Red Hat build of MicroShift

Work around UID and GID drift when migrating to image mode for RHEL

If you do not re-install operating systems that are running MicroShift, you must use a workaround for a possible UID and GID drift during the migration process. One way to solve this problem is to add systemd units that apply the necessary fixes before the affected system services are started.

Prerequisites

You have an existing RHEL for Edge deployment running MicroShift.
You have root access to the build host.
You have an image that you want to deploy.

Procedure

Solve the potential UID or GID drift for the Open vSwitch (OVS) systemd service, ovsdb-server.service, by adding the following command to the MicroShift image-build procedure:

# Install systemd configuration drop-ins to fix potential permission problems when upgrading from rpm-ostree commits to image mode container layers
RUN mkdir -p /usr/lib/systemd/system/ovsdb-server.service.d && \
    cat > /usr/lib/systemd/system/ovsdb-server.service.d/microshift-ovsdb-ownership.conf <<'EOF'
# The openvswitch database files must be owned by the appropriate user and its primary group. That the user and its group can be overwritten, recreate them.
[Service]
ExecStartPre=/bin/sh -c '/bin/getent passwd openvswitch >/dev/null || useradd -r openvswitch'
ExecStartPre=/bin/sh -c '/bin/getent group hugetlbfs >/dev/null || groupadd -r hugetlbfs'
ExecStartPre=/sbin/usermod -a -G hugetlbfs openvswitch
ExecStartPre=/bin/chown -Rhv openvswitch. /etc/openvswitch
EOF

After the MicroShift migration to image mode for RHEL is complete, this workaround is not needed and can be removed.