Add Datadog GlobalTags support

docs/content/observability/tracing/datadog.md

@@ -67,6 +67,8 @@ tracing:
 
 #### `globalTag`
 
+??? warning "Deprecated in favor of the [`globalTags`](#globaltags) option."
+
     _Optional, Default=empty_
     
     Applies a shared key:value tag on all spans.
@@ -87,6 +89,33 @@ tracing:
     --tracing.datadog.globalTag=sample
     ```
 
+#### `globalTags`
+
+_Optional, Default=empty_
+
+Applies a list of shared key:value tags on all spans.
+
+```yaml tab="File (YAML)"
+tracing:
+  datadog:
+    globalTags:
+      tag1: foo
+      tag2: bar
+```
+
+```toml tab="File (TOML)"
+[tracing]
+  [tracing.datadog]
+    [tracing.datadog.globalTags]
+      tag1 = "foo"
+      tag2 = "bar"
+```
+
+```bash tab="CLI"
+--tracing.datadog.globalTags.tag1=foo
+--tracing.datadog.globalTags.tag2=bar
+```
+
 #### `prioritySampling`
 
 _Optional, Default=false_

docs/content/reference/static-configuration/cli-ref.md

@@ -1014,6 +1014,9 @@ Enables Datadog debug. (Default: ```false```)
 `--tracing.datadog.globaltag`:  
 Sets a key:value tag on all spans.
 
+`--tracing.datadog.globaltags.<name>`:  
+Sets a list of key:value tags on all spans.
+
 `--tracing.datadog.localagenthostport`:  
 Sets the Datadog Agent host:port. (Default: ```localhost:8126```)
 

docs/content/reference/static-configuration/env-ref.md

@@ -1014,6 +1014,9 @@ Enables Datadog debug. (Default: ```false```)
 `TRAEFIK_TRACING_DATADOG_GLOBALTAG`:  
 Sets a key:value tag on all spans.
 
+`TRAEFIK_TRACING_DATADOG_GLOBALTAGS_<NAME>`:  
+Sets a list of key:value tags on all spans.
+
 `TRAEFIK_TRACING_DATADOG_LOCALAGENTHOSTPORT`:  
 Sets the Datadog Agent host:port. (Default: ```localhost:8126```)
 

docs/content/reference/static-configuration/file.toml

@@ -373,6 +373,9 @@
   [tracing.datadog]
     localAgentHostPort = "foobar"
     globalTag = "foobar"
+    [tracing.datadog.globalTags]
+      tag1 = "foobar"
+      tag2 = "foobar"
     debug = true
     prioritySampling = true
     traceIDHeaderName = "foobar"

docs/content/reference/static-configuration/file.yaml

@@ -398,6 +398,9 @@ tracing:
   datadog:
     localAgentHostPort: foobar
     globalTag: foobar
+    globalTags:
+      tag1: foobar
+      tag2: foobar
     debug: true
     prioritySampling: true
     traceIDHeaderName: foobar

pkg/tracing/datadog/datadog.go

@@ -18,7 +18,9 @@ const Name = "datadog"
 // Config provides configuration settings for a datadog tracer.
 type Config struct {
 	LocalAgentHostPort string `description:"Sets the Datadog Agent host:port." json:"localAgentHostPort,omitempty" toml:"localAgentHostPort,omitempty" yaml:"localAgentHostPort,omitempty"`
+	// Deprecated: use GlobalTags instead.
 	GlobalTag                  string            `description:"Sets a key:value tag on all spans." json:"globalTag,omitempty" toml:"globalTag,omitempty" yaml:"globalTag,omitempty" export:"true"`
+	GlobalTags                 map[string]string `description:"Sets a list of key:value tags on all spans." json:"globalTags,omitempty" toml:"globalTags,omitempty" yaml:"globalTags,omitempty" export:"true"`
 	Debug                      bool              `description:"Enables Datadog debug." json:"debug,omitempty" toml:"debug,omitempty" yaml:"debug,omitempty" export:"true"`
 	PrioritySampling           bool              `description:"Enables priority sampling. When using distributed tracing, this option must be enabled in order to get all the parts of a distributed trace sampled." json:"prioritySampling,omitempty" toml:"prioritySampling,omitempty" yaml:"prioritySampling,omitempty" export:"true"`
 	TraceIDHeaderName          string            `description:"Sets the header name used to store the trace ID." json:"traceIDHeaderName,omitempty" toml:"traceIDHeaderName,omitempty" yaml:"traceIDHeaderName,omitempty" export:"true"`
@@ -44,17 +46,9 @@ func (c *Config) SetDefaults() {
 
 // Setup sets up the tracer.
 func (c *Config) Setup(serviceName string) (opentracing.Tracer, io.Closer, error) {
-	tag := strings.SplitN(c.GlobalTag, ":", 2)
-
-	value := ""
-	if len(tag) == 2 {
-		value = tag[1]
-	}
-
 	opts := []datadog.StartOption{
 		datadog.WithAgentAddr(c.LocalAgentHostPort),
 		datadog.WithServiceName(serviceName),
-		datadog.WithGlobalTag(tag[0], value),
 		datadog.WithDebugMode(c.Debug),
 		datadog.WithPropagator(datadog.NewPropagator(&datadog.PropagatorConfig{
 			TraceHeader:    c.TraceIDHeaderName,
@@ -63,6 +57,22 @@ func (c *Config) Setup(serviceName string) (opentracing.Tracer, io.Closer, error
 			BaggagePrefix:  c.BagagePrefixHeaderName,
 		})),
 	}
+
+	for k, v := range c.GlobalTags {
+		opts = append(opts, datadog.WithGlobalTag(k, v))
+	}
+
+	if c.GlobalTag != "" {
+		log.WithoutContext().Warn(`Datadog: option "globalTag" is deprecated, please use "globalTags" instead.`)
+
+		key, value, _ := strings.Cut(c.GlobalTag, ":")
+
+		// Don't override a tag already defined with the new option.
+		if _, ok := c.GlobalTags[key]; !ok {
+			opts = append(opts, datadog.WithGlobalTag(key, value))
+		}
+	}
+
 	if c.PrioritySampling {
 		opts = append(opts, datadog.WithPrioritySampling())
 	}