Some starting questions about loki configuration

Grafana Loki
1

I’m starting to explore loki and I have few questions.

I’m using docker.io/grafana/loki:2.8.2 container image.

Here’s my configuration (mostly copied from s3 example):

auth_enabled: false

storage_config:
  aws:
    bucketnames: "${S3_BUCKET}"
    endpoint: "${S3_ENDPOINT}"
    region: "${S3_REGION}"
    access_key_id: "${S3_ACCESS_KEY_ID}"
    secret_access_key: "${S3_SECRET_ACCESS_KEY}"
  boltdb_shipper:
    active_index_directory: "/loki/index"
    shared_store: "s3"
    cache_location: "/loki/index_cache"

schema_config:
  configs:
    - from: "2023-05-01"
      store: "boltdb-shipper"
      object_store: "s3"
      schema: "v11"
      index:
        prefix: "index_"
        period: "24h"

compactor:
  working_directory: "/loki/compactor"
  shared_store: "s3"

common:
  ring:
    instance_addr: "127.0.0.1"
    kvstore:
      store: "inmemory"
  replication_factor: 1
  path_prefix: "/loki"

So my questions are:

with this configuration I’m getting three warnings which are not really clear to me:

level=warn ts=2023-05-30T01:12:44.887370251Z caller=loki.go:286 msg="per-tenant timeout not configured, using default engine timeout (\"5m0s\"). This behavior will change in the next major to always use the default per-tenant timeout (\"5m\")."
level=warn ts=2023-05-30T01:12:44.890365158Z caller=cache.go:114 msg="fifocache config is deprecated. use embedded-cache instead"
level=warn ts=2023-05-30T01:12:44.890392698Z caller=experimental.go:20 msg="experimental feature in use" feature="In-memory (FIFO) cache - chunksembedded-cache"

How do I fix those warnings?

Second question is about /loki volume. I can see that loki creates several subdirectories inside /loki directory. I want to understand how should I treat this volume? I thought that it should be just something like tmpfs which will be discarded, because I configured S3 storage. But I can see that there’s something like /loki/wal/00000001 inside which looks like legitimate data.

So should I configure my system to provide persistent storage for this volume, despite the fact that S3 is used for log storage?

2

Hello,

I have the same scenario/behavior and the second message (fifocache config is deprecated) is related to this issue: Loki's embedded_cache setting is ignored & Loki continues to reference deprecated fifocache · Issue #10278 · grafana/loki · GitHub

In my case, I added that block to my config and the warning disappeared:

chunk_store_config:
  max_look_back_period: 0s
  chunk_cache_config:
    embedded_cache:
      enabled: true
      max_size_mb: 500
      ttl: 24h

Concerning the other messages, I have not figured out how to solve them (yet). To be honest, I did not research in deep.

I hope it helps you.

3

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