From 86752db12024ab5d26b141a4f2a610ae73b1273b Mon Sep 17 00:00:00 2001
From: Masayuki Ishii <masa213f@gmail.com>
Date: Mon, 5 Aug 2024 11:17:17 +0900
Subject: [PATCH 1/2] Add procedure to set cluster to read-only

Signed-off-by: Masayuki Ishii <masa213f@gmail.com>
---
 docs/usage.md | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/docs/usage.md b/docs/usage.md
index 48a5c21d..82e2e7f6 100644
--- a/docs/usage.md
+++ b/docs/usage.md
@@ -37,6 +37,7 @@ After [setting up MOCO](setup.md), you can create MySQL clusters with a custom r
   - [Upgrading mysql version](#upgrading-mysql-version)
   - [Re-initializing an errant replica](#re-initializing-an-errant-replica)
   - [Stop Clustering and Reconciliation](#stop-clustering-and-reconciliation)
+  - [Set to Read Only](#set-to-read-only)
 
 ## Basics
 
@@ -805,3 +806,32 @@ moco_cluster_healthy{name="test",namespace="default"} NaN
 moco_cluster_ready_replicas{name="test",namespace="default"} NaN
 moco_cluster_errant_replicas{name="test",namespace="default"} NaN
 ```
+
+### Set to Read Only
+
+When you want to set MOCO's MySQL to read-only, use the the following commands.
+
+MOCO makes the primary instance writable in the clustering process.
+Therefore, please be sure to stop clustering when you set it to read-only.
+
+```console
+$ kubectl moco stop clustering <CLSUTER_NAME>
+$ kubectl moco mysql -u moco-admin <CLSUTER_NAME> -- -e "SET GLOBAL super_read_only=1"
+```
+
+You can check whether the cluster is read-only with the following command.
+
+```console
+$ kubectl moco mysql -it <CLSUTER_NAME> -- -e "SHOW GLOBAL VARIABLES like 'super_read_only'"
++-----------------+-------+
+| Variable_name   | Value |
++-----------------+-------+
+| super_read_only | ON    |
++-----------------+-------+
+```
+
+If you want to leave read-only mode, restart clustering as follows. Then, MOCO will make the cluster writable.
+
+```console
+$ kubectl moco start clustering <CLSUTER_NAME>
+```

From ce6332b5eb3d6df2770a0cada58f6dd4d4d7788c Mon Sep 17 00:00:00 2001
From: Masayuki Ishii <masa213f@gmail.com>
Date: Mon, 5 Aug 2024 13:18:30 +0900
Subject: [PATCH 2/2] Use SELECT

---
 docs/usage.md | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/docs/usage.md b/docs/usage.md
index 82e2e7f6..264ab7f7 100644
--- a/docs/usage.md
+++ b/docs/usage.md
@@ -822,12 +822,12 @@ $ kubectl moco mysql -u moco-admin <CLSUTER_NAME> -- -e "SET GLOBAL super_read_o
 You can check whether the cluster is read-only with the following command.
 
 ```console
-$ kubectl moco mysql -it <CLSUTER_NAME> -- -e "SHOW GLOBAL VARIABLES like 'super_read_only'"
-+-----------------+-------+
-| Variable_name   | Value |
-+-----------------+-------+
-| super_read_only | ON    |
-+-----------------+-------+
+$ kubectl moco mysql -it <CLSUTER_NAME> -- -e "SELECT @@super_read_only"
++-------------------+
+| @@super_read_only |
++-------------------+
+|                 1 |
++-------------------+
 ```
 
 If you want to leave read-only mode, restart clustering as follows. Then, MOCO will make the cluster writable.