fix(server): do not change primary private IP on apply

internal/service/server/interfaces.go

@@ -12,25 +12,19 @@ import (
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
 )
 
-func findInterface(ifaces []upcloud.ServerInterface, index int, ip string) *upcloud.ServerInterface {
+func findInterface(ifaces []upcloud.ServerInterface, index int) *upcloud.ServerInterface {
 	for _, iface := range ifaces {
 		if iface.Index == index {
 			return &iface
 		}
 	}
-	for _, iface := range ifaces {
-		if len(iface.IPAddresses) > 0 && iface.IPAddresses[0].Address == ip {
-			return &iface
-		}
-	}
 	return nil
 }
 
 func interfacesToMap(ifaces []interface{}) map[int]interface{} {
 	m := make(map[int]interface{})
-	for _, iface := range ifaces {
-		val := iface.(map[string]interface{})
-		m[val["index"].(int)] = iface
+	for i, iface := range ifaces {
+		m[i] = iface
 	}
 	return m
 }
@@ -57,13 +51,13 @@ func canModifyInterface(plan map[string]interface{}, prev *upcloud.ServerInterfa
 	if v, ok := plan["type"].(string); !ok || prev.Type != v {
 		return false
 	}
-	if v, ok := plan["network"].(string); !ok || prev.Network != v {
-		return false
-	}
 	if v, ok := plan["ip_address_family"].(string); !ok || len(prev.IPAddresses) > 0 && prev.IPAddresses[0].Family != v {
 		return false
 	}
 	if prev.Type == upcloud.NetworkTypePrivate {
+		if v, ok := plan["network"].(string); !ok || prev.Network != v {
+			return false
+		}
 		if v, ok := plan["ip_address"].(string); !ok || len(prev.IPAddresses) > 0 && prev.IPAddresses[0].Address != v {
 			return false
 		}
@@ -103,18 +97,31 @@ func shouldModifyInterface(plan map[string]interface{}, addresses request.Create
 	return false
 }
 
-func setInterfaceValues(iface *upcloud.Interface) map[string]interface{} {
+func setInterfaceValues(iface *upcloud.Interface, ipInState interface{}) map[string]interface{} {
 	ni := make(map[string]interface{})
 	additionalIPAddresses := []map[string]interface{}{}
 
+	// IP addresses are not returned in deterministic order. If any of the IP addresses of the interface match the IP address in state, use that.
+	if ip, ok := ipInState.(string); ok {
+		for _, ipAddress := range iface.IPAddresses {
+			if ipAddress.Address == ip {
+				ni["ip_address_family"] = ipAddress.Family
+				ni["ip_address"] = ipAddress.Address
+				if !ipAddress.Floating.Empty() {
+					ni["ip_address_floating"] = ipAddress.Floating.Bool()
+				}
+			}
+		}
+	}
+
 	for i, ipAddress := range iface.IPAddresses {
-		if i == 0 {
+		if i == 0 && ni["ip_address"] == nil {
 			ni["ip_address_family"] = ipAddress.Family
 			ni["ip_address"] = ipAddress.Address
 			if !ipAddress.Floating.Empty() {
 				ni["ip_address_floating"] = ipAddress.Floating.Bool()
 			}
-		} else if iface.Type == upcloud.NetworkTypePrivate {
+		} else if iface.Type == upcloud.NetworkTypePrivate && ipAddress.Address != ni["ip_address"].(string) {
 			additionalIPAddress := map[string]interface{}{
 				"ip_address":        ipAddress.Address,
 				"ip_address_family": ipAddress.Family,
@@ -231,7 +238,7 @@ func updateServerNetworkInterfaces(ctx context.Context, svc *service.Service, d
 		}
 
 		if modified := modifiedInterfaces[index]; modified != nil {
-			newNetworkInterfaces[i] = setInterfaceValues(modified)
+			newNetworkInterfaces[i] = setInterfaceValues(modified, val["ip_address"])
 			continue
 		}
 
@@ -269,7 +276,7 @@ func updateServerNetworkInterfaces(ctx context.Context, svc *service.Service, d
 		if err != nil {
 			return err
 		}
-		newNetworkInterfaces[i] = setInterfaceValues(iface)
+		newNetworkInterfaces[i] = setInterfaceValues(iface, val["ip_address"])
 	}
 
 	if err := d.Set("network_interface", newNetworkInterfaces); err != nil {

internal/service/server/server.go

@@ -597,7 +597,7 @@ func resourceServerRead(ctx context.Context, d *schema.ResourceData, meta interf
 	}
 	networkInterfaces := make([]map[string]interface{}, n)
 	for i := 0; i < n; i++ {
-		key := fmt.Sprintf("network_interface.%d", i)
+		key := interfaceKey(i)
 		val, ok := d.Get(key).(map[string]interface{})
 		if !ok {
 			return diag.Errorf("unable to read '%s' value", key)
@@ -607,13 +607,13 @@ func resourceServerRead(ctx context.Context, d *schema.ResourceData, meta interf
 		if index := val["index"].(int); index == 0 && i < len(server.Networking.Interfaces) {
 			iface = &server.Networking.Interfaces[i]
 		} else {
-			iface = findInterface(server.Networking.Interfaces, val["index"].(int), "")
+			iface = findInterface(server.Networking.Interfaces, val["index"].(int))
 		}
 		if iface == nil {
 			continue
 		}
 
-		ni := setInterfaceValues((*upcloud.Interface)(iface))
+		ni := setInterfaceValues((*upcloud.Interface)(iface), val["ip_address"])
 		networkInterfaces[i] = ni
 
 		if iface.Type == upcloud.NetworkTypePublic &&

upcloud/resource_upcloud_server_network_test.go

@@ -116,8 +116,8 @@ func TestAccUpcloudServerInterfaceMatching(t *testing.T) {
 				Config: testDataS3,
 				Check: resource.ComposeAggregateTestCheckFunc(
 					resource.TestCheckResourceAttr(this, "network_interface.#", "3"),
-					resource.TestCheckResourceAttr(this, "network_interface.0.index", "4"),
-					checkStringDoesNotChange(this, "network_interface.0.ip_address", &thisIP4),
+					resource.TestCheckResourceAttr(this, "network_interface.0.index", "5"),
+					checkStringDoesNotChange(this, "network_interface.0.ip_address", &thisIP5),
 					resource.TestCheckResourceAttr(this, "network_interface.1.index", "10"),
 					checkStringDoesNotChange(this, "network_interface.1.ip_address", &thisIP1),
 					resource.TestCheckResourceAttr(this, "network_interface.2.index", "3"),

upcloud/testdata/upcloud_server/server_ifaces_s3.tf

@@ -19,9 +19,10 @@ resource "upcloud_network" "this" {
   }
 }
 
-resource "upcloud_floating_ip_address" "this" {
-  mac_address = upcloud_server.this.network_interface[0].mac_address
-}
+# Nested field can not be set as unkown, so we need to remove the floating IP address to avoid data consistency error: https://github.com/hashicorp/terraform-plugin-sdk/issues/459
+# resource "upcloud_floating_ip_address" "this" {
+#   mac_address = upcloud_server.this.network_interface[1].mac_address
+# }
 
 resource "upcloud_server" "this" {
   hostname = "${var.prefix}vm"
@@ -34,7 +35,7 @@ resource "upcloud_server" "this" {
     keys = ["ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIIB8Q"]
   }
 
-  // Reorder interfaces
+  // Reorder interfaces, remove interface with index 4
 
   network_interface {
     index = 5