Avoid using type casting on Config, otel core guarantees access to in…

…stances (#368)

* Avoid using type casting on Config, otel core guarantees access to instances

OpenTelemetry collector core in the Host interface does not guarantee access to the Config as a Key in the map (which is NamedInstance and not config.Extension).

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

* Adopt extension as SmartAgentConfigProvider in tests

Co-authored-by: Ryan Fitzpatrick <rmfitzpatrick@signalfx.com>

internal/extension/smartagentextension/config.go

@@ -27,12 +27,6 @@ import (
 	"github.com/signalfx/splunk-otel-collector/internal/utils"
 )
 
-// SmartAgentConfigProvider exposes global saconfig.Config to other components
-type SmartAgentConfigProvider interface {
-	SmartAgentConfig() *saconfig.Config
-}
-
-var _ SmartAgentConfigProvider = (*Config)(nil)
 var _ config.CustomUnmarshable = (*Config)(nil)
 
 type Config struct {
@@ -42,10 +36,6 @@ type Config struct {
 	saconfig.Config `mapstructure:"-,squash"`
 }
 
-func (cfg Config) SmartAgentConfig() *saconfig.Config {
-	return &cfg.Config
-}
-
 func (cfg *Config) Unmarshal(componentParser *config.Parser) error {
 	allSettings := componentParser.Viper().AllSettings()
 

internal/extension/smartagentextension/config_linux_test.go

@@ -16,10 +16,12 @@
 package smartagentextension
 
 import (
+	"context"
 	"path"
 	"testing"
 
 	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/component/componenttest"
 	"go.opentelemetry.io/collector/config/configtest"
 )
@@ -42,7 +44,11 @@ func TestBundleDirDefault(t *testing.T) {
 	allSettingsConfig := cfg.Extensions["smartagent/default_settings"]
 	require.NotNil(t, allSettingsConfig)
 
-	saConfigProvider, ok := allSettingsConfig.(SmartAgentConfigProvider)
+	ext, err := factory.CreateExtension(context.Background(), component.ExtensionCreateParams{}, allSettingsConfig)
+	require.NoError(t, err)
+	require.NotNil(t, ext)
+
+	saConfigProvider, ok := ext.(SmartAgentConfigProvider)
 	require.True(t, ok)
 
 	require.Equal(t, "/usr/lib/splunk-otel-collector/agent-bundle", saConfigProvider.SmartAgentConfig().BundleDir)

internal/extension/smartagentextension/config_test.go

@@ -15,6 +15,7 @@
 package smartagentextension
 
 import (
+	"context"
 	"path"
 	"path/filepath"
 	"testing"
@@ -25,6 +26,7 @@ import (
 	"github.com/signalfx/signalfx-agent/pkg/core/config/sources/file"
 	"github.com/signalfx/signalfx-agent/pkg/utils/timeutil"
 	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/component/componenttest"
 	"go.opentelemetry.io/collector/config"
 	"go.opentelemetry.io/collector/config/configcheck"
@@ -120,7 +122,11 @@ func TestSmartAgentConfigProvider(t *testing.T) {
 	allSettingsConfig := cfg.Extensions["smartagent/all_settings"]
 	require.NotNil(t, allSettingsConfig)
 
-	saConfigProvider, ok := allSettingsConfig.(SmartAgentConfigProvider)
+	ext, err := factory.CreateExtension(context.Background(), component.ExtensionCreateParams{}, allSettingsConfig)
+	require.NoError(t, err)
+	require.NotNil(t, ext)
+
+	saConfigProvider, ok := ext.(SmartAgentConfigProvider)
 	require.True(t, ok)
 
 	require.Equal(t, func() saconfig.CollectdConfig {

internal/extension/smartagentextension/config_windows_test.go

@@ -16,10 +16,12 @@
 package smartagentextension
 
 import (
+	"context"
 	"path"
 	"testing"
 
 	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/component/componenttest"
 	"go.opentelemetry.io/collector/config/configtest"
 )
@@ -42,7 +44,11 @@ func TestBundleDirDefault(t *testing.T) {
 	allSettingsConfig := cfg.Extensions["smartagent/default_settings"]
 	require.NotNil(t, allSettingsConfig)
 
