Log warning when remote read request is cancelled midway

Previously, we were trying to update the header but that cannot be
done in this instance since we are already starting to write the
request body. Only valid way of handling these situations is to
log the error and finish the request.

Author: antekresic

CHANGELOG.md

@@ -16,6 +16,7 @@ We use the following categories for changes:
 
 ### Fixed
 - Register `promscale_ingest_channel_len_bucket` metric and make it a gauge
+- Log warning when failing to write response to remote read requests
 
 ## [0.10.0] - 2022-02-17
 

pkg/api/read.go

@@ -88,7 +88,7 @@ func Read(config *Config, reader querier.Reader, metrics *Metrics, updateMetrics
 		compressed = snappy.Encode(nil, data)
 		if _, err := w.Write(compressed); err != nil {
 			statusCode = "500"
-			http.Error(w, err.Error(), http.StatusInternalServerError)
+			log.Warn("msg", "Error writing HTTP response", "err", err)
 			return
 		}
 		statusCode = "2xx"