feat context: Add support for resource set collections

A resource set collection is a resource set with an addition 'include' array
configured. It is a short-hand for importing multiple resource sets from the
same folder and for excluding/including them as a group.

See https://github.com/tazjin/kontemplate/issues/9 for more information.

Closes #9

2 files changed, 29 insertions, 5 deletions

diff --git a/context/context.go b/context/context.go
index 140f11fce7c6..94838f668d71 100644
--- a/context/context.go
+++ b/context/context.go
@@ -14,6 +14,10 @@ import (
 type ResourceSet struct {
 	Name   string                 `json:"name"`
 	Values map[string]interface{} `json:"values"`
+
+	// Fields for resource set collections
+	Include []ResourceSet `json:"include"`
+	Parent  *string
 }
 
 type Context struct {
@@ -63,3 +67,23 @@ func LoadContextFromFile(filename string) (*Context, error) {
 
 	return &c, nil
 }
+
+// Flattens resource set collections, i.e. resource sets that themselves have an additional 'include' field set.
+// Those will be regarded as a short-hand for including multiple resource sets from a subfolder.
+// See https://github.com/tazjin/kontemplate/issues/9 for more information.
+func flattenResourceSetCollections(rs *[]ResourceSet) *[]ResourceSet {
+	flattened := make([]ResourceSet, 0)
+
+	for _, r := range *rs {
+		if len(r.Include) == 0 {
+			flattened = append(flattened, r)
+		} else {
+			for _, subResourceSet := range r.Include {
+				subResourceSet.Parent = &r.Name
+				flattened = append(flattened, subResourceSet)
+			}
+		}
+	}
+
+	return &flattened
+}
diff --git a/templater/templater.go b/templater/templater.go
index bb65cd1df058..29079eb9425e 100644
--- a/templater/templater.go
+++ b/templater/templater.go
@@ -121,7 +121,7 @@ func applyLimits(rs *[]context.ResourceSet, include *[]string, exclude *[]string
 	// Exclude excluded resource sets
 	excluded := make([]context.ResourceSet, 0)
 	for _, r := range *rs {
-		if !contains(exclude, &r.Name) {
+		if !matchesResourceSet(exclude, &r) {
 			excluded = append(excluded, r)
 		}
 	}
@@ -132,7 +132,7 @@ func applyLimits(rs *[]context.ResourceSet, include *[]string, exclude *[]string
 	}
 	included := make([]context.ResourceSet, 0)
 	for _, r := range excluded {
-		if contains(include, &r.Name) {
+		if matchesResourceSet(include, &r) {
 			included = append(included, r)
 		}
 	}
@@ -140,10 +140,10 @@ func applyLimits(rs *[]context.ResourceSet, include *[]string, exclude *[]string
 	return &included
 }
 
-// Check whether a certain string is contained in a string slice
-func contains(s *[]string, v *string) bool {
+// Check whether an include/exclude string slice matches a resource set
+func matchesResourceSet(s *[]string, rs *context.ResourceSet) bool {
 	for _, r := range *s {
-		if r == *v {
+		if r == rs.Name || r == *rs.Parent {
 			return true
 		}
 	}