Chapter 2. Obtaining and modifying container images
A containerized overcloud requires access to a registry with the required container images. This chapter provides information on how to prepare the registry and your undercloud and overcloud configuration to use container images for Red Hat OpenStack Platform.
2.1. Preparing container images
The overcloud configuration requires initial registry configuration to determine where to obtain images and how to store them. Complete the following steps to generate and customize an environment file for preparing your container images.
Procedure
- Log in to your undercloud host as the stack user.
Generate the default container image preparation file:
$ openstack tripleo container image prepare default \ --local-push-destination \ --output-env-file containers-prepare-parameter.yaml
This command includes the following additional options:
-
--local-push-destination
sets the registry on the undercloud as the location for container images. This means the director pulls the necessary images from the Red Hat Container Catalog and pushes them to the registry on the undercloud. The director uses this registry as the container image source. To pull directly from the Red Hat Container Catalog, omit this option. --output-env-file
is an environment file name. The contents of this file include the parameters for preparing your container images. In this case, the name of the file iscontainers-prepare-parameter.yaml
.NoteYou can also use the same
containers-prepare-parameter.yaml
file to define a container image source for both the undercloud and the overcloud.
-
-
Edit the
containers-prepare-parameter.yaml
and make the modifications to suit your requirements.
2.2. Container image preparation parameters
The default file for preparing your containers (containers-prepare-parameter.yaml
) contains the ContainerImagePrepare
Heat parameter. This parameter defines a list of strategies for preparing a set of images:
parameter_defaults: ContainerImagePrepare: - (strategy one) - (strategy two) - (strategy three) ...
Each strategy accepts a set of sub-parameters that define which images to use and what to do with them. The following table contains information about the sub-parameters you can use with each ContainerImagePrepare
strategy:
Parameter | Description |
---|---|
| List of image name substrings to exclude from a strategy. |
|
List of image name substrings to include in a strategy. At least one image name must match an existing image. All |
|
String to append to the tag for the destination image. For example, if you pull an image with the tag |
| A dictionary of image labels that filter the images to modify. If an image matches the labels defined, the director includes the image in the modification process. |
| String of ansible role names to run during upload but before pushing the image to the destination registry. |
|
Dictionary of variables to pass to |
|
The namespace of the registry to push images during the upload process. When you specify a namespace for this parameter, all image parameters use this namespace too. If set to |
| The source registry from where to pull the original container images. |
|
A dictionary of |
|
Defines the label pattern to tag the resulting images. Usually sets to |
The set
parameter accepts a set of key: value
definitions. The following table contains information about the keys:
Key | Description |
---|---|
| The name of the Ceph Storage container image. |
| The namespace of the Ceph Storage container image. |
| The tag of the Ceph Storage container image. |
| A prefix for each OpenStack service image. |
| A suffix for each OpenStack service image. |
| The namespace for each OpenStack service image. |
|
The driver to use to determine which OpenStack Networking (neutron) container to use. Use a null value to set to the standard |
|
The tag that the director uses to identify the images to pull from the source registry. You usually keep this key set to |
The ContainerImageRegistryCredentials
parameter maps a container registry to a username and password to authenticate to that registry.
If a container registry requires a username and password, you can use ContainerImageRegistryCredentials
to include their values with the following syntax:
ContainerImagePrepare: - push_destination: 192.168.24.1:8787 set: namespace: registry.redhat.io/... ... ContainerImageRegistryCredentials: registry.redhat.io: my_username: my_password
In the example, replace my_username
and my_password
with your authentication credentials. Instead of using your individual user credentials, Red Hat recommends creating a registry service account and using those credentials to access registry.redhat.io
content. For more information, see "Red Hat Container Registry Authentication".
The ContainerImageRegistryLogin
parameter is used to control the registry login on the systems being deployed. This must be set to true
if push_destination
is set to false or not used.
ContainerImagePrepare: - set: namespace: registry.redhat.io/... ... ContainerImageRegistryCredentials: registry.redhat.io: my_username: my_password ContainerImageRegistryLogin: true
2.3. Layering image preparation entries
The value of the ContainerImagePrepare
parameter is a YAML list. This means you can specify multiple entries. The following example demonstrates two entries where the director uses the latest version of all images except for the nova-api
image, which uses the version tagged with 15.0-44
:
ContainerImagePrepare: - tag_from_label: "{version}-{release}" push_destination: true excludes: - nova-api set: namespace: registry.redhat.io/rhosp15-rhel8 name_prefix: openstack- name_suffix: '' tag: latest - push_destination: true includes: - nova-api set: namespace: registry.redhat.io/rhosp15-rhel8 tag: 15.0-44
The includes
and excludes
entries control image filtering for each entry. The images that match the includes
strategy take precedence over excludes
matches. The image name must include the includes
or excludes
value to be considered a match.
