QFw: say which component wrote each log line

telemetry/README.md

@@ -172,6 +172,11 @@ So a job's lines are one query away, from the client and the QPM alike:
 {service_name="qfw-qpm", qfw_device_name="fake-iqm-20q"} | severity_text=~"ERROR|CRITICAL"
 ```
 
+On the dashboards, and in the hop from a span to its logs, each line starts
+with the component that wrote it, `[client]` or `[qpm fake-iqm-20q]`: the
+panels show a line's body, not its labels, and a job's story has two
+writers. The labels are still there in a line's details.
+
 Three links tie the signals together: the QFw Trace dashboard shows a job's
 lines under its waterfall; a span's **Logs for this span** button in Explore
 runs the first query for its trace; and a log line's `trace_id` opens its

telemetry/grafana/dashboards/qfw-jobs.json

@@ -898,7 +898,7 @@
             "uid": "qfw-loki"
           },
           "refId": "A",
-          "expr": "{service_name=~\"qfw-.+\"} | severity_text=~\"WARN.*|ERROR|CRITICAL\"",
+          "expr": "{service_name=~\"qfw-.+\"} | severity_text=~\"WARN.*|ERROR|CRITICAL\" | line_format \"[{{.qfw_component_role}}{{if .qfw_device_name}} {{.qfw_device_name}}{{end}}] {{__line__}}\"",
           "queryType": "range"
         }
       ],

telemetry/grafana/dashboards/qfw-trace.json

@@ -116,7 +116,7 @@
             "uid": "qfw-loki"
           },
           "refId": "A",
-          "expr": "{service_name=~\"qfw-.+\"} | trace_id=\"${traceId}\"",
+          "expr": "{service_name=~\"qfw-.+\"} | trace_id=\"${traceId}\" | line_format \"[{{.qfw_component_role}}{{if .qfw_device_name}} {{.qfw_device_name}}{{end}}] {{__line__}}\"",
           "queryType": "range"
         }
       ],

telemetry/grafana/provisioning/datasources/qfw.yaml

@@ -38,7 +38,7 @@ datasources:
         customQuery: true
         # Grafana expands $VAR in provisioning files, so the span variable
         # the query needs at run time is written with a doubled dollar.
-        query: '{service_name=~"qfw-.+"} | trace_id="$${__span.traceId}"'
+        query: '{service_name=~"qfw-.+"} | trace_id="$${__span.traceId}" | line_format "[{{.qfw_component_role}}{{if .qfw_device_name}} {{.qfw_device_name}}{{end}}] {{__line__}}"'
 
   - name: Loki
     uid: qfw-loki