tryfer 0.1

Client

The client side of this conversation is the TracingAgent which uses Twisted’s composable HTTP/1.1 client architecture to record CLIENT_SEND and CLIENT_RECV annotations for your request. In addition it’ll record the full requested URL as a string annotation named http.uri.

Server

On the server you can wrap the root resource of your application in a TracingWrapperResource and it will automatically record SERVER_RECV and SERVER_SEND annotations. It also provides access to the trace via the request argument, so you can record extra annotations.

def render(self, request):
  trace = request.getComponent(ITrace)
  trace.record(Annotation.string('name', 'value'))

Headers

TracingAgent and TracingWrapperResource support a subset of headers defined by Finagle.

• X-B3-TraceId - hex encoded trace id.

• X-B3-SpanId - hex encoded span id.

• X-B3-ParentSpanId - hex encoded span id of parent span.

Examples

In the examples/ subdirectory you’ll find two python scripts (one client and one server) which demonstrate the usage and expected output.

Start by opening two terminals and going to the tryfer source directory.

In terminal #1 we can start the server using twistd:

tryfer> twistd -n -y examples/tracing-server.tac
2012-09-05 13:22:02-0700 [-] Log opened.
2012-09-05 13:22:02-0700 [-] twistd 12.1.0 (/Users/dreid/.virtualenvs/tracing/bin/python 2.7.2) starting up.
2012-09-05 13:22:02-0700 [-] reactor class: twisted.internet.selectreactor.SelectReactor.
2012-09-05 13:22:02-0700 [-] Site starting on 8080
2012-09-05 13:22:02-0700 [-] Starting factory <twisted.web.server.Site instance at 0x100e78680>

In terminal #2 we will run the client which will make a single HTTP request to the server:

tryfer> python examples/tracing-client.py
[
  {
    "annotations": [
      {
        "type": "string",
        "value": "http://localhost:8080/README.rst",
        "key": "http.uri"
      },
      {
        "type": "timestamp",
        "value": 1346876525257644,
        "key": "cs"
      },
      {
        "type": "timestamp",
        "value": 1346876525270536,
        "key": "cr"
      }
    ],
    "trace_id": "00e5f721d19e25fa",
    "name": "GET",
    "span_id": "007fe79f2c63db97"
  }
]
Received 200 response.

Here we see some output from the DebugTracer which simply prints all annotations it’s asked to trace to stdout in json format. Here we’ve included our first annotation which is the http.uri we are requesting.

Now in terminal #1 we should see the following:

2012-09-05 13:22:05-0700 [HTTPChannel,0,127.0.0.1] 127.0.0.1 - - [05/Sep/2012:20:22:05 +0000] "GET /README.rst HTTP/1.1" 200 4829 "-" "-"
2012-09-05 13:22:05-0700 [EndAnnotationTracer] Sending trace: (64729494289524218, 36001992872811415) w/ (<tryfer.trace.Annotation object at 0x100e7bb90>,)
[
  {
    "annotations": [
      {
        "host": {
          "service_name": "tracing-server-example",
          "ipv4": "127.0.0.1",
          "port": 8080
        },
        "type": "timestamp",
        "value": 1346876525268525,
        "key": "sr"
      },
      {
        "host": {
          "service_name": "tracing-server-example",
          "ipv4": "127.0.0.1",
          "port": 8080
        },
        "type": "timestamp",
        "value": 1346876525270173,
        "key": "ss"
      }
    ],
    "trace_id": "00e5f721d19e25fa",
    "name": "GET",
    "span_id": "007fe79f2c63db97"
  }
]