2.4. Modifying images during preparation
It is possible to modify images during image preparation, then immediately deploy with modified images. Scenarios for modifying images include:
- As part of a continuous integration pipeline where images are modified with the changes being tested before deployment.
- As part of a development workflow where local changes need to be deployed for testing and development.
- When changes need to be deployed but are not available through an image build pipeline. For example, adding proprietry add-ons or emergency fixes.
To modify an image during preparation, invoke an Ansible role on each image that you want to modify. The role takes a source image, makes the requested changes, and tags the result. The prepare command can push the image to the destination registry and set the Heat parameters to refer to the modified image.
The Ansible role tripleo-modify-image
conforms with the required role interface, and provides the behaviour necessary for the modify use-cases. Modification is controlled using modify-specific keys in the ContainerImagePrepare
parameter:
-
modify_role
specifies the Ansible role to invoke for each image to modify. -
modify_append_tag
appends a string to the end of the source image tag. This makes it obvious that the resulting image has been modified. Use this parameter to skip modification if thepush_destination
registry already contains the modified image. It is recommended to changemodify_append_tag
whenever you modify the image. -
modify_vars
is a dictionary of Ansible variables to pass to the role.
To select a use-case that the tripleo-modify-image
role handles, set the tasks_from
variable to the required file in that role.
While developing and testing the ContainerImagePrepare
entries that modify images, it is recommended to run the image prepare command without any additional options to confirm the image is modified as expected:
sudo openstack tripleo container image prepare \ -e ~/containers-prepare-parameter.yaml
2.5. Updating existing packages on container images
The following example ContainerImagePrepare
entry updates in all packages on the images using the undercloud host’s dnf repository configuration:
ContainerImagePrepare: - push_destination: true ... modify_role: tripleo-modify-image modify_append_tag: "-updated" modify_vars: tasks_from: yum_update.yml compare_host_packages: true yum_repos_dir_path: /etc/yum.repos.d ...
2.6. Installing additional RPM files to container images
You can install a directory of RPM files in your container images. This is useful for installing hotfixes, local package builds, or any package not available through a package repository. For example, the following ContainerImagePrepare
entry installs some hotfix packages only on the nova-compute
image:
ContainerImagePrepare: - push_destination: true ... includes: - nova-compute modify_role: tripleo-modify-image modify_append_tag: "-hotfix" modify_vars: tasks_from: rpm_install.yml rpms_path: /home/stack/nova-hotfix-pkgs ...
2.7. Modifying container images with a custom Dockerfile
For maximum flexibility, you can specify a directory containing a Dockerfile to make the required changes. When you invoke the tripleo-modify-image
role, the role generates a Dockerfile.modified
file that changes the FROM
directive and adds extra LABEL
directives. The following example runs the custom Dockerfile on the nova-compute
image:
ContainerImagePrepare: - push_destination: true ... includes: - nova-compute modify_role: tripleo-modify-image modify_append_tag: "-hotfix" modify_vars: tasks_from: modify_image.yml modify_dir_path: /home/stack/nova-custom ...
An example /home/stack/nova-custom/Dockerfile
follows. After running any USER
root directives, you must switch back to the original image default user:
FROM registry.redhat.io/rhosp15-rhel8/openstack-nova-compute:latest USER "root" COPY customize.sh /tmp/ RUN /tmp/customize.sh USER "nova"
2.8. Preparing a Satellite server for container images
Red Hat Satellite 6 offers registry synchronization capabilities. This provides a method to pull multiple images into a Satellite server and manage them as part of an application life cycle. The Satellite also acts as a registry for other container-enabled systems to use. For more details information on managing container images, see "Managing Container Images" in the Red Hat Satellite 6 Content Management Guide.
The examples in this procedure use the hammer
command line tool for Red Hat Satellite 6 and an example organization called ACME
. Substitute this organization for your own Satellite 6 organization.
This procedure requires authentication credentials to access container images from registry.redhat.io
. Instead of using your individual user credentials, Red Hat recommends creating a registry service account and using those credentials to access registry.redhat.io
content. For more information, see "Red Hat Container Registry Authentication".
