[id="understanding-odo"]
= Understanding OpenShift Do
include::modules/openshift-developer-cli-attributes.adoc[]
include::modules/common-attributes.adoc[]
:context: understanding-odo
toc::[]

{odo-title-full} ({odo-title}) is a fast and easy-to-use CLI tool for creating applications on {product-title}. {odo-title} allows developers to concentrate on creating applications without the need to administrate an {product-title} cluster itself.
Creating deployment configurations, build configurations, service routes and other {product-title} elements are all automated by {odo-title}.

Existing tools such as `oc` are more operations-focused and require a deep understanding of Kubernetes and {product-title} concepts. {odo-title} abstracts away complex Kubernetes and {product-title} concepts allowing developers to focus on what is most important to them: code.

[id="odo-key-features"]
== Key features

{odo-title} is designed to be simple and concise with the following key features:

* Simple syntax and design centered around concepts familiar to developers, such as projects, applications, and components.
* Completely client based. No server is required within the {product-title} cluster for deployment.
* Official support for Node.js and Java components.
* Partial compatibility with languages and frameworks such as Ruby, Perl, PHP, and Python.
* Detects changes to local code and deploys it to the cluster automatically, giving instant feedback to validate changes in real time.
* Lists all the available components and services from the {product-title} cluster.

== Core concepts

Project::
A project is your source code, tests, and libraries organized in a separate single unit.
Application::
An application is a program designed for end users. An application consists of multiple microservices or components that work individually to build the entire application.
Examples of applications: a video game, a media player, a web browser.
Component::
A component is a building block of an application. Typically it is a software package, a web service, a web resource, or a module that encapsulates a set of related functions or data.
Examples of components: Node.js, Pearl, PHP, Python, Ruby.
Service::
A service is software that your component links to or depends on.
Examples of services: MariaDB, Jenkins, MySQL.
In {odo-title}, services are provisioned from the OpenShift Service Catalog and must be enabled within your cluster.

[id="odo-supported-languages-and-images"]
=== Officially supported languages and corresponding container images

.Supported container images
[options="header"]
|====
|Node.js|Java
|`centos/nodejs-8-centos7`|`redhat-openjdk-18/openjdk18-openshift`
|`rhoar-nodejs/nodejs-8`|`openjdk/openjdk-11-rhel8`
|`rhoar-nodejs/nodejs-10`|`openjdk/openjdk-11-rhel7`
|`bucharestgold/centos7-s2i-nodejs`|
|`rhscl/nodejs-8-rhel7`|
|`rhscl/nodejs-10-rhel7`|
|====

[id="odo-listing-available-images"]
==== Listing available container images

[NOTE]
====
The list of available container images is sourced from the cluster's internal container registry and external registries associated with the cluster.
====

To list the available components and associated container images for your cluster:

. Log in to the {product-title} cluster with {odo-title}:
+
----
$ odo login -u developer -p developer
----

. List the available {odo-title} supported and unsupported components and corresponding container images:
+
----------------------------------------------------
$ odo catalog list components
Odo Supported OpenShift Components:
NAME        PROJECT      TAGS
java       openshift     8,latest
nodejs     openshift     10,8,8-RHOAR,latest

Odo Unsupported OpenShift Components:
NAME                      PROJECT       TAGS
dotnet                    openshift     1.0,1.1,2.1,2.2,latest
fuse7-eap-openshift       openshift     1.3
----------------------------------------------------
+
The `TAGS` column represents the available image versions, for example, `10` represents the `rhoar-nodejs/nodejs-10` container image.