Add proper labels to eventrouter logs
Follow-up from #706 (closed)
Right now, k8s events aggregated with eventrouter+promtail look like this:
❯ logcli query '{app="eventrouter"} |~ "warning"'
2021-03-12 15:14:33.370353 I | proto: duplicate proto type registered: ingester.Series
http://localhost:3100/loki/api/v1/query_range?direction=BACKWARD&end=1615558473370826618&limit=30&query=%7Bapp%3D%22eventrouter%22%7D+%7C~+%22warning%22&start=1615554873370826618
Common labels: {app="eventrouter", container="eventrouter", filename="/var/log/pods/oas_eventrouter-69cdd4b88-w8hj6_b0286b8a-432c-4067-9b3f-1e3ced88c511/eventrouter/0.log", job="oas/eventrouter", namespace="oas", pod="eventrouter-69cdd4b88-w8hj6", pod_template_hash="69cdd4b88", release="eventrouter"}
…
We should add proper lables, ask pointed out in https://github.com/grafana/loki/issues/940#issuecomment-782892486, or in https://grafana.com/blog/2020/07/21/loki-tutorial-how-to-send-logs-from-eks-with-promtail-to-get-full-visibility-in-grafana/