Sort Fleet integration policy inputs to ensure consistency (#494)

* Sort Fleet integration policy inputs to ensure consistency

- When new inputs are read from the Fleet API, the list is sorted
according to the existing plan. Any new inputs added from the API
will be moved to the end of the list. This ensures a consistency
of inputs and prevents unnecssary changes from appearing.

* Changelog

* Extract sort function and add unit test

Author: taylor-swanson

CHANGELOG.md

@@ -8,6 +8,7 @@
 - Rename fleet package objects to `elasticstack_fleet_integration` and `elasticstack_fleet_integration_policy` ([#476](https://github.com/elastic/terraform-provider-elasticstack/pull/476))
 - Fix a provider crash when managing SLOs outside of the default Kibana space. ([#485](https://github.com/elastic/terraform-provider-elasticstack/pull/485))
 - Make input optional for `elasticstack_fleet_integration_policy` ([#493](https://github.com/elastic/terraform-provider-elasticstack/pull/493))
+- Sort Fleet integration policy inputs to ensure consistency ([#494](https://github.com/elastic/terraform-provider-elasticstack/pull/494))
 
 ## [0.10.0] - 2023-11-02
 

internal/fleet/integration_policy_resource.go

@@ -3,6 +3,7 @@ package fleet
 import (
 	"context"
 	"encoding/json"
+	"sort"
 
 	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
@@ -340,9 +341,9 @@ func resourceIntegrationPolicyRead(ctx context.Context, d *schema.ResourceData,
 		}
 	}
 
-	var inputs []any
+	newInputs := make([]any, 0, len(pkgPolicy.Inputs))
 	for inputID, input := range pkgPolicy.Inputs {
-		inputMap := map[string]any{
+		inputData := map[string]any{
 			"input_id": inputID,
 			"enabled":  input.Enabled,
 		}
@@ -352,19 +353,23 @@ func resourceIntegrationPolicyRead(ctx context.Context, d *schema.ResourceData,
 			if err != nil {
 				return diag.FromErr(err)
 			}
-			inputMap["streams_json"] = string(data)
+			inputData["streams_json"] = string(data)
 		}
 		if input.Vars != nil {
 			data, err := json.Marshal(*input.Vars)
 			if err != nil {
 				return diag.FromErr(err)
 			}
-			inputMap["vars_json"] = string(data)
+			inputData["vars_json"] = string(data)
 		}
 
-		inputs = append(inputs, inputMap)
+		newInputs = append(newInputs, inputData)
 	}
-	if err := d.Set("input", inputs); err != nil {
+
+	existingInputs, _ := d.Get("input").([]any)
+	sortInputs(newInputs, existingInputs)
+
+	if err := d.Set("input", newInputs); err != nil {
 		return diag.FromErr(err)
 	}
 
@@ -386,3 +391,34 @@ func resourceIntegrationPolicyDelete(ctx context.Context, d *schema.ResourceData
 
 	return diags
 }
+
+// sortInputs will sort the 'incoming' list of input definitions based on
+// the order of inputs defined in the 'existing' list. Inputs not present in
+// 'existing' will be placed at the end of the list. Inputs are identified by
+// their ID ('input_id'). The 'incoming' slice will be sorted in-place.
+func sortInputs(incoming []any, existing []any) {
+	idToIndex := make(map[string]int, len(existing))
+	for i, v := range existing {
+		inputData, _ := v.(map[string]any)
+		inputID, _ := inputData["input_id"].(string)
+		idToIndex[inputID] = i
+	}
+
+	sort.Slice(incoming, func(i, j int) bool {
+		iInput, _ := incoming[i].(map[string]any)
+		iID, _ := iInput["input_id"].(string)
+		iIdx, ok := idToIndex[iID]
+		if !ok {
+			return false
+		}
+
+		jInput, _ := incoming[j].(map[string]any)
+		jID, _ := jInput["input_id"].(string)
+		jIdx, ok := idToIndex[jID]
+		if !ok {
+			return true
+		}
+
+		return iIdx < jIdx
+	})
+}

internal/fleet/shared_test.go

@@ -0,0 +1,63 @@
+package fleet
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_SortInputs(t *testing.T) {
+	t.Run("WithExisting", func(t *testing.T) {
+		existing := []any{
+			map[string]any{"input_id": "A", "enabled": true},
+			map[string]any{"input_id": "B", "enabled": true},
+			map[string]any{"input_id": "C", "enabled": true},
+			map[string]any{"input_id": "D", "enabled": true},
+			map[string]any{"input_id": "E", "enabled": true},
+		}
+
+		incoming := []any{
+			map[string]any{"input_id": "G", "enabled": true},
+			map[string]any{"input_id": "F", "enabled": true},
+			map[string]any{"input_id": "B", "enabled": true},
+			map[string]any{"input_id": "E", "enabled": true},
+			map[string]any{"input_id": "C", "enabled": true},
+		}
+
+		want := []any{
+			map[string]any{"input_id": "B", "enabled": true},
+			map[string]any{"input_id": "C", "enabled": true},
+			map[string]any{"input_id": "E", "enabled": true},
+			map[string]any{"input_id": "G", "enabled": true},
+			map[string]any{"input_id": "F", "enabled": true},
+		}
+
+		sortInputs(incoming, existing)
+
+		require.Equal(t, want, incoming)
+	})
+
+	t.Run("WithEmpty", func(t *testing.T) {
+		var existing []any
+
+		incoming := []any{
+			map[string]any{"input_id": "G", "enabled": true},
+			map[string]any{"input_id": "F", "enabled": true},
+			map[string]any{"input_id": "B", "enabled": true},
+			map[string]any{"input_id": "E", "enabled": true},
+			map[string]any{"input_id": "C", "enabled": true},
+		}
+
+		want := []any{
+			map[string]any{"input_id": "G", "enabled": true},
+			map[string]any{"input_id": "F", "enabled": true},
+			map[string]any{"input_id": "B", "enabled": true},
+			map[string]any{"input_id": "E", "enabled": true},
+			map[string]any{"input_id": "C", "enabled": true},
+		}
+
+		sortInputs(incoming, existing)
+
+		require.Equal(t, want, incoming)
+	})
+}