feat(telemetry): instrument inference duration and frame age

vendor/go.opentelemetry.io/otel/sdk/resource/auto.go

@@ -0,0 +1,72 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"errors"
+	"fmt"
+)
+
+var (
+	// ErrPartialResource is returned by a detector when complete source
+	// information for a Resource is unavailable or the source information
+	// contains invalid values that are omitted from the returned Resource.
+	ErrPartialResource = errors.New("partial resource")
+)
+
+// Detector detects OpenTelemetry resource information
+type Detector interface {
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+
+	// Detect returns an initialized Resource based on gathered information.
+	// If the source information to construct a Resource contains invalid
+	// values, a Resource is returned with the valid parts of the source
+	// information used for initialization along with an appropriately
+	// wrapped ErrPartialResource error.
+	Detect(ctx context.Context) (*Resource, error)
+	// DO NOT CHANGE: any modification will not be backwards compatible and
+	// must never be done outside of a new major release.
+}
+
+// Detect calls all input detectors sequentially and merges each result with the previous one.
+// It returns the merged error too.
+func Detect(ctx context.Context, detectors ...Detector) (*Resource, error) {
+	var autoDetectedRes *Resource
+	var errInfo []string
+	for _, detector := range detectors {
+		if detector == nil {
+			continue
+		}
+		res, err := detector.Detect(ctx)
+		if err != nil {
+			errInfo = append(errInfo, err.Error())
+			if !errors.Is(err, ErrPartialResource) {
+				continue
+			}
+		}
+		autoDetectedRes, err = Merge(autoDetectedRes, res)
+		if err != nil {
+			errInfo = append(errInfo, err.Error())
+		}
+	}
+
+	var aggregatedError error
+	if len(errInfo) > 0 {
+		aggregatedError = fmt.Errorf("detecting resources: %s", errInfo)
+	}
+	return autoDetectedRes, aggregatedError
+}

vendor/go.opentelemetry.io/otel/sdk/resource/builtin.go

@@ -0,0 +1,108 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
+)
+
+type (
+	// 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{}
+
+	// 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{}
+
+	stringDetector struct {
+		schemaURL string
+		K         attribute.Key
+		F         func() (string, error)
+	}
+
+	defaultServiceNameDetector struct{}
+)
+
+var (
+	_ 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) {
+	return NewWithAttributes(
+		semconv.SchemaURL,
+		semconv.TelemetrySDKNameKey.String("opentelemetry"),
+		semconv.TelemetrySDKLanguageKey.String("go"),
+		semconv.TelemetrySDKVersionKey.String(otel.Version()),
+	), nil
+}
+
+// Detect returns a *Resource that describes the host being run on.
+func (host) Detect(ctx context.Context) (*Resource, error) {
+	return StringDetector(semconv.SchemaURL, semconv.HostNameKey, os.Hostname).Detect(ctx)
+}
+
+// StringDetector returns a Detector that will produce a *Resource
+// containing the string as a value corresponding to k. The resulting Resource
+// will have the specified schemaURL.
+func StringDetector(schemaURL string, k attribute.Key, f func() (string, error)) Detector {
+	return stringDetector{schemaURL: schemaURL, K: k, F: f}
+}
+
+// Detect returns a *Resource that describes the string as a value
+// corresponding to attribute.Key as well as the specific schemaURL.
+func (sd stringDetector) Detect(ctx context.Context) (*Resource, error) {
+	value, err := sd.F()
+	if err != nil {
+		return nil, fmt.Errorf("%s: %w", string(sd.K), err)
+	}
+	a := sd.K.String(value)
+	if !a.Valid() {
+		return nil, fmt.Errorf("invalid attribute: %q -> %q", a.Key, a.Value.Emit())
+	}
+	return NewWithAttributes(sd.schemaURL, sd.K.String(value)), nil
+}
+
+// Detect implements Detector
+func (defaultServiceNameDetector) Detect(ctx context.Context) (*Resource, error) {
+	return StringDetector(
+		semconv.SchemaURL,
+		semconv.ServiceNameKey,
+		func() (string, error) {
+			executable, err := os.Executable()
+			if err != nil {
+				return "unknown_service:go", nil
+			}
+			return "unknown_service:" + filepath.Base(executable), nil
+		},
+	).Detect(ctx)
+}

