Chapter 3. Working with overcloud images
Red Hat OpenStack Platform (RHOSP) director provides images for the overcloud. The QCOW image in this collection contains a base set of software components that integrate to form various overcloud roles, such as Compute, Controller, and storage nodes. In some situations, you might aim to modify certain aspects of the overcloud image to suit your needs, such as installing additional components to nodes.
You can use the virt-customize tool to modify an existing overcloud image to augment an existing Controller node. For example, use the following procedures to install additional
ml2 plugins, Cinder backends, or monitoring agents that do not ship with the initial image.
If you modify the overcloud image to include third-party software and report an issue, Red Hat might request that you reproduce the issue with an unmodified image in accordance with our general third-party support policy: https://access.redhat.com/articles/1067.
3.1. Obtaining the Overcloud Images
Director requires several disk images to provision overcloud nodes:
- An introspection kernel and ramdisk - For bare metal system introspection over PXE boot.
- A deployment kernel and ramdisk - For system provisioning and deployment.
- An overcloud kernel, ramdisk, and full image - A base overcloud system that director writes to the hard disk of the node.
To obtain these images, install the
$ sudo dnf install rhosp-director-images rhosp-director-images-ipa
Extract the archives to the
imagesdirectory on the
stackuser home (
$ cd ~/images $ for i in /usr/share/rhosp-director-images/overcloud-full-latest-16.1.tar /usr/share/rhosp-director-images/ironic-python-agent-latest-16.1.tar; do tar -xvf $i; done
3.2. Initrd: Modifying the initial ramdisks
Some situations might require that you modify the initial ramdisk. For example, you might require that a certain driver is available when you boot the nodes during the introspection or provisioning processes. In the context of the overcloud, this includes one of the following ramdisks:
The introspection ramdisk -
The provisioning ramdisk -
This procedure adds an additional RPM package to the ironic-python-agent.initramfs ramdisk as an example.
You have installed the pax utility:
$ sudo dnf install -y spax
Log in as the
rootuser and create a temporary directory for the ramdisk:
# mkdir ~/ipa-tmp # cd ~/ipa-tmp
cpiocommands to extract the ramdisk to the temporary directory:
# /usr/lib/dracut/skipcpio ~/images/ironic-python-agent.initramfs | zcat | cpio -ivd | pax -r
Install an RPM package to the extracted contents:
# rpm2cpio ~/RPMs/python-proliantutils-2.1.7-1.el7ost.noarch.rpm | pax -r
Recreate the new ramdisk:
# find . 2>/dev/null | cpio --quiet -c -o | gzip -8 > /home/stack/images/ironic-python-agent.initramfs # chown stack: /home/stack/images/ironic-python-agent.initramfs
Verify that the new package now exists in the ramdisk:
# lsinitrd /home/stack/images/ironic-python-agent.initramfs | grep proliant
3.3. QCOW: Installing virt-customize to director
libguestfs-tools package contains the
$ sudo dnf install libguestfs-tools
If you install the
libguestfs-tools package on the undercloud, disable
iscsid.socket to avoid port conflicts with the
tripleo_iscsid service on the undercloud:
$ sudo systemctl disable --now iscsid.socket
3.4. QCOW: Inspecting the overcloud image
Before you can review the contents of the
overcloud-full.qcow2 image, you must create a virtual machine that uses this image. .Procedure
To create a virtual machine instance that uses the
overcloud-full.qcow2image, enter the
$ mkdir ~/overcloud-full $ guestmount -a overcloud-full.qcow2 -i --ro ~/overcloud-full
You can review the contents of the QCOW2 image in
Alternatively, you can use virt-manager to create a virtual machine with the following boot options:
- Kernel path: /overcloud-full.vmlinuz
- initrd path: /overcloud-full.initrd
- Kernel arguments: root=/dev/sda
3.5. QCOW: Setting the root password
Set the root password to provide administrator-level access for your nodes through the console.
Set the password for the root user on image:
$ virt-customize --selinux-relabel -a overcloud-full.qcow2 --root-password password:test [ 0.0] Examining the guest ... [ 18.0] Setting a random seed [ 18.0] Setting passwords [ 19.0] Finishing off
3.6. QCOW: Registering the image
Register your overcloud image to the Red Hat Content Delivery Network.
