Chapter 6. Service Catalog Components

When developing microservices-based applications to run on cloud native platforms, there are many ways to provision different resources and share their coordinates, credentials, and configuration, depending on the service provider and the platform.

To give developers a more seamless experience, OpenShift Container Platform includes a service catalog, an implementation of the Open Service Broker API (OSB API) for Kubernetes. This allows users to connect any of their applications deployed in OpenShift Container Platform to a wide variety of service brokers.

The service catalog allows cluster administrators to integrate multiple platforms using a single API specification. The OpenShift Container Platform web console displays the service classes offered by brokers in the service catalog, allowing users to discover and instantiate those services for use with their applications.

As a result, service users benefit from ease and consistency of use across different types of services from different providers, while service providers benefit from having one integration point that gives them access to multiple platforms.

The design of the service catalog follows this basic workflow:

This infrastructure allows a loose coupling between applications running in OpenShift Container Platform and the services they use. This allows the application that uses those services to focus on its own business logic while leaving the management of these services to the provider.

OpenShift Container Platform provides the following service brokers for use with the service catalog.

The Ansible service broker (ASB) is an implementation of the OSB API that manages applications defined by Ansible playbook bundles (APBs). APBs provide a new method for defining and distributing container applications in OpenShift Container Platform, consisting of a bundle of Ansible playbooks built into a container image with an Ansible runtime. APBs leverage Ansible to create a standard mechanism for automating complex deployments.

The design of the ASB follows this basic workflow:

An Ansible playbook bundle (APB) is a lightweight application definition that allows you to leverage existing investment in Ansible roles and playbooks.

APBs use a simple directory with named playbooks to perform OSB API actions, such as provision and bind. Metadata defined in apb.yml spec file contains a list of required and optional parameters for use during deployment.

example-apb/
├── Dockerfile
├── apb.yml
└── roles/
│   └── example-apb-openshift
│       ├── defaults
│       │   └── main.yml
│       └── tasks
│           └── main.yml
└── playbooks/
    └── provision.yml
    └── deprovision.yml
    └── bind.yml
    └── unbind.yml

name: fusor/etherpad-apb
description: Note taking web application
bindable: true
async: optional
parameters:
  - name: hostport
    description: The host TCP port as the external endpoint
    type: int
    default: 9001
  - name: db_user
    description: Database User
    type: string

parameters: []