add filelessexec script, build binaries at build-time

Signed-off-by: rksharma95 <ramakant@accuknox.com>

examples/multiubuntu/build/Dockerfile

@@ -1,19 +1,34 @@
 # SPDX-License-Identifier: Apache-2.0
 # Copyright 2021 Authors of KubeArmor
 
-FROM ubuntu:18.04
+FROM ubuntu:20.04 as builder
+
+RUN apt-get update && apt install -y gcc python3 pipx python3-venv
+COPY helloworld/ /helloworld/
+COPY readwrite/ /readwrite/
+
+RUN gcc -o hello /helloworld/hello.c
+RUN gcc -o readwriter /readwrite/readwrite.c
+
+RUN pipx install fee
+
+ENV PATH=$PATH:/root/.local/bin
+
+RUN fee /bin/ls > /ls.py
+
+
+FROM ubuntu:20.04
 
 RUN apt-get update
 
 RUN apt-get install -y net-tools iputils-ping telnet ssh tcpdump nmap dsniff arping
-RUN apt-get install -y curl iperf3 netperf ethtool python-scapy python-pip
+RUN apt-get install -y curl iperf3 netperf ethtool python3 python3-scapy python3-flask pipx python3-venv
 RUN apt-get install -y iptables bridge-utils apache2 vim
 
 RUN apt-get clean
 RUN apt-get autoremove -y
 RUN rm -rf /var/lib/{apt,dpkg,cache,log}/
 
-RUN pip install flask
 ADD flask/http_test.py /
 COPY entrypoint.sh /entrypoint.sh
 
@@ -30,7 +45,7 @@ RUN echo "key file" >> /credentials/keys/priv.key
 
 RUN useradd --create-home --shell /bin/bash user1
 RUN echo 'user1:passwd1' | chpasswd
-COPY hello /home/user1/hello
+COPY --from=builder /hello /home/user1/hello
 RUN chown user1:user1 /home/user1/hello
 
 RUN echo "secret file user1" >> /home/user1/secret_data1.txt
@@ -45,7 +60,9 @@ RUN echo "other file" >> /home/user1/otherfile.txt
 RUN chown user1:user1 /home/user1/otherfile.txt
 
 COPY readwriter /readwrite
-COPY readwriter /home/user1/readwrite
-RUN chown user1:user1 /home/user1/readwrite  
+COPY --from=builder /readwriter /home/user1/readwrite
+RUN chown user1:user1 /home/user1/readwrite
+
+COPY --from=builder /ls.py /ls.py
 
-CMD [ "/entrypoint.sh" ]
+CMD [ "/entrypoint.sh" ]