Removed different types of Detectors for Resources. (#1810)

* Removed different types of Detectors for Resources.

This change simplifies different types of collectors into one list. The
order of this list determines how they are applied.  Defaults are
applied when the user does not supply any detectors.  To achieve
default behavior and additional behavior a DefaultDetectors struct has been
created

* missed prometheus test.

* Changed behavior around WithDetectors(nil)

Added examples of use of WithDetectors.

* Added NoOp example

* Changed test to reflect acutal default case

This changes because WithDetector() no longer is the same as not using WithDetector()

* Unexports the noOp detector

* Updated changelog

* Fixes to spelling mistakes.

* Added NewEmptyResouce and unexported builtin detectors

* Fix for prometheus example

* Resource has two Rs

I need to get a new R key it seems.

Co-authored-by: Sam Xie <xsambundy@gmail.com>

* Replaced NewEmptyResource() with New()

* Fix test function name

* Comment fixups.

* Apply suggestions from code review

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

Co-authored-by: Sam Xie <xsambundy@gmail.com>
Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

CHANGELOG.md

@@ -26,13 +26,17 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 - Make `NewSplitDriver` from `go.opentelemetry.io/otel/exporters/otlp` take variadic arguments instead of a `SplitConfig` item.
   `NewSplitDriver` now automatically implements an internal `noopDriver` for `SplitConfig` fields that are not initialized. (#1798)
+- `resource.New()` now creates a Resource without builtin detectors. Previous behavior is now achieved by using `WithBuiltinDetectors` Option. (#1810)
 - Move the `Event` type from the `go.opentelemetry.io/otel` package to the `go.opentelemetry.io/otel/sdk/trace` package. (#1846)
 - BatchSpanProcessor now report export failures when calling `ForceFlush()` method. (#1860)
 
 ### Deprecated
 
 ### Removed
 
+- Remove `resource.WithoutBuiltin()`. Use `resource.New()`. (#1810)
+- Unexported types `resource.FromEnv`, `resource.Host`, and `resource.TelemetrySDK`, Use the corresponding `With*()` to use individually. (#1810)
+
 ### Fixed
 
 - Only report errors from the `"go.opentelemetry.io/otel/sdk/resource".Environment` function when they are not `nil`. (#1850, #1851)

exporters/metric/prometheus/example_test.go

@@ -40,7 +40,6 @@ func ExampleNewExportPipeline() {
 	// Create a resource, with builtin attributes plus R=V.
 	res, err := resource.New(
 		context.Background(),
-		resource.WithoutBuiltin(), // Test-only!
 		resource.WithAttributes(attribute.String("R", "V")),
 	)
 	if err != nil {

sdk/resource/builtin.go

@@ -26,19 +26,19 @@ import (
 )
 
 type (
-	// TelemetrySDK is a Detector that provides information about
+	// telemetrySDK is a Detector that provides information about
 	// the OpenTelemetry SDK used.  This Detector is included as a
 	// builtin. If these resource attributes are not wanted, use
 	// the WithTelemetrySDK(nil) or WithoutBuiltin() options to
 	// explicitly disable them.
-	TelemetrySDK struct{}
+	telemetrySDK struct{}
 
-	// Host is a Detector that provides information about the host
+	// host is a Detector that provides information about the host
 	// being run on. This Detector is included as a builtin. If
 	// these resource attributes are not wanted, use the
 	// WithHost(nil) or WithoutBuiltin() options to explicitly
 	// disable them.
-	Host struct{}
+	host struct{}
 
 	stringDetector struct {
 		K attribute.Key
@@ -49,14 +49,14 @@ type (
 )
 
 var (
-	_ Detector = TelemetrySDK{}
-	_ Detector = Host{}
+	_ Detector = telemetrySDK{}
+	_ Detector = host{}
 	_ Detector = stringDetector{}
 	_ Detector = defaultServiceNameDetector{}
 )
 
 // Detect returns a *Resource that describes the OpenTelemetry SDK used.
-func (TelemetrySDK) Detect(context.Context) (*Resource, error) {
+func (telemetrySDK) Detect(context.Context) (*Resource, error) {
 	return NewWithAttributes(
 		semconv.TelemetrySDKNameKey.String("opentelemetry"),
 		semconv.TelemetrySDKLanguageKey.String("go"),
@@ -65,7 +65,7 @@ func (TelemetrySDK) Detect(context.Context) (*Resource, error) {
 }
 
