Bug 1311456

The field name that defaults limits is called "default" and not "defaultLimit" for historical reasons because it actually pre-dates the presence of request and limit in the API.

As a result, the converter was just dropping fields it did not understand.

$ cat limitrange-1.yaml
apiVersion: v1
kind: LimitRange
metadata:
  name: limitrange-1
spec:
  limits:
  - max:
      cpu: 500m
      memory: 750Mi
    min:
      cpu: 10m
      memory: 5Mi
    default:
      cpu: 200m
      memory: 400Mi
    maxLimitRequestRatio:
      cpu: 2
      memory: 5
    type: Pod
  - default:
      cpu: 130m
      memory: 120Mi
    defaultRequest:
      cpu: 110m
      memory: 100Mi
    maxLimitRequestRatio:
      cpu: 10
      memory: 8
    max:
      cpu: 400m
      memory: 750Mi
    min:
      cpu: 10m
      memory: 5Mi
    type: Container
$ cluster/kubectl.sh create -f limitrange-1.yaml 
The LimitRange "limitrange-1" is invalid.
spec.limits[0].default: Forbidden: may not be specified when `type` is 'Pod'

If you drop the field from limitType=pod, you get the following:

$ cat limitrange-1.yaml
apiVersion: v1
kind: LimitRange
metadata:
  name: limitrange-1
spec:
  limits:
  - max:
      cpu: 500m
      memory: 750Mi
    min:
      cpu: 10m
      memory: 5Mi
    maxLimitRequestRatio:
      cpu: 2
      memory: 5
    type: Pod
  - default:
      cpu: 130m
      memory: 120Mi
    defaultRequest:
      cpu: 110m
      memory: 100Mi
    maxLimitRequestRatio:
      cpu: 10
      memory: 8
    max:
      cpu: 400m
      memory: 750Mi
    min:
      cpu: 10m
      memory: 5Mi
    type: Container
$ cluster/kubectl.sh create -f limitrange-1.yaml 
limitrange "limitrange-1" created
$ cluster/kubectl.sh describe limits/limitrange-1
Name:		limitrange-1
Namespace:	default
Type		Resource	Min	Max	Default Request	Default Limit	Max Limit/Request Ratio
----		--------	---	---	---------------	-------------	-----------------------
Pod		cpu		10m	500m	-		-		2
Pod		memory		5Mi	750Mi	-		-		5
Container	cpu		10m	400m	110m		130m		10
Container	memory		5Mi	750Mi	100Mi		120Mi		8

Thanks for your detailed explanation.  
If limitType=Container and set DefaultLimit, the value of course is ignored, but the new value is the same with value of Max. Why does it get from Max(Default request and limit are all from Max if didn't set them, probably it's by design)? Should it has a clear message indicates that DefaultLimit is incorrect?

# cat limitrange-2.yaml 
apiVersion: v1
kind: LimitRange
metadata:
  name: limitrange-2
spec:
  limits:
  - defaultLimit:
      cpu: 130m
      memory: 120Mi
    defaultRequest:
      cpu: 110m
      memory: 100Mi
    maxLimitRequestRatio:
      cpu: 10
      memory: 8
    max:
      cpu: 400m
      memory: 750Mi
    min:
      cpu: 10m
      memory: 5Mi
    type: Container


# oc describe limits limitrange-2
Name:		limitrange-2
Namespace:	qwang3
Type		Resource	Min	Max	Default Request	Default Limit	Max Limit/Request Ratio
----		--------	---	---	---------------	-------------	-----------------------
Container	memory		5Mi	750Mi	100Mi		750Mi		8
Container	cpu		10m	400m	110m		400m		10


# oc get limits limitrange-2 -o yaml
apiVersion: v1
kind: LimitRange
metadata:
  creationTimestamp: 2016-02-25T03:14:00Z
  name: limitrange-2
  namespace: qwang3
  resourceVersion: "62696"
  selfLink: /api/v1/namespaces/qwang3/limitranges/limitrange-2
  uid: d0ef10f3-db6d-11e5-80ba-fa163e76dd6a
spec:
  limits:
  - default:
      cpu: 400m
      memory: 750Mi
    defaultRequest:
      cpu: 110m
      memory: 100Mi
    max:
      cpu: 400m
      memory: 750Mi
    maxLimitRequestRatio:
      cpu: "10"
      memory: "8"
    min:
      cpu: 10m
      memory: 5Mi
    type: Container

This is working as designed:

see https://github.com/kubernetes/kubernetes/blob/master/docs/design/admission_control_limit_range.md#default-value-behavior

Let me explain the rationale behind the current behavior.

If you specify a MAX[memory] for a container of 500Mi, then every container must make an explicit resources.limit[memory] <= 500Mi.  To make that convenient for users, we will default the default LIMIT[memory] for a container to match the MAX if not specified.