provider/aws: Various IAM policy normalizations for IAM data source

 * Various string slices are sorted and truncated to strings if they
   only contain one element.
 * Sids are now included if they are empty.

This is to ensure what is sent to AWS matches what comes back, to
prevent recurring diffs even when the policy has changed.

builtin/providers/aws/data_source_aws_iam_policy_document.go

@@ -150,12 +150,19 @@ func dataSourceAwsIamPolicyDocumentRead(d *schema.ResourceData, meta interface{}
 	return nil
 }
 
-func dataSourceAwsIamPolicyDocumentReplaceVarsInList(in []string) []string {
-	out := make([]string, len(in))
-	for i, item := range in {
-		out[i] = dataSourceAwsIamPolicyDocumentVarReplacer.Replace(item)
+func dataSourceAwsIamPolicyDocumentReplaceVarsInList(in interface{}) interface{} {
+	switch v := in.(type) {
+	case string:
+		return dataSourceAwsIamPolicyDocumentVarReplacer.Replace(v)
+	case []string:
+		out := make([]string, len(v))
+		for i, item := range v {
+			out[i] = dataSourceAwsIamPolicyDocumentVarReplacer.Replace(item)
+		}
+		return out
+	default:
+		panic("dataSourceAwsIamPolicyDocumentReplaceVarsInList: input not string nor []string")
 	}
-	return out
 }
 
 func dataSourceAwsIamPolicyDocumentMakeConditions(in []interface{}) IAMPolicyStatementConditionSet {

builtin/providers/aws/data_source_aws_iam_policy_document_test.go

@@ -75,7 +75,6 @@ data "aws_iam_policy_document" "test" {
             test = "StringLike"
             variable = "s3:prefix"
             values = [
-                "",
                 "home/",
                 "home/&{aws:username}/",
             ]
@@ -118,59 +117,45 @@ var testAccAWSIAMPolicyDocumentExpectedJSON = `{
       "Sid": "1",
       "Effect": "Allow",
       "Action": [
-        "s3:GetBucketLocation",
-        "s3:ListAllMyBuckets"
+        "s3:ListAllMyBuckets",
+        "s3:GetBucketLocation"
       ],
-      "Resource": [
-        "arn:aws:s3:::*"
-      ]
+      "Resource": "arn:aws:s3:::*"
     },
     {
+      "Sid": "",
       "Effect": "Allow",
-      "Action": [
-        "s3:ListBucket"
-      ],
-      "Resource": [
-        "arn:aws:s3:::foo"
-      ],
+      "Action": "s3:ListBucket",
+      "Resource": "arn:aws:s3:::foo",
       "NotPrincipal": {
-        "AWS": [
-          "arn:blahblah:example"
-        ]
+        "AWS": "arn:blahblah:example"
       },
       "Condition": {
         "StringLike": {
           "s3:prefix": [
-            "",
-            "home/",
-            "home/${aws:username}/"
+            "home/${aws:username}/",
+            "home/"
           ]
         }
       }
     },
     {
+      "Sid": "",
       "Effect": "Allow",
-      "Action": [
-        "s3:*"
-      ],
+      "Action": "s3:*",
       "Resource": [
         "arn:aws:s3:::foo/home/${aws:username}/*",
         "arn:aws:s3:::foo/home/${aws:username}"
       ],
       "Principal": {
-        "AWS": [
-          "arn:blahblah:example"
-        ]
+        "AWS": "arn:blahblah:example"
       }
     },
     {
+      "Sid": "",
       "Effect": "Deny",
-      "NotAction": [
-        "s3:*"
-      ],
-      "NotResource": [
-        "arn:aws:s3:::*"
-      ]
+      "NotAction": "s3:*",
+      "NotResource": "arn:aws:s3:::*"
     }
   ]
 }`

builtin/providers/aws/iam_policy_model.go

@@ -2,6 +2,7 @@ package aws
 
 import (
 	"encoding/json"
+	"sort"
 )
 
