--- title: Trace Span description: A template that represents\ an individual span within a distributed trace. location: https://istio.io/docs/reference/config/policy-and-telemetry/templates/tracespan.html layout: protoc-gen-docs generator: protoc-gen-docs number_of_entries: 3 ---

The `tracespan` template represents an individual span within a distributed trace.

Example config:

    apiVersion: "config.istio.io/v1alpha2"
    kind: tracespan
    metadata:
      name: default
      namespace: istio-system
    spec:
      traceId: request.headers["x-b3-traceid"]
      spanId: request.headers["x-b3-spanid"] | ""
      parentSpanId: request.headers["x-b3-parentspanid"] | ""
      spanName: request.path | "/"
      startTime: request.time
      endTime: response.time
      spanTags:
        http.method: request.method | ""
        http.status_code: response.code | 200
        http.url: request.path | ""
        request.size: request.size | 0
        response.size: response.size | 0
        source.ip: source.ip | ip("0.0.0.0")
        source.service: source.service | ""
        source.user: source.user | ""
        source.version: source.labels["version"] | ""

See also: Distributed Tracing for information on tracing within Istio.

## Template

TraceSpan represents an individual span within a distributed trace.

When writing the configuration, the value for the fields associated with this template can either be a literal or an expression. Please note that if the datatype of a field is not istio.policy.v1beta1.Value, then the expression’s inferred type must match the datatype of the field.

Field | Type | Description
--- | --- | ---
`traceId` | `string` | Trace ID is the unique identifier for a trace. All spans from the same trace share the same Trace ID. Required.
`spanId` | `string` | Span ID is the unique identifier for a span within a trace. It is assigned when the span is created. Optional.
`parentSpanId` | `string` | Parent Span ID is the unique identifier for a parent span of this span instance. If this is a root span, then this field MUST be empty. Optional.
`spanName` | `string` | Span name is a description of the span’s operation. For example, the name can be a qualified method name or a file name and a line number where the operation is called. A best practice is to use the same display name within an application and at the same call point. This makes it easier to correlate spans in different traces. Required.
`startTime` | `istio.policy.v1beta1.TimeStamp` | The start time of the span. Required.
`endTime` | `istio.policy.v1beta1.TimeStamp` | The end time of the span. Required.
`spanTags` | `map<string, istio.policy.v1beta1.Value>` | Span tags are a set of < key, value > pairs that provide metadata for the entire span. The values can be specified in the form of expressions. Optional.
`httpStatusCode` | `int64` | HTTP status code used to set the span status. If unset or set to 0, the span status will be assumed to be successful.

## istio.policy.v1beta1.TimeStamp

An instance field of type TimeStamp denotes that the expression for the field must evalaute to ValueType.TIMESTAMP

Objects of type TimeStamp are also passed to the adapters during request-time for the instance fields of type TimeStamp

Field | Type | Description
--- | --- | ---
`value` | `google.protobuf.Timestamp` | TimeStamp encoded as google.protobuf.Timestamp.

## istio.policy.v1beta1.Value

An instance field of type Value denotes that the expression for the field is of dynamic type and can evalaute to any ValueType enum values. For example, when authoring an instance configuration for a template that has a field `data` of type `istio.policy.v1beta1.Value`, both of the following expressions are valid `data: source.ip | ip("0.0.0.0")`, `data: request.id | ""`; the resulting type is either ValueType.IP_ADDRESS or ValueType.STRING for the two cases respectively.

Objects of type Value are also passed to the adapters during request-time. There is a 1:1 mapping between oneof fields in `Value` and enum values inside `ValueType`. Depending on the expression’s evaluated `ValueType`, the equivalent oneof field in `Value` is populated by Mixer and passed to the adapters.

Field | Type | Description
--- | --- | ---
`stringValue` | `string (oneof)` | Used for values of type STRING
`int64Value` | `int64 (oneof)` | Used for values of type INT64
`doubleValue` | `double (oneof)` | Used for values of type DOUBLE
`boolValue` | `bool (oneof)` | Used for values of type BOOL
`ipAddressValue` | `istio.policy.v1beta1.IPAddress (oneof)` | Used for values of type IPAddress
`timestampValue` | `istio.policy.v1beta1.TimeStamp (oneof)` | Used for values of type TIMESTAMP
`durationValue` | `istio.policy.v1beta1.Duration (oneof)` | Used for values of type DURATION
`emailAddressValue` | `istio.policy.v1beta1.EmailAddress (oneof)` | Used for values of type EmailAddress
`dnsNameValue` | `istio.policy.v1beta1.DNSName (oneof)` | Used for values of type DNSName
`uriValue` | `istio.policy.v1beta1.Uri (oneof)` | Used for values of type Uri