mirror of
https://github.com/open-telemetry/opentelemetry-go.git
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4d473d105a
Co-authored-by: Chester Cheung <cheung.zhy.csu@gmail.com> Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>
273 lines
7.6 KiB
Go
273 lines
7.6 KiB
Go
// Copyright The OpenTelemetry Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package resource // import "go.opentelemetry.io/otel/sdk/resource"
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import (
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"context"
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"errors"
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"sync"
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"go.opentelemetry.io/otel"
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"go.opentelemetry.io/otel/attribute"
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)
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// Resource describes an entity about which identifying information
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// and metadata is exposed. Resource is an immutable object,
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// equivalent to a map from key to unique value.
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//
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// Resources should be passed and stored as pointers
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// (`*resource.Resource`). The `nil` value is equivalent to an empty
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// Resource.
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type Resource struct {
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attrs attribute.Set
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schemaURL string
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}
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var (
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emptyResource Resource
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defaultResource *Resource
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defaultResourceOnce sync.Once
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)
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var errMergeConflictSchemaURL = errors.New("cannot merge resource due to conflicting Schema URL")
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// New returns a Resource combined from the user-provided detectors.
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func New(ctx context.Context, opts ...Option) (*Resource, error) {
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cfg := config{}
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for _, opt := range opts {
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cfg = opt.apply(cfg)
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}
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r := &Resource{schemaURL: cfg.schemaURL}
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return r, detect(ctx, r, cfg.detectors)
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}
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// NewWithAttributes creates a resource from attrs and associates the resource with a
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// schema URL. If attrs contains duplicate keys, the last value will be used. If attrs
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// contains any invalid items those items will be dropped. The attrs are assumed to be
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// in a schema identified by schemaURL.
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func NewWithAttributes(schemaURL string, attrs ...attribute.KeyValue) *Resource {
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resource := NewSchemaless(attrs...)
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resource.schemaURL = schemaURL
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return resource
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}
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// NewSchemaless creates a resource from attrs. If attrs contains duplicate keys,
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// the last value will be used. If attrs contains any invalid items those items will
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// be dropped. The resource will not be associated with a schema URL. If the schema
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// of the attrs is known use NewWithAttributes instead.
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func NewSchemaless(attrs ...attribute.KeyValue) *Resource {
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if len(attrs) == 0 {
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return &emptyResource
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}
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// Ensure attributes comply with the specification:
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// https://github.com/open-telemetry/opentelemetry-specification/blob/v1.20.0/specification/common/README.md#attribute
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s, _ := attribute.NewSetWithFiltered(attrs, func(kv attribute.KeyValue) bool {
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return kv.Valid()
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})
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// If attrs only contains invalid entries do not allocate a new resource.
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if s.Len() == 0 {
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return &emptyResource
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}
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return &Resource{attrs: s} //nolint
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}
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// String implements the Stringer interface and provides a
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// human-readable form of the resource.
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//
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// Avoid using this representation as the key in a map of resources,
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// use Equivalent() as the key instead.
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func (r *Resource) String() string {
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if r == nil {
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return ""
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}
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return r.attrs.Encoded(attribute.DefaultEncoder())
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}
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// MarshalLog is the marshaling function used by the logging system to represent this exporter.
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func (r *Resource) MarshalLog() interface{} {
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return struct {
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Attributes attribute.Set
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SchemaURL string
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}{
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Attributes: r.attrs,
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SchemaURL: r.schemaURL,
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}
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}
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// Attributes returns a copy of attributes from the resource in a sorted order.
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// To avoid allocating a new slice, use an iterator.
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func (r *Resource) Attributes() []attribute.KeyValue {
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if r == nil {
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r = Empty()
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}
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return r.attrs.ToSlice()
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}
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// SchemaURL returns the schema URL associated with Resource r.
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func (r *Resource) SchemaURL() string {
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if r == nil {
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return ""
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}
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return r.schemaURL
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}
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// Iter returns an iterator of the Resource attributes.
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// This is ideal to use if you do not want a copy of the attributes.
