4-node manual failover installation
Manual HA is now deprecated. Please do not perform new installations using this procedure.
Prerequisitesβ
Understandingβ
Before applying this procedure, you should have a good knowledge of Linux OS, of Centreon, and of the Pacemaker-Corosync clustering tools in order to have a proper understanding of what is being done and to be able to correct any mistakes that might occur.
WARNING: Anyone following this procedure does so at their own risk. Under no circumstances shall Centreon be liable for any breakdown or data loss.
Installation of Centreonβ
The installation of a Centreon-HA cluster can only be done based on a functional installation of Centreon. Before following this procedure, it is therefore imperative to have applied this installation procedure until the end by reserving about 5GB of free space on the volume group which contains the MySQL data (mount point /var/lib/mysql
by default).
The vgs
command should return a display of the form below (especially the value under VFree
):
VG #PV #LV #SN Attr VSize VFree
centos_centreon-c1 1 5 0 wz--n- <31,00g <5,00g
WARNING: If this prerequisite is not checked, it will not be possible to synchronize the databases as described in this document.
Definition of server names and IP addressesβ
In this procedure we will refer to parameters that vary from one installation to another (names and IP addresses of nodes for example) via the following macros:
@CENTRAL_MASTER_IPADDR@
: IP address of the main central server@CENTRAL_MASTER_NAME@
: name of the main central server@CENTRAL_SLAVE_IPADDR@
: IP address of the second central server@CENTRAL_SLAVE_NAME@
: name of the second central server@DB_MASTER_IPADDR@
: IP address of the main database server@DB_MASTER_NAME@
: name of the main database server@DB_SLAVE_IPADDR@
: IP address of the secondary database server@DB_SLAVE_NAME@
: name of the secondary database server@MYSQL_REPL_USER@
: MySQL replication account name (suggested: centreon-repl)@MYSQL_REPL_PASSWD@
: password for this account@MYSQL_CENTREON_USER@
: MySQL account name of Centreon (suggested: centreon)@MYSQL_CENTREON_PASSWD@
: password for this account@CENTRAL_VIP_IPADDR@
: virtual IP address of the cluster@CENTRAL_VIP_IFNAME@
: name of the interface that will carry the VIP@CENTRAL_VIP_CIDR_NETMASK@
: subnet mask expressed in the number of bits without the '/' (example: 24)@CENTRAL_VIP_BROADCAST_IPADDR@
: broadcast address@DB_VIP_IPADDR@
: virtual IP address of the cluster, in the case of a 2 node HA, is the same as the central one.@DB_VIP_IFNAME@
: name of the interface that will carry the VIP, in the case of a 2-node HA, it is the same as the central one.@DB_VIP_CIDR_NETMASK@
: subnet mask expressed in number bits without the '/' (example: 24), in the case of a 2-node HA, it is the same as the central one.@DB_VIP_BROADCAST_IPADDR@
: broadcast address, in the case of a 2 nodes HA, it is the same as the central one.
Centreon-broker configurationβ
Linking to the cbd serviceβ
In a standard Centreon installation, the cbd
service drives two instances of centreon-broker-daemon
:
central-broker-master
: also known as "central broker" or "SQL broker", which redirects all I/O from pollers to databases, to the RRD broker, etc.central-rrd-master
: the RRD broker which receives its flow from the SQL broker, and whose only function is to write the RRD files used to display the graphs.
In a Centreon-HA cluster, the two broker processes will each be managed via a separate service that will be driven by the cluster:
central-broker-master
as thecbd_central_broker
resource, linked to the systemdcbd-sql
servicecentral-rrd-master
as the clone resourcecbd_rrd
, linked to the standard Centreon systemdcbd
service.
For everything to work properly in the following, you must now undo the link between central-broker-master and the cbd
service by checking "no" for the parameter "Linked to cbd service " in Configuration > Pollers > Broker configuration > central-broker-master in the General tab.
Dual RRD streamsβ
Rather than setting up a real-time replication of RRD data files, the technical choice that was made to allow graphs to be displayed on any node as soon as it becomes master
was to duplicate the output stream from central-broker-master
to central-rrd-master
. This is configured in the same menu as in the previous paragraph, but this time in the Output tab of Configuration > Collectors > Centreon Broker Configuration.
- Modify the output "IPv4" by replacing "localhost" by
@CENTRAL_MASTER_IPADDR@
.
Output IPv4 | |
---|---|
Name | centreon-broker-master-rrd |
Connection port | 5670 |
Host to connect to | @CENTRAL_MASTER_IPADDR@ |
- Add a new IPv4 output, similar to the first one and named for example "centreon-broker-slave-rrd" pointing this time to
@CENTRAL_SLAVE_IPADDR@
.
