CHANGELOG: clarify debugging metrics, backend quota metrics

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

CHANGELOG-3.1.md

@@ -13,6 +13,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.1.18...v3.1.19) and
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add [`etcd_server_slow_read_indexes_total`](https://github.com/coreos/etcd/pull/9897) Prometheus metric.
 
 
@@ -22,6 +24,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.1.17...v3.1.18) and
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add [`etcd_server_version`](https://github.com/coreos/etcd/pull/8960) Prometheus metric.
   - To replace [Kubernetes `etcd-version-monitor`](https://github.com/coreos/etcd/issues/8948).
 
@@ -82,6 +86,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.1.13...v3.1.14) and
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add [`etcd_server_is_leader`](https://github.com/coreos/etcd/pull/9587) Prometheus metric.
 
 ### etcd server
@@ -113,6 +119,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.1.12...v3.1.13) and
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add missing [`etcd_network_peer_sent_failures_total` count](https://github.com/coreos/etcd/pull/9437).
 
 ### Go

CHANGELOG-3.2.md

@@ -12,6 +12,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.2.23...v3.2.24) and
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add [`etcd_server_slow_read_indexes_total`](https://github.com/coreos/etcd/pull/9897) Prometheus metric.
 
 ### gRPC Proxy
@@ -35,6 +37,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.2.22...v3.2.23) and
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add [`etcd_server_version`](https://github.com/coreos/etcd/pull/8960) Prometheus metric.
   - To replace [Kubernetes `etcd-version-monitor`](https://github.com/coreos/etcd/issues/8948).
 
@@ -97,6 +101,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.2.18...v3.2.19) and
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Fix [`etcd_debugging_server_lease_expired_total`](https://github.com/coreos/etcd/pull/9557) Prometheus metric.
 - Fix [race conditions in v2 server stat collecting](https://github.com/coreos/etcd/pull/9562).
 - Add [`etcd_server_is_leader`](https://github.com/coreos/etcd/pull/9587) Prometheus metric.
@@ -137,6 +143,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.2.17...v3.2.18) and
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add missing [`etcd_network_peer_sent_failures_total` count](https://github.com/coreos/etcd/pull/9437).
 
 ### Go
@@ -380,6 +388,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.2.5...v3.2.6) and [
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Fix `etcd_debugging_mvcc_keys_total` inconsistency.
 
 ### Go
@@ -403,6 +413,8 @@ See [security doc](https://github.com/coreos/etcd/blob/master/Documentation/op-g
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Fix unreachable `/metrics` endpoint when `--enable-v2=false`.
 
 ### gRPC Proxy
@@ -498,6 +510,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.2.0...v3.2.1) and [
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Fix backend database size debugging metrics.
 
 ### Go
@@ -532,6 +546,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.1.0...v3.2.0) and [
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add `etcd_debugging_server_lease_expired_total` metrics.
 
 ### Security, Authentication

CHANGELOG-3.3.md

@@ -13,6 +13,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.3.8...v3.3.9) and [
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add [`etcd_server_slow_read_indexes_total`](https://github.com/coreos/etcd/pull/9897) Prometheus metric.
 
 
@@ -92,6 +94,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.3.3...v3.3.4) and [
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add [`etcd_server_is_leader`](https://github.com/coreos/etcd/pull/9587) Prometheus metric.
 - Fix [`etcd_debugging_server_lease_expired_total`](https://github.com/coreos/etcd/pull/9557) Prometheus metric.
 - Fix [race conditions in v2 server stat collecting](https://github.com/coreos/etcd/pull/9562).
@@ -146,6 +150,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.3.2...v3.3.3) and [
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add missing [`etcd_network_peer_sent_failures_total` count](https://github.com/coreos/etcd/pull/9437).
 
 ### Go
@@ -258,6 +264,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.2.0...v3.3.0) and [
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add [`etcd --listen-metrics-urls`](https://github.com/coreos/etcd/pull/8242) flag for additional `/metrics` and `/health` endpoints.
   - Useful for [bypassing critical APIs when monitoring etcd](https://github.com/coreos/etcd/issues/8060).
 - Add [`etcd_server_version`](https://github.com/coreos/etcd/pull/8960) Prometheus metric.

