Merge pull request #10 from matthewfischer/master

Add a way to manually disable the node

Author: olafz

README.md

@@ -86,4 +86,8 @@ The clustercheck script accepts several arguments:
 - **available_when_readonly** (default 1): Depending on this setting and the MySQL status variable 'read_only', the node is reported available
 - **defaults_extra_file** (default /etc/my.cnf): This file (if exists) will be passed to the mysql-command with the commandline option --defaults-extra-file
 
-Note: You can also specify the username and password for the check in the **defaults_extra_file** and pass empty values for **user** and **pass**. That way, nobody can see the username and password (which can otherwise be seen, since they are passed to the MySQL CLI)
+Note: You can also specify the username and password for the check in the **defaults_extra_file** and pass empty values for **user** and **pass**. That way, nobody can see the username and password (which can otherwise be seen, since they are passed to the MySQL CLI)
+
+## Manually removing a node from the cluster ##
+
+By touching /var/tmp/clustercheck.disabled, an admin may force clustercheck to return 503, regardless as to the actual state of the node. This is useful when the node is being put into maintenance mode.

clustercheck

@@ -15,6 +15,20 @@ if [[ $1 == '-h' || $1 == '--help' ]];then
     exit
 fi
 
+# if the disabled file is present, return 503. This allows
+# admins to manually remove a node from a cluster easily.
+if [ -e "/var/tmp/clustercheck.disabled" ]; then
+    # Shell return-code is 1
+    echo -en "HTTP/1.1 503 Service Unavailable\r\n"
+    echo -en "Content-Type: text/plain\r\n"
+    echo -en "Connection: close\r\n"
+    echo -en "Content-Length: 51\r\n"
+    echo -en "\r\n"
+    echo -en "Percona XtraDB Cluster Node is manually disabled.\r\n"
+    sleep 0.1
+    exit 1
+fi
+
 MYSQL_USERNAME="${1-clustercheckuser}"
 MYSQL_PASSWORD="${2-clustercheckpassword!}"
 AVAILABLE_WHEN_DONOR=${3:-0}