vendor/go.opentelemetry.io/otel/sdk/resource/config.go

@@ -0,0 +1,171 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// config contains configuration for Resource creation.
+type config struct {
+	// detectors that will be evaluated.
+	detectors []Detector
+	// SchemaURL to associate with the Resource.
+	schemaURL string
+}
+
+// Option is the interface that applies a configuration option.
+type Option interface {
+	// apply sets the Option value of a config.
+	apply(*config)
+}
+
+// WithAttributes adds attributes to the configured Resource.
+func WithAttributes(attributes ...attribute.KeyValue) Option {
+	return WithDetectors(detectAttributes{attributes})
+}
+
+type detectAttributes struct {
+	attributes []attribute.KeyValue
+}
+
+func (d detectAttributes) Detect(context.Context) (*Resource, error) {
+	return NewSchemaless(d.attributes...), nil
+}
+
+// WithDetectors adds detectors to be evaluated for the configured resource.
+func WithDetectors(detectors ...Detector) Option {
+	return detectorsOption{detectors: detectors}
+}
+
+type detectorsOption struct {
+	detectors []Detector
+}
+
+func (o detectorsOption) apply(cfg *config) {
+	cfg.detectors = append(cfg.detectors, o.detectors...)
+}
+
+// WithFromEnv adds attributes from environment variables to the configured resource.
+func WithFromEnv() Option {
+	return WithDetectors(fromEnv{})
+}
+
+// WithHost adds attributes from the host to the configured resource.
+func WithHost() Option {
+	return WithDetectors(host{})
+}
+
+// WithTelemetrySDK adds TelemetrySDK version info to the configured resource.
+func WithTelemetrySDK() Option {
+	return WithDetectors(telemetrySDK{})
+}
+
+// WithSchemaURL sets the schema URL for the configured resource.
+func WithSchemaURL(schemaURL string) Option {
+	return schemaURLOption(schemaURL)
+}
+
+type schemaURLOption string
+
+func (o schemaURLOption) apply(cfg *config) {
+	cfg.schemaURL = string(o)
+}
+
+// WithOS adds all the OS attributes to the configured Resource.
+// See individual WithOS* functions to configure specific attributes.
+func WithOS() Option {
+	return WithDetectors(
+		osTypeDetector{},
+		osDescriptionDetector{},
+	)
+}
+
+// WithOSType adds an attribute with the operating system type to the configured Resource.
+func WithOSType() Option {
+	return WithDetectors(osTypeDetector{})
+}
+
+// WithOSDescription adds an attribute with the operating system description to the
+// configured Resource. The formatted string is equivalent to the output of the
+// `uname -snrvm` command.
+func WithOSDescription() Option {
+	return WithDetectors(osDescriptionDetector{})
+}
+
+// WithProcess adds all the Process attributes to the configured Resource.
+// See individual WithProcess* functions to configure specific attributes.
+func WithProcess() Option {
+	return WithDetectors(
+		processPIDDetector{},
+		processExecutableNameDetector{},
+		processExecutablePathDetector{},
+		processCommandArgsDetector{},
+		processOwnerDetector{},
+		processRuntimeNameDetector{},
+		processRuntimeVersionDetector{},
+		processRuntimeDescriptionDetector{},
+	)
+}
+
+// WithProcessPID adds an attribute with the process identifier (PID) to the
+// configured Resource.
+func WithProcessPID() Option {
+	return WithDetectors(processPIDDetector{})
+}
+
+// WithProcessExecutableName adds an attribute with the name of the process
+// executable to the configured Resource.
+func WithProcessExecutableName() Option {
+	return WithDetectors(processExecutableNameDetector{})
+}
+
+// WithProcessExecutablePath adds an attribute with the full path to the process
+// executable to the configured Resource.
+func WithProcessExecutablePath() Option {
+	return WithDetectors(processExecutablePathDetector{})
+}
+
+// WithProcessCommandArgs adds an attribute with all the command arguments (including
+// the command/executable itself) as received by the process the configured Resource.
+func WithProcessCommandArgs() Option {
+	return WithDetectors(processCommandArgsDetector{})
+}
+
+// WithProcessOwner adds an attribute with the username of the user that owns the process
+// to the configured Resource.
+func WithProcessOwner() Option {
+	return WithDetectors(processOwnerDetector{})
+}
+
+// WithProcessRuntimeName adds an attribute with the name of the runtime of this
+// process to the configured Resource.
+func WithProcessRuntimeName() Option {
+	return WithDetectors(processRuntimeNameDetector{})
+}
+
+// WithProcessRuntimeVersion adds an attribute with the version of the runtime of
+// this process to the configured Resource.
+func WithProcessRuntimeVersion() Option {
+	return WithDetectors(processRuntimeVersionDetector{})
+}
+
+// WithProcessRuntimeDescription adds an attribute with an additional description
+// about the runtime of the process to the configured Resource.
+func WithProcessRuntimeDescription() Option {
+	return WithDetectors(processRuntimeDescriptionDetector{})
+}

vendor/go.opentelemetry.io/otel/sdk/resource/doc.go

@@ -0,0 +1,28 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package resource provides detecting and representing resources.
+//
+// The fundamental struct is a Resource which holds identifying information
+// about the entities for which telemetry is exported.
+//
+// To automatically construct Resources from an environment a Detector
+// interface is defined. Implementations of this interface can be passed to
+// the Detect function to generate a Resource from the merged information.
+//
+// To load a user defined Resource from the environment variable
+// OTEL_RESOURCE_ATTRIBUTES the FromEnv Detector can be used. It will interpret
+// the value as a list of comma delimited key/value pairs
+// (e.g. `<key1>=<value1>,<key2>=<value2>,...`).
+package resource // import "go.opentelemetry.io/otel/sdk/resource"

