Install python dependencies via pip

Author: dalehamel

Dockerfile.ubuntu

@@ -23,5 +23,10 @@ COPY --from=builder /root/bcc/*.deb /root/bcc/
 
 RUN \
   apt-get update -y && \
-  DEBIAN_FRONTEND=noninteractive apt-get install -y python python3 binutils libelf1 kmod python-dnslib python-cachetools python3-dnslib python3-cachetools && \
+  DEBIAN_FRONTEND=noninteractive apt-get install -y python python3 python3-pip binutils libelf1 kmod  && \
+  if [ ${OS_TAG} = "18.04" ];then \
+    apt-get -y install python-pip && \
+    pip install dnslib cachetools ; \
+  fi ; \
+  pip3 install dnslib cachetools  && \
   dpkg -i /root/bcc/*.deb