Creating a Container Image with an AlmaLinux OS Upgrade

This procedure describes how to create a Docker container image from controlm/agent that includes an upgrade of the AlmaLinux OS stream (where the default is AlmaLinux 10.2) without rebuilding the full upstream image.

Such an image enables you to upgrade to a newer version of AlmaLinux immediately, without having to wait for a new version of Control-M for Kubernetes.

BMC-provided images are based on AlmaLinux Minimal, which includes a microdnf package manager.

Before You Begin

Ensure that you meet the following prerequisites:

• A Docker installed and running

• Access to pull controlm/agent from the Docker Hub

• Network access to AlmaLinux repositories during the image build

Begin

1. Create a Dockerfile named Dockerfile.os-upgrade with the following content:

   Copy

   ARG SOURCE_IMAGE=controlm/agent:9.22.110-k8s
   FROM ${SOURCE_IMAGE}
   ARG ALMALINUX_RELEASEVER=10.2
   
   USER root
   
   # Upgrade to target AlmaLinux stream
   RUN microdnf -y --releasever=${ALMALINUX_RELEASEVER} distro-sync \
       && microdnf -y --releasever=${ALMALINUX_RELEASEVER} update \
       && microdnf clean all
       
   # Recreate build metadata so it reflects the upgraded OS
   RUN rm -rf /etc/image-build-info \
       && mkdir -p /etc/image-build-info \
       && cat /etc/os-release > /etc/image-build-info/os-release.txt \
       && cat /etc/redhat-release > /etc/image-build-info/redhat-release.txt \
                   && if command -v rpm >/dev/null 2>&1; then rpm -q almalinux-release >
   /etc/image-build-info/almalinux-release-rpm.txt; fi \
       && microdnf repoquery --installed --info > /etc/image-build-info/installed-packages.txt \
       && date -u > /etc/image-build-info/build-date-utc.txt \
       && uname -r > /etc/image-build-info/kernel.txt \
       && echo "===== /etc/image-build-info =====" \
       && for f in /etc/image-build-info/*; do echo "--- ${f} ---"; cat "${f}"; done
       
   USER controlm

   To create a custom image on top of an MFT base image, use 9.22.110-k8s-mft instead of 9.22.110-k8s.

2. Build an image based on the Dockerfile that you created by running one of the following commands:

   • (Default target OS stream)

     docker build -f <Dockerfile name> -t <image name> .

   • (With target OS stream override)

     docker build -f <Dockerfile name> --build-arg ALMALINUX_RELEASEVER=<version> -t <image name> .

   The image name includes the name of the repository where you want to upload the created image.

   • For a default target OS stream:

     docker build -f Dockerfile.os-upgrade -t myrepo/controlm-agent:alma10.2

   • With a target OS stream override:

     docker build -f Dockerfile.os-upgrade \

     --build-arg ALMALINUX_RELEASEVER=10.2 \

     -t myrepo/controlm-agent:alma10.2 .

3. Verify the AlmaLinux OS version by doing the following:

   1. Run a command such as the following:

      docker run --rm --entrypoint /bin/sh myrepo/controlm-agent:alma10.2 \

      -c "cat /etc/os-release; echo; cat /etc/redhat-release; echo; rpm -q almalinux-release"

   2. Check the command output for the following elements:

      • VERSION_ID="10.2" (or the value of ALMALINUX_RELEASEVER)

      • AlmaLinux release 10.2

      • almalinux-release-10.2-*.el9.*

4. Push the image to your private repository by running the following command:

   docker push <image name>

   The image name includes the name of the repository where you want to upload the image.

   docker push myrepo/controlm-agent:alma10.2