If enabled, print log framing content to stdout/stderr (#81)

* If enabled, print log framing content to stdout/stderr

* Test log frame header

* Refactor, get env values at module level

* Minor refactor

Author: harryjsmith

fdk/constants.py

@@ -31,6 +31,8 @@
 CONTENT_LENGTH = "Content-Length"
 FN_ENFORCED_RESPONSE_CODES = [200, 502, 504]
 FN_DEFAULT_RESPONSE_CODE = 200
+FN_LOGFRAME_NAME = "FN_LOGFRAME_NAME"
+FN_LOGFRAME_HDR = "FN_LOGFRAME_HDR"
 
 
 # todo: python 3.8 is on its way, make more flexible

fdk/event_handler.py

@@ -14,13 +14,18 @@
 
 import io
 import logging
+import os
+import sys
 
 from fdk import constants
 
 from fdk.async_http import response
 
 logger = logging.getLogger(__name__)
 
+fn_logframe_name = os.environ.get(constants.FN_LOGFRAME_NAME)
+fn_logframe_hdr = os.environ.get(constants.FN_LOGFRAME_HDR)
+
 
 def event_handle(handle_code):
     """
@@ -32,9 +37,11 @@ def event_handle(handle_code):
     async def pure_handler(request):
         from fdk import runner
         logger.info("in pure_handler")
+        headers = dict(request.headers)
+        log_frame_header(headers)
         func_response = await runner.handle_request(
             handle_code, constants.HTTPSTREAM,
-            headers=dict(request.headers), data=io.BytesIO(request.body))
+            headers=headers, data=io.BytesIO(request.body))
         logger.info("request execution completed")
 
         headers = func_response.context().GetResponseHeaders()
@@ -50,3 +57,13 @@ async def pure_handler(request):
         )
 
     return pure_handler
+
+
+def log_frame_header(headers):
+    if all((fn_logframe_name, fn_logframe_hdr)):
+        frm = fn_logframe_hdr.lower()
+        if frm in headers:
+            id = headers.get(frm)
+            frm = "\n{}={}\n".format(fn_logframe_name, id)
+            print(frm, file=sys.stderr, flush=True)
+            print(frm, file=sys.stdout, flush=True)

fdk/tests/test_http_stream.py

@@ -143,3 +143,15 @@ async def test_enforced_response_codes_504():
 
     assert http_resp.status == 504
     assert http_resp.headers.get(constants.FN_HTTP_STATUS) == "504"
+
+
+def test_log_frame_header(monkeypatch, capsys):
+    monkeypatch.setattr("fdk.event_handler.fn_logframe_name", "foo")
+    monkeypatch.setattr("fdk.event_handler.fn_logframe_hdr", "Fn-Call-Id")
+    headers = {"fn-call-id": 12345}
+
+    event_handler.log_frame_header(headers)
+
+    captured = capsys.readouterr()
+    assert "\nfoo=12345\n" in captured.out
+    assert "\nfoo=12345\n" in captured.err