Output IPv4 | |
---|---|
Name | centreon-broker-slave-rrd |
Connection port | 5670 |
Host to connect to | @CENTRAL_SLAVE_IPADDR@ |
Export the configurationβ
Once the actions of the two previous paragraphs have been performed, the configuration must be exported (the first 3 boxes for the export of the "Central" Poller) for it to be effective.
These actions must be performed either on both nodes or only on @CENTRAL_MASTER_NAME@
and then the broker configuration files must be copied to @CENTRAL_SLAVE_NAME@
.
rsync -a /etc/centreon-broker/*json @CENTRAL_SLAVE_IPADDR@:/etc/centreon-broker/
Modification of the cbd
reload commandβ
This may not be known to all Centreon users, but every time a reload of the Central Poller configuration is done via the interface, the broker service (cbd
) is reloaded (not just centengine), hence the "Centreon Broker reload command" parameter in Configuration > Pollers > Central.
As explained above, the broker processes are split between two services: cbd
for the RRD broker, cbd-sql
for the central broker. In the context of a centreon-ha cluster, the service that must be reloaded during the configuration export is cbd-sql
and not cbd
. You must therefore apply the value service cbd-sql reload
to the "Centreon Broker reload command" parameter.
Synchronize Centreon configuration files (PHP, Perl, Gorgone)β
rsync -av /etc/centreon/* root@@CENTRAL_SLAVE_IPADDR@:/etc/centreon/
System preparationβ
Before getting to the actual cluster setup, a few preparatory steps are necessary at the OS level.
Note: unless otherwise stated, each of the following steps must be performed on the two central nodes.
Tuning the network configurationβ
To improve the reliability of the cluster and since Centreon HA only runs on IP v4, it is recommended to apply the following tuning on all servers of the Centreon platform:
- Alma / RHEL / Oracle Linux 8
cat >> /etc/sysctl.conf <<EOF
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv4.tcp_retries2 = 3
net.ipv4.tcp_keepalive_time = 200
net.ipv4.tcp_keepalive_probes = 2
net.ipv4.tcp_keepalive_intvl = 2
EOF
systemctl restart NetworkManager
To avoid problems with the management of fixed and virtual IP addresses, it is necessary to declare the fixed IP address of each server in the network configuration.
To do this, execute the following commands on each node:
For the server @CENTRAL_MASTER_NAME@
:
nmcli con mod @CENTRAL_VIP_IFNAME@ +ipv4.addresses "@CENTRAL_MASTER_IPADDR@/@CENTRAL_VIP_CIDR_NETMASK@"
nmcli con up @CENTRAL_VIP_IFNAME@
For the server @CENTRAL_SLAVE_NAME@
:
nmcli con mod @CENTRAL_VIP_IFNAME@ +ipv4.addresses "@CENTRAL_SLAVE_IPADDR@/@CENTRAL_VIP_CIDR_NETMASK@"
nmcli con up @CENTRAL_VIP_IFNAME@
For the server @DB_MASTER_NAME@
:
nmcli con mod @DB_VIP_IFNAME@ +ipv4.addresses "@DB_MASTER_IPADDR@/@DB_VIP_CIDR_NETMASK@"
nmcli con up @DB_VIP_IFNAME@
For the server @DB_SLAVE_NAME@
:
nmcli con mod @DB_VIP_IFNAME@ +ipv4.addresses "@DB_SLAVE_IPADDR@/@DB_VIP_CIDR_NETMASK@"
nmcli con up @DB_VIP_IFNAME@
You can verify on each node if the IP address is declared with this command on the Central node for example:
cat /etc/sysconfig/network-scripts/ifcfg-@CENTRAL_VIP_IFNAME@
The result is like that for @CENTRAL_MASTER_NAME@
:
...
DEVICE=@CENTRAL_VIP_IFNAME@
ONBOOT=yes
IPADDR=@CENTRAL_MASTER_IPADDR@
PREFIX=23
...
Name resolutionβ
In order to ensure that the cluster functions properly even if the name resolution service fails, it is imperative that the nodes know each other through the /etc/hosts
file.
cat >/etc/hosts <<"EOF"
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
@CENTRAL_MASTER_IPADDR@ @CENTRAL_MASTER_NAME@
@CENTRAL_SLAVE_IPADDR@ @CENTRAL_SLAVE_NAME@
@DB_MASTER_IPADDR@ @DB_MASTER_NAME@
@DB_SLAVE_IPADDR@ @DB_SLAVE_NAME@
EOF
In the rest of this document, we will refer to the primary node as the primary node and the secondary node as the secondary node. This distinction is purely arbitrary, the roles can of course be exchanged once the installation is complete.