-	saConfigProvider, ok := allSettingsConfig.(SmartAgentConfigProvider)
+	ext, err := factory.CreateExtension(context.Background(), component.ExtensionCreateParams{}, allSettingsConfig)
+	require.NoError(t, err)
+	require.NotNil(t, ext)
+
+	saConfigProvider, ok := ext.(SmartAgentConfigProvider)
 	require.True(t, ok)
 
 	require.Equal(t, "C:\\Program Files\\Splunk\\OpenTelemetry Collector\\agent-bundle", saConfigProvider.SmartAgentConfig().BundleDir)

internal/extension/smartagentextension/extension.go

@@ -17,14 +17,20 @@ package smartagentextension
 import (
 	"context"
 
+	saconfig "github.com/signalfx/signalfx-agent/pkg/core/config"
 	"go.opentelemetry.io/collector/component"
-	"go.opentelemetry.io/collector/config"
 )
 
+// SmartAgentConfigProvider exposes global saconfig.Config to other components
+type SmartAgentConfigProvider interface {
+	SmartAgentConfig() *saconfig.Config
+}
+
 type smartAgentConfigExtension struct {
+	saCfg *saconfig.Config
 }
 
-var _ component.Extension = (*smartAgentConfigExtension)(nil)
+var _ SmartAgentConfigProvider = (*smartAgentConfigExtension)(nil)
 
 func (sae *smartAgentConfigExtension) Start(_ context.Context, _ component.Host) error {
 	return nil
@@ -34,6 +40,10 @@ func (sae *smartAgentConfigExtension) Shutdown(_ context.Context) error {
 	return nil
 }
 
-func newSmartAgentConfigExtension(_ config.Extension) (*smartAgentConfigExtension, error) {
-	return &smartAgentConfigExtension{}, nil
+func (sae *smartAgentConfigExtension) SmartAgentConfig() *saconfig.Config {
+	return sae.saCfg
+}
+
+func newSmartAgentConfigExtension(cfg *Config) (component.Extension, error) {
+	return &smartAgentConfigExtension{saCfg: &cfg.Config}, nil
 }

internal/extension/smartagentextension/factory.go

@@ -88,5 +88,5 @@ func createExtension(
 	_ component.ExtensionCreateParams,
 	cfg config.Extension,
 ) (component.Extension, error) {
-	return newSmartAgentConfigExtension(cfg)
+	return newSmartAgentConfigExtension(cfg.(*Config))
 }

internal/receiver/smartagentreceiver/receiver.go

@@ -57,7 +57,7 @@ var (
 	rusToZap                 *logrusToZap
 	configureCollectdOnce    sync.Once
 	configureEnvironmentOnce sync.Once
-	saConfigProvider         smartagentextension.SmartAgentConfigProvider
+	saConfig                 *saconfig.Config
 	configureRusToZapOnce    sync.Once
 	nonWordCharacters        = regexp.MustCompile(`[^\w]+`)
 )
@@ -113,7 +113,7 @@ func (r *Receiver) Start(_ context.Context, host component.Host) error {
 		return fmt.Errorf("failed creating monitor %q: %w", monitorType, err)
 	}
 
-	configCore.ProcPath = saConfigProvider.SmartAgentConfig().ProcPath
+	configCore.ProcPath = saConfig.ProcPath
 
 	return saconfig.CallConfigure(r.monitor, r.config.monitorConfig)
 }
@@ -185,7 +185,7 @@ func (r *Receiver) createMonitor(monitorType string, host component.Host) (monit
 	if r.config.monitorConfig.MonitorConfigCore().IsCollectdBased() {
 		configureCollectdOnce.Do(func() {
 			r.logger.Info("Configuring collectd")
-			err = collectd.ConfigureMainCollectd(&saConfigProvider.SmartAgentConfig().Collectd)
+			err = collectd.ConfigureMainCollectd(&saConfig.Collectd)
 		})
 	}
 
