Add deprecation node for write dedupe cache (#10736)

**What this PR does / why we need it**:
Adds a deprecation node for write dedupe cache. This cannot be fully
removed yet as legacy indexes rely on this.

**Which issue(s) this PR fixes**:
Fixes #<issue number>

**Special notes for your reviewer**:

**Checklist**
- [x] Reviewed the
[`CONTRIBUTING.md`](https://github.com/grafana/loki/blob/main/CONTRIBUTING.md)
guide (**required**)
- [ ] Documentation added
- [ ] Tests updated
- [x] `CHANGELOG.md` updated
- [ ] If the change is worth mentioning in the release notes, add
`add-to-release-notes` label
- [x] Changes that require user attention or interaction to upgrade are
documented in `docs/sources/setup/upgrade/_index.md`
- [ ] For Helm chart changes bump the Helm chart version in
`production/helm/loki/Chart.yaml` and update
`production/helm/loki/CHANGELOG.md` and
`production/helm/loki/README.md`. [Example
PR](d10549e3ec)

CHANGELOG.md

@@ -19,6 +19,7 @@
 * [10534](https://github.com/grafana/loki/pull/10534) **chaudum** Remove configuration `use_boltdb_shipper_as_backup`
 * [10620](https://github.com/grafana/loki/pull/10620) **ashwanthgoli** Enable embedded cache if no other cache is explicitly enabled.
 * [10655](https://github.com/grafana/loki/pull/10655) **chaudum** Remove legacy ingester shutdown handler `/ingester/flush_shutdown`.
+* [10736](https://github.com/grafana/loki/pull/10736) **ashwanthgoli** Deprecate write dedupe cache as this is not required by the newer single store indexes (tsdb and boltdb-shipper).
 * [10693](https://github.com/grafana/loki/pull/10693) **ashwanthgoli** Embedded cache: Updates the metric prefix from `querier_cache_` to `loki_embeddedcache_` and removes duplicate metrics.
 
 ##### Fixes

docs/sources/configure/_index.md

@@ -2119,7 +2119,10 @@ The `chunk_store_config` block configures how chunks will be cached and how long
 # The CLI flags prefix for this block configuration is: store.chunks-cache
 [chunk_cache_config: <cache_config>]
 
-# The cache block configures the cache backend.
+# Write dedupe cache is deprecated along with legacy index types (aws,
+# aws-dynamo, bigtable, bigtable-hashed, cassandra, gcp, gcp-columnkey,
+# grpc-store).
+# Consider using TSDB index which does not require a write dedupe cache.
 # The CLI flags prefix for this block configuration is: store.index-cache-write
 [write_dedupe_cache_config: <cache_config>]
 

docs/sources/setup/upgrade/_index.md

@@ -69,6 +69,10 @@ This new metric will provide a more clear signal that there is an issue with ing
 
 1. `frontend.embedded-cache.max-size-mb` Embedded results cache size now defaults to 100MB.
 
+#### Write dedupe cache is deprecated
+Write dedupe cache is deprecated because it not required by the newer single store indexes ([TSDB]({{< relref "../../operations/storage/tsdb" >}}) and [boltdb-shipper]({{< relref "../../operations/storage/boltdb-shipper" >}})).
+If you using a [legacy index type]({{< relref "../../storage#index-storage" >}}), consider migrating to TSDB (recommended).
+
 #### Embedded cache metric changes
 
 - The following embedded cache metrics are removed. Instead use `loki_cache_fetched_keys`, `loki_cache_hits`, `loki_cache_request_duration_seconds` which instruments requests made to the configured cache (`embeddedcache`, `memcached` or `redis`).

pkg/storage/config/store.go

@@ -15,7 +15,7 @@ import (
 type ChunkStoreConfig struct {
 	ChunkCacheConfig       cache.Config `yaml:"chunk_cache_config"`
 	ChunkCacheConfigL2     cache.Config `yaml:"chunk_cache_config_l2" doc:"hidden"`
-	WriteDedupeCacheConfig cache.Config `yaml:"write_dedupe_cache_config"`
+	WriteDedupeCacheConfig cache.Config `yaml:"write_dedupe_cache_config" doc:"description=Write dedupe cache is deprecated along with legacy index types (aws, aws-dynamo, bigtable, bigtable-hashed, cassandra, gcp, gcp-columnkey, grpc-store).\nConsider using TSDB index which does not require a write dedupe cache."`
 
 	L2ChunkCacheHandoff   time.Duration  `yaml:"l2_chunk_cache_handoff" doc:"hidden"`
 	CacheLookupsOlderThan model.Duration `yaml:"cache_lookups_older_than"`

pkg/storage/store.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
@@ -103,6 +104,10 @@ func NewStore(cfg Config, storeCfg config.ChunkStoreConfig, schemaCfg config.Sch
 		return nil, err
 	}
 
+	if cache.IsCacheConfigured(storeCfg.WriteDedupeCacheConfig) {
+		level.Warn(logger).Log("msg", "write dedupe cache is deprecated along with legacy index types. Consider using TSDB index which does not require a write dedupe cache.")
+	}
+
 	writeDedupeCache, err := cache.New(storeCfg.WriteDedupeCacheConfig, registerer, logger, stats.WriteDedupeCache)
 	if err != nil {
 		return nil, err