Installing the packagesβ
Centreon offers the centreon-ha
package, which provides all the scripts and dependencies needed to run a Centreon cluster.
On the central servers:
- Alma Linux 8
- RHEL 8
- Oracle Linux 8
dnf config-manager --enable ha
dnf install centreon-ha-web
subscription-manager repos --enable rhel-8-for-x86_64-highavailability-rpms
dnf install centreon-ha-web
dnf config-manager --enable ol8_addons
dnf install centreon-ha-web
Then, on the database servers :
- Alma Linux 8
- RHEL 8
- Oracle Linux 8
dnf config-manager --enable ha
dnf install centreon-ha-common
subscription-manager repos --enable rhel-8-for-x86_64-highavailability-rpms
dnf install centreon-ha-common
dnf config-manager --enable ol8_addons
dnf install centreon-ha-common
SSH key exchangeβ
To allow servers to exchange files and commands, it is necessary to set up the possibility to connect through SSH from one server to the other for the users:
mysql
centreon
There are 2 ways to exchange SSH keys:
- Using
sh-copy-id
: using this command requires the ability to validate authentication with a password. However, it is not desirable to define a password for the service accounts we are talking about here. If this method is used anyway, it is recommended to remove the password after the exchange, with the commandspasswd -d centreon
andpasswd -d mysql
. - By manually copying the public key into
~/.ssh/authorized_keys
. This method is to be preferred, but requires, to work properly, that only the owner of the file is able to read it.
This is the second method which will be proposed below.
Centreon accountβ
This procedure is to be applied to the two central nodes. To begin, switch to the bash
environment of centreon
:
su - centreon
Then run these commands on the two central nodes:
ssh-keygen -t ed25519 -a 100
cat ~/.ssh/id_ed25519.pub | tee ~/.ssh/authorized_keys
After running these commands on both nodes, copy the contents of the file that was displayed under the cat
command and paste it into the ~/.ssh/authorized_keys
file on the other node and then apply the correct permissions to the file (still as centreon
):
chmod 600 ~/.ssh/authorized_keys
The key exchange must then be validated by a first connection that will accept the signature of the SSH server (always as centreon
) :
ssh @CENTRAL_MASTER_NAME@
ssh @CENTRAL_SLAVE_NAME@
Then exit the centreon
session with exit
or Ctrl-D
.
Mysql accountβ
For the mysql
account the procedure differs somewhat because this user does not normally have a home directory or the ability to open a Shell session. This procedure is to be applied to both database nodes.
systemctl stop mysql
mkdir /home/mysql
chown mysql: /home/mysql
usermod -d /home/mysql mysql
usermod -s /bin/bash mysql
touch /var/log/mysqld.log
chown mysql. /var/log/mysqld.log
systemctl start mysql
Then switch to the bash
environment of mysql
and generate the SSH keys, run these commands on both database nodes:
su - mysql
ssh-keygen -t ed25519 -a 100
cat ~/.ssh/id_ed25519.pub | tee ~/.ssh/authorized_keys
After running these commands on both nodes, copy the contents of the file and paste it into ~/.ssh/authorized_keys
on the other node and then apply the correct permissions to the file (still as mysql
):
chmod 600 ~/.ssh/authorized_keys
The key exchange must then be validated by a first connection which will accept the signature of the SSH server by typing "yes" (always as mysql
) :
ssh @DB_MASTER_NAME@
ssh @DB_SLAVE_NAME@
Then exit the mysql
session with exit
or Ctrl-D
.
Setting up MySQL replicationβ
For the two nodes to be interchangeable at any time, the two databases must be continuously replicated. To do this we will set up a Master-Slave replication.
Since Centreon 22.04, The mariaDB Replication is now based on GTID.
Note: unless otherwise stated, each of the following steps must be performed on both database nodes.
MySQL configurationβ
To begin with, we need to tune the MySQL configuration, which will be concentrated in the single file /etc/my.cnf.d/server.cnf
. By default, the [server]
section of this file is empty, which is where the following lines should be pasted:
[server]
sql_mode = 'NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION'
server-id=1 # SET TO 1 FOR MASTER AND 2 FOR SLAVE
#read_only
log-bin=mysql-bin
binlog-do-db=centreon
binlog-do-db=centreon_storage
innodb_flush_log_at_trx_commit=1
sync_binlog=1
binlog_format=MIXED
slave_compressed_protocol=1
datadir=/var/lib/mysql
pid-file=/var/lib/mysql/mysql.pid
skip-slave-start
log-slave-updates
gtid_strict_mode=ON
expire_logs_days=7
ignore-db-dir=lost+found
# Tuning standard Centreon
innodb_file_per_table=1
open_files_limit=32000
key_buffer_size=256M
sort_buffer_size=32M
join_buffer_size=4M
thread_cache_size=64
read_buffer_size=512K
read_rnd_buffer_size=256K
max_allowed_packet=64M
# Uncomment for 4 Go Ram
#innodb_buffer_pool_size=512M
# Uncomment for 8 Go Ram
#innodb_buffer_pool_size=1G
Important: the value of server-id
must be different from one server to another, so that they can identify each other correctly. The values 1 => Master and 2 => Slave are not mandatory but are recommended.
