BUGFIX: IGNORE() deletes ignored records on ByZone() platforms (#3263)

integrationTest/integration_test.go

@@ -2093,6 +2093,7 @@ func makeTests() []*TestGroup {
 				a("bar", "5.5.5.5"),
 				cname("mail", "ghs.googlehosted.com."),
 			),
+
 			tc("ignore label",
 				// NB(tlim): This ignores 1 record of a recordSet. This should
 				// fail for diff2.ByRecordSet() providers if diff2 is not
@@ -2104,6 +2105,14 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("foo", "", ""),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.2.3.4"),
+				a("foo", "2.3.4.5"),
+				txt("foo", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
 			tc("ignore label,type",
 				//a("foo", "1.2.3.4"),
 				//a("foo", "2.3.4.5"),
@@ -2112,6 +2121,14 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("foo", "A", ""),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.2.3.4"),
+				a("foo", "2.3.4.5"),
+				txt("foo", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
 			tc("ignore label,type,target",
 				//a("foo", "1.2.3.4"),
 				a("foo", "2.3.4.5"),
@@ -2120,6 +2137,14 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("foo", "A", "1.2.3.4"),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.2.3.4"),
+				a("foo", "2.3.4.5"),
+				txt("foo", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
 			tc("ignore type",
 				//a("foo", "1.2.3.4"),
 				//a("foo", "2.3.4.5"),
@@ -2128,6 +2153,14 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("", "A", ""),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.2.3.4"),
+				a("foo", "2.3.4.5"),
+				txt("foo", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
 			tc("ignore type,target",
 				a("foo", "1.2.3.4"),
 				//a("foo", "2.3.4.5"),
@@ -2136,6 +2169,14 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("", "A", "2.3.4.5"),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.2.3.4"),
+				a("foo", "2.3.4.5"),
+				txt("foo", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
 			tc("ignore target",
 				a("foo", "1.2.3.4"),
 				//a("foo", "2.3.4.5"),
@@ -2144,7 +2185,14 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("", "", "2.3.4.5"),
 			).ExpectNoChanges(),
-			//
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.2.3.4"),
+				a("foo", "2.3.4.5"),
+				txt("foo", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
 			// Many types:
 			tc("ignore manytypes",
 				//a("foo", "1.2.3.4"),
@@ -2154,7 +2202,14 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("", "A,TXT", ""),
 			).ExpectNoChanges(),
-			//
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.2.3.4"),
+				a("foo", "2.3.4.5"),
+				txt("foo", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
 			// Target with wildcard:
 			tc("ignore label,type,target=*",
 				a("foo", "1.2.3.4"),
@@ -2164,6 +2219,13 @@ func makeTests() []*TestGroup {
 				//cname("mail", "ghs.googlehosted.com."),
 				ignore("", "CNAME", "*.googlehosted.com."),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.2.3.4"),
+				a("foo", "2.3.4.5"),
+				txt("foo", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
 		),
 
