Oracle Linux/MySQL

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Line 409: Line 409:
 
NDB cluster status script:
 
NDB cluster status script:
 
<div class="mw-collapsible-content"><pre style="white-space: pre-wrap;"><nowiki>
 
<div class="mw-collapsible-content"><pre style="white-space: pre-wrap;"><nowiki>
−
Test
+
#!/bin/bash
 +
#
 +
# Description: Script that reports status of ndb sql cluster nodes via HTTP, allowing HAProxy monitoring.
 +
# Author: <[email protected]>
 +
#
 +
 
 +
# Package name must be exact. generally this is in the format <name>-<version>-<release>.<arch>
 +
# use yum info <package> to get the above values.
 +
 
 +
# Default values for parameters in case they are not specified.
 +
sqlhost="localhost"
 +
sqluser="root"
 +
sqlpass='7,q(hf`U+3=?STg4]5a4xG!7DQL%Le'
 +
logfile="/var/log/ndbclustercheck/xinetd.log"
 +
 
 +
# Independent parameters for script, passed in any order. ie. ~$ script.sh -b -a -c
 +
while getopts s:u:p:l: option
 +
do
 +
    case "${option}"
 +
    in
 +
        s) sqlhost=${OPTARG};;
 +
        u) sqluser=${OPTARG};;
 +
        p) sqlpass=${OPTARG};;
 +
        l) logfile=${OPTARG};;
 +
    esac
 +
done
 +
 
 +
# Dependent parameters
 +
dateprefix=$(date +%F.%T)
 +
 
 +
# function to check if log file is writable
 +
function check_log {
 +
    logdir=$(dirname $logfile)
 +
    if [ -d $logdir ]; then
 +
        touch $logdir/test
 +
        if [ $? -eq 0 ]; then
 +
            rm $logdir/test
 +
        else
 +
            echo "$dateprefix unable to write to log directory: $logdir" &> /tmp/xinetd.log
 +
            #exit 1
 +
        fi
 +
    else
 +
        echo "$dateprefix log directory does not exist: $logdir" &> /tmp/xinetd.log
 +
        #exit 1
 +
    fi
 +
}
 +
 
 +
# function to check if the specified package exists
 +
function check_packages {
 +
    echo "$dateprefix Checking Packages" &> $logfile
 +
    packages=("xinetd-2.3.15-13.el7.x86_64" "nmap.x86_64 2:6.40-19.el7")
 +
    for package in ${packages[@]}
 +
    do
 +
        rpm -qa | grep $package &>/dev/null
 +
        if [ $? -ne 0 ]; then
 +
            echo "$dateprefix package: $package is not installed.  EOL" &> $logfile
 +
            #exit 1
 +
        fi
 +
    done
 +
}
 +
 
 +
# function to check if sql is accepting connections on port 3306 and if data nodes are available.
 +
# return a 503 HTTP response if either condition is false, otherwise return a 200 HTTP response.
 +
function check_sql {
 +
    echo "$dateprefix Checking SQL" &> $logfile
 +
    #change default field separator, white space, to newline character so arrays are parsed properly
 +
    saveifs=$IFS
 +
    IFS=$'\n'
 +
    declare -a sql_available=("HTTP/1.1 200 OK\r\n"
 +
        "Content-Type: text/plain\r\n"
 +
        "Connection: close\r\n"
 +
        "Content-Length: 40\r\n"
 +
        "\r\n"
 +
        "SQL server is available.\r\n")
 +
    declare -a no_datanodes=("HTTP/1.1 503 Service Unavailable\r\n"
 +
        "Content-Type: text/plain\r\n"
 +
        "Connection: close\r\n"
 +
        "Content-Length: 44\r\n"
 +
        "\r\n"
 +
        "No available data nodes from SQL node.\r\n")
 +
    declare -a sql_unavailable=("HTTP/1.1 503 Service Unavailable\r\n"
 +
        "Content-Type: text/plain\r\n"
 +
        "Connection: close\r\n"
 +
        "Content-Length: 44\r\n"
 +
        "\r\n"
 +
        "SQL Node is unresponsive.\r\n")
 +
    nc -z $sqlhost 3306
 +
    if [ $? -eq 0 ]; then
 +
        data_nodes=$(mysql --user=$sqluser --password=$sqlpass -sN -e "select count(*) from ndbinfo.nodes where status = 'STARTED';" 2> $logfile)
 +
        if [ -n "$data_nodes" ]; then
 +
            for http in ${sql_available[@]}
 +
            do
 +
                echo -en $http | tee -a $logfile
 +
            done
 +
            sleep 0.1
 +
            #exit 0
 +
        else
 +
            for http in ${no_datanodes[@]}
 +
            do
 +
                echo -en $http | tee -a $logfile
 +
            done
 +
            sleep 0.1
 +
            #exit 1
 +
        fi
 +
    else
 +
        for http in ${sql_unavailable[@]}
 +
        do
 +
            echo -en $http | tee -a $logfile
 +
        done
 +
        sleep 0.1
 +
        #exit 1
 +
    fi
 +
    #restore default field separator to a whitespace
 +
    IFS=$saveifs
 +
}
 +
 
