[chore] Update connection method of Cisco OS Receiver (open-telemetry#43920)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
Refactors the Cisco OS receiver connection handling:

<!-- Issue number (e.g. open-telemetry#1234) or full URL to issue, if applicable. -->
#### Link to tracking issue

open-telemetry#42647

Fixes
- Centralized connection establishment logic into shared connection
factory
- Removed duplicate validation checks across receiver and connection
layers
- Simplified scraper nil checks and updated related tests
- Cleaned up linting issues (unused imports, context usage)
<!--Describe what testing was performed and which tests were added.-->
#### Testing
- Connection factory tests for password and key file authentication
- Scraper initialization and shutdown tests added
<!--Describe the documentation added.-->
#### Documentation
- Simplified inline documentation throughout connection handling code

<!--Please delete paragraphs that you did not use before submitting.-->

Author: etserend

receiver/ciscoosreceiver/config.go

@@ -8,48 +8,21 @@ import (
 	"fmt"
 
 	"go.opentelemetry.io/collector/component"
-	"go.opentelemetry.io/collector/config/configopaque"
 	"go.opentelemetry.io/collector/confmap"
 	"go.opentelemetry.io/collector/confmap/xconfmap"
 	"go.opentelemetry.io/collector/scraper/scraperhelper"
 	"go.uber.org/multierr"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ciscoosreceiver/internal/connection"
 )
 
 // Config defines configuration for Cisco OS receiver.
 type Config struct {
 	scraperhelper.ControllerConfig `mapstructure:",squash"`
-	Device                         DeviceConfig                        `mapstructure:"device"`
+	Device                         connection.DeviceConfig             `mapstructure:"device"`
 	Scrapers                       map[component.Type]component.Config `mapstructure:"-"`
 }
 
-// DeviceConfig represents configuration for a single Cisco device using semantic conventions
-type DeviceConfig struct {
-	Device DeviceInfo `mapstructure:"device"`
-	Auth   AuthConfig `mapstructure:"auth"`
-}
-
-// DeviceInfo follows semantic conventions for device identification
-type DeviceInfo struct {
-	// DO NOT USE unkeyed struct initialization
-	_ struct{} `mapstructure:"-"`
-
-	Host HostInfo `mapstructure:"host"`
-}
-
-// HostInfo contains host-specific information
-type HostInfo struct {
-	Name string `mapstructure:"name"`
-	IP   string `mapstructure:"ip"`
-	Port int    `mapstructure:"port"`
-}
-
-// AuthConfig represents authentication configuration
-type AuthConfig struct {
-	Username string              `mapstructure:"username"`
-	Password configopaque.String `mapstructure:"password"`
-	KeyFile  string              `mapstructure:"key_file"`
-}
-
 var (
 	_ xconfmap.Validator  = (*Config)(nil)
 	_ confmap.Unmarshaler = (*Config)(nil)

receiver/ciscoosreceiver/config_test.go

@@ -12,6 +12,8 @@ import (
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/config/configopaque"
 	"go.opentelemetry.io/collector/scraper/scraperhelper"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ciscoosreceiver/internal/connection"
 )
 