 		// Same as "main" but with an apex ("@") record.
@@ -2175,7 +2237,8 @@ func makeTests() []*TestGroup {
 				a("bar", "5.5.5.5"),
 				cname("mail", "ghs.googlehosted.com."),
 			),
-			tc("ignore label",
+
+			tc("apex label",
 				// NB(tlim): This ignores 1 record of a recordSet. This should
 				// fail for diff2.ByRecordSet() providers if diff2 is not
 				// implemented correctly.
@@ -2190,7 +2253,15 @@ func makeTests() []*TestGroup {
 				// that providers injects into zones are treated like input
 				// from dnsconfig.js.
 			).ExpectNoChanges().UnsafeIgnore(),
-			tc("ignore label,type",
+			tc("VERIFY PREVIOUS",
+				a("@", "1.2.3.4"),
+				a("@", "2.3.4.5"),
+				txt("@", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
+			tc("apex label,type",
 				//a("@", "1.2.3.4"),
 				//a("@", "2.3.4.5"),
 				txt("@", "simple"),
@@ -2198,7 +2269,15 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("@", "A", ""),
 			).ExpectNoChanges(),
-			tc("ignore label,type,target",
+			tc("VERIFY PREVIOUS",
+				a("@", "1.2.3.4"),
+				a("@", "2.3.4.5"),
+				txt("@", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
+			tc("apex label,type,target",
 				//a("@", "1.2.3.4"),
 				a("@", "2.3.4.5"),
 				txt("@", "simple"),
@@ -2209,7 +2288,15 @@ func makeTests() []*TestGroup {
 				// that providers injects into zones are treated like input
 				// from dnsconfig.js.
 			).ExpectNoChanges().UnsafeIgnore(),
-			tc("ignore type",
+			tc("VERIFY PREVIOUS",
+				a("@", "1.2.3.4"),
+				a("@", "2.3.4.5"),
+				txt("@", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
+			tc("apex type",
 				//a("@", "1.2.3.4"),
 				//a("@", "2.3.4.5"),
 				txt("@", "simple"),
@@ -2217,7 +2304,15 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("", "A", ""),
 			).ExpectNoChanges(),
-			tc("ignore type,target",
+			tc("VERIFY PREVIOUS",
+				a("@", "1.2.3.4"),
+				a("@", "2.3.4.5"),
+				txt("@", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
+			tc("apex type,target",
 				a("@", "1.2.3.4"),
 				//a("@", "2.3.4.5"),
 				txt("@", "simple"),
@@ -2225,7 +2320,15 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("", "A", "2.3.4.5"),
 			).ExpectNoChanges(),
-			tc("ignore target",
+			tc("VERIFY PREVIOUS",
+				a("@", "1.2.3.4"),
+				a("@", "2.3.4.5"),
+				txt("@", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
+			tc("apex target",
 				a("@", "1.2.3.4"),
 				//a("@", "2.3.4.5"),
 				txt("@", "simple"),
@@ -2233,8 +2336,16 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("", "", "2.3.4.5"),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("@", "1.2.3.4"),
+				a("@", "2.3.4.5"),
+				txt("@", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
 			// Many types:
-			tc("ignore manytypes",
+			tc("apex manytypes",
 				//a("@", "1.2.3.4"),
 				//a("@", "2.3.4.5"),
 				//txt("@", "simple"),
@@ -2242,31 +2353,52 @@ func makeTests() []*TestGroup {
 				cname("mail", "ghs.googlehosted.com."),
 				ignore("", "A,TXT", ""),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("@", "1.2.3.4"),
+				a("@", "2.3.4.5"),
+				txt("@", "simple"),
+				a("bar", "5.5.5.5"),
+				cname("mail", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
 		),
 
 		// IGNORE with unsafe notation
 
-		testgroup("IGNORE cross",
+		testgroup("IGNORE unsafe",
 			tc("Create some records",
 				txt("foo", "simple"),
 				a("foo", "1.2.3.4"),
 				txt("@", "asimple"),
 				a("@", "2.2.2.2"),
 			),
-			tc("ignore label=apex",
+
+			tc("ignore unsafe apex",
 				txt("foo", "simple"),
 				a("foo", "1.2.3.4"),
 				txt("@", "asimple"),
 				a("@", "2.2.2.2"),
-				ignore("foo", "TXT", ""),
+				ignore("@", "", ""),
 			).ExpectNoChanges().UnsafeIgnore(),
-			tc("ignore label=apex",
+			tc("VERIFY PREVIOUS",
 				txt("foo", "simple"),
 				a("foo", "1.2.3.4"),
 				txt("@", "asimple"),
 				a("@", "2.2.2.2"),
-				ignore("@", "TXT", ""),
+			).ExpectNoChanges(),
+
+			tc("ignore unsafe label",
+				txt("foo", "simple"),
+				a("foo", "1.2.3.4"),
+				txt("@", "asimple"),
+				a("@", "2.2.2.2"),
+				ignore("foo", "", ""),
 			).ExpectNoChanges().UnsafeIgnore(),
+			tc("VERIFY PREVIOUS",
+				txt("foo", "simple"),
+				a("foo", "1.2.3.4"),
+				txt("@", "asimple"),
+				a("@", "2.2.2.2"),
+			).ExpectNoChanges(),
 		),
 