vendor/go.opentelemetry.io/otel/sdk/resource/env.go

@@ -0,0 +1,99 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"strings"
+
+	"go.opentelemetry.io/otel/attribute"
+	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
+)
+
+const (
+	// resourceAttrKey is the environment variable name OpenTelemetry Resource information will be read from.
+	resourceAttrKey = "OTEL_RESOURCE_ATTRIBUTES"
+
+	// svcNameKey is the environment variable name that Service Name information will be read from.
+	svcNameKey = "OTEL_SERVICE_NAME"
+)
+
+var (
+	// errMissingValue is returned when a resource value is missing.
+	errMissingValue = fmt.Errorf("%w: missing value", ErrPartialResource)
+)
+
+// fromEnv is a Detector that implements the Detector and collects
+// resources from environment.  This Detector is included as a
+// builtin.
+type fromEnv struct{}
+
+// compile time assertion that FromEnv implements Detector interface
+var _ Detector = fromEnv{}
+
+// Detect collects resources from environment
+func (fromEnv) Detect(context.Context) (*Resource, error) {
+	attrs := strings.TrimSpace(os.Getenv(resourceAttrKey))
+	svcName := strings.TrimSpace(os.Getenv(svcNameKey))
+
+	if attrs == "" && svcName == "" {
+		return Empty(), nil
+	}
+
+	var res *Resource
+
+	if svcName != "" {
+		res = NewSchemaless(semconv.ServiceNameKey.String(svcName))
+	}
+
+	r2, err := constructOTResources(attrs)
+
+	// Ensure that the resource with the service name from OTEL_SERVICE_NAME
+	// takes precedence, if it was defined.
+	res, err2 := Merge(r2, res)
+
+	if err == nil {
+		err = err2
+	} else if err2 != nil {
+		err = fmt.Errorf("detecting resources: %s", []string{err.Error(), err2.Error()})
+	}
+
+	return res, err
+}
+
+func constructOTResources(s string) (*Resource, error) {
+	if s == "" {
+		return Empty(), nil
+	}
+	pairs := strings.Split(s, ",")
+	attrs := []attribute.KeyValue{}
+	var invalid []string
+	for _, p := range pairs {
+		field := strings.SplitN(p, "=", 2)
+		if len(field) != 2 {
+			invalid = append(invalid, p)
+			continue
+		}
+		k, v := strings.TrimSpace(field[0]), strings.TrimSpace(field[1])
+		attrs = append(attrs, attribute.String(k, v))
+	}
+	var err error
+	if len(invalid) > 0 {
+		err = fmt.Errorf("%w: %v", errMissingValue, invalid)
+	}
+	return NewSchemaless(attrs...), err
+}

vendor/go.opentelemetry.io/otel/sdk/resource/os.go

@@ -0,0 +1,97 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"strings"
+
+	"go.opentelemetry.io/otel/attribute"
+	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
+)
+
+type osDescriptionProvider func() (string, error)
+
+var defaultOSDescriptionProvider osDescriptionProvider = platformOSDescription
+
+var osDescription = defaultOSDescriptionProvider
+
+func setDefaultOSDescriptionProvider() {
+	setOSDescriptionProvider(defaultOSDescriptionProvider)
+}
+
+func setOSDescriptionProvider(osDescriptionProvider osDescriptionProvider) {
+	osDescription = osDescriptionProvider
+}
+
+type osTypeDetector struct{}
+type osDescriptionDetector struct{}
+
+// Detect returns a *Resource that describes the operating system type the
+// service is running on.
+func (osTypeDetector) Detect(ctx context.Context) (*Resource, error) {
+	osType := runtimeOS()
+
+	osTypeAttribute := mapRuntimeOSToSemconvOSType(osType)
+
+	return NewWithAttributes(
+		semconv.SchemaURL,
+		osTypeAttribute,
+	), nil
+}
+
+// Detect returns a *Resource that describes the operating system the
+// service is running on.
+func (osDescriptionDetector) Detect(ctx context.Context) (*Resource, error) {
+	description, err := osDescription()
+
+	if err != nil {
+		return nil, err
+	}
+
+	return NewWithAttributes(
+		semconv.SchemaURL,
+		semconv.OSDescriptionKey.String(description),
+	), nil
+}
+
+// mapRuntimeOSToSemconvOSType translates the OS name as provided by the Go runtime
+// into an OS type attribute with the corresponding value defined by the semantic
+// conventions. In case the provided OS name isn't mapped, it's transformed to lowercase
+// and used as the value for the returned OS type attribute.
+func mapRuntimeOSToSemconvOSType(osType string) attribute.KeyValue {
+	// the elements in this map are the intersection between
+	// available GOOS values and defined semconv OS types
+	osTypeAttributeMap := map[string]attribute.KeyValue{
+		"darwin":    semconv.OSTypeDarwin,
+		"dragonfly": semconv.OSTypeDragonflyBSD,
+		"freebsd":   semconv.OSTypeFreeBSD,
+		"linux":     semconv.OSTypeLinux,
+		"netbsd":    semconv.OSTypeNetBSD,
+		"openbsd":   semconv.OSTypeOpenBSD,
+		"solaris":   semconv.OSTypeSolaris,
+		"windows":   semconv.OSTypeWindows,
+	}
+
+	var osTypeAttribute attribute.KeyValue
+
+	if attr, ok := osTypeAttributeMap[osType]; ok {
+		osTypeAttribute = attr
+	} else {
+		osTypeAttribute = semconv.OSTypeKey.String(strings.ToLower(osType))
+	}
+
+	return osTypeAttribute
+}

