Merge pull request #5 from T-Systems-MMS/add_image_config_part

add image config step

Author: mikaEz

Dockerfile.template

@@ -1,6 +1,5 @@
 ###################################### Image ######################################
 ARG CENTOS_VERSION=8
-ARG PACKAGES
 
 ## build Image
 FROM centos:${CENTOS_VERSION}
@@ -20,14 +19,20 @@ RUN yum update -y && \
   glibc && \
   yum clean all
 
+# pip
+## upgrade only base packages which are installed by 'yum install python3-pip'
+RUN pip3 list -o | cut -d' ' -f1 | xargs -n1 pip3 install --upgrade
+
+################################## Image Config ###################################
+ARG PACKAGES
+
+WORKDIR /root
+
 ## custom packages to install
 RUN test -n "${PACKAGES}" && \
-    yum install -y "${PACKAGES}" && \
+    yum install -y ${PACKAGES} && \
     yum clean all || :
 
-## pip
-RUN pip3 list -o | cut -d' ' -f1 | xargs -n1 pip3 install --upgrade
-
 ###################################### Tools ######################################
 # define versions
 ARG ANSIBLE_VERSION

README.MD

@@ -18,7 +18,7 @@ vi .docker_build
 | ---------------- | -------- | ------- |
 | CENTOS_VERSION   | no       | 8       |
 
-### Packages
+### Image Config
 
 Further packages to install can be specified