 +
check_log
 +
check_packages
 +
check_sql
 
</nowiki></pre></div></div>
 
</nowiki></pre></div></div>

Revision as of 13:07, 17 March 2020

Contents

Simple Cluster configuration

Will consist of 5 components:

Management Node
holds the configuration for MySQL Cluster in a file called config.ini. It also writes a cluster log, and takes part in arbitration to prevent split-brain or network partitioning.
(2) Data Nodes
stores the data and the tables. The data nodes takes cares of managing the transactions, recovery, etc
(2) SQL Nodes
the most common way to read/write data to the Data Nodes is by using the MySQL Server (aka SQL Node)

Management Node Configuration

dependencies

There are some packages you may need to install, but are not required. More info can be found here. 

~$ sudo yum install -y wget telnet vim net-tools bind-utils

While most of the guides I found perform installation directly using the RPM packages, I prefer to install packages from a repository whenever available. MySQL provides a YUM repository. 

~$ wget https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm
~$ sudo yum localinstall -y mysql80-community-release-el7-3.noarch.rpm

Verify you can see the new cluster packages and search them. 

~$ yum repolist all | grep mysql
~$ yum --enablerepo=mysql-cluster-8.0-community search mysql

Enable the cluster repo by setting enabled=1 

~$ sudo vim /etc/yum.repos.d/mysql-community.repo
...
[mysql-cluster-8.0-community]
name=MySQL Cluster 8.0 Community
baseurl=http://repo.mysql.com/yum/mysql-cluster-8.0-community/el/7/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

Do a quick check-update to refresh the package list cache 

~$ sudo yum check-update

We also need to open a port and make sure our networking interface is setup correctly. In my environment, servers communicate with each other through a virtual 10GB network rather than traversing the physical 1GB network. 

~$ sudo firewall-cmd --permanent --zone=internal --change-interface=eth1
~$ sudo firewall-cmd --zone=internal --permanent --add-port=1186/tcp
~$ sudo firewall-cmd --reload
~$ sudo firewall-cmd --zone=internal --list-all

package installation

There are a couple of dependencies we need to install. 

~$ sudo yum install -y epel-release && sudo yum install -y perl-Class-MethodMaker

Install the packages 

 ~$ sudo yum install -y mysql-cluster-community-management-server mysql-cluster-community-client mysql-cluster-community-libs

configure management node cluster

Now we can setup a basic configuration file for the cluster. reccommended 

~$ sudo mkdir -p /var/lib/mysql-cluster
~$ sudo vim /var/lib/mysql-cluster/config.ini
...
# TCP PARAMETERS
[tcp default]SendBufferMemory=2M
ReceiveBufferMemory=2M

# MANAGEMENT NODE PARAMETERS
[ndb_mgmd default]
# Directory for MGM node log files
DataDir=/var/lib/mysql-cluster

[ndb_mgmd]
#Management Node db1
HostName=rncv-sqlmgmt01.virtual.local

# DATA NODE PARAMETERS
[ndbd default]
NoOfReplicas=2      # Number of replicas
DataMemory=256M     # Memory allocate for data storage
IndexMemory=128M    # Memory allocate for index storage
#LockPagesInMainMemory=1 # Locks data node processes into memory  ##causes crash
#Directory for Data Node
DataDir=/var/lib/mysql-cluster

