configurable prom timeout, increase init query timeout

Author: bdribault

src/process.py

@@ -58,13 +58,13 @@ async def load_metric(metric: Metrics, timestamp, options: Options):
         recatch_dots_by_key[key] = last_dot
 
     # Fine tuned query to compute input increments
-
+    # Prometheus needs some time to process this complex query, so we use a longer timeout
     query = (
         "query_range?query="
         + metric.get_query()
         + f"&start={start}&end={timestamp}&step=15s"
     )
-    data = await prom.fetch(query)
+    data = await prom.fetch(query, timeout=40.0)
 
     for element in data:
         labels = element["metric"]

src/prom.py

@@ -16,10 +16,10 @@ class PrometheusException(Exception):
 logger = logging.getLogger(__name__)
 
 
-async def fetch(query: str,) -> dict:
+async def fetch(query: str, timeout=20.0) -> dict:
     url = PROM_URL + query
     try:
-        async with httpx.AsyncClient(timeout=20.0) as client:
+        async with httpx.AsyncClient(timeout=timeout) as client:
             reply = await client.get(url)
     except httpx.RequestError as exc:
         raise PrometheusException(