 func TestConfigValidate(t *testing.T) {
@@ -27,15 +29,15 @@ func TestConfigValidate(t *testing.T) {
 					Timeout:            30 * time.Second,
 					CollectionInterval: 60 * time.Second,
 				},
-				Device: DeviceConfig{
-					Device: DeviceInfo{
-						Host: HostInfo{
+				Device: connection.DeviceConfig{
+					Device: connection.DeviceInfo{
+						Host: connection.HostInfo{
 							Name: "test-device",
 							IP:   "192.168.1.1",
 							Port: 22,
 						},
 					},
-					Auth: AuthConfig{
+					Auth: connection.AuthConfig{
 						Username: "admin",
 						Password: configopaque.String("password"),
 					},
@@ -53,15 +55,15 @@ func TestConfigValidate(t *testing.T) {
 					Timeout:            30 * time.Second,
 					CollectionInterval: 60 * time.Second,
 				},
-				Device: DeviceConfig{
-					Device: DeviceInfo{
-						Host: HostInfo{
+				Device: connection.DeviceConfig{
+					Device: connection.DeviceInfo{
+						Host: connection.HostInfo{
 							Name: "test-device",
 							IP:   "192.168.1.1",
 							Port: 22,
 						},
 					},
-					Auth: AuthConfig{
+					Auth: connection.AuthConfig{
 						Username: "admin",
 						KeyFile:  "/path/to/key",
 					},
@@ -79,7 +81,7 @@ func TestConfigValidate(t *testing.T) {
 					Timeout:            30 * time.Second,
 					CollectionInterval: 60 * time.Second,
 				},
-				Device: DeviceConfig{},
+				Device: connection.DeviceConfig{},
 				Scrapers: map[component.Type]component.Config{
 					component.MustNewType("system"): nil,
 				},
@@ -93,15 +95,15 @@ func TestConfigValidate(t *testing.T) {
 					Timeout:            30 * time.Second,
 					CollectionInterval: 60 * time.Second,
 				},
-				Device: DeviceConfig{
-					Device: DeviceInfo{
-						Host: HostInfo{
+				Device: connection.DeviceConfig{
+					Device: connection.DeviceInfo{
+						Host: connection.HostInfo{
 							Name: "test-device",
 							IP:   "192.168.1.1",
 							Port: 0,
 						},
 					},
-					Auth: AuthConfig{
+					Auth: connection.AuthConfig{
 						Username: "admin",
 						Password: configopaque.String("password"),
 					},
@@ -119,15 +121,15 @@ func TestConfigValidate(t *testing.T) {
 					Timeout:            30 * time.Second,
 					CollectionInterval: 60 * time.Second,
 				},
-				Device: DeviceConfig{
-					Device: DeviceInfo{
-						Host: HostInfo{
+				Device: connection.DeviceConfig{
+					Device: connection.DeviceInfo{
+						Host: connection.HostInfo{
 							Name: "test-device",
 							IP:   "192.168.1.1",
 							Port: 22,
 						},
 					},
-					Auth: AuthConfig{
+					Auth: connection.AuthConfig{
 						Username: "",
 						Password: configopaque.String("password"),
 					},
@@ -145,15 +147,15 @@ func TestConfigValidate(t *testing.T) {
 					Timeout:            30 * time.Second,
 					CollectionInterval: 60 * time.Second,
 				},
-				Device: DeviceConfig{
-					Device: DeviceInfo{
-						Host: HostInfo{
+				Device: connection.DeviceConfig{
+					Device: connection.DeviceInfo{
+						Host: connection.HostInfo{
 							Name: "test-device",
 							IP:   "192.168.1.1",
 							Port: 22,
 						},
 					},
-					Auth: AuthConfig{
+					Auth: connection.AuthConfig{
 						Username: "admin",
 					},
 				},
@@ -170,15 +172,15 @@ func TestConfigValidate(t *testing.T) {
 					Timeout:            30 * time.Second,
 					CollectionInterval: 60 * time.Second,
 				},
-				Device: DeviceConfig{
-					Device: DeviceInfo{
-						Host: HostInfo{
+				Device: connection.DeviceConfig{
+					Device: connection.DeviceInfo{
+						Host: connection.HostInfo{
 							Name: "test-device",
 							IP:   "192.168.1.1",
 							Port: 22,
 						},
 					},
-					Auth: AuthConfig{
+					Auth: connection.AuthConfig{
 						Username: "admin",
 						Password: configopaque.String("password"),
 					},

receiver/ciscoosreceiver/factory.go

@@ -66,10 +66,10 @@ func createMetricsReceiver(
 
 		// Inject device configuration into scraper config
 		if sysCfg, ok := scraperCfg.(*systemscraper.Config); ok {
-			sysCfg.Device = convertToSystemScraperDeviceConfig(conf.Device)
+			sysCfg.Device = conf.Device
 		}
 		if intfCfg, ok := scraperCfg.(*interfacesscraper.Config); ok {
-			intfCfg.Device = convertToInterfacesScraperDeviceConfig(conf.Device)
+			intfCfg.Device = conf.Device
 		}
 
 		scraperOptions = append(scraperOptions, scraperhelper.AddFactoryWithConfig(factory, scraperCfg))
@@ -87,36 +87,6 @@ func createMetricsReceiver(
 	)
 }
 