#NoOfFragmentLogFiles=300 ##causes crash
MaxNoOfConcurrentOperations=100000
#SchedulerSpinTimer=400  ##causes crash
#SchedulerExecutionTimer=100  ##causes crash
#RealTimeScheduler=1  ##causes crash
TimeBetweenGlobalCheckpoints=1000
TimeBetweenEpochs=200
RedoBuffer=32M
MaxNoOfTables=1024
MaxNoOfOrderedIndexes=256

[ndbd]
#Data Node db2
HostName=rncv-sqldata01.virtual.local
#LockExecuteThreadToCPU=1  ##causes crash
#LockMaintThreadsToCPU=0  ##causes crash

[ndbd]
#Data Node db3
HostName=rncv-sqldata02.virtual.local
#LockExecuteThreadToCPU=1  ##causes crash
#LockMaintThreadsToCPU=0  #causes crash

[mysqld]
#SQL Node db4
HostName=rncv-sql01.virtual.local

[mysqld]
#SQL Node db5
HostName=rncv-sql02.virtual.local

[mysqld]

[api]

Now we can implement the config 

~$ sudo ndb_mgmd --config-file=/var/lib/mysql-cluster/config.ini --reload
MySQL Cluster Management Server mysql-8.0.19 ndb-8.0.19
2020-02-24 17:54:57 [MgmtSrvr] INFO     -- The default config directory '/usr/mysql-cluster' does not exist. Trying to create it...
2020-02-24 17:54:57 [MgmtSrvr] INFO     -- Sucessfully created config directory
2020-02-24 17:54:57 [MgmtSrvr] WARNING  -- at line 12: [DB] IndexMemory is deprecated, will use Number bytes on each ndbd(DB) node allocated for storing indexes instead

And finally we can view the implementation: 

~$ ndb_mgm
-- NDB Cluster -- Management Client --
ndb_mgm> show
Connected to Management Server at: localhost:1186
Cluster Configuration
---------------------
[ndbd(NDB)]	2 node(s)
id=2 (not connected, accepting connect from rncv-sqldata01.virtual.local)
id=3 (not connected, accepting connect from rncv-sqldata02.virtual.local)

[ndb_mgmd(MGM)]	1 node(s)
id=1	@10.10.0.40  (mysql-8.0.19 ndb-8.0.19)

[mysqld(API)]	2 node(s)
id=4 (not connected, accepting connect from rncv-sql01.virtual.local)
id=5 (not connected, accepting connect from rncv-sql02.virtual.local)

ndb_mgm> quit

autostart

quick systemd service to manage ndb_mgmd
Kill it. 

~$ ndb_mgm
-- NDB Cluster -- Management Client --
ndb_mgm> SHUTDOWN
Connected to Management Server at: localhost:1186
Node 2: Cluster shutdown initiated
Node 3: Cluster shutdown initiated
3 NDB Cluster node(s) have shutdown.
Disconnecting to allow management server to shutdown.
Node 3: Node shutdown completed.
ndb_mgm> quit
~$ sudo pkill -f ndb_mgmd

Create the service 

~$ sudo vim /etc/systemd/system/ndb_mgmd.service
...
[Unit]
Description=MySQL NDB Cluster Management Server
After=network.target auditd.service

[Service]
Type=forking
ExecStart=/usr/sbin/ndb_mgmd --config-file=/var/lib/mysql-cluster/config.ini --reload
ExecReload=/bin/kill -HUP $MAINPID
KillMode=process
Restart=on-failure

[Install]
WantedBy=multi-user.target

~$ sudo systemctl daemon-reload

Start/Enable 

~$ sudo systemctl start ndb_mgmd.service
~$ sudo systemctl status ndb_mgmd.service
ndb_mgmd.service - MySQL NDB Cluster Management Server
   Loaded: loaded (/etc/systemd/system/ndb_mgmd.service; disabled; vendor preset: disabled)
   Active: active (running) since Mon 2020-03-09 17:59:55 EDT; 6s ago
  Process: 91567 ExecStart=/usr/sbin/ndb_mgmd --config-file=/var/lib/mysql-cluster/config.ini --reload (code=exited, status=0/SUCCESS)
 Main PID: 91568 (ndb_mgmd)
   CGroup: /system.slice/ndb_mgmd.service
           └─91568 /usr/sbin/ndb_mgmd --config-file=/var/lib/mysql-clu...

