Avoid root when installing cbpi

Dockerfile

@@ -3,7 +3,7 @@ RUN apk --no-cache add curl && mkdir /downloads
 # Download installation files
 RUN curl https://github.com/avollkopf/craftbeerpi4-ui/archive/main.zip -L -o ./downloads/cbpi-ui.zip
 
-FROM python:3.7
+FROM python:3.9
 
 # Install dependencies
 RUN     apt-get update \
@@ -14,28 +14,39 @@ RUN apt-get install --no-install-recommends -y \
     python3-pip \
     && rm -rf /var/lib/apt/lists/*
 
-RUN python -m pip install --upgrade pip setuptools wheel
+ENV VIRTUAL_ENV=/opt/venv
 
-WORKDIR /cbpi
 # Create non-root user working directory
 RUN groupadd -g 1000 -r craftbeerpi \
     && useradd -u 1000 -r -s /bin/false -g craftbeerpi craftbeerpi \
-    && chown craftbeerpi:craftbeerpi /cbpi
-
-# Install craftbeerpi from source
-COPY . /cbpi-src
-RUN pip3 install --no-cache-dir /cbpi-src
-
-# Install craftbeerpi-ui
-COPY --from=download /downloads /downloads
-RUN pip3 install --no-cache-dir /downloads/cbpi-ui.zip
-
-# Clean up installation files
-RUN rm -rf /downloads /cbpi-src
+    && mkdir /cbpi \
+    && chown craftbeerpi:craftbeerpi /cbpi \
+    && mkdir -p $VIRTUAL_ENV \
+    && chown -R craftbeerpi:craftbeerpi ${VIRTUAL_ENV}
 
 USER craftbeerpi
 
-RUN cbpi setup
+# create virtual environment
+RUN python3 -m venv $VIRTUAL_ENV
+ENV PATH="$VIRTUAL_ENV/bin:$PATH"
+
+RUN python3 -m pip install --no-cache-dir --upgrade pip setuptools wheel
+
+# Install craftbeerpi from source
+COPY --chown=craftbeerpi . /cbpi-src
+RUN pip3 install --no-cache-dir /cbpi-src
+
+# Install craftbeerpi-ui
+COPY --from=download --chown=craftbeerpi /downloads /downloads
+RUN pip3 install --no-cache-dir /downloads/cbpi-ui.zip
+
+# Clean up installation files
+USER root
+RUN rm -rf /downloads /cbpi-src
+USER craftbeerpi
+
+WORKDIR /cbpi
+RUN ["cbpi", "setup"]
 
 EXPOSE 8000