x-pack/filebeat/input/http_endpoint: canonicalise tls consistency err…

…or (#33720)

Configs may be run in arbitrary order during tests, so make sure that
the error is invariant with respect to the address and reason. This has
no impact on the logic of the input in production.

x-pack/filebeat/input/http_endpoint/input.go

@@ -164,16 +164,32 @@ func (p *pool) serve(ctx v2.Context, e *httpEndpoint, pub stateless.Publisher) e
 }
 
 func checkTLSConsistency(addr string, old, new *tlscommon.ServerConfig) error {
+	if old == nil && new == nil {
+		return nil
+	}
 	if (old == nil) != (new == nil) {
-		return fmt.Errorf("inconsistent TLS usage on %s: mixed TLS and unencrypted", addr)
+		return invalidTLSStateErr{addr: addr, reason: "mixed TLS and unencrypted", old: old, new: new}
 	}
 	if !reflect.DeepEqual(old, new) {
-		return fmt.Errorf("inconsistent TLS configuration on %s: configuration options do not agree: old=%s new=%s",
-			addr, renderTLSConfig(old), renderTLSConfig(new))
+		return invalidTLSStateErr{addr: addr, reason: "configuration options do not agree", old: old, new: new}
 	}
 	return nil
 }
 
+type invalidTLSStateErr struct {
+	addr     string
+	reason   string
+	old, new *tlscommon.ServerConfig
+}
+
+func (e invalidTLSStateErr) Error() string {
+	if e.old == nil || e.new == nil {
+		return fmt.Sprintf("inconsistent TLS usage on %s: %s", e.addr, e.reason)
+	}
+	return fmt.Sprintf("inconsistent TLS configuration on %s: %s: old=%s new=%s",
+		e.addr, e.reason, renderTLSConfig(e.old), renderTLSConfig(e.new))
+}
+
 func renderTLSConfig(tls *tlscommon.ServerConfig) string {
 	c, err := conf.NewConfigFrom(tls)
 	if err != nil {

x-pack/filebeat/input/http_endpoint/input_test.go

@@ -162,7 +162,7 @@ var serverPoolTests = []struct {
 				},
 			},
 		},
-		wantErr: errors.New("inconsistent TLS usage on 127.0.0.1:9001: mixed TLS and unencrypted"),
+		wantErr: invalidTLSStateErr{addr: "127.0.0.1:9001", reason: "mixed TLS and unencrypted"},
 	},
 	{
 		name: "inconsistent_tls_config",
@@ -198,10 +198,7 @@ var serverPoolTests = []struct {
 				},
 			},
 		},
-		wantErr: errors.New(`inconsistent TLS configuration on 127.0.0.1:9001: ` +
-			`configuration options do not agree: ` +
-			`old={"ca_sha256":[],"certificate":"","certificate_authorities":[],"cipher_suites":[],"client_authentication":0,"curve_types":[],"key":"","key_passphrase":"","supported_protocols":[],"verification_mode":1} ` +
-			`new={"ca_sha256":[],"certificate":"","certificate_authorities":[],"cipher_suites":[],"client_authentication":0,"curve_types":[],"key":"","key_passphrase":"","supported_protocols":[],"verification_mode":3}`),
+		wantErr: invalidTLSStateErr{addr: "127.0.0.1:9001", reason: "configuration options do not agree"},
 	},
 }
 
@@ -241,7 +238,7 @@ func TestServerPool(t *testing.T) {
 			case err := <-fails:
 				if test.wantErr == nil {
 					t.Errorf("unexpected error calling serve: %#q", err)
-				} else if test.wantErr.Error() != err.Error() {
+				} else if !errors.Is(err, test.wantErr) {
 					t.Errorf("unexpected error calling serve: got=%#q, want=%#q", err, test.wantErr)
 				}
 			default:
@@ -272,6 +269,18 @@ func TestServerPool(t *testing.T) {
 	}
 }
 
+// Is is included to simplify testing, but is not exposed to avoid unwanted error
+// matching outside tests.
+func (e invalidTLSStateErr) Is(err error) bool {
+	if err, ok := err.(invalidTLSStateErr); ok { //nolint:errorlint // "An Is method should only shallowly compare err and the target and not call Unwrap on either."
+		// However for our purposes here, we will abuse
+		// the Is convention and also consider the addr
+		// and reason fields.
+		return e.addr == err.addr && e.reason == err.reason
+	}
+	return false
+}
+
 func newCtx(log, id string) (_ v2.Context, cancel func()) {
 	ctx, cancel := context.WithCancel(context.Background())
 	return v2.Context{