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Difference between revisions of "Heat/Blueprints/ScalableResourceGroup"

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== Design ==
 
== Design ==
−
Define a new heat resource type: OS::HEAT::ScalableResourceGroup with the following properties:
+
(1) Define a new heat resource type: OS::HEAT::ScalableResourceGroup with the following properties:
 
     resource_def : Map
 
     resource_def : Map
−
    Resource definition for the resources in the group.  
+
    Resource definition for the resources in the group.  
−
    Required property.
+
    Required property.
−
    Can be updated without replacement.
+
    Can be updated without replacement.
  
 
     index_var : String
 
     index_var : String
−
    A variable that this resource will use to replace with the current index of a given resource in the group.  
+
    A variable that this resource will use to replace with the current index of a given resource in the group.  
−
    Updates cause replacement.
+
    Updates cause replacement.
−
    Optional property, defaults to “%index%”.
+
    Optional property, defaults to “%index%”.
  
 
     initial_size: Integer
 
     initial_size: Integer
−
    Initial number of resources in the group at creation time.
+
    Initial number of resources in the group at creation time.
−
    Optional property, defaults to 1.
+
    Optional property, defaults to 1.
−
    The value must be at least 0.
+
    The value must be at least 0.
  
 
     max_size: Integer
 
     max_size: Integer
−
    Maximum number of resources in the group.
+
    Maximum number of resources in the group.
−
    Optional Property, defaults to 1.
+
    Optional Property, defaults to 1.
−
    Updates can cause creation/deletion of some resources according to scale_in_criteria/scale_in_order.
+
    Updates can cause creation/deletion of some resources according to scale_in_criteria/scale_in_order.
−
    The value must be at least 0.
+
    The value must be at least 0.
  
 
     min_size: Integer
 
     min_size: Integer
−
    Minimum number of resources in the group.
+
    Minimum number of resources in the group.
−
    Optional property, defaults to 1.
+
    Optional property, defaults to 1.
−
    Updates can cause addition/removal of resources according to scale_in_criteria/scale_in_order.
+
    Updates can cause addition/removal of resources according to scale_in_criteria/scale_in_order.
−
    The value must be at least 0, less than or equal to max_size.
+
    The value must be at least 0, less than or equal to max_size.
  
 
   scale_in_criteria:String
 
   scale_in_criteria:String
−
  Removal criteria of resources in the group.
+
    Removal criteria of resources in the group.
−
  Optional property, defaults to "Index".
+
    Optional property, defaults to "Index".
−
  Possible Values: "Index" or "Age"
+
    Possible Values: "Index" or "Age"
−
  Default: "Index"
 
  
 
   scale_in_order:String
 
   scale_in_order:String
−
  Removal order of resources in the group according to the specified criteria.
+
    Removal order of resources in the group according to the specified criteria.
−
  Optional property, defaults to "Decreasing".  
+
    Optional property, defaults to "Decreasing".  
−
  Possible Values: "Increasing" or "Decreasing"
+
    Possible Values: "Increasing" or "Decreasing"
−
  Default: "Decreasing"
 
  
−
ScalableResourceGroup class inherits from ResourceGroup:
+
  scale_batch_size:Integer
−
     - Provide handle_signal implementation to receive signals to add/delete and grow/degrow signals.
+
    Number of resources to be added/removed simultaneously.
−
    - Override create/validate/update/delete handlers.
+
    Optional property, defaults to 1.
 +
    Possible Values: "Increasing" or "Decreasing"
 +
 
 +
  scale_batch_pause:Integer
 +
    Number of seconds between batches.
 +
    Optional property, defaults to 0.
 +
 
 +
(2) Introduce ScalableResourceGroup class inherits from ResourceGroup.
 +
    The new class adds a signal handler for signals with the following specification:
 +
     - signal handler for signals with the following structure:
 +
      command: String
 +
      Actions to perform on the group.
 +
      Possible Values: "ADD", "REMOVE", RECREATE, "SCALE_OUT", "SCALE_OUT"
 +
 
 +
      parameters: depends on the command
 +
      - ADD/REMOVE/RECREATE parameters:
 +
          resources: List of Integers
 +
          list of resource indices to add, remove or recreate
 +
   
 +
      - SCALE_OUT/SCALE_IN parameters:
 +
          scale_size: Integer
 +
          Size adjustment.
 +
          Value Must be positive.

