# Haystack To enable the Haystack tracer: ```yaml tab="File (YAML)" tracing: haystack: {} ``` ```toml tab="File (TOML)" [tracing] [tracing.haystack] ``` ```bash tab="CLI" --tracing.haystack=true ``` #### `localAgentHost` _Required, Default="127.0.0.1"_ Local Agent Host instructs reporter to send spans to the Haystack Agent at this address. ```yaml tab="File (YAML)" tracing: haystack: localAgentHost: 127.0.0.1 ``` ```toml tab="File (TOML)" [tracing] [tracing.haystack] localAgentHost = "127.0.0.1" ``` ```bash tab="CLI" --tracing.haystack.localAgentHost=127.0.0.1 ``` #### `localAgentPort` _Required, Default=35000_ Local Agent Port instructs reporter to send spans to the Haystack Agent at this port. ```yaml tab="File (YAML)" tracing: haystack: localAgentPort: 35000 ``` ```toml tab="File (TOML)" [tracing] [tracing.haystack] localAgentPort = 35000 ``` ```bash tab="CLI" --tracing.haystack.localAgentPort=35000 ``` #### `globalTag` _Optional, Default=empty_ Applies shared key:value tag on all spans. ```yaml tab="File (YAML)" tracing: haystack: globalTag: sample:test ``` ```toml tab="File (TOML)" [tracing] [tracing.haystack] globalTag = "sample:test" ``` ```bash tab="CLI" --tracing.haystack.globalTag=sample:test ``` #### `traceIDHeaderName` _Optional, Default=empty_ Sets the header name used to store the trace ID. ```yaml tab="File (YAML)" tracing: haystack: traceIDHeaderName: Trace-ID ``` ```toml tab="File (TOML)" [tracing] [tracing.haystack] traceIDHeaderName = "Trace-ID" ``` ```bash tab="CLI" --tracing.haystack.traceIDHeaderName=Trace-ID ``` #### `parentIDHeaderName` _Optional, Default=empty_ Sets the header name used to store the parent ID. ```yaml tab="File (YAML)" tracing: haystack: parentIDHeaderName: Parent-Message-ID ``` ```toml tab="File (TOML)" [tracing] [tracing.haystack] parentIDHeaderName = "Parent-Message-ID" ``` ```bash tab="CLI" --tracing.haystack.parentIDHeaderName=Parent-Message-ID ``` #### `spanIDHeaderName` _Optional, Default=empty_ Sets the header name used to store the span ID. ```yaml tab="File (YAML)" tracing: haystack: spanIDHeaderName: Message-ID ``` ```toml tab="File (TOML)" [tracing] [tracing.haystack] spanIDHeaderName = "Message-ID" ``` ```bash tab="CLI" --tracing.haystack.spanIDHeaderName=Message-ID ``` #### `baggagePrefixHeaderName` _Optional, Default=empty_ Sets the header name prefix used to store baggage items in a map. ```yaml tab="File (YAML)" tracing: haystack: baggagePrefixHeaderName: "sample" ``` ```toml tab="File (TOML)" [tracing] [tracing.haystack] baggagePrefixHeaderName = "sample" ``` ```bash tab="CLI" --tracing.haystack.baggagePrefixHeaderName=sample ```