Class: ZipkinTracer::FaradayHandler

Inherits:
Faraday::Middleware
  • Object
show all
Defined in:
lib/zipkin-tracer/faraday/zipkin-tracer.rb

Constant Summary collapse

B3_HEADERS = 
{
  :trace_id => "X-B3-TraceId",
  :parent_id => "X-B3-ParentSpanId",
  :span_id => "X-B3-SpanId",
  :sampled => "X-B3-Sampled",
  :flags => "X-B3-Flags"
}.freeze

Instance Method Summary collapse

Constructor Details

#initialize(app, service_name = nil) ⇒ FaradayHandler

Returns a new instance of FaradayHandler.



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# File 'lib/zipkin-tracer/faraday/zipkin-tracer.rb', line 16

def initialize(app, service_name=nil)
  @app = app
  @service_name = service_name
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/zipkin-tracer/faraday/zipkin-tracer.rb', line 21

def call(env)
  # handle either a URI object (passed by Faraday v0.8.x in testing), or something string-izable
  url = env[:url].respond_to?(:host) ? env[:url] : URI.parse(env[:url].to_s)
  service_name = @service_name || url.host.split('.').first # default to url-derived service name
  endpoint = ::Trace::Endpoint.new(host_ip_for(url.host), url.port, service_name)

  ::Trace.unwind do
    trace_id = ::Trace.id
    ::Trace.push(trace_id.next_id)
    B3_HEADERS.each do |method, header|
      env[:request_headers][header] = ::Trace.id.send(method).to_s
    end

    # annotate with method (GET/POST/etc.) and uri path
    ::Trace.set_rpc_name(env[:method].to_s.upcase)
    record(::Trace::BinaryAnnotation.new("http.uri", url.path, "STRING", endpoint))
    record(::Trace::Annotation.new(::Trace::Annotation::CLIENT_SEND, endpoint))
    result = @app.call(env).on_complete do |renv|
      # record HTTP status code on response
      record(::Trace::BinaryAnnotation.new("http.status", [renv[:status]].pack('n'), "I16", endpoint))
    end
    record(::Trace::Annotation.new(::Trace::Annotation::CLIENT_RECV, endpoint))
    result
  end
end