认证（⇒ Operations/Authentication）
Authentication | Grafana Loki documentation
Grafana Loki 服务并不提供认证层，官方文件建议在前端的 Reverse Porxy 进行相关的认证服务。
题外话，Reverse Proxy 同时需要负责多租户的 X-Scope-OrgID HTTP Header 的添加；
Template variable service failed Query error: 504
query_range request returns a 504 · Issue #4721 · grafana/loki · GitHub
问题描述
在 Loki 中，如果时间范围选择的较旧，则会产生如下错误：
Templating Template variable service failed Query error: 504 // 这里的主要错误还是 504 网关问题
原因分析
根据 Loki 架构，我们查看 Querier 日志，发现在索引下载或日志取回的过程中，请求被取消
level=error ts=2022-11-16T12:57:19.037772819Z caller=frontend_processor.go:69 msg="error processing requests" address=10.34.0.76:9095 err="rpc error: code = Unknown desc = context canceled" level=error ts=2022-11-16T12:57:19.037798173Z caller=frontend_processor.go:69 msg="error processing requests" address=10.34.0.76:9095 err="rpc error: code = Unknown desc = context canceled" level=error ts=2022-11-16T12:57:19.037829129Z caller=frontend_processor.go:69 msg="error processing requests" address=10.34.0.76:9095 err="rpc error: code = Unknown desc = context canceled" level=error ts=2022-11-16T12:57:19.037863643Z caller=frontend_processor.go:69 msg="error processing requests" address=10.34.0.76:9095 err="rpc error: code = Unknown desc = context canceled" level=error ts=2022-11-16T12:57:19.060024914Z caller=batch.go:716 org_id=fake msg="error fetching chunks" err="failed to get s3 object: RequestCanceled: request context canceled\ncaused by: context canceled" level=warn ts=2022-11-16T12:57:19.060120216Z caller=logging.go:72 traceID=59d5437158c6d9d5 orgID=fake msg="GET /loki/api/v1/series?end=1667347199999000000&match%5B%5D=%7Bcluster_name%3D~%22rivtower-developing-130%22%7D&shards=8_of_16&start=1667260800000000000 (500) 3.105483321s Response: \"failed to get s3 object: RequestCanceled: request context canceled\\ncaused by: context canceled\\n\" ws: false; X-Scope-Orgid: fake; uber-trace-id: 59d5437158c6d9d5:7a0dd68144a4d862:2ff6a77108d5a4e1:0; " level=error ts=2022-11-16T12:57:19.060189252Z caller=frontend_processor.go:145 msg="error processing requests" err=EOF level=error ts=2022-11-16T12:57:19.060343147Z caller=batch.go:716 org_id=fake msg="error fetching chunks" err="failed to get s3 object: RequestCanceled: request context canceled\ncaused by: context canceled" level=warn ts=2022-11-16T12:57:19.060388366Z caller=logging.go:72 traceID=59d5437158c6d9d5 orgID=fake msg="GET /loki/api/v1/series?end=1667347199999000000&match%5B%5D=%7Bcluster_name%3D~%22rivtower-developing-130%22%7D&shards=7_of_16&start=1667260800000000000 (500) 3.266632968s Response: \"failed to get s3 object: RequestCanceled: request context canceled\\ncaused by: context canceled\\n\" ws: false; X-Scope-Orgid: fake; uber-trace-id: 59d5437158c6d9d5:7a0dd68144a4d862:2ff6a77108d5a4e1:0; " level=error ts=2022-11-16T12:57:19.060416449Z caller=frontend_processor.go:145 msg="error processing requests" err=EOF
根据 Querier 日志量，我们猜测是请求较多而导致的请求被取消。而请求较多的可能原因是：查询时间分片太小，而产生很多查询分片，进而导致请求过多。
解决方案
尝试增大查询分片（split_queries_by_interval: 6h，默认 15 分钟），目前 504 情况得以改善。
但是如果时间范围更长（30d），仍旧会存在 504 的问题，其原因在于索引以 15min 为单位，过程时间范围要下载多个索引文件。
至于是否要进行相关调整，这取决于在日常中常用的查询范围。目前，能够支持 7d 查询，我们不需要进行其他调整。