 		// IGNORE with wildcards
@@ -2279,6 +2411,7 @@ func makeTests() []*TestGroup {
 				a("bar.bat", "5.5.5.5"),
 				cname("mail.bat", "ghs.googlehosted.com."),
 			),
+
 			tc("ignore label=foo.*",
 				//a("foo.bat", "1.2.3.4"),
 				//a("foo.bat", "2.3.4.5"),
@@ -2287,6 +2420,14 @@ func makeTests() []*TestGroup {
 				cname("mail.bat", "ghs.googlehosted.com."),
 				ignore("foo.*", "", ""),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("foo.bat", "1.2.3.4"),
+				a("foo.bat", "2.3.4.5"),
+				txt("foo.bat", "simple"),
+				a("bar.bat", "5.5.5.5"),
+				cname("mail.bat", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
 			tc("ignore label=foo.bat,type",
 				//a("foo.bat", "1.2.3.4"),
 				//a("foo.bat", "2.3.4.5"),
@@ -2295,6 +2436,14 @@ func makeTests() []*TestGroup {
 				cname("mail.bat", "ghs.googlehosted.com."),
 				ignore("*.bat", "A", ""),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("foo.bat", "1.2.3.4"),
+				a("foo.bat", "2.3.4.5"),
+				txt("foo.bat", "simple"),
+				a("bar.bat", "5.5.5.5"),
+				cname("mail.bat", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+
 			tc("ignore target=*.domain",
 				a("foo.bat", "1.2.3.4"),
 				a("foo.bat", "2.3.4.5"),
@@ -2303,6 +2452,119 @@ func makeTests() []*TestGroup {
 				//cname("mail.bat", "ghs.googlehosted.com."),
 				ignore("", "", "*.googlehosted.com."),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("foo.bat", "1.2.3.4"),
+				a("foo.bat", "2.3.4.5"),
+				txt("foo.bat", "simple"),
+				a("bar.bat", "5.5.5.5"),
+				cname("mail.bat", "ghs.googlehosted.com."),
+			).ExpectNoChanges(),
+		),
+
+		// IGNORE with changes
+		testgroup("IGNORE with modify",
+			tc("Create some records",
+				a("foo", "1.1.1.1"),
+				a("foo", "10.10.10.10"),
+				aaaa("foo", "2003:dd:d7ff::fe71:aaaa"),
+				mx("foo", 10, "aspmx.l.google.com."),
+				mx("foo", 20, "alt1.aspmx.l.google.com."),
+				a("zzz", "3.3.3.3"),
+				a("zzz", "4.4.4.4"),
+				aaaa("zzz", "2003:dd:d7ff::fe71:cccc"),
+			),
+
+			// ByZone: Change (anywhere)
+			tc("IGNORE change ByZone",
+				ignore("zzz", "A", ""),
+				a("foo", "1.1.1.1"),
+				a("foo", "11.11.11.11"), // CHANGE
+				aaaa("foo", "2003:dd:d7ff::fe71:aaaa"),
+				mx("foo", 10, "aspmx.l.google.com."),
+				mx("foo", 20, "alt1.aspmx.l.google.com."),
+				//a("zzz", "3.3.3.3"),
+				//a("zzz", "4.4.4.4"),
+				aaaa("zzz", "2003:dd:d7ff::fe71:cccc"),
+			),
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.1.1.1"),
+				a("foo", "11.11.11.11"),
+				aaaa("foo", "2003:dd:d7ff::fe71:aaaa"),
