Add additional tags for x509 Input Plugin (#6686)

plugins/inputs/x509_cert/x509_cert_test.go

@@ -5,6 +5,7 @@ import (
 	"encoding/base64"
 	"fmt"
 	"io/ioutil"
+	"math/big"
 	"os"
 	"testing"
 	"time"
@@ -195,6 +196,61 @@ func TestGatherLocal(t *testing.T) {
 	}
 }
 
+func TestTags(t *testing.T) {
+	cert := fmt.Sprintf("%s\n%s", pki.ReadServerCert(), pki.ReadCACert())
+
+	f, err := ioutil.TempFile("", "x509_cert")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = f.Write([]byte(cert))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = f.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	defer os.Remove(f.Name())
+
+	sc := X509Cert{
+		Sources: []string{f.Name()},
+	}
+	sc.Init()
+
+	acc := testutil.Accumulator{}
+	err = sc.Gather(&acc)
+	require.NoError(t, err)
+
+	assert.True(t, acc.HasMeasurement("x509_cert"))
+
+	assert.True(t, acc.HasTag("x509_cert", "common_name"))
+	assert.Equal(t, "server.localdomain", acc.TagValue("x509_cert", "common_name"))
+
+	assert.True(t, acc.HasTag("x509_cert", "signature_algorithm"))
+	assert.Equal(t, "SHA256-RSA", acc.TagValue("x509_cert", "signature_algorithm"))
+
+	assert.True(t, acc.HasTag("x509_cert", "public_key_algorithm"))
+	assert.Equal(t, "RSA", acc.TagValue("x509_cert", "public_key_algorithm"))
+
+	assert.True(t, acc.HasTag("x509_cert", "issuer_common_name"))
+	assert.Equal(t, "Telegraf Test CA", acc.TagValue("x509_cert", "issuer_common_name"))
+
+	assert.True(t, acc.HasTag("x509_cert", "san"))
+	assert.Equal(t, "localhost,127.0.0.1", acc.TagValue("x509_cert", "san"))
+
+	assert.True(t, acc.HasTag("x509_cert", "serial_number"))
+	serialNumber := new(big.Int)
+	_, validSerialNumber := serialNumber.SetString(acc.TagValue("x509_cert", "serial_number"), 16)
+	if !validSerialNumber {
+		t.Errorf("Expected a valid Hex serial number but got %s", acc.TagValue("x509_cert", "serial_number"))
+	}
+	assert.Equal(t, big.NewInt(1), serialNumber)
+}
+
 func TestGatherChain(t *testing.T) {
 	cert := fmt.Sprintf("%s\n%s", pki.ReadServerCert(), pki.ReadCACert())