adapters: handle 204's on HttpAdapter

- adapters: add debug info on ping errors

elstat/adapters.py

@@ -70,12 +70,13 @@ class PingAdapter(Adapter):
             # we dont need to keep sending err_msg on alive scenarios
             return cls._construct(alive, latency)
 
-        # only log on errors
-        worker.log.info(f'alive={alive} latency={latency}ms')
-
         err = PING_ERROR_RGX.search(out)
         err_msg = err.group(2) if not alive and err else 'packet lost'
 
+        # only log on errors
+        worker.log.info(f'alive={alive} latency={latency}ms '
+                        f'err={err_msg!r} out={out}')
+
         return cls._construct(alive, latency, err_msg)
 
 
@@ -87,9 +88,11 @@ class HttpAdapter(Adapter):
     }
 
     @classmethod
-    def get_phrase(cls, status: int):
-        with open('./status.json', 'r') as fd:
-            statuses = json.load(fd)
+    def get_phrase(cls, status: int) -> str:
+        """Get a string representing the error
+        given by the http status code."""
+        with open('./status.json', 'r') as status_file:
+            statuses = json.load(status_file)
 
         try:
             return statuses[str(status)]
@@ -105,7 +108,8 @@ class HttpAdapter(Adapter):
         resp = await session.get(f'{adp_args["url"]}')
         t_end = time.monotonic()
 
-        succ = resp.status == 200
+        # handle both 200 and 204
+        succ = resp.status in (200, 204)
         latency = round((t_end - t_start) * 1000)
 
         # drop latency to 0 to signal a non-success