+				mx("foo", 10, "aspmx.l.google.com."),
+				mx("foo", 20, "alt1.aspmx.l.google.com."),
+				a("zzz", "3.3.3.3"),
+				a("zzz", "4.4.4.4"),
+				aaaa("zzz", "2003:dd:d7ff::fe71:cccc"),
+			).ExpectNoChanges(),
+
+			// ByLabel: Change within a (name) while we ignore the rest
+			tc("IGNORE change ByLabel",
+				ignore("foo", "MX", ""),
+				a("foo", "1.1.1.1"),
+				a("foo", "12.12.12.12"), // CHANGE
+				aaaa("foo", "2003:dd:d7ff::fe71:aaaa"),
+				//mx("foo", 10, "aspmx.l.google.com."),
+				//mx("foo", 20, "alt1.aspmx.l.google.com"),
+				a("zzz", "3.3.3.3"),
+				a("zzz", "4.4.4.4"),
+				aaaa("zzz", "2003:dd:d7ff::fe71:cccc"),
+			),
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.1.1.1"),
+				a("foo", "12.12.12.12"),
+				aaaa("foo", "2003:dd:d7ff::fe71:aaaa"),
+				mx("foo", 10, "aspmx.l.google.com."),
+				mx("foo", 20, "alt1.aspmx.l.google.com."),
+				a("zzz", "3.3.3.3"),
+				a("zzz", "4.4.4.4"),
+				aaaa("zzz", "2003:dd:d7ff::fe71:cccc"),
+			).ExpectNoChanges(),
+
+			// ByRecordSet: Change within a (name+type) while we ignore the rest
+			tc("IGNORE change ByRecordSet",
+				ignore("foo", "MX,AAAA", ""),
+				a("foo", "1.1.1.1"),
+				a("foo", "13.13.13.13"), // CHANGE
+				//aaaa("foo", "2003:dd:d7ff::fe71:aaaa"),
+				//mx("foo", 10, "aspmx.l.google.com."),
+				//mx("foo", 20, "alt1.aspmx.l.google.com"),
+				a("zzz", "3.3.3.3"),
+				a("zzz", "4.4.4.4"),
+				aaaa("zzz", "2003:dd:d7ff::fe71:cccc"),
+			),
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.1.1.1"),
+				a("foo", "13.13.13.13"),
+				aaaa("foo", "2003:dd:d7ff::fe71:aaaa"),
+				mx("foo", 10, "aspmx.l.google.com."),
+				mx("foo", 20, "alt1.aspmx.l.google.com."),
+				a("zzz", "3.3.3.3"),
+				a("zzz", "4.4.4.4"),
+				aaaa("zzz", "2003:dd:d7ff::fe71:cccc"),
+			).ExpectNoChanges(),
+
+			// Change within a (name+type+data) ("ByRecord")
+			tc("IGNORE change ByRecord",
+				ignore("foo", "A", "1.1.1.1"),
+				//a("foo", "1.1.1.1"),
+				a("foo", "14.14.14.14"),
+				aaaa("foo", "2003:dd:d7ff::fe71:aaaa"),
+				mx("foo", 10, "aspmx.l.google.com."),
+				mx("foo", 20, "alt1.aspmx.l.google.com."),
+				a("zzz", "3.3.3.3"),
+				a("zzz", "4.4.4.4"),
+				aaaa("zzz", "2003:dd:d7ff::fe71:cccc"),
+			),
+			tc("VERIFY PREVIOUS",
+				a("foo", "1.1.1.1"),
+				a("foo", "14.14.14.14"),
+				aaaa("foo", "2003:dd:d7ff::fe71:aaaa"),
+				mx("foo", 10, "aspmx.l.google.com."),
+				mx("foo", 20, "alt1.aspmx.l.google.com."),
+				a("zzz", "3.3.3.3"),
+				a("zzz", "4.4.4.4"),
+				aaaa("zzz", "2003:dd:d7ff::fe71:cccc"),
+			).ExpectNoChanges(),
 		),
 
