Class: Tracekit::Middleware

Inherits:
Object
  • Object
show all
Defined in:
lib/tracekit/middleware.rb

Overview

Rack middleware for automatic TraceKit instrumentation of HTTP requests Creates server spans with kind: :server for all incoming HTTP requests

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ Middleware

Returns a new instance of Middleware.



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# File 'lib/tracekit/middleware.rb', line 7

def initialize(app)
  @app = app
  @tracer = OpenTelemetry.tracer_provider.tracer('tracekit-ruby', Tracekit::VERSION)
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/tracekit/middleware.rb', line 12

def call(env)
  sdk = SDK.current
  return @app.call(env) unless sdk

  request = Rack::Request.new(env)
  path = request.path
  method = request.request_method

  # Create server span for incoming HTTP request
  @tracer.in_span(
    span_name(request),
    attributes: span_attributes(request),
    kind: :server
  ) do |span|
    # Track metrics
    request_counter = sdk.counter("http.server.requests", {
      "http.method" => method,
      "http.route" => path
    })

    active_gauge = sdk.gauge("http.server.active_requests", {
      "http.method" => method
    })

    duration_histogram = sdk.histogram("http.server.request.duration", {
      "unit" => "ms"
    })

    active_gauge.inc
    start_time = Time.now

    # Add client IP to span
    if client_ip = extract_client_ip(request)
      span.set_attribute("http.client_ip", client_ip)
    end

    begin
      status, headers, body = @app.call(env)

      # Set response attributes
      span.set_attribute("http.status_code", status)

      # Set span status based on HTTP status code
      if status >= 500
        span.status = OpenTelemetry::Trace::Status.error("HTTP #{status}")
      elsif status >= 400
        span.status = OpenTelemetry::Trace::Status.error("HTTP #{status}")
      else
        span.status = OpenTelemetry::Trace::Status.ok
      end

      # Record successful request
      request_counter.inc

      # Record errors
      if status >= 400
        error_counter = sdk.counter("http.server.errors", {
          "http.method" => method,
          "http.status_code" => status.to_s
        })
        error_counter.inc
      end

      [status, headers, body]
    rescue => e
      # Record exception on span
      span.record_exception(e)
      span.status = OpenTelemetry::Trace::Status.error("Exception: #{e.class.name}")

      # Record exception metric
      error_counter = sdk.counter("http.server.errors", {
        "http.method" => method,
        "error.type" => e.class.name
      })
      error_counter.inc

      raise
    ensure
      active_gauge.dec
      duration = ((Time.now - start_time) * 1000).round(2)
      duration_histogram.record(duration)
    end
  end
end