Feature Request Overview (mandatory - Complete while in New status){_}
{}What user goal or problem do you need to solve?{_} 
In RHOSP17.1, puppet-horizon provides an interface to customize WSGIDaemonProcess.
The default, `WSGIDaemonProcess apache display-name=horizon group=apache processes=4 threads=1 user=apache`, is really small for production.
For example, if the horizon uses legacy upload mode for glance, horizon call glanceclient to upload the image to glance. It is likely to consume all 4 processes when simultaneous image uploads happens. Then, liveness probe will kill the pods then then image upload will fail.

To prevent the such situation, a user needs to tune the number of process and number of pods.

In RHOSO18, the modification flexibility is reduced and to overcome the real production issue, we should implement this feature to tune the configuration.

Business justification (mandatory - Complete while in New status)
How would this feature benefit the customer?
By this feature, our customers can get the flexibility to tune Horizon pod and prevent the unexpected kill of horizon pod.

Functional requirements (mandatory - Complete while in New status){_}
{}What do you want the result of this feature to be? Add as many requirements as needed.{_}

•  Add an interface to tune items in WSGIDaemonProcess
•  Modify template to accept the tuned values.

Describe the customer impact
Without this RFE, horizon pods is easily to be killed by livevness probe when simultaneous large image upload happens.

(Optional) Point of contact

• Provide any additional points of contact for this feature request, such as an account executive, SA, or TAM: 
•  TAM

(Optional) Additional links
Original discussion was done at https://issues.redhat.com/browse/OSPRH-18633

Feature Overview (mandatory - Complete while in New status)
An elevator pitch (value statement) that describes the Feature in a clear, concise way. ie: Executive Summary of the user goal or problem that is being solved, why does this matter to the user? The “What & Why”... 
<your text here>

Goals (mandatory - Complete while in New status)
Provide high-level goal statement, providing user context and expected user outcome(s) for this Feature

• Who benefits from this Feature, and how? 
• What is the difference between today’s current state and a world with this Feature?
  <your text here>

Requirements (mandatory -_ Complete while in Refinement status):
A list of specific needs, capabilities, or objectives that a Feature must deliver to satisfy the Feature. Some requirements will be flagged as MVP. If an MVP gets shifted, the Feature shifts. If a non MVP requirement slips, it does not shift the feature.

 
Done - Acceptance Criteria (mandatory - Complete while in Refinement status):
Acceptance Criteria articulates and defines the value proposition - what is required to meet the goal and intent of this Feature. The Acceptance Criteria provides a detailed definition of scope and the expected outcomes - from a users point of view
…
<your text here>
Use Cases - i.e. User Experience & Workflow: (Initial completion while in Refinement status):
Include use case diagrams, main success scenarios, alternative flow scenarios.
<your text here>
Out of Scope _ _(Initial completion while in Refinement status):
High-level list of items or persona’s that are out of scope.
<your text here>
Documentation Considerations _ _(Initial completion while in Refinement status):
Provide information that needs to be considered and planned so that documentation will meet customer needs. If the feature extends existing functionality, provide a link to its current documentation..
<your text here>
 
Questions to Answer _ _(Initial completion while in Refinement status):
Include a list of refinement / architectural questions that may need to be answered before coding can begin.
<your text here>
Background and Strategic Fit (Initial completion while in Refinement status):
Provide any additional context is needed to frame the feature.
<your text here>
Customer Considerations _ _(Initial completion while in Refinement status):
Provide any additional customer-specific considerations that must be made when designing and delivering the Feature.
<your text here>
Team Sign Off (Completion while in Planning status)

• All required Epics (known at the time) are linked to the this Feature
• All required Stories, Tasks (known at the time) for the most immediate Epics have been created and estimated
• Add - Reviewers name, Team Name
• Acceptance == Feature as “Ready” - well understood and scope is clear - Acceptance Criteria (scope) is elaborated, well defined, and understood
• Note: Only set FixVersion/s: on a Feature if the delivery team agrees they have the capacity and have committed that capability for that milestone

  Reviewed By	Team Name	Accepted	Notes