Mar 09 17:59:55 rncv-sqlmgmt01.virtual.local systemd[1]: Starting MySQ...
Mar 09 17:59:55 rncv-sqlmgmt01.virtual.local ndb_mgmd[91567]: MySQL Cl...
Mar 09 17:59:55 rncv-sqlmgmt01.virtual.local systemd[1]: Started MySQL...
Hint: Some lines were ellipsized, use -l to show in full.

~$ sudo systemctl enable ndb_mgmd.service

Data Node Configuration

The data node configuration is very similar to the Management node configuration.

dependencies

Again, same as with the management node configuration, there are some packages you may need to install, but are not required. More info can be found here. 

~$ sudo yum install -y wget telnet vim net-tools bind-utils

While most of the guides I found perform installation directly using the RPM packages, I prefer to install packages from a repository whenever available. MySQL provides a YUM repository. 

~$ wget https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm
~$ sudo yum localinstall -y mysql80-community-release-el7-3.noarch.rpm

Verify you can see the new cluster packages and search them. 

~$ yum repolist all | grep mysql
~$ yum --enablerepo=mysql-cluster-8.0-community search mysql

Enable the cluster repo by setting enabled=1 

~$ sudo vim /etc/yum.repos.d/mysql-community.repo
...
[mysql-cluster-8.0-community]
name=MySQL Cluster 8.0 Community
baseurl=http://repo.mysql.com/yum/mysql-cluster-8.0-community/el/7/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

Do a quick check-update to refresh the package list cache 

~$ sudo yum check-update

We also need to open a port and make sure our networking interface is setup correctly. In my environment, servers communicate with each other through a virtual 10GB network rather than traversing the physical 1GB network. 

~$ sudo firewall-cmd --permanent --zone=internal --change-interface=eth1
~$ sudo firewall-cmd --zone=internal --permanent --add-port=32768-60999/tcp
~$ sudo firewall-cmd --reload
~$ sudo firewall-cmd --zone=internal --list-all

package installation

There are a couple of dependencies we need to install. 

~$ sudo yum install -y epel-release && sudo yum install -y perl-Class-MethodMaker perl-Data-Dumper

Install the packages 

~$ sudo yum install -y mysql-cluster-community-data-node
~$ sudo yum install -y mysql-cluster-community-client mysql-cluster-community-libs

configure data node

We now need to tell the data node where to find the sql management node. 

~$ sudo vim /etc/my.cnf
...
[mysqld]
ndbcluster
ndb-connectstring=rncv-sqlmgmt01.virtual.local     # IP address of Management Node
 
[mysql_cluster]
ndb-connectstring=rncv-sqlmgmt01.virtual.local     # IP address of Management Node

Create a folder for the configuration files and data. 

~$ sudo mkdir -p /var/lib/mysql-cluster

I had an issue starting the ndbd client because of the folder permissions set on the folder above. Since ndbd runs as whatever user it is launched from, make sure that user has read, write, and execute permissions to the folder.

I also had to configure SELinux as it was blocking ndbd from starting. It is best to follow the steps listed here, but ultimately you'll just be creating a policy allowing ndbd the ability to manipulate files. It should look something like this: 

$ cat ndbd1-01.te

module ndbd-01 1.0;

require {
	type var_lib_t;
	type mysqld_t;
	class file open;
	class file append;
	class file { read write };
	class file lock;
	class file getattr;
        type ephemeral_port_t;
        class tcp_socket name_connect;
}

#============= mysqld_t ==============

#!!!! WARNING: 'var_lib_t' is a base type.
allow mysqld_t var_lib_t:file open;
allow mysqld_t var_lib_t:file append;
allow mysqld_t var_lib_t:file { read write };
allow mysqld_t var_lib_t:file lock;
allow mysqld_t var_lib_t:file getattr;
allow mysqld_t ephemeral_port_t:tcp_socket name_connect;

start data node

manually

Now we can start the data node and confirm it's connected. 

