replacing ubuntu os with python env for cord-api dockerfile

Change-Id: I8ca3366bbeaeb5cb827c26805964f8b6b9b38a5f
diff --git a/src/test/cord-api/Dockerfile.k8s-api-tester b/src/test/cord-api/Dockerfile.k8s-api-tester
index a8e17fb..75a68db 100644
--- a/src/test/cord-api/Dockerfile.k8s-api-tester
+++ b/src/test/cord-api/Dockerfile.k8s-api-tester
@@ -16,11 +16,9 @@
 # Manual build example:
 # docker build -f Dockerfile.k8s-api-tester -t xos-api-tester:local .
 
-FROM ubuntu:16.04
+FROM python:2.7
 
-RUN apt-get update  && \
-    apt-get install -y python python-pip python-setuptools && \
-    pip install robotframework robotframework-requests pexpect \
+RUN pip install robotframework robotframework-requests pexpect \
      robotframework-httplibrary robotframework-ride robotframework-kafkalibrary pygments pyyaml && \
     pip install -U requests && rm -rf /var/lib/apt/lists/*
 
@@ -47,4 +45,4 @@
       org.opencord.vcs-commit-date=$org_opencord_vcs_commit_date
 
 ENTRYPOINT ["pybot", "-L", "TRACE", "-d", "Log", "-T"]
-CMD ["Ch_ServiceTest.txt"]
\ No newline at end of file
+CMD ["Ch_ServiceTest.txt"]