vendor/go.opentelemetry.io/otel/sdk/resource/os_release_darwin.go

@@ -0,0 +1,102 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"encoding/xml"
+	"fmt"
+	"io"
+	"os"
+)
+
+type plist struct {
+	XMLName xml.Name `xml:"plist"`
+	Dict    dict     `xml:"dict"`
+}
+
+type dict struct {
+	Key    []string `xml:"key"`
+	String []string `xml:"string"`
+}
+
+// osRelease builds a string describing the operating system release based on the
+// contents of the property list (.plist) system files. If no .plist files are found,
+// or if the required properties to build the release description string are missing,
+// an empty string is returned instead. The generated string resembles the output of
+// the `sw_vers` commandline program, but in a single-line string. For more information
+// about the `sw_vers` program, see: https://www.unix.com/man-page/osx/1/SW_VERS.
+func osRelease() string {
+	file, err := getPlistFile()
+	if err != nil {
+		return ""
+	}
+
+	defer file.Close()
+
+	values, err := parsePlistFile(file)
+	if err != nil {
+		return ""
+	}
+
+	return buildOSRelease(values)
+}
+
+// getPlistFile returns a *os.File pointing to one of the well-known .plist files
+// available on macOS. If no file can be opened, it returns an error.
+func getPlistFile() (*os.File, error) {
+	return getFirstAvailableFile([]string{
+		"/System/Library/CoreServices/SystemVersion.plist",
+		"/System/Library/CoreServices/ServerVersion.plist",
+	})
+}
+
+// parsePlistFile process the file pointed by `file` as a .plist file and returns
+// a map with the key-values for each pair of correlated <key> and <string> elements
+// contained in it.
+func parsePlistFile(file io.Reader) (map[string]string, error) {
+	var v plist
+
+	err := xml.NewDecoder(file).Decode(&v)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(v.Dict.Key) != len(v.Dict.String) {
+		return nil, fmt.Errorf("the number of <key> and <string> elements doesn't match")
+	}
+
+	properties := make(map[string]string, len(v.Dict.Key))
+	for i, key := range v.Dict.Key {
+		properties[key] = v.Dict.String[i]
+	}
+
+	return properties, nil
+}
+
+// buildOSRelease builds a string describing the OS release based on the properties
+// available on the provided map. It tries to find the `ProductName`, `ProductVersion`
+// and `ProductBuildVersion` properties. If some of these properties are not found,
+// it returns an empty string.
+func buildOSRelease(properties map[string]string) string {
+	productName := properties["ProductName"]
+	productVersion := properties["ProductVersion"]
+	productBuildVersion := properties["ProductBuildVersion"]
+
+	if productName == "" || productVersion == "" || productBuildVersion == "" {
+		return ""
+	}
+
+	return fmt.Sprintf("%s %s (%s)", productName, productVersion, productBuildVersion)
+}

vendor/go.opentelemetry.io/otel/sdk/resource/os_release_unix.go

@@ -0,0 +1,154 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build aix || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
+// +build aix dragonfly freebsd linux netbsd openbsd solaris zos
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+)
+
+// osRelease builds a string describing the operating system release based on the
+// properties of the os-release file. If no os-release file is found, or if the
+// required properties to build the release description string are missing, an empty
+// string is returned instead. For more information about os-release files, see:
+// https://www.freedesktop.org/software/systemd/man/os-release.html
+func osRelease() string {
+	file, err := getOSReleaseFile()
+	if err != nil {
+		return ""
+	}
+
+	defer file.Close()
+
+	values := parseOSReleaseFile(file)
+
+	return buildOSRelease(values)
+}
+
+// getOSReleaseFile returns a *os.File pointing to one of the well-known os-release
+// files, according to their order of preference. If no file can be opened, it
+// returns an error.
+func getOSReleaseFile() (*os.File, error) {
+	return getFirstAvailableFile([]string{"/etc/os-release", "/usr/lib/os-release"})
+}
+
+// parseOSReleaseFile process the file pointed by `file` as an os-release file and
+// returns a map with the key-values contained in it. Empty lines or lines starting
+// with a '#' character are ignored, as well as lines with the missing key=value
+// separator. Values are unquoted and unescaped.
+func parseOSReleaseFile(file io.Reader) map[string]string {
+	values := make(map[string]string)
+	scanner := bufio.NewScanner(file)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		if skip(line) {
+			continue
+		}
+
+		key, value, ok := parse(line)
+		if ok {
+			values[key] = value
+		}
+	}
+
+	return values
+}
+
+// skip returns true if the line is blank or starts with a '#' character, and
+// therefore should be skipped from processing.
+func skip(line string) bool {
+	line = strings.TrimSpace(line)
+
+	return len(line) == 0 || strings.HasPrefix(line, "#")
+}
+
+// parse attempts to split the provided line on the first '=' character, and then
+// sanitize each side of the split before returning them as a key-value pair.
+func parse(line string) (string, string, bool) {
+	parts := strings.SplitN(line, "=", 2)
+
+	if len(parts) != 2 || len(parts[0]) == 0 {
+		return "", "", false
+	}
+
+	key := strings.TrimSpace(parts[0])
+	value := unescape(unquote(strings.TrimSpace(parts[1])))
+
+	return key, value, true
+}
+
+// unquote checks whether the string `s` is quoted with double or single quotes
+// and, if so, returns a version of the string without them. Otherwise it returns
+// the provided string unchanged.
+func unquote(s string) string {
+	if len(s) < 2 {
+		return s
+	}
+
+	if (s[0] == '"' || s[0] == '\'') && s[0] == s[len(s)-1] {
+		return s[1 : len(s)-1]
+	}
+
+	return s
+}
+
+// unescape removes the `\` prefix from some characters that are expected
+// to have it added in front of them for escaping purposes.
+func unescape(s string) string {
+	return strings.NewReplacer(
+		`\$`, `$`,
+		`\"`, `"`,
+		`\'`, `'`,
+		`\\`, `\`,
+		"\\`", "`",
+	).Replace(s)
+}
+
+// buildOSRelease builds a string describing the OS release based on the properties
+// available on the provided map. It favors a combination of the `NAME` and `VERSION`
+// properties as first option (falling back to `VERSION_ID` if `VERSION` isn't
+// found), and using `PRETTY_NAME` alone if some of the previous are not present. If
+// none of these properties are found, it returns an empty string.
+//
+// The rationale behind not using `PRETTY_NAME` as first choice was that, for some
+// Linux distributions, it doesn't include the same detail that can be found on the
+// individual `NAME` and `VERSION` properties, and combining `PRETTY_NAME` with
+// other properties can produce "pretty" redundant strings in some cases.
+func buildOSRelease(values map[string]string) string {
+	var osRelease string
+
+	name := values["NAME"]
+	version := values["VERSION"]
+
+	if version == "" {
+		version = values["VERSION_ID"]
+	}
+
+	if name != "" && version != "" {
+		osRelease = fmt.Sprintf("%s %s", name, version)
+	} else {
+		osRelease = values["PRETTY_NAME"]
+	}
+
+	return osRelease
+}