~$ ndbd
2020-03-04 13:35:04 [ndbd] INFO     -- Angel connected to 'rncv-sqlmgmt01.virtual.local:1186'
2020-03-04 13:35:04 [ndbd] INFO     -- Angel allocated nodeid: 2

autostart

If you prefer to auto start ndbd and manage it through systemctl, you can do this:
Kill it. 

~$ sudo pkill -f ndbd

Create the service 

~$ sudo vim /etc/systemd/system/ndbd.service
...
[Unit]
Description=MySQL NDB Data Node Daemon
After=network.target auditd.service

[Service]
Type=forking
ExecStart=/bin/sh -c "/usr/sbin/ndbd"
ExecReload=/bin/kill -HUP $MAINPID
KillMode=control-group
Restart=on-failure

[Install]
WantedBy=multi-user.target

~$ sudo systemctl daemon-reload

Start/Enable 

~$ sudo systemctl start ndbd
~$ sudo systemctl enable ndbd

confirm connectivity

From the management node you can also confirm this: 

#management_node~$ ndb_mgm
-- NDB Cluster -- Management Client --
ndb_mgm> show
Connected to Management Server at: localhost:1186
Cluster Configuration
---------------------
[ndbd(NDB)]	2 node(s)
id=2	@10.10.0.41  (mysql-8.0.19 ndb-8.0.19, starting, Nodegroup: 0)
id=3 (not connected, accepting connect from rncv-sqldata02.virtual.local)

[ndb_mgmd(MGM)]	1 node(s)
id=1	@10.10.0.40  (mysql-8.0.19 ndb-8.0.19)

[mysqld(API)]	2 node(s)
id=4 (not connected, accepting connect from rncv-sql01.virtual.local)
id=5 (not connected, accepting connect from rncv-sql02.virtual.local)


If you have a 2nd data node, repeat this process

SQL Node Configuration

dependencies

Again, same as with the management node configuration, there are some packages you may need to install, but are not required. More info can be found here. 

~$ sudo yum install -y wget telnet vim net-tools bind-utils

While most of the guides I found perform installation directly using the RPM packages, I prefer to install packages from a repository whenever available. MySQL provides a YUM repository. 

~$ wget https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm
~$ sudo yum localinstall -y mysql80-community-release-el7-3.noarch.rpm

Verify you can see the new cluster packages and search them. 

~$ yum repolist all | grep mysql
~$ yum --enablerepo=mysql-cluster-8.0-community search mysql

Enable the cluster repo by setting enabled=1 

~$ sudo vim /etc/yum.repos.d/mysql-community.repo
...
[mysql-cluster-8.0-community]
name=MySQL Cluster 8.0 Community
baseurl=http://repo.mysql.com/yum/mysql-cluster-8.0-community/el/7/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-mysql

Do a quick check-update to refresh the package list cache 

~$ sudo yum check-update

We also need to open a port and make sure our networking interface is setup correctly. In my environment, servers communicate with each other through a virtual 10GB network rather than traversing the physical 1GB network. 

~$ sudo firewall-cmd --permanent --zone=internal --change-interface=eth1
~$ sudo firewall-cmd --permanent --zone=internal --add-service=mysql
~$ sudo firewall-cmd --permanent --zone=internal --add-port=33060/tcp
~$ sudo firewall-cmd --reload
~$ sudo firewall-cmd --zone=internal --list-all

package installation

There are a couple of dependencies we need to install. 

~$ sudo yum install -y epel-release && sudo yum install -y perl-Class-MethodMaker perl-Data-Dumper

Install the packages 

~$ sudo yum install -y mysql-cluster-community-server
~$ sudo yum install -y mysql-cluster-community-client mysql-cluster-community-libs mysql-cluster-community-common

configure sql node

We now need to tell the sql node where to find the sql management node. When I did this, my.cnf already existed and had a [mysqld] section. 