CHANGELOG-3.4.md

@@ -138,6 +138,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.3.0...v3.4.0) and [
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Add [`etcd_network_active_peers`](https://github.com/coreos/etcd/pull/9762) Prometheus metric.
   - Let's say `"7339c4e5e833c029"` server `/metrics` returns `etcd_network_active_peers{Local="7339c4e5e833c029",Remote="729934363faa4a24"} 1` and `etcd_network_active_peers{Local="7339c4e5e833c029",Remote="b548c2511513015"} 1`. This indicates that the local node `"7339c4e5e833c029"` currently has two active remote peers `"729934363faa4a24"` and `"b548c2511513015"` in a 3-node cluster. If the node `"b548c2511513015"` is down, the local node `"7339c4e5e833c029"` will show `etcd_network_active_peers{Local="7339c4e5e833c029",Remote="729934363faa4a24"} 1` and `etcd_network_active_peers{Local="7339c4e5e833c029",Remote="b548c2511513015"} 0`.
 - Add [`etcd_network_disconnected_peers_total`](https://github.com/coreos/etcd/pull/9762) Prometheus metric.
@@ -148,18 +150,27 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.3.0...v3.4.0) and [
 - Increase [`etcd_network_peer_round_trip_time_seconds`](https://github.com/coreos/etcd/pull/9762) Prometheus metric histogram upper-bound.
   - Previously, highest bucket only collects requests taking 0.8192 seconds or more.
   - Now, highest buckets collect 0.8192 seconds, 1.6384 seconds, and 3.2768 seconds or more.
-- Add [`etcd_server_slow_read_indexes_total`](https://github.com/coreos/etcd/pull/9897) Prometheus metric.
 - Add [`etcd_server_is_leader`](https://github.com/coreos/etcd/pull/9587) Prometheus metric.
 - Add [`etcd_server_heartbeat_send_failures_total`](https://github.com/coreos/etcd/pull/9761) Prometheus metric.
+- Add [`etcd_server_slow_apply_total`](https://github.com/coreos/etcd/pull/9761) Prometheus metric.
+- Add [`etcd_server_slow_read_indexes_total`](https://github.com/coreos/etcd/pull/9897) Prometheus metric.
 - Add [`etcd_server_quota_backend_bytes`](https://github.com/coreos/etcd/pull/9820) Prometheus metric.
   - Use it with `etcd_mvcc_db_total_size_in_bytes` and `etcd_mvcc_db_total_size_in_use_in_bytes`.
-- Add [`etcd_server_slow_apply_total`](https://github.com/coreos/etcd/pull/9761) Prometheus metric.
+  - `etcd_server_quota_backend_bytes 2.147483648e+09` means current quota size is 2 GB.
+  - `etcd_mvcc_db_total_size_in_bytes 20480` means current physically allocated DB size is 20 KB.
+  - `etcd_mvcc_db_total_size_in_use_in_bytes 16384` means future DB size if defragment operation is complete.
+  - `etcd_mvcc_db_total_size_in_bytes - etcd_mvcc_db_total_size_in_use_in_bytes` is the number of bytes that can be saved on disk with defragment operation.
+- Add [`etcd_mvcc_db_total_size_in_use_in_bytes`](https://github.com/coreos/etcd/pull/9256) Prometheus metric.
+  - Renamed from [`etcd_debugging_mvcc_db_total_size_in_use_in_bytes`](https://github.com/coreos/etcd/pull/9819).
+  - Use it with `etcd_mvcc_db_total_size_in_bytes` and `etcd_mvcc_db_total_size_in_use_in_bytes`.
+  - `etcd_server_quota_backend_bytes 2.147483648e+09` means current quota size is 2 GB.
+  - `etcd_mvcc_db_total_size_in_bytes 20480` means current physically allocated DB size is 20 KB.
+  - `etcd_mvcc_db_total_size_in_use_in_bytes 16384` means future DB size if defragment operation is complete.
+  - `etcd_mvcc_db_total_size_in_bytes - etcd_mvcc_db_total_size_in_use_in_bytes` is the number of bytes that can be saved on disk with defragment operation.
 - Add [`etcd_snap_fsync_duration_seconds`](https://github.com/coreos/etcd/pull/9762) Prometheus metric.
 - Add [`etcd_disk_backend_defrag_duration_seconds`](https://github.com/coreos/etcd/pull/9761) Prometheus metric.
 - Add [`etcd_mvcc_hash_duration_seconds`](https://github.com/coreos/etcd/pull/9761) Prometheus metric.
 - Add [`etcd_mvcc_hash_rev_duration_seconds`](https://github.com/coreos/etcd/pull/9761) Prometheus metric.
-- Rename [`etcd_debugging_mvcc_db_total_size_in_bytes` to `etcd_mvcc_db_total_size_in_bytes`](https://github.com/coreos/etcd/pull/9819).
-- Add [`etcd_mvcc_db_total_size_in_use_in_bytes`](https://github.com/coreos/etcd/pull/9256) Prometheus metric (renamed from [`etcd_debugging_mvcc_db_total_size_in_use_in_bytes`](https://github.com/coreos/etcd/pull/9819)).
 - Add [`etcd_debugging_disk_backend_commit_rebalance_duration_seconds`](https://github.com/coreos/etcd/pull/9834) Prometheus metric.
 - Add [`etcd_debugging_disk_backend_commit_spill_duration_seconds`](https://github.com/coreos/etcd/pull/9834) Prometheus metric.
 - Add [`etcd_debugging_disk_backend_commit_write_duration_seconds`](https://github.com/coreos/etcd/pull/9834) Prometheus metric.

CHANGELOG-3.5.md

@@ -30,6 +30,8 @@ See [code changes](https://github.com/coreos/etcd/compare/v3.4.0...v3.5.0) and [
 
 ### Metrics, Monitoring
 
+Note that any `etcd_debugging_*` metrics are experimental and subject to change.
+
 - Deprecated `etcd_debugging_mvcc_db_total_size_in_bytes` Prometheus metric. Instead, use `etcd_mvcc_db_total_size_in_bytes`.
 
 ### gRPC gateway