Overview

Your OpenShift installation includes useful sets of Red Hat-provided image streams and templates to make it easy for developers to create new applications. By default, the quick and advanced installation methods automatically create these sets in the openshift project, which is a default global project to which all users have view access.

Before you consider using this topic, confirm if these image streams and templates are already registered in your OpenShift cluster by doing one of the following:

  • Log into the web console and click Add to Project.

  • List them for the openshift project using the CLI:

    $ oc get is -n openshift
    $ oc get templates -n openshift

If the default image streams and templates are ever removed or changed, you can follow this topic to create the default objects yourself. Otherwise, the following instructions are not necessary.

The core set of image streams and templates are provided and supported by Red Hat with an active OpenShift Enterprise subscription for the following technologies:

Languages
Database
Other Services

If you also have the relevant xPaaS Middleware subscription active on your account, image streams and templates are also provided and supported by Red Hat for each of following middleware services:

Prerequisites

Before you can create the default image streams and templates:

  • The integrated Docker registry service must be deployed in your OpenShift installation.

  • You must be able to run the oc create command with cluster-admin privileges, because they operate on the default openshift project.

  • You must have installed the atomic-openshift-utils RPM package. See Software Prerequisites for instructions.

  • Define shell variables for the directories containing image streams and templates. This significantly shortens the commands in the following sections. To do this:

    $ IMAGESTREAMDIR="/usr/share/ansible/openshift-ansible/roles/openshift_examples/files/examples/v1.1/image-streams"; \
        XPAASSTREAMDIR="/usr/share/ansible/openshift-ansible/roles/openshift_examples/files/examples/v1.1/xpaas-streams"; \
        XPAASTEMPLATES="/usr/share/ansible/openshift-ansible/roles/openshift_examples/files/examples/v1.1/xpaas-templates"; \
        DBTEMPLATES="/usr/share/ansible/openshift-ansible/roles/openshift_examples/files/examples/v1.1/db-templates"; \
        QSTEMPLATES="/usr/share/ansible/openshift-ansible/roles/openshift_examples/files/examples/v1.1/quickstart-templates"

Creating Image Streams for OpenShift Images

The core set of image streams provide images that can be used to build Node.js, Perl, PHP, Python, and Ruby applications. It also defines images for MongoDB, MySQL, and PostgreSQL to support data storage.

If your node hosts are subscribed using Red Hat Subscription Manager and you want to use the Red Hat Enterprise Linux (RHEL) 7 based images:

$ oc create -f $IMAGESTREAMDIR/image-streams-rhel7.json -n openshift

Alternatively, to create the core set of image streams that use the CentOS 7 based images:

$ oc create -f $IMAGESTREAMDIR/image-streams-centos7.json -n openshift

It is not possible to create both the CentOS and RHEL sets of image streams because they use the same names. If you desire to have both sets of image streams available to users, either create one set in a different project, or edit one of the files and modify the image stream names to make them unique.

Creating Image Streams for xPaaS Middleware Images

The xPaaS Middleware image streams provide images for JBoss EAP, JBoss JWS, JBoss A-MQ, JBoss Fuse Integration Services, Decision Server, and JBoss Data Grid. They can be used to build applications for those platforms using the provided templates.

To create the xPaaS Middleware set of image streams:

$ oc create -f $XPAASSTREAMDIR/jboss-image-streams.json -n openshift

Access to the images referenced by these image streams requires the relevant xPaaS Middleware subscriptions.

Creating Database Service Templates

The database service templates make it easy to run a database image which can be utilized by other components. For each database (MongoDB, MySQL, and PostgreSQL), two templates are defined.

One template uses ephemeral storage in the container which means data stored will be lost if the container is restarted, for example if the pod moves. This template should be used for demonstration purposes only.

The other template defines a persistent volume for storage, however it requires your OpenShift installation to have persistent volumes configured.

To create the core set of database templates:

$ oc create -f $DBTEMPLATES -n openshift

After creating the templates, users are able to easily instantiate the various templates, giving them quick access to a database deployment.

Creating Instant App and Quickstart Templates

The Instant App and Quickstart templates define a full set of objects for a running application. These include:

Some of the templates also define a database deployment and service so the application can perform database operations.

The templates which define a database use ephemeral storage for the database content. These templates should be used for demonstration purposes only as all database data will be lost if the database pod restarts for any reason.

After creating the templates, users are able to easily instantiate full applications using the various language images provided with OpenShift. They can also customize the template parameters during instantiation so that it builds source from their own repository rather than the sample repository, so this provides a simple starting point for building new applications.

To create the core Instant App and Quickstart templates:

$ oc create -f $QSTEMPLATES -n openshift

There is also a set of templates for creating applications using various xPaaS Middleware products (JBoss EAP, JBoss JWS, JBoss A-MQ, JBoss Fuse Integration Services, Decision Server, and JBoss Data Grid), which can be registered by running:

$ oc create -f $XPAASTEMPLATES -n openshift

The xPaaS Middleware templates require the xPaaS Middleware image streams, which in turn require the relevant xPaaS Middleware subscriptions.

The templates which define a database use ephemeral storage for the database content. These templates should be used for demonstration purposes only as all database data will be lost if the database pod restarts for any reason.

What’s Next?

With these artifacts created, developers can now log into the web console and follow the flow for creating from a template. Any of the database or application templates can be selected to create a running database service or application in the current project. Note that some of the application templates define their own database services as well.

The example applications are all built out of GitHub repositories which are referenced in the templates by default, as seen in the SOURCE_REPOSITORY_URL parameter value. Those repositories can be forked, and the fork can be provided as the SOURCE_REPOSITORY_URL parameter value when creating from the templates. This allows developers to experiment with creating their own applications.

You can direct your developers to the Using the Instant App and Quickstart Templates section in the Developer Guide for these instructions.