 		// IGNORE repro bug reports
@@ -2316,6 +2578,10 @@ func makeTests() []*TestGroup {
 			tc("Add a new record - ignoring test.foo.com.",
 				ignoreTarget("**.acm-validations.aws.", "CNAME"),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				cname("foo", "redact1.acm-validations.aws."),
+				cname("bar", "redact2.acm-validations.aws."),
+			).ExpectNoChanges(),
 		),
 
 		// https://github.com/StackExchange/dnscontrol/issues/2822
@@ -2338,6 +2604,12 @@ func makeTests() []*TestGroup {
 				ignore("dyndns-city1", "A,AAAA", ""),
 				ignore("dyndns-city2", "A,AAAA", ""),
 			).ExpectNoChanges().UnsafeIgnore(),
+			tc("VERIFY PREVIOUS",
+				a("dyndns-city1", "91.42.1.1"),
+				a("dyndns-city2", "91.42.1.2"),
+				aaaa("dyndns-city1", "2003:dd:d7ff::fe71:ce77"),
+				aaaa("dyndns-city2", "2003:dd:d7ff::fe71:ce78"),
+			).ExpectNoChanges(),
 		),
 
 		// https://github.com/StackExchange/dnscontrol/issues/3227
@@ -2351,11 +2623,29 @@ func makeTests() []*TestGroup {
 				a("testdefined", "9.9.9.9"),
 				ignore("testignore", "", ""),
 			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("testignore", "8.8.8.8"),
+				a("testdefined", "9.9.9.9"),
+			).ExpectNoChanges(),
+
+			tc("Verify nothing changed",
+				a("testignore", "8.8.8.8"),
+				a("testdefined", "9.9.9.9"),
+			).ExpectNoChanges(),
+			tc("VERIFY PREVIOUS",
+				a("testignore", "8.8.8.8"),
+				a("testdefined", "9.9.9.9"),
+			).ExpectNoChanges(),
+
 			tc("ignore with change",
 				//a("testignore", "8.8.8.8"),
 				a("testdefined", "2.2.2.2"),
 				ignore("testignore", "", ""),
 			),
+			tc("VERIFY PREVIOUS",
+				a("testignore", "8.8.8.8"),
+				a("testdefined", "2.2.2.2"),
+			).ExpectNoChanges(),
 		),
 
 		// OVH features

pkg/diff2/diff2.go

@@ -195,29 +195,47 @@ func ByRecord(existing models.Records, dc *models.DomainConfig, compFunc Compara
 //
 // Example usage:
 //
-//	msgs, changes, err := diff2.ByZone(foundRecords, dc, nil)
+//	result, err := diff2.ByZone(foundRecords, dc, nil)
 //	if err != nil {
 //	  return nil, err
 //	}
 //	if changes {
 //		// Generate a "correction" that uploads the entire zone.
-//		// (dc.Records are the new records for the zone).
+//		// (result.DesiredPlus are the new records for the zone).
 //	}
 //
 // Example providers include: BIND, AUTODNS
-func ByZone(existing models.Records, dc *models.DomainConfig, compFunc ComparableFunc) ([]string, bool, int, error) {
+func ByZone(existing models.Records, dc *models.DomainConfig, compFunc ComparableFunc) (ByResults, error) {
-	// Only return the messages.  The caller has the list of records needed to build the new zone.
+	// Only return the messages and a list of records needed to build the new zone.
-	instructions, actualChangeCount, err := byHelper(analyzeByRecord, existing, dc, compFunc)
+	result, err := byHelperStruct(analyzeByRecord, existing, dc, compFunc)
-	return justMsgs(instructions), actualChangeCount > 0, actualChangeCount, err
+	result.Msgs = justMsgs(result.Instructions)
+	return result, err
 }
 
-//
+// ByResults is the results of ByZone() and perhaps someday all the By*() functions.
+// It is partially populated by // byHelperStruct() and partially by the By*()
+// functions that use it.
+type ByResults struct {
+	// Fields filled in by byHelperStruct():
+	Instructions      ChangeList     // Instructions to turn existing into desired.
+	ActualChangeCount int            // Number of actual changes, not including REPORTs.
+	HasChanges        bool           // True if there are any changes.
+	DesiredPlus       models.Records // Desired + foreign + ignored
+	// Fields filled in by ByZone():
+	Msgs []string // Just the messages from the instructions.
+}
 
-// byHelper does 90% of the work for the By*() calls.
+// byHelper is like byHelperStruct but has a signature that is compatible with legacy code.
+// Deprecated: Use byHelperStruct instead.
 func byHelper(fn func(cc *CompareConfig) (ChangeList, int), existing models.Records, dc *models.DomainConfig, compFunc ComparableFunc) (ChangeList, int, error) {
+	result, err := byHelperStruct(fn, existing, dc, compFunc)
+	return result.Instructions, result.ActualChangeCount, err
+}
 
