Use prefix base detection for ints in grok parser (#6434)

plugins/parsers/grok/parser.go

@@ -248,7 +248,7 @@ func (p *Parser) ParseLine(line string) (telegraf.Metric, error) {
 		case MEASUREMENT:
 			p.Measurement = v
 		case INT:
-			iv, err := strconv.ParseInt(v, 10, 64)
+			iv, err := strconv.ParseInt(v, 0, 64)
 			if err != nil {
 				log.Printf("E! Error parsing %s to int: %s", v, err)
 			} else {

plugins/parsers/grok/parser_test.go

@@ -649,6 +649,31 @@ func TestParseErrors_WrongTimeLayout(t *testing.T) {
 		testutil.MustMetric("grok", map[string]string{}, map[string]interface{}{}, time.Unix(0, 0)))
 }
 
+func TestParseInteger_Base16(t *testing.T) {
+	p := &Parser{
+		Patterns: []string{"%{TEST_LOG_C}"},
+		CustomPatterns: `
+			DURATION %{NUMBER}[nuµm]?s
+			BASE10OR16NUM (?:%{BASE10NUM}|%{BASE16NUM})
+			TEST_LOG_C %{NUMBER:myfloat} %{BASE10OR16NUM:response_code:int} %{IPORHOST:clientip} %{DURATION:rt}
+		`,
+	}
+	assert.NoError(t, p.Compile())
+
+	metricA, err := p.ParseLine(`1.25 0xc8 192.168.1.1 5.432µs`)
+	require.NotNil(t, metricA)
+	assert.NoError(t, err)
+	assert.Equal(t,
+		map[string]interface{}{
+			"clientip":      "192.168.1.1",
+			"response_code": int64(200),
+			"myfloat":       "1.25",
+			"rt":            "5.432µs",
+		},
+		metricA.Fields())
+	assert.Equal(t, map[string]string{}, metricA.Tags())
+}
+
 func TestTsModder(t *testing.T) {
 	tsm := &tsModder{}