-func convertToSystemScraperDeviceConfig(device DeviceConfig) systemscraper.DeviceConfig {
-	return systemscraper.DeviceConfig{
-		Host: systemscraper.HostInfo{
-			Name: device.Device.Host.Name,
-			IP:   device.Device.Host.IP,
-			Port: device.Device.Host.Port,
-		},
-		Auth: systemscraper.AuthConfig{
-			Username: device.Auth.Username,
-			Password: string(device.Auth.Password),
-			KeyFile:  device.Auth.KeyFile,
-		},
-	}
-}
-
-func convertToInterfacesScraperDeviceConfig(device DeviceConfig) interfacesscraper.DeviceConfig {
-	return interfacesscraper.DeviceConfig{
-		Host: interfacesscraper.HostInfo{
-			Name: device.Device.Host.Name,
-			IP:   device.Device.Host.IP,
-			Port: device.Device.Host.Port,
-		},
-		Auth: interfacesscraper.AuthConfig{
-			Username: device.Auth.Username,
-			Password: string(device.Auth.Password),
-			KeyFile:  device.Auth.KeyFile,
-		},
-	}
-}
-
 type nopMetricsReceiver struct{}
 
 func (*nopMetricsReceiver) Start(_ context.Context, _ component.Host) error { return nil }

receiver/ciscoosreceiver/factory_test.go

@@ -15,6 +15,7 @@ import (
 	"go.opentelemetry.io/collector/consumer/consumertest"
 	"go.opentelemetry.io/collector/receiver/receivertest"
 
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ciscoosreceiver/internal/connection"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ciscoosreceiver/internal/metadata"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ciscoosreceiver/internal/scraper/interfacesscraper"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ciscoosreceiver/internal/scraper/systemscraper"
@@ -45,15 +46,15 @@ func TestCreateMetricsReceiver(t *testing.T) {
 
 	// Add a device and scraper to make config valid
 	config := cfg.(*Config)
-	config.Device = DeviceConfig{
-		Device: DeviceInfo{
-			Host: HostInfo{
+	config.Device = connection.DeviceConfig{
+		Device: connection.DeviceInfo{
+			Host: connection.HostInfo{
 				Name: "test-device",
 				IP:   "192.168.1.1",
 				Port: 22,
 			},
 		},
-		Auth: AuthConfig{
+		Auth: connection.AuthConfig{
 			Username: "admin",
 			Password: configopaque.String("password"),
 		},
@@ -85,15 +86,15 @@ func TestCreateMetricsReceiverWithInterfacesScraper(t *testing.T) {
 
 	// Add a device and interfaces scraper
 	config := cfg.(*Config)
-	config.Device = DeviceConfig{
-		Device: DeviceInfo{
-			Host: HostInfo{
+	config.Device = connection.DeviceConfig{
+		Device: connection.DeviceInfo{
+			Host: connection.HostInfo{
 				Name: "test-device",
 				IP:   "192.168.1.1",
 				Port: 22,
 			},
 		},
-		Auth: AuthConfig{
+		Auth: connection.AuthConfig{
 			Username: "admin",
 			Password: configopaque.String("password"),
 		},
@@ -118,15 +119,15 @@ func TestCreateMetricsReceiverWithBothScrapers(t *testing.T) {
 
 	// Add a device and both scrapers
 	config := cfg.(*Config)
-	config.Device = DeviceConfig{
-		Device: DeviceInfo{
-			Host: HostInfo{
+	config.Device = connection.DeviceConfig{
+		Device: connection.DeviceInfo{
+			Host: connection.HostInfo{
 				Name: "test-device",
 				IP:   "192.168.1.1",
 				Port: 22,
 			},
 		},
-		Auth: AuthConfig{
+		Auth: connection.AuthConfig{
 			Username: "admin",
 			Password: configopaque.String("password"),
 		},

receiver/ciscoosreceiver/internal/connection/config.go

@@ -0,0 +1,34 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package connection // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/ciscoosreceiver/internal/connection"
+
+import "go.opentelemetry.io/collector/config/configopaque"
+
+// DeviceConfig represents configuration for a single Cisco device using semantic conventions
+type DeviceConfig struct {
+	Device DeviceInfo `mapstructure:"device"`
+	Auth   AuthConfig `mapstructure:"auth"`
+}
+
+// DeviceInfo follows semantic conventions for device identification
+type DeviceInfo struct {
+	// DO NOT USE unkeyed struct initialization
+	_ struct{} `mapstructure:"-"`
+
+	Host HostInfo `mapstructure:"host"`
+}
+
+// HostInfo contains host-specific information
+type HostInfo struct {
+	Name string `mapstructure:"name"`
+	IP   string `mapstructure:"ip"`
+	Port int    `mapstructure:"port"`
+}
+
+// AuthConfig represents authentication configuration
+type AuthConfig struct {
+	Username string              `mapstructure:"username"`
+	Password configopaque.String `mapstructure:"password"`
+	KeyFile  string              `mapstructure:"key_file"`
+}