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Chapter 2. Planning a deployment of AMQ Broker on OpenShift Container Platform
2.1. Comparison of deployment methods
There are two ways to deploy AMQ Broker on OpenShift Container Platform:
- Using the AMQ Broker Operator (recommended)
- Using application templates
This section describes each of these deployment methods.
- Deployment using the AMQ Broker Operator (recommended)
Operators are programs that enable you to package, deploy, and manage OpenShift applications. Often, Operators automate common or complex tasks. Commonly, Operators are intended to provide:
- Consistent, repeatable installations
- Health checks of system components
- Over-the-air (OTA) updates
- Managed upgrades
The AMQ Broker Operator is the recommended way to create broker deployments on OpenShift Container Platform. Operators enable you to make changes while your broker instances are running, because they are always listening for changes to the Custom Resource (CR) instances that you used to configure your deployment. When you make changes to a CR, the Operator reconciles the changes with the existing broker deployment and updates the deployment to reflect the changes. In addition, the Operator provides a message migration capability, which ensures the integrity of messaging data. When a broker in a clustered deployment shuts down due to failure or intentional scaledown of the deployment, this capability migrates messages to a broker Pod that is still running in the same broker cluster.
- Deployment using application templates
- Important
Starting in 7.8, the use of application templates for deploying AMQ Broker on OpenShift Container Platform is a deprecated feature. This feature will be removed in a future release. Red Hat continues to support existing deployments that are based on application templates. However, Red Hat does not recommend using application templates for new deployments. For new deployments, Red Hat recommends using the AMQ Broker Operator.
A template is a way to describe objects that can be parameterized and processed for creation by OpenShift Container Platform. You can use a template to describe anything that you have permission to create within an OpenShift project, for example, Services or build configurations. AMQ Broker has some sample application templates that enable you to create various types of broker deployments as DeploymentConfig- or StatefulSet-based applications. You configure your broker deployments by specifying values for the environment variables included in the application templates. A limitation of templates is that while they are effective for creating an initial broker deployment, they do not provide a mechanism for updating the deployment. In addition, because AMQ Broker does not provide a message migration capability for template-based deployments, templates are not recommended for use in a production environment.
Additional resources
- To learn how to use the AMQ Broker Operator to create a broker deployment, see Chapter 3, Deploying AMQ Broker on OpenShift Container Platform using the AMQ Broker Operator.
- For more information about message migration using the Operator, see Section 4.8, “High availability and message migration”.
2.2. Overview of the AMQ Broker Operator Custom Resource Definitions
In general, a Custom Resource Definition (CRD) is a schema of configuration items that you can modify for a custom OpenShift object deployed with an Operator. By creating a corresponding Custom Resource (CR) instance, you can specify values for configuration items in the CRD. If you are an Operator developer, what you expose through a CRD essentially becomes the API for how a deployed object is configured and used. You can directly access the CRD through regular HTTP curl commands, because the CRD gets exposed automatically through Kubernetes.
You can install the AMQ Broker Operator using either the OpenShift command-line interface (CLI), or the Operator Lifecycle Manager, through the OperatorHub graphical interface. In either case, the AMQ Broker Operator includes the CRDs described below.
- Main broker CRD
You deploy a CR instance based on this CRD to create and configure a broker deployment.
Based on how you install the Operator, this CRD is:
-
The
broker_activemqartemis_crdfile in thecrdsdirectory of the Operator installation archive (OpenShift CLI installation method) -
The
ActiveMQArtemisCRD in theCustom Resource Definitionssection of the OpenShift Container Platform web console (OperatorHub installation method)
-
The
- Address CRD
You deploy a CR instance based on this CRD to create addresses and queues for a broker deployment.
Based on how you install the Operator, this CRD is:
-
The
broker_activemqartemisaddress_crdfile in thecrdsdirectory of the Operator installation archive (OpenShift CLI installation method) -
The
ActiveMQArtemisAddresssCRD in theCustom Resource Definitionssection of the OpenShift Container Platform web console (OperatorHub installation method)
-
The
- Scaledown CRD
The Operator automatically creates a CR instance based on this CRD when instantiating a scaledown controller for message migration.
Based on how you install the Operator, this CRD is:
-
The
broker_activemqartemisscaledown_crdfile in thecrdsdirectory of the Operator installation archive (OpenShift CLI installation method) -
The
ActiveMQArtemisScaledownCRD in theCustom Resource Definitionssection of the OpenShift Container Platform web console (OperatorHub installation method).
-
The
Additional resources
To learn how to install the AMQ Broker Operator (and all included CRDs) using:
- The OpenShift CLI, see Section 3.2, “Installing the Operator using the CLI”
- The Operator Lifecycle Manager and OperatorHub graphical interface, see Section 3.3, “Installing the Operator using OperatorHub”.
