Said the one who has the highest number of points. I think it should not be too much expensive, and it will be a good goal for some participants.

Interesting looks like such error expectable for RedHat. But don't have any RedHat subscription, and I managed to build an image with RedHat, but with centos repo. And in my case, it works without any errors. Maybe you can contact me directly and send your image, so I can check on it?

My differences from your Dockerfile

RUN /bin/echo -e '[centos]' \
    '\nname=CentOS $releasever - $basearch' \
    '\nbaseurl=$basearch/' \
    '\nenabled=1' \
    '\ngpgcheck=0' > /etc/yum.repos.d/centos.repo \
 && cat /etc/yum.repos.d/centos.repo \
 && yum -y --nogpgcheck update \
 && yum -y --nogpgcheck install which tar hostname net-tools wget \
 && yum -y clean all \
 && ln -sf /etc/locatime /usr/share/zoneinfo/Australia/Brisbane

and I used the latest version of ccontainermain from releases, maybe with this version will be better for you as well.

curl -L -o /ccontainermain

look at $zf function in the documentation, it gives a possibility to execute a command in OS.

so, the same Legacy task and your code should be 

set res=$zf(-2, "c:\path\to\your\shutdown_ensemble.bat")

batch file means, that you want to do it outside of Ensemble. In this case you should use ccontrol command or iris if you use IRIS.

ccontrol stop <ensemble> quietly

ccontrol start <ensemble>

where you should replace <ensemble> with your instance name.

if you work on windows, you can find ccontrol tool in bin directory of installed Ensemble.

you can find more details about using ccontrol in the documentation

2018.2 version which Preview already released recently, works well with overlay now. 

Fixed, and also changed from DO to JOB, if we do not want to manually restore this task after every run.

At this time, it is supported only with Studio. I can easily add support to VSCode, not sure how it will be possible for Eclipse Atelier.