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opentelemetry-go/sdk/resource/resource.go
Robert Pająk 4d473d105a
[chore] Pin otel-specification hyperlinks (#4033)
Co-authored-by: Chester Cheung <cheung.zhy.csu@gmail.com>
Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>
2023-05-09 08:45:39 -07:00

273 lines
7.6 KiB
Go

// 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"
"sync"
"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 *Resource
defaultResourceOnce sync.Once
)
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 {
cfg = opt.apply(cfg)
}
r := &Resource{schemaURL: cfg.schemaURL}
return r, detect(ctx, r, cfg.detectors)
}
// 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/v1.20.0/specification/common/README.md#attribute
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())
}
// MarshalLog is the marshaling function used by the logging system to represent this exporter.
func (r *Resource) MarshalLog() interface{} {
return struct {
Attributes attribute.Set
SchemaURL string
}{
Attributes: r.attrs,
SchemaURL: r.schemaURL,
}
}
// 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()
}
// SchemaURL returns the schema URL associated with Resource r.
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/v1.20.0/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
switch true {
case a.schemaURL == "":
schemaURL = b.schemaURL
case b.schemaURL == "":
schemaURL = a.schemaURL
case a.schemaURL == b.schemaURL:
schemaURL = a.schemaURL
default:
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.Attribute())
}
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 {
defaultResourceOnce.Do(func() {
var err error
defaultResource, err = Detect(
context.Background(),
defaultServiceNameDetector{},
fromEnv{},
telemetrySDK{},
)
if err != nil {
otel.Handle(err)
}
// If Detect did not return a valid resource, fall back to emptyResource.
if defaultResource == nil {
defaultResource = &emptyResource
}
})
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)
}