For complete configuration references to use when creating CR instances based on the main broker and address CRDs, see:
2.3. Overview of the AMQ Broker Operator sample Custom Resources
The AMQ Broker Operator archive that you download and extract during installation includes sample Custom Resource (CR) files in the deploy/crs directory. These sample CR files enable you to:
- Deploy a minimal broker without SSL or clustering.
- Define addresses.
The broker Operator archive that you download and extract also includes CRs for example deployments in the deploy/examples directory, as listed below.
artemis-basic-deployment.yaml- Basic broker deployment.
artemis-persistence-deployment.yaml- Broker deployment with persistent storage.
artemis-cluster-deployment.yaml- Deployment of clustered brokers.
artemis-persistence-cluster-deployment.yaml- Deployment of clustered brokers with persistent storage.
artemis-ssl-deployment.yaml- Broker deployment with SSL security.
artemis-ssl-persistence-deployment.yaml- Broker deployment with SSL security and persistent storage.
artemis-aio-journal.yaml- Use of asynchronous I/O (AIO) with the broker journal.
address-queue-create.yaml- Address and queue creation.
2.4. How the Operator chooses container images
When you create a Custom Resource (CR) instance for a broker deployment based on at least version 7.8.5-opr-2 of the Operator, you do not need to explicitly specify broker or Init Container image names in the CR. By default, if you deploy a CR and do not explicitly specify container image values, the Operator automatically chooses the appropriate container images to use.
If you install the Operator using the OpenShift command-line interface, the Operator installation archive includes a sample CR file called broker_activemqartemis_cr.yaml. In the sample CR, the spec.deploymentPlan.image property is included and set to its default value of placeholder. This value indicates that the Operator does not choose a broker container image until you deploy the CR.
The spec.deploymentPlan.initImage property, which specifies the Init Container image, is not included in the broker_activemqartemis_cr.yaml sample CR file. If you do not explicitly include the spec.deploymentPlan.initImage property in your CR and specify a value, the Operator chooses an appropriate built-in Init Container image to use when you deploy the CR.
How the Operator chooses these images is described in this section.
To choose broker and Init Container images, the Operator first determines an AMQ Broker version to which the images should correspond. The Operator determines the version as follows:
-
If the
spec.upgrades.enabledproperty in the main CR is already set totrueand thespec.versionproperty specifies7.7.0,7.8.0,7.8.1, or7.8.2, the Operator uses that specified version. -
If
spec.upgrades.enabledis not set totrue, orspec.versionis set to an AMQ Broker version earlier than7.7.0, the Operator uses the latest version of AMQ Broker (that is,7.8.5).
Note: For IBM Z and IBM Power Systems, 7.8.1 and 7.8.2 are the only valid value for spec.version.
The Operator then detects your container platform. The AMQ Broker Operator can run on the following container platforms:
- OpenShift Container Platform (x86_64)
- OpenShift Container Platform on IBM Z (s390x)
- OpenShift Container Platform on IBM Power Systems (ppc64le)
Based on the version of AMQ Broker and your container platform, the Operator then references two sets of environment variables in the operator.yaml configuration file. These sets of environment variables specify broker and Init Container images for various versions of AMQ Broker, as described in the following sub-sections.
2.4.1. Environment variables for broker container images
The environment variables included in the operator.yaml configuration file for broker container images have the following naming convention:
- OpenShift Container Platform
-
RELATED_IMAGE_ActiveMQ_Artemis_Broker_Kubernetes_<AMQ_Broker_version_identifier> - OpenShift Container Platform on IBM Z
-
RELATED_IMAGE_ActiveMQ_Artemis_Broker_Kubernetes_<AMQ_Broker_version_identifier>_s390x - OpenShift Container Platform on IBM Power Systems
-
RELATED_IMAGE_ActiveMQ_Artemis_Broker_Kubernetes_<AMQ_Broker_version_identifier>_ppc64le
Environment variable names for each supported container platform and specific AMQ Broker versions are shown in the table.
| Container platform | Environment variable names |
|---|---|
| OpenShift Container Platform |
|
| OpenShift Container Platform on IBM Z |
|
| OpenShift Container Platform on IBM Power Systems |
|
The value of each environment variable specifies a broker container image that is available from Red Hat. For example:
- name: RELATED_IMAGE_ActiveMQ_Artemis_Broker_Kubernetes_787 #value: registry.redhat.io/amq7/amq-broker:7.8-33 value: registry.redhat.io/amq7/amq-broker@sha256:4d60775cd384067147ab105f41855b5a7af855c4d9cbef1d4dea566cbe214558
Therefore, based on an AMQ Broker version and your container platform, the Operator determines the applicable environment variable name. The Operator uses the corresponding image value when starting the broker container.
In the operator.yaml file, the Operator uses an image that is represented by a Secure Hash Algorithm (SHA) value. The comment line, which begins with a number sign (#) symbol, denotes that the SHA value corresponds to a specific container image tag.