vendor/go.opentelemetry.io/otel/sdk/resource/os_unix.go

@@ -0,0 +1,100 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
+// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris zos
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+type unameProvider func(buf *unix.Utsname) (err error)
+
+var defaultUnameProvider unameProvider = unix.Uname
+
+var currentUnameProvider = defaultUnameProvider
+
+func setDefaultUnameProvider() {
+	setUnameProvider(defaultUnameProvider)
+}
+
+func setUnameProvider(unameProvider unameProvider) {
+	currentUnameProvider = unameProvider
+}
+
+// platformOSDescription returns a human readable OS version information string.
+// The final string combines OS release information (where available) and the
+// result of the `uname` system call.
+func platformOSDescription() (string, error) {
+	uname, err := uname()
+	if err != nil {
+		return "", err
+	}
+
+	osRelease := osRelease()
+	if osRelease != "" {
+		return fmt.Sprintf("%s (%s)", osRelease, uname), nil
+	}
+
+	return uname, nil
+}
+
+// uname issues a uname(2) system call (or equivalent on systems which doesn't
+// have one) and formats the output in a single string, similar to the output
+// of the `uname` commandline program. The final string resembles the one
+// obtained with a call to `uname -snrvm`.
+func uname() (string, error) {
+	var utsName unix.Utsname
+
+	err := currentUnameProvider(&utsName)
+	if err != nil {
+		return "", err
+	}
+
+	return fmt.Sprintf("%s %s %s %s %s",
+		charsToString(utsName.Sysname[:]),
+		charsToString(utsName.Nodename[:]),
+		charsToString(utsName.Release[:]),
+		charsToString(utsName.Version[:]),
+		charsToString(utsName.Machine[:]),
+	), nil
+}
+
+// charsToString converts a C-like null-terminated char array to a Go string.
+func charsToString(charArray []byte) string {
+	if i := bytes.IndexByte(charArray, 0); i >= 0 {
+		charArray = charArray[:i]
+	}
+
+	return string(charArray)
+}
+
+// getFirstAvailableFile returns an *os.File of the first available
+// file from a list of candidate file paths.
+func getFirstAvailableFile(candidates []string) (*os.File, error) {
+	for _, c := range candidates {
+		file, err := os.Open(c)
+		if err == nil {
+			return file, nil
+		}
+	}
+
+	return nil, fmt.Errorf("no candidate file available: %v", candidates)
+}

vendor/go.opentelemetry.io/otel/sdk/resource/os_unsupported.go

@@ -0,0 +1,34 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !aix
+// +build !darwin
+// +build !dragonfly
+// +build !freebsd
+// +build !linux
+// +build !netbsd
+// +build !openbsd
+// +build !solaris
+// +build !windows
+// +build !zos
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+// platformOSDescription is a placeholder implementation for OSes
+// for which this project currently doesn't support os.description
+// attribute detection. See build tags declaration early on this file
+// for a list of unsupported OSes.
+func platformOSDescription() (string, error) {
+	return "<unknown>", nil
+}

