terraform/helper/variables/merge.go

67 lines
1.7 KiB
Go

package variables
// Merge merges raw variable values b into a.
//
// The parameters given here should be the full map of set variables, such
// as those created by Flag and FlagFile.
//
// The merge behavior is to override the top-level key except for map
// types. Map types are merged together by key. Any other types are overwritten:
// primitives and lists.
//
// This returns the resulting map. This merges into a but if a is nil a new
// map will be allocated. A non-nil "a" value is returned regardless.
func Merge(a, b map[string]interface{}) map[string]interface{} {
if a == nil {
a = map[string]interface{}{}
}
for k, raw := range b {
switch v := raw.(type) {
case map[string]interface{}:
// For maps, we do a deep merge. If the value in the original
// map (a) is not a map, we just overwrite. For invalid types
// they're caught later in the validation step in Terraform.
// If there is no value set, just set it
rawA, ok := a[k]
if !ok {
a[k] = v
continue
}
// If the value is not a map, just set it
mapA, ok := rawA.(map[string]interface{})
if !ok {
a[k] = v
continue
}
// Go over the values in the map. If we're setting a raw value,
// then override. If we're setting a nested map, then recurse.
for k, v := range v {
// If the value isn't a map, then there is nothing to merge
// further so we just set it.
mv, ok := v.(map[string]interface{})
if !ok {
mapA[k] = v
continue
}
switch av := mapA[k].(type) {
case map[string]interface{}:
mapA[k] = Merge(av, mv)
default:
// Unset or non-map, just set it
mapA[k] = mv
}
}
default:
// Any other type we just set directly
a[k] = v
}
}
return a
}