~$ sudo vim /etc/my.cnf
...
[mysqld]
ndbcluster
ndb-connectstring=rncv-sqlmgmt01.virtual.local       # IP address for server management node
default-storage-engine=ndbcluster     # Define default Storage Engine used by MySQL
 
[mysql_cluster]
ndb-connectstring=rncv-sqlmgmt01.virtual.local      # IP address for server management node

I also had to configure SELinux as it was blocking mysqld from connecting to the sql management node. It is best to follow the steps listed here, but ultimately you'll just be creating a policy allowing mysqld the ability to create tcp socket connections over ephemeral ports. It should look something like this: 

$ cat local-mysql1.te

module local-mysql1 1.0;

require {
	type ephemeral_port_t;
	type mysqld_t;
	class tcp_socket name_connect;
}

#============= mysqld_t ==============

#!!!! This avc can be allowed using one of the these booleans:
#     nis_enabled, mysql_connect_any
allow mysqld_t ephemeral_port_t:tcp_socket name_connect;

start sql node

~$ sudo systemctl restart mysqld.service


If you have a 2nd sql node, repeat this process

MySQL 8 Distributed Privileges

At the time of this writing, I still have not gotten distributed privileges working, but i'm following the steps listed here.
So far, you have to grant the NDB_STORED_USER privilege to said user like so: 

mysql> GRANT NDB_STORED_USER ON *.* TO 'cluster_app_user'@'localhost'
or
mysql> GRANT NDB_STORED_USER ON *.* TO 'admin'@'%';
Query OK, 0 rows affected (0.26 sec)

With the privilege in place, you can verify the appropriate values are in the ndb_sql_metadata NDB table. 

~$ ndb_select_all -d mysql ndb_sql_metadata
type	name	seq	note	sql_ddl_text
11	"'admin'@'%'"	0	2	"CREATE USER 'admin'@'%' IDENTIFIED WITH 'caching_sha2_password' AS '$A$005$MGBmokOj
                                m!<=P9q7BhmH0ANKg1Fs3JGEv.ITwLdXa7KC0n2GOogn6Xc/' REQUIRE NONE PASSWORD EXPIRE DEFAULT ACCOUNT UNLOCK PASSWORD HISTORY DEFAULT PASSWORD REUSE INTERVAL DEFAULT PASSWORD REQUIRE CURRENT DEFAULT"
12	"'admin'@'%'"	1	[NULL]	"GRANT APPLICATION_PASSWORD_ADMIN,AUDIT_ADMIN,BACKUP_ADMIN,BINLOG_ADMIN,BINLOG_ENCRYPTION_ADMIN,CLONE_ADMIN,CONNECTION_ADMIN,ENCRYPTION_KEY_ADMIN,GROUP_REPLICATION_ADMIN,INNODB_REDO_LOG_ARCHIVE,NDB_STORED_USER,PERSIST_RO_VARIABLES_ADMIN,REPLICATION_APPLIER,REPLICATION_SLAVE_ADMIN,RESOURCE_GROUP_ADMIN,RESOURCE_GROUP_USER,ROLE_ADMIN,SERVICE_CONNECTION_ADMIN,SESSION_VARIABLES_ADMIN,SET_USER_ID,SYSTEM_USER,SYSTEM_VARIABLES_ADMIN,TABLE_ENCRYPTION_ADMIN,XA_RECOVER_ADMIN ON *.* TO `admin`@`%`"
12	"'admin'@'%'"	0	[NULL]	"GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, RELOAD, SHUTDOWN, PROCESS, FILE, REFERENCES, INDEX, ALTER, SHOW DATABASES, SUPER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, REPLICATION SLAVE, REPLICATION CLIENT, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, CREATE USER, EVENT, TRIGGER, CREATE TABLESPACE, CREATE ROLE, DROP ROLE ON *.* TO `admin`@`%`"
3 rows returned

You should only need to restart the mysqld.service on the rest of the SQL nodes for them to pull in the changes. 

Whenever a MySQL server starts up and joins the cluster as an SQL node it executes these stored CREATE USER and GRANT statements as part of the cluster schema synchronization process.

NDB cluster status script

Using HAProxy in front of a MySQL 8 NDB cluster, i ran into a couple of challenges.

  1. I could not get user/pass data to sync across the mysql nodes
  2. This in turn made it impossible for HAProxy's built in mysql status checking plugin to work.
  3. Something else i'm forgetting as well.

So, in lieu of these issues, I opted to write my own NDB cluster status service that the HAProxy httpd plugin can query to determine availability. This is based off of this script.

