From 7ea2b8c17944e5399fef79e8d4580ed8f8235f67 Mon Sep 17 00:00:00 2001
From: Ralf Haferkamp <rhaferkamp@owncloud.com>
Date: Fri, 12 May 2023 16:05:25 +0200
Subject: [PATCH] settings: Added hints about caching to the README

---
 services/settings/README.md | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/services/settings/README.md b/services/settings/README.md
index bb98a027b3..cf61e2932e 100644
--- a/services/settings/README.md
+++ b/services/settings/README.md
@@ -22,6 +22,8 @@ can be set using `SETTINGS_STORE_TYPE` environment variable. Supported values ar
 <!--- Note: The diagramm is outdate, leaving it here for a future rework
 The diagram shows how the settings service integrates into oCIS:
 
+The diagram shows how the settings service integrates into oCIS:
+
 ```mermaid
 graph TD
     ows ---|"listSettingsBundles(),<br>saveSettingsValue(value)"| os[ocis-settings]
@@ -33,7 +35,31 @@ graph TD
 ```
 -->
 
-The diagram shows how the settings service integrates into oCIS:
+## Caching
+
+When using the `SETTINGS_STORE_TYPE=metadata` The `settings` services, caches
+the results of queries to the `system-storage` for providing faster responses.
+The store used for the cache can be configured using the `SETTINGS_CACHE_STORE`
+environment variable. Possible stores are:
+  -   `memory`: Basic in-memory store and the default.
+  -   `redis`: Stores metadata in a configured Redis cluster.
+  -   `redis-sentinel`: Stores metadata in a configured Redis Sentinel cluster.
+  -   `etcd`: Stores metadata in a configured etcd cluster.
+  -   `nats-js`: Stores metadata using the key-value-store feature of [nats jetstream](https://docs.nats.io/nats-concepts/jetstream/key-value-store)
+  -   `noop`: Stores nothing. Useful for testing. Not recommended in production environments.
+
+1.  Note that in-memory stores are by nature not reboot-persistent.
+2.  Though usually not necessary, a database name can be configured for event
+    stores if the event store supports this. Generally not applicable for
+    stores of type `in-memory`, `redis` and `redis-sentinel`. These settings
+    are blank by default which means that the standard settings of the
+    configured store apply.
+3.  The `settings` service can be scaled if not using `in-memory` stores and
+    the stores are configured identically over all instances.
+4.  When using `redis-sentinel`, the Redis master to use is configured via
+    `SETTINGS_CACHE_STORE_NODES` in the form of
+    `<sentinel-host>:<sentinel-port>/<redis-master>` like
+    `10.10.0.200:26379/mymaster`.
 
 ## Settings Management