$ eb -C --experimental --container-base-config bootstrap=yum,osversion=7 bzip2-1.0.6.eb

Bootstrap: yum
OSVersion: 7
MirrorURL: http://mirror.centos.org/centos-%{OSVERSION}/%{OSVERSION}/os/x86_64/
Include: yum

%post
yum install -y epel-release
yum install -y python setuptools Lmod
yum install -y bzip2 gzip tar unzip xz
yum install -y curl wget
yum install -y patch make
yum install -y file git which
yum install -y python-pip
yum install -y vim
yum install -y gcc-c++
yum install -y perl-Data-Dumper
yum install -y perl-Thread-Queue

# install EasyBuild using pip
pip install -U setuptools
pip install -U 'vsc-install<0.11.4' 'vsc-base<2.9.0'
pip install -U easybuild

# create 'easybuild' user (if missing)
id easybuild || useradd easybuild

# create /app software installation prefix + /scratch sandbox directory
if [ ! -d /app ]; then mkdir -p /app; chown easybuild:easybuild -R /app; fi
if [ ! -d /scratch ]; then mkdir -p /scratch; chown easybuild:easybuild -R /scratch; fi

# change to 'easybuild' user
su - easybuild

eb bzip2-1.0.6.eb --robot --installpath=/app/ --prefix=/scratch --tmpdir=/scratch/tmp

# exit from 'easybuild' user
exit

# cleanup
rm -rf /scratch/tmp/* /scratch/build /scratch/sources /scratch/ebfiles_repo

%runscript
eval "$@"

%environment
source /etc/profile
module use /app/modules/all
module load bzip2/1.0.6

$ eb -C --experimental --container-base-config bootstrap=localimage,from=centos7-ncurses-6.1.sif CMake-3.12.1.eb

Bootstrap: localimage
From: centos7-ncurses-6.1.sif

%post
yum --skip-broken -y install openssl-devel libssl-dev libopenssl-devel

# install EasyBuild using pip
pip install -U setuptools
pip install 'vsc-install<0.11.4' 'vsc-base<2.9.0'
pip install easybuild

# create 'easybuild' user (if missing)
id easybuild || useradd easybuild

# create /app software installation prefix + /scratch sandbox directory
if [ ! -d /app ]; then mkdir -p /app; chown easybuild:easybuild -R /app; fi
if [ ! -d /scratch ]; then mkdir -p /scratch; chown easybuild:easybuild -R /scratch; fi

# change to 'easybuild' user
su - easybuild

eb CMake-3.12.1.eb --robot --installpath=/app/ --prefix=/scratch --tmpdir=/scratch/tmp

# exit from 'easybuild' user
exit

# cleanup
rm -rf /scratch/tmp/* /scratch/build /scratch/sources /scratch/ebfiles_repo

%runscript
eval "$@"

%environment
source /etc/profile
module use /app/modules/all
module load CMake/3.12.1