2.4.2. Environment variables for Init Container images
The environment variables included in the operator.yaml configuration file for Init Container images have the following naming convention:
- OpenShift Container Platform
-
RELATED_IMAGE_ActiveMQ_Artemis_Broker_Init_<AMQ_Broker_version_identifier> - OpenShift Container Platform on IBM Z
-
RELATED_IMAGE_ActiveMQ_Artemis_Broker_Init_s390x_<AMQ_Broker_version_identifier> - OpenShift Container Platform on IBM Power Systems
-
RELATED_IMAGE_ActiveMQ_Artemis_Broker_Init_ppc64le_<AMQ_Broker_version_identifier>
Environment variable names for each supported container platform and specific AMQ Broker versions are shown in the table.
| Container platform | Environment variable names |
|---|---|
| OpenShift Container Platform |
|
| OpenShift Container Platform on IBM Z |
|
| OpenShift Container Platform on IBM Power Systems |
|
The value of each environment variable specifies an Init Container image that is available from Red Hat. For example:
- name: RELATED_IMAGE_ActiveMQ_Artemis_Broker_Init_787 #value: registry.redhat.io/amq7/amq-broker-init-rhel7:7.8-1 value: registry.redhat.io/amq7/amq-broker-init-rhel7@sha256:f7482d07ecaa78d34c37981447536e6f73d4013ec0c64ff787161a75e4ca3567
Therefore, based on an AMQ Broker version and your container platform, the Operator determines the applicable environment variable name. The Operator uses the corresponding image value when starting the Init Container.
As shown in the example, the Operator uses an image that is represented by a Secure Hash Algorithm (SHA) value. The comment line, which begins with a number sign (#) symbol, denotes that the SHA value corresponds to a specific container image tag. Observe that the corresponding container image tag is not a floating tag in the form of 0.2. This means that the container image used by the Operator remains fixed. The Operator does not automatically pull and use a new micro image version (that is, 0.2-n, where n is the latest micro version) when it becomes available from Red Hat.
Additional resources
- To learn how to use the AMQ Broker Operator to create a broker deployment, see Chapter 3, Deploying AMQ Broker on OpenShift Container Platform using the AMQ Broker Operator.
- For more information about how the Operator uses an Init Container to generate the broker configuration, see Section 4.1, “How the Operator generates the broker configuration”.
- To learn how to build and specify a custom Init Container image, see Section 4.5, “Specifying a custom Init Container image”.
2.5. Operator deployment notes
This section describes some important considerations when planning an Operator-based deployment
- Deploying the Custom Resource Definitions (CRDs) that accompany the AMQ Broker Operator requires cluster administrator privileges for your OpenShift cluster. When the Operator is deployed, non-administrator users can create broker instances via corresponding Custom Resources (CRs). To enable regular users to deploy CRs, the cluster administrator must first assign roles and permissions to the CRDs. For more information, see Creating cluster roles for Custom Resource Definitions in the OpenShift Container Platform documentation.
- When you update your cluster with the CRDs for the latest Operator version, this update affects all projects in the cluster. Any broker Pods deployed from previous versions of the Operator might become unable to update their status. When you click the Logs tab of a running broker Pod in the OpenShift Container Platform web console, you see messages indicating that 'UpdatePodStatus' has failed. However, the broker Pods and Operator in that project continue to work as expected. To fix this issue for an affected project, you must also upgrade that project to use the latest version of the Operator.
- You cannot create more than one broker deployment in a given OpenShift project by deploying multiple broker Custom Resource (CR) instances. However, when you have created a broker deployment in a project, you can deploy multiple CR instances for addresses.
If you intend to deploy brokers with persistent storage and do not have container-native storage in your OpenShift cluster, you need to manually provision Persistent Volumes (PVs) and ensure that these are available to be claimed by the Operator. For example, if you want to create a cluster of two brokers with persistent storage (that is, by setting
persistenceEnabled=truein your CR), you need to have two persistent volumes available. By default, each broker instance requires storage of 2 GiB.If you specify
persistenceEnabled=falsein your CR, the deployed brokers uses ephemeral storage. Ephemeral storage means that that every time you restart the broker Pods, any existing data is lost.For more information about provisioning persistent storage in OpenShift Container Platform, see:
- Understanding persistent storage (OpenShift Container Platform 4.5)
- Persistent Storage (OpenShift Container Platform 3.11).
You must add configuration for the items listed below to the main broker CR instance before deploying the CR for the first time. You cannot add configuration for these items to a broker deployment that is already running.
The procedures in the next section show you how to install the Operator and use Custom Resources (CRs) to create broker deployments on OpenShift Container Platform. When you have successfully completed the procedures, you will have the Operator running in an individual Pod. Each broker instance that you create will run as an individual Pod in a StatefulSet in the same project as the Operator. Later, you will you will see how to use a dedicated addressing CR to define addresses in your broker deployment.