vendor/go.opentelemetry.io/otel/sdk/resource/os_windows.go

@@ -0,0 +1,101 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"fmt"
+	"strconv"
+
+	"golang.org/x/sys/windows/registry"
+)
+
+// platformOSDescription returns a human readable OS version information string.
+// It does so by querying registry values under the
+// `SOFTWARE\Microsoft\Windows NT\CurrentVersion` key. The final string
+// resembles the one displayed by the Version Reporter Applet (winver.exe).
+func platformOSDescription() (string, error) {
+	k, err := registry.OpenKey(
+		registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion`, registry.QUERY_VALUE)
+
+	if err != nil {
+		return "", err
+	}
+
+	defer k.Close()
+
+	var (
+		productName               = readProductName(k)
+		displayVersion            = readDisplayVersion(k)
+		releaseID                 = readReleaseID(k)
+		currentMajorVersionNumber = readCurrentMajorVersionNumber(k)
+		currentMinorVersionNumber = readCurrentMinorVersionNumber(k)
+		currentBuildNumber        = readCurrentBuildNumber(k)
+		ubr                       = readUBR(k)
+	)
+
+	if displayVersion != "" {
+		displayVersion += " "
+	}
+
+	return fmt.Sprintf("%s %s(%s) [Version %s.%s.%s.%s]",
+		productName,
+		displayVersion,
+		releaseID,
+		currentMajorVersionNumber,
+		currentMinorVersionNumber,
+		currentBuildNumber,
+		ubr,
+	), nil
+}
+
+func getStringValue(name string, k registry.Key) string {
+	value, _, _ := k.GetStringValue(name)
+
+	return value
+}
+
+func getIntegerValue(name string, k registry.Key) uint64 {
+	value, _, _ := k.GetIntegerValue(name)
+
+	return value
+}
+
+func readProductName(k registry.Key) string {
+	return getStringValue("ProductName", k)
+}
+
+func readDisplayVersion(k registry.Key) string {
+	return getStringValue("DisplayVersion", k)
+}
+
+func readReleaseID(k registry.Key) string {
+	return getStringValue("ReleaseID", k)
+}
+
+func readCurrentMajorVersionNumber(k registry.Key) string {
+	return strconv.FormatUint(getIntegerValue("CurrentMajorVersionNumber", k), 10)
+}
+
+func readCurrentMinorVersionNumber(k registry.Key) string {
+	return strconv.FormatUint(getIntegerValue("CurrentMinorVersionNumber", k), 10)
+}
+
+func readCurrentBuildNumber(k registry.Key) string {
+	return getStringValue("CurrentBuildNumber", k)
+}
+
+func readUBR(k registry.Key) string {
+	return strconv.FormatUint(getIntegerValue("UBR", k), 10)
+}

vendor/go.opentelemetry.io/otel/sdk/resource/process.go

@@ -0,0 +1,175 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/user"
+	"path/filepath"
+	"runtime"
+
+	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
+)
+
+type pidProvider func() int
+type executablePathProvider func() (string, error)
+type commandArgsProvider func() []string
+type ownerProvider func() (*user.User, error)
+type runtimeNameProvider func() string
+type runtimeVersionProvider func() string
+type runtimeOSProvider func() string
+type runtimeArchProvider func() string
+
+var (
+	defaultPidProvider            pidProvider            = os.Getpid
+	defaultExecutablePathProvider executablePathProvider = os.Executable
+	defaultCommandArgsProvider    commandArgsProvider    = func() []string { return os.Args }
+	defaultOwnerProvider          ownerProvider          = user.Current
+	defaultRuntimeNameProvider    runtimeNameProvider    = func() string { return runtime.Compiler }
+	defaultRuntimeVersionProvider runtimeVersionProvider = runtime.Version
+	defaultRuntimeOSProvider      runtimeOSProvider      = func() string { return runtime.GOOS }
+	defaultRuntimeArchProvider    runtimeArchProvider    = func() string { return runtime.GOARCH }
+)
+
+var (
+	pid            = defaultPidProvider
+	executablePath = defaultExecutablePathProvider
+	commandArgs    = defaultCommandArgsProvider
+	owner          = defaultOwnerProvider
+	runtimeName    = defaultRuntimeNameProvider
+	runtimeVersion = defaultRuntimeVersionProvider
+	runtimeOS      = defaultRuntimeOSProvider
+	runtimeArch    = defaultRuntimeArchProvider
+)
+
+func setDefaultOSProviders() {