 type IAMPolicyDoc struct {
@@ -11,64 +12,84 @@ type IAMPolicyDoc struct {
 }
 
 type IAMPolicyStatement struct {
-	Sid           string                         `json:",omitempty"`
+	Sid           string
 	Effect        string                         `json:",omitempty"`
-	Actions       []string                       `json:"Action,omitempty"`
-	NotActions    []string                       `json:"NotAction,omitempty"`
-	Resources     []string                       `json:"Resource,omitempty"`
-	NotResources  []string                       `json:"NotResource,omitempty"`
+	Actions       interface{}                    `json:"Action,omitempty"`
+	NotActions    interface{}                    `json:"NotAction,omitempty"`
+	Resources     interface{}                    `json:"Resource,omitempty"`
+	NotResources  interface{}                    `json:"NotResource,omitempty"`
 	Principals    IAMPolicyStatementPrincipalSet `json:"Principal,omitempty"`
 	NotPrincipals IAMPolicyStatementPrincipalSet `json:"NotPrincipal,omitempty"`
 	Conditions    IAMPolicyStatementConditionSet `json:"Condition,omitempty"`
 }
 
 type IAMPolicyStatementPrincipal struct {
 	Type        string
-	Identifiers []string
+	Identifiers interface{}
 }
 
 type IAMPolicyStatementCondition struct {
 	Test     string
 	Variable string
-	Values   []string
+	Values   interface{}
 }
 
 type IAMPolicyStatementPrincipalSet []IAMPolicyStatementPrincipal
 type IAMPolicyStatementConditionSet []IAMPolicyStatementCondition
 
 func (ps IAMPolicyStatementPrincipalSet) MarshalJSON() ([]byte, error) {
-	raw := map[string][]string{}
+	raw := map[string]interface{}{}
 
 	for _, p := range ps {
-		if _, ok := raw[p.Type]; !ok {
-			raw[p.Type] = make([]string, 0, len(p.Identifiers))
+		switch i := p.Identifiers.(type) {
+		case []string:
+			if _, ok := raw[p.Type]; !ok {
+				raw[p.Type] = make([]string, 0, len(i))
+			}
+			sort.Sort(sort.Reverse(sort.StringSlice(i)))
+			raw[p.Type] = append(raw[p.Type].([]string), i...)
+		case string:
+			raw[p.Type] = i
+		default:
+			panic("Unsupported data type for IAMPolicyStatementPrincipalSet")
 		}
-		raw[p.Type] = append(raw[p.Type], p.Identifiers...)
 	}
 
 	return json.Marshal(&raw)
 }
 
 func (cs IAMPolicyStatementConditionSet) MarshalJSON() ([]byte, error) {
-	raw := map[string]map[string][]string{}
+	raw := map[string]map[string]interface{}{}
 
 	for _, c := range cs {
 		if _, ok := raw[c.Test]; !ok {
-			raw[c.Test] = map[string][]string{}
+			raw[c.Test] = map[string]interface{}{}
 		}
-		if _, ok := raw[c.Test][c.Variable]; !ok {
-			raw[c.Test][c.Variable] = make([]string, 0, len(c.Values))
+		switch i := c.Values.(type) {
+		case []string:
+			if _, ok := raw[c.Test][c.Variable]; !ok {
+				raw[c.Test][c.Variable] = make([]string, 0, len(i))
+			}
+			sort.Sort(sort.Reverse(sort.StringSlice(i)))
+			raw[c.Test][c.Variable] = append(raw[c.Test][c.Variable].([]string), i...)
+		case string:
+			raw[c.Test][c.Variable] = i
+		default:
+			panic("Unsupported data type for IAMPolicyStatementConditionSet")
 		}
-		raw[c.Test][c.Variable] = append(raw[c.Test][c.Variable], c.Values...)
 	}
 
 	return json.Marshal(&raw)
 }
 
-func iamPolicyDecodeConfigStringList(lI []interface{}) []string {
+func iamPolicyDecodeConfigStringList(lI []interface{}) interface{} {
+	if len(lI) == 1 {
+		return lI[0].(string)
+	}
 	ret := make([]string, len(lI))
 	for i, vI := range lI {
 		ret[i] = vI.(string)
 	}
+	sort.Sort(sort.Reverse(sort.StringSlice(ret)))
 	return ret
 }