+// byHelperStruct does 90% of the work for the By*() calls.
+func byHelperStruct(fn func(cc *CompareConfig) (ChangeList, int), existing models.Records, dc *models.DomainConfig, compFunc ComparableFunc) (ByResults, error) {
 	// Process NO_PURGE/ENSURE_ABSENT and IGNORE*().
-	desired, msgs, err := handsoff(
+	desiredPlus, msgs, err := handsoff(
 		dc.Name,
 		existing, dc.Records, dc.EnsureAbsent,
 		dc.Unmanaged,
@@ -225,11 +243,11 @@ func byHelper(fn func(cc *CompareConfig) (ChangeList, int), existing models.Reco
 		dc.KeepUnknown,
 	)
 	if err != nil {
-		return nil, 0, err
+		return ByResults{}, err
 	}
 
 	// Regroup existing/desiredd for easy comparison:
-	cc := NewCompareConfig(dc.Name, existing, desired, compFunc)
+	cc := NewCompareConfig(dc.Name, existing, desiredPlus, compFunc)
 
 	// Analyze and generate the instructions:
 	instructions, actualChangeCount := fn(cc)
@@ -245,5 +263,10 @@ func byHelper(fn func(cc *CompareConfig) (ChangeList, int), existing models.Reco
 		instructions = append([]Change{chg}, instructions...)
 	}
 
-	return instructions, actualChangeCount, nil
+	return ByResults{
+		Instructions:      instructions,
+		ActualChangeCount: actualChangeCount,
+		HasChanges:        actualChangeCount > 0,
+		DesiredPlus:       desiredPlus,
+	}, nil
 }

providers/autodns/autoDnsProvider.go

@@ -77,16 +77,18 @@ func (api *autoDNSProvider) GetZoneRecordsCorrections(dc *models.DomainConfig, e
 
 	var corrections []*models.Correction
 
-	msgs, changed, actualChangeCount, err := diff2.ByZone(existingRecords, dc, nil)
+	result, err := diff2.ByZone(existingRecords, dc, nil)
 	if err != nil {
 		return nil, 0, err
 	}
+	msgs, changed, actualChangeCount := result.Msgs, result.HasChanges, result.ActualChangeCount
+
 	if changed {
 
 		msgs = append(msgs, "Zone update for "+domain)
 		msg := strings.Join(msgs, "\n")
 
-		nameServers, zoneTTL, resourceRecords := recordsToNative(dc.Records)
+		nameServers, zoneTTL, resourceRecords := recordsToNative(result.DesiredPlus)
 
 		corrections = append(corrections,
 			&models.Correction{

providers/bind/bindProvider.go

@@ -211,7 +211,7 @@ func ParseZoneContents(content string, zoneName string, zonefileName string) (mo
 	return foundRecords, nil
 }
 
-func (n *bindProvider) EnsureZoneExists(_ string) error {
+func (c *bindProvider) EnsureZoneExists(_ string) error {
 	return nil
 }
 
@@ -247,12 +247,12 @@ func (c *bindProvider) GetZoneRecordsCorrections(dc *models.DomainConfig, foundR
 	}
 
 	var msgs []string
-	var err error
 	var actualChangeCount int
-	msgs, changes, actualChangeCount, err = diff2.ByZone(foundRecords, dc, nil)
+	result, err := diff2.ByZone(foundRecords, dc, nil)
 	if err != nil {
 		return nil, 0, err
 	}
+	msgs, changes, actualChangeCount = result.Msgs, result.HasChanges, result.ActualChangeCount
 	if !changes {
 		return nil, 0, nil
 	}
@@ -299,7 +299,7 @@ func (c *bindProvider) GetZoneRecordsCorrections(dc *models.DomainConfig, foundR
 				// Beware that if there are any fake types, then they will
 				// be commented out on write, but we don't reverse that when
 				// reading, so there will be a diff on every invocation.
-				err = prettyzone.WriteZoneFileRC(zf, dc.Records, dc.Name, 0, comments)
+				err = prettyzone.WriteZoneFileRC(zf, result.DesiredPlus, dc.Name, 0, comments)
 
 				if err != nil {
 					return fmt.Errorf("failed WriteZoneFile: %w", err)

providers/mythicbeasts/mythicbeastsProvider.go

@@ -115,10 +115,11 @@ func zoneFileToRecords(r io.Reader, origin string) (models.Records, error) {
 
