Add doc about usage stats tracking (#2733)

* Docs: document how usage statistics tracking work

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Add PR number to CHANGELOG

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Apply suggestions from code review

Co-authored-by: Ursula Kallio <ursula.kallio@grafana.com>

* Apply suggestions from code review

Co-authored-by: Ursula Kallio <ursula.kallio@grafana.com>

* Update docs/sources/operators-guide/configure/about-anonymous-usage-statistics-reporting.md

Signed-off-by: Marco Pracucci <marco@pracucci.com>
Co-authored-by: Ursula Kallio <ursula.kallio@grafana.com>

CHANGELOG.md

@@ -8,7 +8,7 @@
 * [CHANGE] Ingester: experimental `-blocks-storage.tsdb.new-chunk-disk-mapper` has been removed, new chunk disk mapper is now always used, and is no longer marked experimental. Default value of `-blocks-storage.tsdb.head-chunks-write-queue-size` has changed to 1000000, this enables async chunk queue by default, which leads to improved latency on the write path when new chunks are created in ingesters. #2762
 * [CHANGE] Ingester: removed deprecated `-blocks-storage.tsdb.isolation-enabled` option. TSDB-level isolation is now always disabled in Mimir. #2782
 * [CHANGE] Compactor: `-compactor.partial-block-deletion-delay` must either be set to 0 (to disable partial blocks deletion) or a value higher than `4h`. #2787
-* [FEATURE] Introduced an experimental anonymous usage statistics tracking (disabled by default), to help Mimir maintainers driving better decisions to support the opensource community. The tracking system anonymously collects non-sensitive and non-personal identifiable information about the running Mimir cluster, and is disabled by default. #2643 #2662 #2685 #2732 #2735
+* [FEATURE] Introduced an experimental anonymous usage statistics tracking (disabled by default), to help Mimir maintainers make better decisions to support the open source community. The tracking system anonymously collects non-sensitive, non-personally identifiable information about the running Mimir cluster, and is disabled by default. #2643 #2662 #2685 #2732 #2733 #2735
 * [FEATURE] Introduced an experimental deployment mode called read-write and running a fully featured Mimir cluster with three components: write, read and backend. The read-write deployment mode is a trade-off between the monolithic mode (only one component, no isolation) and the microservices mode (many components, high isolation). #2754 #2838
 * [ENHANCEMENT] Distributor: Add `cortex_distributor_query_ingester_chunks_deduped_total` and `cortex_distributor_query_ingester_chunks_total` metrics for determining how effective ingester chunk deduplication at query time is. #2713
 * [ENHANCEMENT] Upgrade Docker base images to `alpine:3.16.2`. #2729

docs/sources/operators-guide/configure/about-anonymous-usage-statistics-reporting.md

@@ -0,0 +1,63 @@
+---
+description: Learn about Grafana Mimir anonymous usage statistics reporting
+menuTitle: About anonymous usage statistics reporting
+title: About Grafana Mimir anonymous usage statistics reporting
+weight: 30
+---
+
+# About Grafana Mimir anonymous usage statistics reporting
+
+Grafana Mimir includes a system that optionally and anonymously reports non-sensitive, non-personally identifiable information about the running Mimir cluster to a remote statistics server.
+Mimir maintainers use this anonymous information to learn more about how the open source community runs Mimir and what the Mimir team should focus on when working on the next features and documentation improvements.
+
+The anonymous usage statistics reporting is **disabled by default**.
+If you agree to anonymous collection of usage statistics, you can enable this feature.
+
+## The statistics server
+
+When usage statistics reporting is enabled, information is collected by a server that Grafana Labs runs. Statistics are collected at `https://stats.grafana.org`.
+
+## Which information is collected
+
+When the usage statistics reporting is enabled, Grafana Mimir collects the following information:
+
+- Information about the **Mimir cluster and version**:
+  - A unique, randomly-generated Mimir cluster identifier, such as `3749b5e2-b727-4107-95ae-172abac27496`.
+  - The timestamp when the anonymous usage statistics reporting was enabled for the first time, and the cluster identifier was created.
+  - The Mimir version, such as `2.3.0`.
+  - The Mimir branch, revision, and Golang version that was used to build the binary.
+- Information about the **environment** where Mimir is running:
+  - The operating system, such as `linux`.
+  - The architecture, such as `amd64`.
+  - The Mimir memory utilization and number of goroutines.
+  - The number of logical CPU cores available to the Mimir process.
+- Information about the Mimir **configuration**:
+  - The `-target` parameter value, such as `all` when running Mimir in monolithic mode.
+  - The `-blocks-storage.backend` value, such as `s3`.
+  - The `-ingester.ring.replication-factor` value, such as `3`.
+- Information about the Mimir **cluster scale**:
+  - Ingester:
+    - The number of in-memory series.
+    - The number of tenants that have in-memory series.
+    - The number of samples and exemplars ingested.
+  - Querier, _where no information is tracked about the actual request or query_:
+    - The number of requests to queriers that are split by API endpoint type:
+      - Remote read.
+      - Instant query.
+      - Range query.
+      - Exemplars query.
+      - Labels query.
+      - Series query.
+      - Metadata query.
+      - Cardinality analysis query.
+
+> **Note**: Mimir maintainers commit to keeping the list of tracked information updated over time, and reporting any change both via the CHANGELOG and the release notes.
+
+## Enable the anonymous usage statistics reporting
+
+If you would like to participate in usage statistics reporting, set the CLI flag `-usage-stats.enabled=true` or change the following YAML configuration:
+
+```yaml
+usage_stats:
+  enabled: true
+```