+	setOSProviders(
+		defaultPidProvider,
+		defaultExecutablePathProvider,
+		defaultCommandArgsProvider,
+	)
+}
+
+func setOSProviders(
+	pidProvider pidProvider,
+	executablePathProvider executablePathProvider,
+	commandArgsProvider commandArgsProvider,
+) {
+	pid = pidProvider
+	executablePath = executablePathProvider
+	commandArgs = commandArgsProvider
+}
+
+func setDefaultRuntimeProviders() {
+	setRuntimeProviders(
+		defaultRuntimeNameProvider,
+		defaultRuntimeVersionProvider,
+		defaultRuntimeOSProvider,
+		defaultRuntimeArchProvider,
+	)
+}
+
+func setRuntimeProviders(
+	runtimeNameProvider runtimeNameProvider,
+	runtimeVersionProvider runtimeVersionProvider,
+	runtimeOSProvider runtimeOSProvider,
+	runtimeArchProvider runtimeArchProvider,
+) {
+	runtimeName = runtimeNameProvider
+	runtimeVersion = runtimeVersionProvider
+	runtimeOS = runtimeOSProvider
+	runtimeArch = runtimeArchProvider
+}
+
+func setDefaultUserProviders() {
+	setUserProviders(defaultOwnerProvider)
+}
+
+func setUserProviders(ownerProvider ownerProvider) {
+	owner = ownerProvider
+}
+
+type processPIDDetector struct{}
+type processExecutableNameDetector struct{}
+type processExecutablePathDetector struct{}
+type processCommandArgsDetector struct{}
+type processOwnerDetector struct{}
+type processRuntimeNameDetector struct{}
+type processRuntimeVersionDetector struct{}
+type processRuntimeDescriptionDetector struct{}
+
+// Detect returns a *Resource that describes the process identifier (PID) of the
+// executing process.
+func (processPIDDetector) Detect(ctx context.Context) (*Resource, error) {
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessPIDKey.Int(pid())), nil
+}
+
+// Detect returns a *Resource that describes the name of the process executable.
+func (processExecutableNameDetector) Detect(ctx context.Context) (*Resource, error) {
+	executableName := filepath.Base(commandArgs()[0])
+
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessExecutableNameKey.String(executableName)), nil
+}
+
+// Detect returns a *Resource that describes the full path of the process executable.
+func (processExecutablePathDetector) Detect(ctx context.Context) (*Resource, error) {
+	executablePath, err := executablePath()
+	if err != nil {
+		return nil, err
+	}
+
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessExecutablePathKey.String(executablePath)), nil
+}
+
+// Detect returns a *Resource that describes all the command arguments as received
+// by the process.
+func (processCommandArgsDetector) Detect(ctx context.Context) (*Resource, error) {
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessCommandArgsKey.StringSlice(commandArgs())), nil
+}
+
+// Detect returns a *Resource that describes the username of the user that owns the
+// process.
+func (processOwnerDetector) Detect(ctx context.Context) (*Resource, error) {
+	owner, err := owner()
+	if err != nil {
+		return nil, err
+	}
+
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessOwnerKey.String(owner.Username)), nil
+}
+
+// Detect returns a *Resource that describes the name of the compiler used to compile
+// this process image.
+func (processRuntimeNameDetector) Detect(ctx context.Context) (*Resource, error) {
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessRuntimeNameKey.String(runtimeName())), nil
+}
+
+// Detect returns a *Resource that describes the version of the runtime of this process.
+func (processRuntimeVersionDetector) Detect(ctx context.Context) (*Resource, error) {
+	return NewWithAttributes(semconv.SchemaURL, semconv.ProcessRuntimeVersionKey.String(runtimeVersion())), nil
+}
+
+// Detect returns a *Resource that describes the runtime of this process.
+func (processRuntimeDescriptionDetector) Detect(ctx context.Context) (*Resource, error) {
+	runtimeDescription := fmt.Sprintf(
+		"go version %s %s/%s", runtimeVersion(), runtimeOS(), runtimeArch())
+
+	return NewWithAttributes(
+		semconv.SchemaURL,
+		semconv.ProcessRuntimeDescriptionKey.String(runtimeDescription),
+	), nil
+}