 // Detect returns a *Resource that describes the host being run on.
-func (Host) Detect(ctx context.Context) (*Resource, error) {
+func (host) Detect(ctx context.Context) (*Resource, error) {
 	return StringDetector(semconv.HostNameKey, os.Hostname).Detect(ctx)
 }
 

sdk/resource/builtin_test.go

@@ -61,7 +61,6 @@ func TestStringDetectorErrors(t *testing.T) {
 	for _, test := range tests {
 		res, err := resource.New(
 			context.Background(),
-			resource.WithoutBuiltin(),
 			resource.WithAttributes(attribute.String("A", "B")),
 			resource.WithDetectors(test.s),
 		)

sdk/resource/config.go

@@ -24,18 +24,6 @@ import (
 type config struct {
 	// detectors that will be evaluated.
 	detectors []Detector
-
-	// telemetrySDK is used to specify non-default
-	// `telemetry.sdk.*` attributes.
-	telemetrySDK Detector
-
-	// HostResource is used to specify non-default `host.*`
-	// attributes.
-	host Detector
-
-	// FromEnv is used to specify non-default OTEL_RESOURCE_ATTRIBUTES
-	// attributes.
-	fromEnv Detector
 }
 
 // Option is the interface that applies a configuration option.
@@ -81,85 +69,24 @@ func (o detectorsOption) Apply(cfg *config) {
 	cfg.detectors = append(cfg.detectors, o.detectors...)
 }
 
-// WithTelemetrySDK overrides the builtin `telemetry.sdk.*`
-// attributes.  Use nil to disable these attributes entirely.
-func WithTelemetrySDK(d Detector) Option {
-	return telemetrySDKOption{Detector: d}
-}
-
-type telemetrySDKOption struct {
-	option
-	Detector
+// WithBuiltinDetectors adds the built detectors to the configured resource.
+func WithBuiltinDetectors() Option {
+	return WithDetectors(telemetrySDK{},
+		host{},
+		fromEnv{})
 }
 
-// Apply implements Option.
-func (o telemetrySDKOption) Apply(cfg *config) {
-	cfg.telemetrySDK = o.Detector
-}
-
-// WithHost overrides the builtin `host.*` attributes.  Use nil to
-// disable these attributes entirely.
-func WithHost(d Detector) Option {
-	return hostOption{Detector: d}
-}
-
-type hostOption struct {
-	option
-	Detector
-}
-
-// Apply implements Option.
-func (o hostOption) Apply(cfg *config) {
-	cfg.host = o.Detector
+// WithFromEnv adds attributes from environment variables to the  configured resource.
+func WithFromEnv() Option {
+	return WithDetectors(fromEnv{})
 }
 
-// WithFromEnv overrides the builtin detector for
-// OTEL_RESOURCE_ATTRIBUTES.  Use nil to disable environment checking.
-func WithFromEnv(d Detector) Option {
-	return fromEnvOption{Detector: d}
-}
-
-type fromEnvOption struct {
-	option
-	Detector
-}
-
-// Apply implements Option.
-func (o fromEnvOption) Apply(cfg *config) {
-	cfg.fromEnv = o.Detector
-}
-
-// WithoutBuiltin disables all the builtin detectors, including the
-// telemetry.sdk.*, host.*, and the environment detector.
-func WithoutBuiltin() Option {
-	return noBuiltinOption{}
-}
-
-type noBuiltinOption struct {
-	option
-}
-
-// Apply implements Option.
-func (o noBuiltinOption) Apply(cfg *config) {
-	cfg.host = nil
-	cfg.telemetrySDK = nil
-	cfg.fromEnv = nil
+// WithHost adds attributes from the host to the configured resource.
+func WithHost() Option {
+	return WithDetectors(host{})
 }
 
-// New returns a Resource combined from the provided attributes,
-// user-provided detectors and builtin detectors.
-func New(ctx context.Context, opts ...Option) (*Resource, error) {
-	cfg := config{
-		telemetrySDK: TelemetrySDK{},
-		host:         Host{},
-		fromEnv:      FromEnv{},
-	}
-	for _, opt := range opts {
-		opt.Apply(&cfg)
-	}
-	detectors := append(
-		[]Detector{cfg.telemetrySDK, cfg.host, cfg.fromEnv},
-		cfg.detectors...,
-	)
-	return Detect(ctx, detectors...)
+// WithTelemetrySDK adds TelemetrySDK version info to the configured resource.
+func WithTelemetrySDK() Option {
+	return WithDetectors(telemetrySDK{})
 }

sdk/resource/env.go

@@ -31,18 +31,18 @@ var (
 	errMissingValue = fmt.Errorf("%w: missing value", ErrPartialResource)
 )
 
-// FromEnv is a Detector that implements the Detector and collects
+// fromEnv is a Detector that implements the Detector and collects
 // resources from environment.  This Detector is included as a
 // builtin.  If these resource attributes are not wanted, use the
 // WithFromEnv(nil) or WithoutBuiltin() options to explicitly disable
 // them.
-type FromEnv struct{}
+type fromEnv struct{}
 
 // compile time assertion that FromEnv implements Detector interface
-var _ Detector = FromEnv{}
+var _ Detector = fromEnv{}
 
 // Detect collects resources from environment
-func (FromEnv) Detect(context.Context) (*Resource, error) {
+func (fromEnv) Detect(context.Context) (*Resource, error) {
 	attrs := strings.TrimSpace(os.Getenv(envVar))
 
 	if attrs == "" {