Revision as of 16:06, 10 August 2015

< Heat Launchpad Entry: HeatSpec:ScalableResourceGroup
Created: 26 July 2015
Contributors: Ahmed El-Khouly

Summary

OS::Heat::ResourceGroup provides a way to create several instances of identically configured nested resource; resources within the group can be addressed with their resource index.
OS::Heat::ResourceGroup can only scale by changing the count property followed by a stack update of the root stack.
OS::Heat::AutoScalingGroup/Policy also provide a way to create several instances identically configured nested resources with the added ability of changing size(scale) when the accompanying AutoScalingPolicy receives a signal. Auto-scaling policy defines characteristics of the scale operation (size of adjustment, size of adjustment, cool down period).

Some cloud applications need a resource group type that can change size and with the added ability of removal or addition of specific resources.


Release Note

TBD

Rationale

Some cloud applications need a new resource group with the following features:
1) Create an initial number of identically configured nested resources.
2) Address single resource within the group using the index with the ability to specify a variable to be replaced by the index.
3) Add(Remove) specific resource within the group by specifying the indices of involved resources.
4) Scale out(in) by adjusting the group size (with a certain increment) when user defined triggers are met.

User Stories

1) Recreate a (failed) resource by adding/deleting the corresponding nested resource in the group.
2) Add new resources to group when certain criteria met(ex. increase in workload).
3) Remove a number of resources according to a predefined criteria(increasing or decreasing order of age or index).
4) Specify certain resources for removal.

Assumptions

None.

Design

(1) Define a new heat resource type: OS::HEAT::ScalableResourceGroup with the following properties: 

   resource_def : Map
    Resource definition for the resources in the group. 
    Required property.
    Can be updated without replacement.

   index_var : String
    A variable that this resource will use to replace with the current index of a given resource in the group. 
    Updates cause replacement.
    Optional property, defaults to “%index%”.

   initial_size: Integer
    Initial number of resources in the group at creation time.
    Optional property, defaults to 1.
    The value must be at least 0.

   max_size: Integer
    Maximum number of resources in the group.
    Optional Property, defaults to 1.
    Updates can cause creation/deletion of some resources according to scale_in_criteria/scale_in_order.
    The value must be at least 0.

   min_size: Integer
    Minimum number of resources in the group.
    Optional property, defaults to 1.
    Updates can cause addition/removal of resources according to scale_in_criteria/scale_in_order.
    The value must be at least 0, less than or equal to max_size.

  scale_in_criteria:String
   Removal criteria of resources in the group.
   Optional property, defaults to "Index".
   Possible Values: "Index" or "Age"

  scale_in_order:String
   Removal order of resources in the group according to the specified criteria.
   Optional property, defaults to "Decreasing". 
   Possible Values: "Increasing" or "Decreasing"

  scale_batch_size:Integer
   Number of resources to be added/removed simultaneously.
   Optional property, defaults to 1. 
   Possible Values: "Increasing" or "Decreasing"

  scale_batch_pause:Integer
   Number of seconds between batches.
   Optional property, defaults to 0.

(2) Introduce ScalableResourceGroup class inherits from ResourceGroup. 

    The new class adds a signal handler for signals with the following specification:
   - signal handler for signals with the following structure:
     command: String
      Actions to perform on the group.
      Possible Values: "ADD", "REMOVE", RECREATE, "SCALE_OUT", "SCALE_OUT" 

     parameters: depends on the command
      - ADD/REMOVE/RECREATE parameters:
         resources: List of Integers
          list of resource indices to add, remove or recreate
    
      - SCALE_OUT/SCALE_IN parameters:
         scale_size: Integer
          Size adjustment. 
          Value Must be positive.
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