Bug 1435577

From the RFE template
> 3. What is the nature and description of the request?
In the documentation it is specified the following:

~~~
io.openshift.non-scalable

An image might use this variable to suggest that it does not support scaling. The UI will then communicate this to consumers of that image. Being not-scalable basically means that the value of replicas should initially not be set higher than 1.
~~~

Given the complexity to limit the number of running instances for an image. It will be useful though to have a warning in the UI when the replication controller is asked to scale to a number bigger than 1 in a similar way as when trying to scale down to zero.

> 4. Why does the customer need this? (List the business requirements here)
The customer wants to limit the possibility of an incident while someone scale up by mistake to minimize the business impact.

> 5. How would the customer like to achieve this? (List the functional requirements here)
As an image developer I want to inform the image users that there is a limitation in having more than one running instance of this image.

As a web console user I would like to be notified whenever I click on the "up arrow" in order to scale up the application warning me about the existing limitation.

> 6. For each functional requirement listed, specify how Red Hat and the customer can test to confirm the requirement is successfully implemented.

Given a Docker image containing the following label in the Dockerfile
  LABEL io.openshift.non-scalable true

In the Web console the user will try to click the "up arrow" in order to scale up the application from 1 to any other number.
After the click a modal would appear informing the user about the existing limitation so that the user can ignore or continue at his/her own risk.

> 10. List any affected packages or components.
Openshift web console