@@ -195,15 +195,14 @@ func (r *Receiver) createMonitor(monitorType string, host component.Host) (monit
 func (r *Receiver) setUpSmartAgentConfigProvider(extensions map[config.NamedEntity]component.Extension) {
 	// If smartagent extension is not configured, use the default config.
 	f := smartagentextension.NewFactory()
-	defaultCfg := f.CreateDefaultConfig().(smartagentextension.SmartAgentConfigProvider)
-	saConfigProvider = defaultCfg
+	saConfig = &f.CreateDefaultConfig().(*smartagentextension.Config).Config
 
 	// Do a lookup for any smartagent extensions to pick up common collectd options
 	// to be applied across instances of the receiver.
 	var foundAtLeastOne bool
 	var multipleSAExtensions bool
 	var chosenExtension string
-	for c := range extensions {
+	for c, ext := range extensions {
 		if c.Type() != f.Type() {
 			continue
 		}
@@ -214,11 +213,11 @@ func (r *Receiver) setUpSmartAgentConfigProvider(extensions map[config.NamedEnti
 		}
 
 		var cfgProvider smartagentextension.SmartAgentConfigProvider
-		cfgProvider, foundAtLeastOne = c.(smartagentextension.SmartAgentConfigProvider)
+		cfgProvider, foundAtLeastOne = ext.(smartagentextension.SmartAgentConfigProvider)
 		if !foundAtLeastOne {
 			continue
 		}
-		saConfigProvider = cfgProvider
+		saConfig = cfgProvider.SmartAgentConfig()
 		chosenExtension = c.Name()
 		r.logger.Info("Smart Agent Config provider configured", zap.String("extension_name", chosenExtension))
 	}
@@ -229,15 +228,14 @@ func (r *Receiver) setUpSmartAgentConfigProvider(extensions map[config.NamedEnti
 }
 
 func setUpEnvironment() {
-	cfg := saConfigProvider.SmartAgentConfig()
-	os.Setenv(constants.BundleDirEnvVar, cfg.BundleDir)
+	os.Setenv(constants.BundleDirEnvVar, saConfig.BundleDir)
 	if runtime.GOOS != "windows" { // Agent bundle doesn't include jre for Windows
-		os.Setenv("JAVA_HOME", filepath.Join(cfg.BundleDir, "jre"))
+		os.Setenv("JAVA_HOME", filepath.Join(saConfig.BundleDir, "jre"))
 	}
 
-	os.Setenv(hostfs.HostProcVar, cfg.ProcPath)
-	os.Setenv(hostfs.HostEtcVar, cfg.EtcPath)
-	os.Setenv(hostfs.HostVarVar, cfg.VarPath)
-	os.Setenv(hostfs.HostRunVar, cfg.RunPath)
-	os.Setenv(hostfs.HostSysVar, cfg.SysPath)
+	os.Setenv(hostfs.HostProcVar, saConfig.ProcPath)
+	os.Setenv(hostfs.HostEtcVar, saConfig.EtcPath)
+	os.Setenv(hostfs.HostVarVar, saConfig.VarPath)
+	os.Setenv(hostfs.HostRunVar, saConfig.RunPath)
+	os.Setenv(hostfs.HostSysVar, saConfig.SysPath)
 }

internal/receiver/smartagentreceiver/receiver_test.go

@@ -323,7 +323,7 @@ func TestSmartAgentConfigProviderOverrides(t *testing.T) {
 		HasGenericJMXMonitor: false,
 		InstanceName:         "",
 		WriteServerQuery:     "",
-	}, saConfigProvider.SmartAgentConfig().Collectd)
+	}, saConfig.Collectd)
 
 	// Ensure envs are setup.
 	require.Equal(t, "/opt/", os.Getenv("SIGNALFX_BUNDLE_DIR"))
@@ -384,7 +384,7 @@ func (m *mockHost) GetExtensions() map[config.NamedEntity]component.Extension {
 	return map[config.NamedEntity]component.Extension{
 		m.smartagentextensionConfig:      getExtension(smartagentextension.NewFactory(), m.smartagentextensionConfig),
 		randomExtensionConfig:            getExtension(exampleFactory, randomExtensionConfig),
-		m.smartagentextensionConfigExtra: nil,
+		m.smartagentextensionConfigExtra: getExtension(smartagentextension.NewFactory(), m.smartagentextensionConfigExtra),
 	}
 }