Galera Cluster

Setup the Cluster

Install the packages

On each node do as root:

• Add sources

<syntaxhighlight lang=bash>

1. cat > /etc/apt/sources.list.d/mariadb.list << EOF
2. MariaDB Server
3. To use a different major version of the server, or to pin to a specific minor version, change URI below.

deb [arch=amd64] http://downloads.mariadb.com/MariaDB/mariadb-10.5/repo/ubuntu $(lsb_release -cs) main

deb [arch=amd64] http://downloads.mariadb.com/MariaDB/mariadb-10.5/repo/ubuntu $(lsb_release -cs) main/debug

1. MariaDB MaxScale
2. To use the latest stable release of MaxScale, use "latest" as the version
3. To use the latest beta (or stable if no current beta) release of MaxScale, use "beta" as the version

deb [arch=amd64] https://dlm.mariadb.com/repo/maxscale/latest/apt $(lsb_release -cs) main

1. MariaDB Tools

deb [arch=amd64] http://downloads.mariadb.com/Tools/ubuntu $(lsb_release -cs) main EOF </source>

• Install the packages

<syntaxhighlight lang=bash>

1. apt update
2. apt install mariadb-server mariadb-backup galera-4

</source>

Setup certificates for the cluster comunication

Make a CA certificate

Make a CA certificate with a very long lifetime as you dont want to make normal certificate updates at this point. <syntaxhighlight lang=bash> $ subject='/C=DE/ST=Hamburg/L=Hamburg/O=Organisation/OU=Databases/CN=Galera Cluster' $ openssl req -new -x509 -nodes -days 365000 -newkey rsa:4096 -sha256 -keyout ca-key.pem -out ca-cert.pem -batch -subj "${subject}" </source>

Create a certificate for each cluster node

<syntaxhighlight lang=bash> $ for node in {1..4} do

 emailAddress="dbadmin@server.de"
 servername="maria-${node}.server.de"
 subject="/C=DE/ST=Hamburg/L=Hamburg/O=Organisation/OU=Databases/CN=${servername}/emailAddress=${emailAddress}"
 openssl req  -newkey rsa:4096 -nodes -keyout ${servername}-key.pem    -out ${servername}-req.pem -batch -subj "${subject}"
 openssl x509 -req -days 365000 -set_serial $(printf "%02d" "${node}") -in  ${servername}-req.pem -out ${servername}-cert.pem -CA ca-cert.pem -CAkey ca-key.pem

done </source>

Copy keys and certificates to the nodes

Copy the specific keys and certs to each node: <syntaxhighlight lang=bash> $ sudo mkdir --mode=0700 /etc/mysql/priv # put in here: maria-${node}.server.de-key.pem $ sudo mkdir --mode=0750 /etc/mysql/cert # put in here: maria-${node}.server.de-cert.pem , ca-cert.pem </source>

Configure the MariaDB Galera Cluster

Create a mariabackup user on each node

<syntaxhighlight lang=bash>

1. mariadb

MariaDB [(none)]> grant reload, process, lock tables, replication client on *.* to 'mariabackup'@'localhost' identified by 'the_very_secret_mariabackup_password'; MariaDB [(none)]> grant reload, process, lock tables, binlog monitor on *.* to 'mariabackup'@'maria-1.server.de' identified by 'the_very_secret_mariabackup_password'; MariaDB [(none)]> grant reload, process, lock tables, binlog monitor on *.* to 'mariabackup'@'maria-2.server.de' identified by 'the_very_secret_mariabackup_password'; MariaDB [(none)]> grant reload, process, lock tables, binlog monitor on *.* to 'mariabackup'@'maria-3.server.de' identified by 'the_very_secret_mariabackup_password'; MariaDB [(none)]> grant reload, process, lock tables, binlog monitor on *.* to 'mariabackup'@'maria-4.server.de' identified by 'the_very_secret_mariabackup_password'; MariaDB [(none)]> flush privileges; MariaDB [(none)]> </source>

Galera settings

/etc/mysql/mariadb.conf.d/zz-galera.cnf <syntaxhighlight lang=ini> [galera]

1. Cluster Configuration

wsrep_provider = /usr/lib/galera/libgalera_smm.so

1. gcomm://{ comma seperated list of all cluster node IPs }

wsrep_cluster_address = gcomm://10.33.6.1,10.33.6.2,10.33.6.3,10.33.6.4 wsrep_cluster_name = MariaDB Galera Cluster wsrep_on = ON

1. Snapshot state transfer (SST): copy entire database, when new node joins

wsrep_sst_method = mariabackup

1. set the the_very_secret_mariabackup_password to your real mariabackup password

wsrep_sst_auth = mariabackup:the_very_secret_mariabackup_password

[mariadb] binlog_format = ROW innodb_autoinc_lock_mode = 2 </source>

Get knowledge about your Cluster

Show wsrep_provider_options

<syntaxhighlight lang=bash> $ mariadb -NBABe 'show variables like "wsrep_provider_options"' | awk '{gsub(/$/,":\n",$1); gsub(/(;|$)/,";\n"); printf $0; }' </source>