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func (r *Resource) Iter() attribute.Iterator {
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if r == nil {
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r = Empty()
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}
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return r.attrs.Iter()
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}
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// Equal returns true when a Resource is equivalent to this Resource.
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func (r *Resource) Equal(eq *Resource) bool {
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if r == nil {
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r = Empty()
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}
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if eq == nil {
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eq = Empty()
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}
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return r.Equivalent() == eq.Equivalent()
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}
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// Merge creates a new resource by combining resource a and b.
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//
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// If there are common keys between resource a and b, then the value
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// from resource b will overwrite the value from resource a, even
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// if resource b's value is empty.
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//
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// The SchemaURL of the resources will be merged according to the spec rules:
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// https://github.com/open-telemetry/opentelemetry-specification/blob/v1.20.0/specification/resource/sdk.md#merge
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// If the resources have different non-empty schemaURL an empty resource and an error
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// will be returned.
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func Merge(a, b *Resource) (*Resource, error) {
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if a == nil && b == nil {
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return Empty(), nil
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}
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if a == nil {
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return b, nil
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}
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if b == nil {
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return a, nil
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}
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// Merge the schema URL.
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var schemaURL string
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switch true {
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case a.schemaURL == "":
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schemaURL = b.schemaURL
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case b.schemaURL == "":
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schemaURL = a.schemaURL
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case a.schemaURL == b.schemaURL:
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schemaURL = a.schemaURL
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default:
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return Empty(), errMergeConflictSchemaURL
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}
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// Note: 'b' attributes will overwrite 'a' with last-value-wins in attribute.Key()
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// Meaning this is equivalent to: append(a.Attributes(), b.Attributes()...)
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mi := attribute.NewMergeIterator(b.Set(), a.Set())
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combine := make([]attribute.KeyValue, 0, a.Len()+b.Len())
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for mi.Next() {
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combine = append(combine, mi.Attribute())
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}
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merged := NewWithAttributes(schemaURL, combine...)
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return merged, nil
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}
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// Empty returns an instance of Resource with no attributes. It is
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// equivalent to a `nil` Resource.
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func Empty() *Resource {
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return &emptyResource
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}
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// Default returns an instance of Resource with a default
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// "service.name" and OpenTelemetrySDK attributes.
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func Default() *Resource {
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defaultResourceOnce.Do(func() {
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var err error
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defaultResource, err = Detect(
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context.Background(),
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defaultServiceNameDetector{},
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fromEnv{},
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telemetrySDK{},
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)
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if err != nil {
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otel.Handle(err)
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}
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// If Detect did not return a valid resource, fall back to emptyResource.
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if defaultResource == nil {
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defaultResource = &emptyResource
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}
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})
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return defaultResource
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}
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// Environment returns an instance of Resource with attributes
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// extracted from the OTEL_RESOURCE_ATTRIBUTES environment variable.
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func Environment() *Resource {
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detector := &fromEnv{}
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resource, err := detector.Detect(context.Background())
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if err != nil {
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otel.Handle(err)
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}
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return resource
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}
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// Equivalent returns an object that can be compared for equality
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// between two resources. This value is suitable for use as a key in
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// a map.
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func (r *Resource) Equivalent() attribute.Distinct {
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return r.Set().Equivalent()
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}
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// Set returns the equivalent *attribute.Set of this resource's attributes.
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func (r *Resource) Set() *attribute.Set {
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if r == nil {
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r = Empty()
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}
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return &r.attrs
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}
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// MarshalJSON encodes the resource attributes as a JSON list of { "Key":
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// "...", "Value": ... } pairs in order sorted by key.
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func (r *Resource) MarshalJSON() ([]byte, error) {
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if r == nil {
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r = Empty()
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}
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return r.attrs.MarshalJSON()
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}
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// Len returns the number of unique key-values in this Resource.
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func (r *Resource) Len() int {
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if r == nil {
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return 0
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}
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return r.attrs.Len()
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}
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// Encoded returns an encoded representation of the resource.
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func (r *Resource) Encoded(enc attribute.Encoder) string {
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if r == nil {
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return ""
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}
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return r.attrs.Encoded(enc)
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}
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