Wraps a Req request in an opentelemetry span.

Spans are not created until the request is completed or errored.

Req Path Params

It is strongly encouraged to use the put_path_params step option. This allows the span name to include the {target} portion of the span name described in the HTTP Span Name guidelines.

Requirements

• path_params option should be set along with a templated path. Only :colon style is supported
• URLAttributes.url_template() opt-in attribute must be set to true

Semantic Conventions

All available required and recommended Client HTTP Span semantic conventions are implemented. Supported opt-in and experimental attributes can be configured using the opt_in_attrs option.

Options

Opt-in Semantic Convention Attributes

Otel SemConv requires users to explicitly opt in for any attribute with a requirement level of opt-in or experimental. To ensure compatability, always use the SemConv attribute.

Example:

client =
  Req.new()
  |> OpentelemetryReq.attach(
    opt_in_attrs: [SemConv.URLAttributes.url_template()]
  )

client
|> Req.get(
  url: "/api/users/:user_id",
  path_params: [user_id: user_id]
)

Request and response header attributes are opt-in and can be set with the request_header_attrs and response_header_attrs options. Values should be lower-case.

Trace Header Propagation

By default, trace propagation headers are not injected to requests. There are two options available to propagate trace headers:

• set propagate_trace_headers option to true when attaching or in the call
• manually use :otel_propagator_text_map.inject/1

Example:

client =
  Req.new()
  |> OpentelemetryReq.attach(propagate_trace_headers: true)

# or

client =
  Req.new()
  |> OpentelemetryReq.attach()

Req.get(client, "/", propagate_trace_headers: true)

Span Name Override

The span name can be overridden by setting the span_name option in the call.

Example:

client =
  Req.new()
  |> OpentelemetryReq.attach()

Req.get(client, "/", span_name: "custom")

Option Precedence

Options passed in a request take precedence over those passed in attach/1.