update with pr comments

Author: pwittrock

keps/sig-cli/kustomize-ordering.md

@@ -54,59 +54,109 @@ sorting by Resource Type is insufficient.
 
 ### Goals
 
-- Provide the ability for users to break glass and override Kustomize's sort ordering.
+- Provide the ability for users to override the order that Kustomize emits Resources
+  - Used by `kubectl apply` or order Resource operations
+  - Used to override creation order for meta-Resources such as Namespaces
 
 ### Non-Goals
 
-## Proposal
+- Ensure certain Resources are *Settled* or *Ready* before other Resources
+  - Ensure dependencies between Workloads
 
-Add a new field `resourceOrdering` that is a list of `key, value, type` tuples to define the ordering.
+## Proposal
 
+Provide a simple mechanism allowing users to override the order that
+Resource operations are Applied.  Add a new field `sortOrder` that is
+a list of `ResourceSelector`s which match Resources based
+off their annotations.
+
+```go
+
+type Kustomization struct {
+	// ...
+	
+	// sortOrder defines a precedence for ordering Resources.  Resources
+	// will be sorted in the order the match a ResourecSelector before
+	// they are emitted.
+	SortOrder []ResourceSelector `json:"sortOrder"`
+
+	// ...
+}
+
+// ResourceSelector selects Resources that it matches
+type ResourceSelector struct {
+	// annotationSelector matches Resources based on their Annotations.
+	AnnotationSelector AnnotationSelector `json:"annotationSelector"`
+}
+
+// A annotation selector is a annotation query over a set of resources. The results of matchAnnotations is ANDed.
+// An empty annotation selector matches all objects. A null annotation selector matches no objects.
+type AnnotationSelector struct {
+	// matchAnnotations is a map of {key,value} pairs.  A Resource matches if it has
+	// *all* of the annotations in matchAnnotations appear in the Resource metaData.
+	// Null and empty values are not allowed.
+	// +optional
+	MatchAnnotations map[string]string `json:"matchAnnotations,omitempty"`
+	
+	// TODO: Consider adding field: MatchExpressions []AnnotationSelectorRequirement 
+}
+```
 Example:
 
 ```
-resourceOrdering:
-- name: first
-  - type: label
-    key: some-label-name-1
-    value: some-label-value-1
-  - type: annotation
-    key: some-annotation-name-a
-    value: some-label-value-a
-- name: second
-  - type: annotation
-    key: some-annotation-name-b
-    value: some-annotation-value-b
-- name: third
-  type: label
-  key: some-label-name-2
-  value: some-label-value-2
+sortOrder:
+- annotationSelector:
+    some-annotation-name-1: some-annotation-value-1
+    some-annotation-name-a: some-label-value-a
+- annotationSelector:
+    some-annotation-name-1: some-annotation-value-1
+- annotationSelector:
+    some-annotation-name-2: some-annotation-value-2
 ```
 
-The explicit user defined ordering using labels and annotations would take precedence over the
- ordering based off types.  Types would be used as a secondary sorting function.
+The explicit user defined ordering using annotations will take precedence over the type based
+orderings.  Types would be used as a fallback sorting function amongst Resource with equal
+precedence in the explicit ordering.
 
-- Resources labeled with `some-label-name-1=some-label-value-1` *and* annotated
-  with `some-annotation-name-a=some-label-value-a` are first
+- Resources annotated with `some-annotation-name-1: some-annotation-value-1` *and* annotated
+  with `some-annotation-name-a: some-annotation-value-a` are first
   - These Resources are sorted by type
-- Resources annotated with `some-annotation-name-a=some-annotation-value-b` are second
+- Resources annotated with `some-annotation-name-1=some-annotation-value-1`
+  (without `some-annotation-name-a: some-annotation-value-a`) appear second
   - These Resources are sorted by type
-- Resources labeled with `some-label-name-2=some-label-value-2` are third
+- Resources annotated with `some-annotation-name-2=some-annotation-value-2`
   - These Resources are sorted by type
-- Resources not matching any label or annotation are last
+- Resources not matching any annotation are last
   - These Resources are sorted by type
 
-Resources matching multiple orderings (e.g. have multiple matching labels and annotations) appear
+Resources matching multiple orderings (e.g. have multiple matching annotations) appear
 in the position matching the earliest label / annotation.
 
+**Note:** Throw an error if there is a selector that selects a superset of another selector 
+and it appears first.  e.g. this should throw an error because the first selector will match
+everything that the second selector does, and it will have no effect.
+
+```
+sortOrder:
+- annotationSelector:
+    some-annotation-name-1: some-annotation-value-1
+- annotationSelector:
+    some-annotation-name-1: some-annotation-value-1
+    some-annotation-name-a: some-label-value-a
+```
+
 ### Risks and Mitigations
 
 Risk: Users build complex orderings that are hard to reason about.
 Mitigation: Good documentation and recommendations about how to keep things simple.
 
 ## Graduation Criteria
 
-NA
+Use customer feedback to determine if we should support:
+
+- `LabelSelectors`
+- `AnnotationSelectorRequirement` (like `LabelSelectorRequirement` but for annotations)
+- Explicitly ordering things
 
 
 ## Docs
@@ -117,13 +167,14 @@ Update Kubectl Book and Kustomize Documentation
 
 Unit Tests for:
 
-- [ ] Resources with labels and annotations follow the ordering override semantics
+- [ ] Resources with annotations follow the ordering override semantics
 - [ ] Resources matching multiple orderings land in the right spot
+- [ ] Throw an error if a superset selector appears after its subset (e.g. a more restrict selector appears later)
+  - This will have no effect, as everything will have already been matched
 - [ ] Resources are sorted by type as a secondary factor
-- [ ] Having multiple labels / annotations with the same key and different values works correctly
-- [ ] Having multiple labels / annotations with different keys and the same values works correctly
-- [ ] Mixing labels and annotations works
-- [ ] Unrecognized type values throw and error
+- [ ] Having multiple annotations with the same key and different values works correctly
+- [ ] Having multiple annotations with different keys and the same values works correctly
+- [ ] Empty and Null `MatchAnnotations` throw an error
 - [ ] Resources that don't appear in the ordering overrides appear last and are sorted by type
 
 ### Version Skew Tests