Procedure
Create a list of all container images:
$ sudo podman search --limit 1000 "registry.redhat.io/rhosp15-rhel8" | awk '{ print $2 }' | grep -v beta | sed "s/registry.redhat.io\///g" | tail -n+2 > satellite_images
-
Copy the
satellite_images_names
file to a system that contains the Satellite 6hammer
tool. Alternatively, use the instructions in the Hammer CLI Guide to install thehammer
tool to the undercloud. Run the following
hammer
command to create a new product (OSP15 Containers
) in your Satellite organization:$ hammer product create \ --organization "ACME" \ --name "OSP15 Containers"
This custom product will contain our images.
Add the base container image to the product:
$ hammer repository create \ --organization "ACME" \ --product "OSP15 Containers" \ --content-type docker \ --url https://registry.redhat.io \ --docker-upstream-name rhosp15-rhel8/openstack-base \ --upstream-username USERNAME \ --upstream-password PASSWORD \ --name base
Add the overcloud container images from the
satellite_images
file.$ while read IMAGE; do \ IMAGENAME=$(echo $IMAGE | cut -d"/" -f2 | sed "s/openstack-//g" | sed "s/:.*//g") ; \ hammer repository create \ --organization "ACME" \ --product "OSP15 Containers" \ --content-type docker \ --url https://registry.redhat.io \ --docker-upstream-name $IMAGE \ --upstream-username USERNAME \ --upstream-password PASSWORD \ --name $IMAGENAME ; done < satellite_images_names
Add the Ceph Storage 4 container image:
$ hammer repository create \ --organization "ACME" \ --product "OSP15 Containers" \ --content-type docker \ --url https://registry.redhat.io \ --docker-upstream-name rhceph-beta/rhceph-4-rhel8 \ --upstream-username USERNAME \ --upstream-password PASSWORD \ --name rhceph-4-rhel8
Synchronize the container images:
$ hammer product synchronize \ --organization "ACME" \ --name "OSP15 Containers"
Wait for the Satellite server to complete synchronization.
NoteDepending on your configuration,
hammer
might ask for your Satellite server username and password. You can configurehammer
to automatically login using a configuration file. For more information, see the "Authentication" section in the Hammer CLI Guide.-
If your Satellite 6 server uses content views, create a new content view version to incorporate the images and promote it along environments in your application life cycle. This largely depends on how you structure your application lifecycle. For example, if you have an environment called
production
in your lifecycle and you want the container images available in that environment, create a content view that includes the container images and promote that content view to theproduction
environment. For more information, see "Managing Container Images with Content Views". Check the available tags for the
base
image:$ hammer docker tag list --repository "base" \ --organization "ACME" \ --environment "production" \ --content-view "myosp15" \ --product "OSP15 Containers"
This command displays tags for the OpenStack Platform container images within a content view for an particular environment.
Return to the undercloud and generate a default environment file for preparing images using your Satellite server as a source. Run the following example command to generate the environment file:
(undercloud) $ openstack tripleo container image prepare default \ --output-env-file containers-prepare-parameter.yaml
-
--output-env-file
is an environment file name. The contents of this file will include the parameters for preparing your container images for the undercloud. In this case, the name of the file iscontainers-prepare-parameter.yaml
.
-
Edit the
containers-prepare-parameter.yaml
file and modify the following parameters:-
namespace
- The URL and port of the registry on the Satellite server. The default registry port on Red Hat Satellite is 5000. name_prefix
- The prefix is based on a Satellite 6 convention. This differs depending on whether you use content views:-
If you use content views, the structure is
[org]-[environment]-[content view]-[product]-
. For example:acme-production-myosp15-osp15_containers-
. -
If you do not use content views, the structure is
[org]-[product]-
. For example:acme-osp15_containers-
.
-
If you use content views, the structure is
-
ceph_namespace
,ceph_image
,ceph_tag
- If using Ceph Storage, include the additional parameters to define the Ceph Storage container image location. Note thatceph_image
now includes a Satellite-specific prefix. This prefix is the same value as thename_prefix
option.
-
The following example environment file contains Satellite-specific parameters:
parameter_defaults: ContainerImagePrepare: - push_destination: true set: ceph_image: acme-production-myosp15-osp15_containers-rhceph-4 ceph_namespace: satellite.example.com:5000 ceph_tag: latest name_prefix: acme-production-myosp15-osp15_containers- name_suffix: '' namespace: satellite.example.com:5000 neutron_driver: null tag: latest ... tag_from_label: '{version}-{release}'
Use this environment file when creating both your undercloud and overcloud.