NDB cluster status script: 

#!/bin/bash
#
# Description: Script that reports status of ndb sql cluster nodes via HTTP, allowing HAProxy monitoring.
# Author: <[email protected]>
#

# Package name must be exact. generally this is in the format <name>-<version>-<release>.<arch>
# use yum info <package> to get the above values.

# Default values for parameters in case they are not specified.
sqlhost="localhost"
sqluser="root"
sqlpass='7,q(hf`U+3=?STg4]5a4xG!7DQL%Le'
logfile="/var/log/ndbclustercheck/xinetd.log"

# Independent parameters for script, passed in any order. ie. ~$ script.sh -b -a -c
while getopts s:u:p:l: option
do
    case "${option}"
    in
        s) sqlhost=${OPTARG};;
        u) sqluser=${OPTARG};;
        p) sqlpass=${OPTARG};;
        l) logfile=${OPTARG};;
    esac
done

# Dependent parameters
dateprefix=$(date +%F.%T)

# function to check if log file is writable
function check_log {
    logdir=$(dirname $logfile)
    if [ -d $logdir ]; then
        touch $logdir/test
        if [ $? -eq 0 ]; then
            rm $logdir/test
        else
            echo "$dateprefix unable to write to log directory: $logdir" &> /tmp/xinetd.log
            #exit 1
        fi
    else
        echo "$dateprefix log directory does not exist: $logdir" &> /tmp/xinetd.log
        #exit 1
    fi
}

# function to check if the specified package exists
function check_packages {
    echo "$dateprefix Checking Packages" &> $logfile
    packages=("xinetd-2.3.15-13.el7.x86_64" "nmap.x86_64 2:6.40-19.el7")
    for package in ${packages[@]}
    do
        rpm -qa | grep $package &>/dev/null
        if [ $? -ne 0 ]; then
            echo "$dateprefix package: $package is not installed.  EOL" &> $logfile
            #exit 1
        fi
    done
}

# function to check if sql is accepting connections on port 3306 and if data nodes are available.
# return a 503 HTTP response if either condition is false, otherwise return a 200 HTTP response.
function check_sql {
    echo "$dateprefix Checking SQL" &> $logfile
    #change default field separator, white space, to newline character so arrays are parsed properly
    saveifs=$IFS
    IFS=$'\n'
    declare -a sql_available=("HTTP/1.1 200 OK\r\n" 
        "Content-Type: text/plain\r\n" 
        "Connection: close\r\n" 
        "Content-Length: 40\r\n" 
        "\r\n" 
        "SQL server is available.\r\n")
    declare -a no_datanodes=("HTTP/1.1 503 Service Unavailable\r\n" 
        "Content-Type: text/plain\r\n" 
        "Connection: close\r\n" 
        "Content-Length: 44\r\n" 
        "\r\n" 
        "No available data nodes from SQL node.\r\n")
    declare -a sql_unavailable=("HTTP/1.1 503 Service Unavailable\r\n" 
        "Content-Type: text/plain\r\n" 
        "Connection: close\r\n" 
        "Content-Length: 44\r\n" 
        "\r\n" 
        "SQL Node is unresponsive.\r\n")
    nc -z $sqlhost 3306
    if [ $? -eq 0 ]; then
        data_nodes=$(mysql --user=$sqluser --password=$sqlpass -sN -e "select count(*) from ndbinfo.nodes where status = 'STARTED';" 2> $logfile)
        if [ -n "$data_nodes" ]; then
            for http in ${sql_available[@]}
            do
                echo -en $http | tee -a $logfile
            done
            sleep 0.1
            #exit 0
        else
            for http in ${no_datanodes[@]}
            do
                echo -en $http | tee -a $logfile
            done
            sleep 0.1
            #exit 1
        fi
    else
        for http in ${sql_unavailable[@]}
        do
            echo -en $http | tee -a $logfile
        done 
        sleep 0.1
        #exit 1
    fi
    #restore default field separator to a whitespace
    IFS=$saveifs
}

check_log
check_packages
check_sql
Retrieved from "https://wiki.r00tedvw.com/index.php?title=Oracle_Linux/MySQL&oldid=3005"
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