[exporter/syslog]: fix setting network connection (#31202)

**Description:** fix setting network connection, do not load TLS
configuration for UDP

**Link to tracking Issue:** #31130 

**Testing:** unit test, manual tests with syslog server

**Documentation:** added information that TLS config is applied only
when TCP is used

Signed-off-by: Katarzyna Kujawa <[email protected]>

.chloggen/fix-31130.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: syslogexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: fix setting network connection, do not load TLS configuration for UDP
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [31130]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

exporter/syslogexporter/README.md

@@ -28,7 +28,7 @@ This means that syslog messages received via the Syslog receiver and exported vi
   - `rfc5424` - Expects the syslog messages to be rfc5424 compliant
   - `rfc3164` - Expects the syslog messages to be rfc3164 compliant
 - `enable_octet_counting` (default = `false`) - Whether or not to enable rfc6587 octet counting
-- `tls` - configuration for TLS/mTLS
+- `tls` - configuration for TLS/mTLS (applied only when `network` is set to `tcp`)
   - `insecure` (default = `false`) whether to enable client transport security, by default, TLS is enabled.
   - `cert_file` - Path to the TLS cert to use for TLS required connections. Should only be used if `insecure` is set to `false`.
   - `key_file` - Path to the TLS key to use for TLS required connections. Should only be used if `insecure` is set to `false`.

exporter/syslogexporter/exporter.go

@@ -25,17 +25,21 @@ type syslogexporter struct {
 }
 
 func initExporter(cfg *Config, createSettings exporter.CreateSettings) (*syslogexporter, error) {
-	tlsConfig, err := cfg.TLSSetting.LoadTLSConfig()
-	if err != nil {
-		return nil, err
-	}
-
 	cfg.Network = strings.ToLower(cfg.Network)
 
+	var loadedTLSConfig *tls.Config
+	if cfg.Network == "tcp" {
+		var err error
+		loadedTLSConfig, err = cfg.TLSSetting.LoadTLSConfig()
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	s := &syslogexporter{
 		config:    cfg,
 		logger:    createSettings.Logger,
-		tlsConfig: tlsConfig,
+		tlsConfig: loadedTLSConfig,
 		formatter: createFormatter(cfg.Protocol, cfg.EnableOctetCounting),
 	}
 

exporter/syslogexporter/exporter_test.go

@@ -5,6 +5,7 @@ package syslogexporter
 
 import (
 	"context"
+	"crypto/tls"
 	"errors"
 	"io"
 	"net"
@@ -15,6 +16,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/config/configtls"
 	"go.opentelemetry.io/collector/consumer/consumererror"
 	"go.opentelemetry.io/collector/exporter"
 	"go.opentelemetry.io/collector/pdata/pcommon"
@@ -183,3 +185,55 @@ func TestSyslogExportFail(t *testing.T) {
 	assert.ErrorContains(t, consumerErr, "dial tcp 127.0.0.1:112: connect")
 	assert.Equal(t, droppedLog, originalForm)
 }
+
+func TestTLSConfig(t *testing.T) {
+
+	tests := []struct {
+		name        string
+		network     string
+		tlsSettings configtls.TLSClientSetting
+		tlsConfig   *tls.Config
+	}{
+		{name: "TCP with TLS configuration",
+			network:     "tcp",
+			tlsSettings: configtls.TLSClientSetting{},
+			tlsConfig:   &tls.Config{},
+		},
+		{name: "TCP insecure",
+			network:     "tcp",
+			tlsSettings: configtls.TLSClientSetting{Insecure: true},
+			tlsConfig:   nil,
+		},
+		{name: "UDP with TLS configuration",
+			network:     "udp",
+			tlsSettings: configtls.TLSClientSetting{},
+			tlsConfig:   nil,
+		},
+		{name: "UDP insecure",
+			network:     "udp",
+			tlsSettings: configtls.TLSClientSetting{Insecure: true},
+			tlsConfig:   nil,
+		},
+	}
+
+	for _, testInstance := range tests {
+		t.Run(testInstance.name, func(t *testing.T) {
+
+			exporter, err := initExporter(
+				&Config{Endpoint: "test.com",
+					Network:    testInstance.network,
+					Port:       514,
+					Protocol:   "rfc5424",
+					TLSSetting: testInstance.tlsSettings},
+				createExporterCreateSettings())
+
+			assert.NoError(t, err)
+			if testInstance.tlsConfig != nil {
+				assert.NotNil(t, exporter.tlsConfig)
+			} else {
+				assert.Nil(t, exporter.tlsConfig)
+			}
+
+		})
+	}
+}

exporter/syslogexporter/sender.go

@@ -78,8 +78,8 @@ func (s *sender) dial() error {
 		s.conn = nil
 	}
 	var err error
-	if s.tlsConfig != nil {
-		s.conn, err = tls.Dial("tcp", s.addr, s.tlsConfig)
+	if s.tlsConfig != nil && s.network == "tcp" {
+		s.conn, err = tls.Dial(s.network, s.addr, s.tlsConfig)
 	} else {
 		s.conn, err = net.Dial(s.network, s.addr)
 	}