Record: Add warning if TTL has changed (#1157)

* Record: Add warning if TTL has changed

* remove example

* Update digitalocean/domain/resource_record.go

Co-authored-by: Andrew Starr-Bochicchio <andrewsomething@users.noreply.github.com>

---------

Co-authored-by: Andrew Starr-Bochicchio <andrewsomething@users.noreply.github.com>

digitalocean/domain/resource_record.go

@@ -183,6 +183,7 @@ func resourceDigitalOceanRecordCreate(ctx context.Context, d *schema.ResourceDat
 func resourceDigitalOceanRecordRead(ctx context.Context, d *schema.ResourceData, meta interface{}) diag.Diagnostics {
 	client := meta.(*config.CombinedConfig).GodoClient()
 	domain := d.Get("domain").(string)
+	ttl := d.Get("ttl")
 	id, err := strconv.Atoi(d.Id())
 	if err != nil {
 		return diag.Errorf("invalid record ID: %v", err)
@@ -200,6 +201,20 @@ func resourceDigitalOceanRecordRead(ctx context.Context, d *schema.ResourceData,
 		return diag.FromErr(err)
 	}
 
+	var warn = []diag.Diagnostic{}
+
+	if ttl != rec.TTL {
+		ttlChangeWarn := fmt.Sprintf("The TTL for record ID %d changed from %d to %d. DNS requires that multiple records with the same FQDN share the same TTL. If inconsistent TTLs are provided, DigitalOcean will rectify them automatically.\n\nFor reference, see RFC 2181, section 5.2: https://www.rfc-editor.org/rfc/rfc2181#section-5.", rec.ID, ttl, rec.TTL)
+
+		warn = []diag.Diagnostic{
+			{
+				Severity: diag.Warning,
+				Summary:  "digitalocean_record TTL changed",
+				Detail:   ttlChangeWarn,
+			},
+		}
+	}
+
 	if t := rec.Type; t == "CNAME" || t == "MX" || t == "NS" || t == "SRV" || t == "CAA" {
 		if rec.Data != "@" && rec.Tag != "iodef" {
 			rec.Data += "."
@@ -220,7 +235,7 @@ func resourceDigitalOceanRecordRead(ctx context.Context, d *schema.ResourceData,
 	log.Printf("[DEBUG] Constructed FQDN: %s", en)
 	d.Set("fqdn", en)
 
-	return nil
+	return warn
 }
 
 func resourceDigitalOceanRecordImport(d *schema.ResourceData, meta interface{}) ([]*schema.ResourceData, error) {