Update Dockerfile

Author: sachin-pikle

samples/imagedims-python/Dockerfile

@@ -1,21 +1,20 @@
-FROM fnproject/python:3.6-dev
+FROM fnproject/python:3.6-dev as build-stage
 WORKDIR /function
 ADD requirements.txt /function/
-RUN pip3 install --no-cache --no-cache-dir --upgrade pip && \
-      pip3 install --target /python/  --no-cache --no-cache-dir -r requirements.txt && \
-	    rm -fr ~/.cache/pip /tmp* requirements.txt func.yaml Dockerfile .venv && \
-      chmod -R o+r /function
+
+RUN pip3 install --target /python/  --no-cache --no-cache-dir -r requirements.txt &&\
+  rm -fr ~/.cache/pip /tmp* requirements.txt func.yaml Dockerfile .venv &&\
+  chmod -R o+r /python
 ADD . /function/
 RUN rm -fr /function/.pip_cache
-
 FROM fnproject/python:3.6
 RUN microdnf install oracle-epel-release-el8 &&\
       microdnf install ImageMagick &&\
       microdnf remove oracle-epel-release-el8 &&\
       microdnf clean all
 WORKDIR /function
-COPY --from=build-stage /function /function
 COPY --from=build-stage /python /python
-ENV PYTHONPATH=/python:/function
+COPY --from=build-stage /function /function
+RUN chmod -R o+r /function
+ENV PYTHONPATH=/function:/python
 ENTRYPOINT ["/python/bin/fdk", "/function/func.py", "handler"]
-