vendor/go.opentelemetry.io/otel/sdk/resource/resource.go

@@ -0,0 +1,266 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resource // import "go.opentelemetry.io/otel/sdk/resource"
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// Resource describes an entity about which identifying information
+// and metadata is exposed.  Resource is an immutable object,
+// equivalent to a map from key to unique value.
+//
+// Resources should be passed and stored as pointers
+// (`*resource.Resource`).  The `nil` value is equivalent to an empty
+// Resource.
+type Resource struct {
+	attrs     attribute.Set
+	schemaURL string
+}
+
+var (
+	emptyResource Resource
+
+	defaultResource = func(r *Resource, err error) *Resource {
+		if err != nil {
+			otel.Handle(err)
+		}
+		return r
+	}(
+		Detect(
+			context.Background(),
+			defaultServiceNameDetector{},
+			fromEnv{},
+			telemetrySDK{},
+		),
+	)
+)
+
+var (
+	errMergeConflictSchemaURL = errors.New("cannot merge resource due to conflicting Schema URL")
+)
+
+// New returns a Resource combined from the user-provided detectors.
+func New(ctx context.Context, opts ...Option) (*Resource, error) {
+	cfg := config{}
+	for _, opt := range opts {
+		opt.apply(&cfg)
+	}
+
+	resource, err := Detect(ctx, cfg.detectors...)
+
+	var err2 error
+	resource, err2 = Merge(resource, &Resource{schemaURL: cfg.schemaURL})
+	if err == nil {
+		err = err2
+	} else if err2 != nil {
+		err = fmt.Errorf("detecting resources: %s", []string{err.Error(), err2.Error()})
+	}
+
+	return resource, err
+}
+
+// NewWithAttributes creates a resource from attrs and associates the resource with a
+// schema URL. If attrs contains duplicate keys, the last value will be used. If attrs
+// contains any invalid items those items will be dropped. The attrs are assumed to be
+// in a schema identified by schemaURL.
+func NewWithAttributes(schemaURL string, attrs ...attribute.KeyValue) *Resource {
+	resource := NewSchemaless(attrs...)
+	resource.schemaURL = schemaURL
+	return resource
+}
+
+// NewSchemaless creates a resource from attrs. If attrs contains duplicate keys,
+// the last value will be used. If attrs contains any invalid items those items will
+// be dropped. The resource will not be associated with a schema URL. If the schema
+// of the attrs is known use NewWithAttributes instead.
+func NewSchemaless(attrs ...attribute.KeyValue) *Resource {
+	if len(attrs) == 0 {
+		return &emptyResource
+	}
+
+	// Ensure attributes comply with the specification:
+	// https://github.com/open-telemetry/opentelemetry-specification/blob/v1.0.1/specification/common/common.md#attributes
+	s, _ := attribute.NewSetWithFiltered(attrs, func(kv attribute.KeyValue) bool {
+		return kv.Valid()
+	})
+
+	// If attrs only contains invalid entries do not allocate a new resource.
+	if s.Len() == 0 {
+		return &emptyResource
+	}
+
+	return &Resource{attrs: s} //nolint
+}
+
+// String implements the Stringer interface and provides a
+// human-readable form of the resource.
+//
+// Avoid using this representation as the key in a map of resources,
+// use Equivalent() as the key instead.
+func (r *Resource) String() string {
+	if r == nil {
+		return ""
+	}
+	return r.attrs.Encoded(attribute.DefaultEncoder())
+}
+
+// Attributes returns a copy of attributes from the resource in a sorted order.
+// To avoid allocating a new slice, use an iterator.
+func (r *Resource) Attributes() []attribute.KeyValue {
+	if r == nil {
+		r = Empty()
+	}
+	return r.attrs.ToSlice()
+}
+
+func (r *Resource) SchemaURL() string {
+	if r == nil {
+		return ""
+	}
+	return r.schemaURL
+}
+
+// Iter returns an iterator of the Resource attributes.
+// This is ideal to use if you do not want a copy of the attributes.
+func (r *Resource) Iter() attribute.Iterator {
+	if r == nil {
+		r = Empty()
+	}
+	return r.attrs.Iter()
+}
+
+// Equal returns true when a Resource is equivalent to this Resource.
+func (r *Resource) Equal(eq *Resource) bool {
+	if r == nil {
+		r = Empty()
+	}
+	if eq == nil {
+		eq = Empty()
+	}
+	return r.Equivalent() == eq.Equivalent()
+}
+
+// Merge creates a new resource by combining resource a and b.
+//
+// If there are common keys between resource a and b, then the value
+// from resource b will overwrite the value from resource a, even
+// if resource b's value is empty.
+//
+// The SchemaURL of the resources will be merged according to the spec rules:
+// https://github.com/open-telemetry/opentelemetry-specification/blob/bad49c714a62da5493f2d1d9bafd7ebe8c8ce7eb/specification/resource/sdk.md#merge
+// If the resources have different non-empty schemaURL an empty resource and an error
+// will be returned.
+func Merge(a, b *Resource) (*Resource, error) {
+	if a == nil && b == nil {
+		return Empty(), nil
+	}
+	if a == nil {
+		return b, nil
+	}
+	if b == nil {
+		return a, nil
+	}
+
+	// Merge the schema URL.
+	var schemaURL string
+	if a.schemaURL == "" {
+		schemaURL = b.schemaURL
+	} else if b.schemaURL == "" {
+		schemaURL = a.schemaURL
+	} else if a.schemaURL == b.schemaURL {
+		schemaURL = a.schemaURL
+	} else {
+		return Empty(), errMergeConflictSchemaURL
+	}
+
+	// Note: 'b' attributes will overwrite 'a' with last-value-wins in attribute.Key()
+	// Meaning this is equivalent to: append(a.Attributes(), b.Attributes()...)
+	mi := attribute.NewMergeIterator(b.Set(), a.Set())
+	combine := make([]attribute.KeyValue, 0, a.Len()+b.Len())
+	for mi.Next() {
+		combine = append(combine, mi.Label())
+	}
+	merged := NewWithAttributes(schemaURL, combine...)
+	return merged, nil
+}
+
+// Empty returns an instance of Resource with no attributes. It is
+// equivalent to a `nil` Resource.
+func Empty() *Resource {
+	return &emptyResource
+}
+
+// Default returns an instance of Resource with a default
+// "service.name" and OpenTelemetrySDK attributes.
+func Default() *Resource {
+	return defaultResource
+}
+
+// Environment returns an instance of Resource with attributes
+// extracted from the OTEL_RESOURCE_ATTRIBUTES environment variable.
+func Environment() *Resource {
+	detector := &fromEnv{}
+	resource, err := detector.Detect(context.Background())
+	if err != nil {
+		otel.Handle(err)
+	}
+	return resource
+}
+
+// Equivalent returns an object that can be compared for equality
+// between two resources. This value is suitable for use as a key in
+// a map.
+func (r *Resource) Equivalent() attribute.Distinct {
+	return r.Set().Equivalent()
+}
+
+// Set returns the equivalent *attribute.Set of this resource's attributes.
+func (r *Resource) Set() *attribute.Set {
+	if r == nil {
+		r = Empty()
+	}
+	return &r.attrs
+}
+
+// MarshalJSON encodes the resource attributes as a JSON list of { "Key":
+// "...", "Value": ... } pairs in order sorted by key.
+func (r *Resource) MarshalJSON() ([]byte, error) {
+	if r == nil {
+		r = Empty()
+	}
+	return r.attrs.MarshalJSON()
+}
+
+// Len returns the number of unique key-values in this Resource.
+func (r *Resource) Len() int {
+	if r == nil {
+		return 0
+	}
+	return r.attrs.Len()
+}
+
+// Encoded returns an encoded representation of the resource.
+func (r *Resource) Encoded(enc attribute.Encoder) string {
+	if r == nil {
+		return ""
+	}
+	return r.attrs.Encoded(enc)
+}