@ RUN if ! id -u %USER > /dev/null 2>&1; then \
 	$USER; \
 	fi
 
-# Make sudo and setup sudoers
+RUN echo "---> Make sudo & setup sudoers"
 RUN adduser $USER sudo
 RUN echo "$USER ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers
+RUN chown -R $USER:$GID docker
+
+
 
 ARG RETICULATE_MINICONDA_PATH=/usr/local/share/r-miniconda
 ARG RETICULATE_PYTHON_ENV=/usr/virtualenvs/venv_shiny_app