 // GetZoneRecordsCorrections returns a list of corrections that will turn existing records into dc.Records.
 func (n *mythicBeastsProvider) GetZoneRecordsCorrections(dc *models.DomainConfig, actual models.Records) ([]*models.Correction, int, error) {
-	msgs, changes, actualChangeCount, err := diff2.ByZone(actual, dc, nil)
+	result, err := diff2.ByZone(actual, dc, nil)
 	if err != nil {
 		return nil, 0, err
 	}
+	msgs, changes, actualChangeCount := result.Msgs, result.HasChanges, result.ActualChangeCount
 
 	var corrections []*models.Correction
 	if changes {
@@ -127,7 +128,7 @@ func (n *mythicBeastsProvider) GetZoneRecordsCorrections(dc *models.DomainConfig
 				Msg: strings.Join(msgs, "\n"),
 				F: func() error {
 					var b strings.Builder
-					for _, record := range dc.Records {
+					for _, record := range result.DesiredPlus {
 						switch rr := record.ToRR().(type) {
 						case *dns.SSHFP:
 							// "Hex strings [for SSHFP] must be in lower-case", per Mythic Beasts API docs.

providers/realtimeregister/realtimeregisterProvider.go

@@ -107,10 +107,11 @@ func (api *realtimeregisterAPI) GetZoneRecords(domain string, meta map[string]st
 }
 
 func (api *realtimeregisterAPI) GetZoneRecordsCorrections(dc *models.DomainConfig, existing models.Records) ([]*models.Correction, int, error) {
-	msgs, changes, actualChangeCount, err := diff2.ByZone(existing, dc, nil)
+	result, err := diff2.ByZone(existing, dc, nil)
 	if err != nil {
 		return nil, 0, err
 	}
+	msgs, changes, actualChangeCount := result.Msgs, result.HasChanges, result.ActualChangeCount
 
 	var corrections []*models.Correction
 
@@ -149,8 +150,8 @@ func (api *realtimeregisterAPI) GetZoneRecordsCorrections(dc *models.DomainConfi
 			&models.Correction{
 				Msg: strings.Join(msgs, "\n"),
 				F: func() error {
-					records := make([]Record, len(dc.Records))
+					records := make([]Record, len(result.DesiredPlus))
-					for i, r := range dc.Records {
+					for i, r := range result.DesiredPlus {
 						records[i] = toRecord(r)
 					}
 					zone := &Zone{Records: records, Dnssec: dnssec}

providers/sakuracloud/records.go

@@ -65,10 +65,11 @@ func (s *sakuracloudProvider) GetZoneRecordsCorrections(dc *models.DomainConfig,
 		}
 	}
 
-	msgs, changes, actualChangeCount, err := diff2.ByZone(existing, dc, nil)
+	result, err := diff2.ByZone(existing, dc, nil)
 	if err != nil {
 		return nil, 0, err
 	}
+	msgs, changes, actualChangeCount := result.Msgs, result.HasChanges, result.ActualChangeCount
 	if !changes {
 		return nil, actualChangeCount, nil
 	}
@@ -78,8 +79,8 @@ func (s *sakuracloudProvider) GetZoneRecordsCorrections(dc *models.DomainConfig,
 		&models.Correction{
 			Msg: msg,
 			F: func() error {
-				drs := make([]domainRecord, 0, len(dc.Records))
+				drs := make([]domainRecord, 0, len(result.DesiredPlus))
-				for _, rc := range dc.Records {
+				for _, rc := range result.DesiredPlus {
 					drs = append(drs, toNative(rc))
 				}
 				return s.api.UpdateZone(dc.Name, drs)