Register your image temporarily to enable Red Hat repositories relevant to your customizations:
$ virt-customize --selinux-relabel -a overcloud-full.qcow2 --run-command 'subscription-manager register --username=[username] --password=[password]' [ 0.0] Examining the guest ... [ 10.0] Setting a random seed [ 10.0] Running: subscription-manager register --username=[username] --password=[password] [ 24.0] Finishing off
Replace the [username] and [password] with your Red Hat customer account details. This runs the following command on the image:
subscription-manager register --username=[username] --password=[password]
3.7. QCOW: Attaching a subscription and enabling Red Hat repositories
Find a list of pool ID from your account subscriptions:
$ sudo subscription-manager list
Choose a subscription pool ID and attach it to the image:
$ virt-customize --selinux-relabel -a overcloud-full.qcow2 --run-command 'subscription-manager attach --pool [subscription-pool]' [ 0.0] Examining the guest ... [ 12.0] Setting a random seed [ 12.0] Running: subscription-manager attach --pool [subscription-pool] [ 52.0] Finishing off
Replace the [subscription-pool] with your chosen subscription pool ID:
subscription-manager attach --pool [subscription-pool]
This adds the pool to the image so that you can enable the repositories.
Enable the Red Hat repositories:
$ subscription-manager repos --enable=[repo-id]
3.8. QCOW: Copying a Custom Repository File
Adding third-party software to the image requires additional repositories. The following is an example repo file that contains configuration to use the OpenDaylight repository content.
List the contents of the opendaylight.repo file:
$ cat opendaylight.repo [opendaylight] name=OpenDaylight Repository baseurl=https://nexus.opendaylight.org/content/repositories/opendaylight-yum-epel-8-x86_64/ gpgcheck=0
Copy the repository file on to the image:
$ virt-customize --selinux-relabel -a overcloud-full.qcow2 --upload opendaylight.repo:/etc/yum.repos.d/ [ 0.0] Examining the guest ... [ 12.0] Setting a random seed [ 12.0] Copying: opendaylight.repo to /etc/yum.repos.d/ [ 13.0] Finishing off
--uploadoption copies the repository file to
/etc/yum.repos.d/on the overcloud image.
Red Hat does not offer support for software from non-certified vendors. Check with your Red Hat support representative that the software you want to install is supported.
3.9. QCOW: Installing RPMs
virt-customizecommand to install packages to the image:
$ virt-customize --selinux-relabel -a overcloud-full.qcow2 --install opendaylight [ 0.0] Examining the guest ... [ 11.0] Setting a random seed [ 11.0] Installing packages: opendaylight [ 91.0] Finishing off
--installoption to specify a package to install.
3.10. QCOW: Cleaning the subscription pool
After you install the necessary packages to customize the image, remove the subscription pools and unregister the image:
$ virt-customize --selinux-relabel -a overcloud-full.qcow2 --run-command 'subscription-manager remove --all' [ 0.0] Examining the guest ... [ 12.0] Setting a random seed [ 12.0] Running: subscription-manager remove --all [ 18.0] Finishing off
3.11. QCOW: Unregistering the image
Unregister the image so that the overcloud deployment process can deploy the image to your nodes and register each of them individually:
$ virt-customize --selinux-relabel -a overcloud-full.qcow2 --run-command 'subscription-manager unregister' [ 0.0] Examining the guest ... [ 11.0] Setting a random seed [ 11.0] Running: subscription-manager unregister [ 17.0] Finishing off
3.12. QCOW: Reset the machine ID
Reset the machine ID for the image so that machines that use this image do not use duplicate machine IDs:
$ virt-sysprep --operation machine-id -a overcloud-full.qcow2
3.13. Uploading the images to director
After you modify the image, you need to upload it to director.
stackrcfile so that you can access director from the command line:
$ source stackrc
Upload the default director images to use for deploying the overcloud:
$ openstack overcloud image upload --image-path /home/stack/images/
This uploads the following images into the director:
The script also installs the introspection images on the directors PXE server.
View a list of the images in the CLI:
$ openstack image list +--------------------------------------+------------------------+ | ID | Name | +--------------------------------------+------------------------+ | 765a46af-4417-4592-91e5-a300ead3faf6 | bm-deploy-ramdisk | | 09b40e3d-0382-4925-a356-3a4b4f36b514 | bm-deploy-kernel | | ef793cd0-e65c-456a-a675-63cd57610bd5 | overcloud-full | | 9a51a6cb-4670-40de-b64b-b70f4dd44152 | overcloud-full-initrd | | 4f7e33f4-d617-47c1-b36f-cbe90f132e5d | overcloud-full-vmlinuz | +--------------------------------------+------------------------+
This list does not show the introspection PXE images (agent.*). Director copies these files to
[stack@host1 ~]$ ls /httpboot -l total 151636 -rw-r--r--. 1 ironic ironic 269 Sep 19 02:43 boot.ipxe -rw-r--r--. 1 root root 252 Sep 10 15:35 inspector.ipxe -rwxr-xr-x. 1 root root 5027584 Sep 10 16:32 agent.kernel -rw-r--r--. 1 root root 150230861 Sep 10 16:32 agent.ramdisk drwxr-xr-x. 2 ironic ironic 4096 Sep 19 02:45 pxelinux.cfg