Handle settings drift for all resources (#211)

Co-authored-by: Copilot <[email protected]>

Author: deanhuynh

go.mod

@@ -11,6 +11,7 @@ require (
 	github.com/hashicorp/terraform-plugin-go v0.26.0
 	github.com/hashicorp/terraform-plugin-testing v1.12.0
 	github.com/segmentio/public-api-sdk-go v0.0.0-20250113195817-34106b6e08dd
+	github.com/stretchr/testify v1.10.0
 	gotest.tools/gotestsum v1.13.0
 )
 
@@ -19,8 +20,10 @@ require (
 	github.com/Kunde21/markdownfmt/v3 v3.1.0 // indirect
 	github.com/bitfield/gotestdox v0.2.2 // indirect
 	github.com/bmatcuk/doublestar/v4 v4.8.1 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/hashicorp/cli v1.1.7 // indirect
 	github.com/mattn/go-runewidth v0.0.9 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/yuin/goldmark v1.7.7 // indirect
 	github.com/yuin/goldmark-meta v1.1.0 // indirect
 	go.abhg.dev/goldmark/frontmatter v0.2.0 // indirect

internal/provider/destination_resource.go

@@ -615,9 +615,18 @@ func (r *destinationResource) Read(ctx context.Context, req resource.ReadRequest
 		return
 	}
 
-	// This is to satisfy terraform requirements that the returned fields must match the input ones because new settings can be generated in the response
+	// Merge settings: keep config-defined settings while ignoring backend-generated ones not in config
 	if !previousState.Settings.IsNull() && !previousState.Settings.IsUnknown() {
-		state.Settings = previousState.Settings
+		mergedSettings, err := mergeSettings(previousState.Settings, state.Settings, false)
+		if err != nil {
+			resp.Diagnostics.AddError(
+				"Unable to merge Destination settings",
+				err.Error(),
+			)
+
+			return
+		}
+		state.Settings = mergedSettings
 	}
 
 	diags = resp.State.Set(ctx, &state)

internal/provider/destination_subscription_resource.go

@@ -255,8 +255,18 @@ func (r *destinationSubscriptionResource) Read(ctx context.Context, req resource
 		return
 	}
 
+	// Merge settings: keep config-defined settings while ignoring backend-generated ones not in config
 	if !previousState.Settings.IsNull() && !previousState.Settings.IsUnknown() {
-		state.Settings = previousState.Settings
+		mergedSettings, err := mergeSettings(previousState.Settings, state.Settings, false)
+		if err != nil {
+			resp.Diagnostics.AddError(
+				"Unable to merge Destination subscription settings",
+				err.Error(),
+			)
+
+			return
+		}
+		state.Settings = mergedSettings
 	}
 
 	diags = resp.State.Set(ctx, &state)

internal/provider/insert_function_instance_resource.go

@@ -186,8 +186,18 @@ func (r *insertFunctionInstanceResource) Read(ctx context.Context, req resource.
 		return
 	}
 
+	// Merge settings: keep config-defined settings while ignoring backend-generated ones not in config
 	if !previousState.Settings.IsNull() && !previousState.Settings.IsUnknown() {
-		state.Settings = previousState.Settings
+		mergedSettings, err := mergeSettings(previousState.Settings, state.Settings, false)
+		if err != nil {
+			resp.Diagnostics.AddError(
+				"Unable to merge Insert Function instance settings",
+				err.Error(),
+			)
+
+			return
+		}
+		state.Settings = mergedSettings
 	}
 
 	// This is to satisfy terraform requirements that the input fields must match the returned ones. The input FunctionID can be prefixed with "ifnd_" and the returned one is not.

internal/provider/profiles_warehouse_resource.go

@@ -195,8 +195,18 @@ func (r *profilesWarehouseResource) Read(ctx context.Context, req resource.ReadR
 		return
 	}
 
+	// Merge settings: keep config-defined settings while ignoring backend-generated ones not in config
 	if !previousState.Settings.IsNull() && !previousState.Settings.IsUnknown() {
-		state.Settings = previousState.Settings
+		mergedSettings, err := mergeSettings(previousState.Settings, state.Settings, true)
+		if err != nil {
+			resp.Diagnostics.AddError(
+				"Unable to merge Profiles Warehouse settings",
+				err.Error(),
+			)
+
+			return
+		}
+		state.Settings = mergedSettings
 	}
 
 	diags = resp.State.Set(ctx, &state)

internal/provider/source_resource.go

@@ -415,9 +415,18 @@ func (r *sourceResource) Read(ctx context.Context, req resource.ReadRequest, res
 		return
 	}
 
-	// This is to satisfy terraform requirements that the returned fields must match the input ones because new settings can be generated in the response
+	// Merge settings: keep config-defined settings while ignoring backend-generated ones not in config
 	if !previousState.Settings.IsNull() && !previousState.Settings.IsUnknown() {
-		state.Settings = previousState.Settings
+		mergedSettings, err := mergeSettings(previousState.Settings, state.Settings, false)
+		if err != nil {
+			resp.Diagnostics.AddError(
+				"Unable to merge Source settings",
+				err.Error(),
+			)
+
+			return
+		}
+		state.Settings = mergedSettings
 	}
 
 	diags = resp.State.Set(ctx, &state)

internal/provider/utils.go

@@ -3,8 +3,13 @@ package provider
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
 	"io"
 	"net/http"
+	"strings"
+
+	"github.com/hashicorp/terraform-plugin-framework-jsontypes/jsontypes"
+	"github.com/segmentio/terraform-provider-segment/internal/provider/models"
 )
 
 func getError(err error, body *http.Response) string {
@@ -23,3 +28,39 @@ func getError(err error, body *http.Response) string {
 
 	return err.Error() + "\n" + formattedBody.String()
 }
+
+// mergeSettings merges config settings with remote settings, preserving only the keys defined in config.
+func mergeSettings(configSettings, remoteSettings jsontypes.Normalized, isWarehouse bool) (jsontypes.Normalized, error) {
+	var configMap map[string]interface{}
+	if diags := configSettings.Unmarshal(&configMap); diags.HasError() {
+		return jsontypes.NewNormalizedNull(), fmt.Errorf("failed to unmarshal config settings: %s", diags.Errors())
+	}
+
+	var remoteMap map[string]interface{}
+	if diags := remoteSettings.Unmarshal(&remoteMap); diags.HasError() {
+		return jsontypes.NewNormalizedNull(), fmt.Errorf("failed to unmarshal remote settings: %s", diags.Errors())
+	}
+
+	// Create merged map with only config-defined keys that exist in remote (to detect drift)
+	// Keys in config but not in remote are excluded (they don't exist or aren't supported)
+	merged := make(map[string]interface{})
+	for key := range configMap {
+		if isWarehouse && key == "password" { // Warehouses do not output password in the response
+			merged[key] = configMap[key]
+		} else if value, exists := remoteMap[key]; exists {
+			strValue, ok := value.(string)
+			if ok && strings.Contains(strValue, "•") { // If the secret is censored, do not update it
+				merged[key] = configMap[key]
+			} else {
+				merged[key] = value
+			}
+		}
+	}
+
+	result, err := models.GetSettings(merged)
+	if err != nil {
+		return jsontypes.Normalized{}, fmt.Errorf("failed to merge settings: %w", err)
+	}
+
+	return result, nil
+}