Chapter 4. Migrating MicroShift from RHEL for Edge to image mode for RHEL

• Follow the instructions in the RHEL documentation for converting rpm-ostree blueprint files to image mode container files.
• You can use the rpm-ostree compose container-encapsulate image-compose command to create a base container image that can be used for bootc container builds. Then you can derive and familiarize yourself with an image mode for RHEL image that is based on existing ostree commits.
• To fully adopt image mode for RHEL, define a container build pipeline.
• Plan for UID and GID drift because RHEL for Edge and image mode for RHEL are not derived from the same parent image. See the RHEL documentation for more information.

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

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