### First create a repo file in CentOS:

    ===> cat /etc/yum.repos.d/opensuse-leap-15.3.repo 
    [opensuse-leap-15.3]
    name=OpenSUSE Leap 15.3
    baseurl=https://download.opensuse.org/distribution/leap/15.3/repo/oss/
    enabled=0
    gpgcheck=0
    #gpgkey=

### Make the chroot and RPM directory

    mkdir /mnt/opensuse-leap-15.3
    mkdir /mnt/opensuse-leap-15.3/var/lib/rpm -p

### Mount /dev, proc, and sysfs

    for i in proc sys dev; do
      mkdir -p /mnt/opensuse-leap-15.3/$i
      mount --bind /$i /mnt/opensuse-leap-15.3/$i
    done

### Initialize the RPM database

    rpm --root /mnt/opensuse-leap-15.3 --initdb

### Deploy!

    yum --disablerepo=\* --enablerepo=opensuse-leap-15.3 --installroot=/mnt/opensuse-leap-15.3 install aaa_base rpm-repos-openSUSE-Leap bash zypper util-linux


## Get inside the chroot:

    chroot /mnt/opensuse-leap-15.3 /bin/su -
    el7-dev:~ # 

### The rest of these commands are inside the chroot:

### Setup DNS:
    echo nameserver 1.1.1.1 > /etc/resolv.conf

### Add the zypper repos:
    rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-openSUSE

    zypper ar -r /etc/yum.repos.d/opensuse-leap-oss.repo

### Here are a few other nice-to-have packages:
    zypper install vim openssl ca-certificates wget curl

### You may wish to import the RPM signing keys:

    rpm --import https://download.opensuse.org/distribution/leap/15.3/repo/oss/gpg-pubkey-3dbdc284-53674dd4.asc
    rpm --import https://download.opensuse.org/distribution/leap/15.3/repo/oss/gpg-pubkey-39db7c82-5847eb1f.asc
    rpm --import https://download.opensuse.org/distribution/leap/15.3/repo/oss/gpg-pubkey-307e3d54-5aaa90a5.asc
    rpm --import https://download.opensuse.org/distribution/leap/15.3/repo/oss/gpg-pubkey-65176565-59787af5.asc