NB: Do not forget to uncomment (remove the '#' at the beginning of the line) the innodb_buffer_pool_size
parameter which corresponds to your platform.
For these modifications to be taken into account, you must restart the database server:
systemctl restart mariadb
Make sure that the reboot was successful with the following command:
systemctl status mariadb
Warning: The centreon.cnf
file will no longer be taken into account, if parameters have been customized there, they must be transferred to server.cnf
.
Securing the databaseβ
Access to databases should be restricted as strictly as possible. The command mysql_secure_installation
allows to remove the accesses not protected by passwords and the test database. Run this command and be guided by the default choices. Be careful to choose a password that does not belong to any dictionary.
mysql_secure_installation
Creating the centreon accountβ
To be able to administer MySQL users, you must first connect as root (with the password entered in the previous paragraph):
mysql -p
Then paste in the MySQL prompt the commands below by changing the IP addresses and passwords.
CREATE USER '@MYSQL_CENTREON_USER@'@'@CENTRAL_SLAVE_IPADDR@' IDENTIFIED BY '@MYSQL_CENTREON_PASSWD@';
GRANT ALL PRIVILEGES ON centreon.* TO '@MYSQL_CENTREON_USER@'@'@CENTRAL_SLAVE_IPADDR@';
GRANT ALL PRIVILEGES ON centreon_storage.* TO '@MYSQL_CENTREON_USER@'@'@CENTRAL_SLAVE_IPADDR@';
CREATE USER '@MYSQL_CENTREON_USER@'@'@CENTRAL_MASTER_IPADDR@' IDENTIFIED BY '@MYSQL_CENTREON_PASSWD@';
GRANT ALL PRIVILEGES ON centreon.* TO '@MYSQL_CENTREON_USER@'@'@CENTRAL_MASTER_IPADDR@';
GRANT ALL PRIVILEGES ON centreon_storage.* TO '@MYSQL_CENTREON_USER@'@'@CENTRAL_MASTER_IPADDR@';
Creating the replication accountβ
Still in the MySQL prompt (see the previous paragraph) create the user @MYSQL_REPL_USER@
, dedicated to replication, using the following commands:
CREATE USER '@MYSQL_REPL_USER@'@'localhost' IDENTIFIED BY '@MYSQL_REPL_PASSWD@';
GRANT PROCESS, RELOAD, SHUTDOWN, SUPER, REPLICATION CLIENT, REPLICATION SLAVE ON *.* TO '@MYSQL_REPL_USER@'@'localhost';
CREATE USER '@MYSQL_REPL_USER@'@'@CENTRAL_SLAVE_IPADDR@' IDENTIFIED BY '@MYSQL_REPL_PASSWD@';
GRANT PROCESS, RELOAD, SHUTDOWN, SUPER, REPLICATION CLIENT, REPLICATION SLAVE ON *.* TO '@MYSQL_REPL_USER@'@'@DB_SLAVE_IPADDR@';
CREATE USER '@MYSQL_REPL_USER@'@'@CENTRAL_MASTER_IPADDR@' IDENTIFIED BY '@MYSQL_REPL_PASSWD@';
GRANT PROCESS, RELOAD, SHUTDOWN, SUPER, REPLICATION CLIENT, REPLICATION SLAVE ON *.* TO '@MYSQL_REPL_USER@'@'@DB_MASTER_IPADDR@';
Configuring environment variables for MySQL scriptsβ
The file /etc/centreon-ha/mysql-resources.sh
contains environment variables that must be adapted to the current installation by replacing the macros with the appropriate value.
#!/bin/bash
###############################
# Database access credentials #
###############################
DBHOSTNAMEMASTER='@DB_MASTER_NAME@'
DBHOSTNAMESLAVE='@DB_SLAVE_NAME@'
DBREPLUSER='@MYSQL_REPL_USER@'
DBREPLPASSWORD='@MYSQL_REPL_PASSWD@'
DBROOTUSER='@MYSQL_REPL_USER@'
DBROOTPASSWORD='@MYSQL_REPL_PASSWD@'
CENTREON_DB='centreon'
CENTREON_STORAGE_DB='centreon_storage'
##########################################
# Manual failover additional informations #
##########################################
CENTRAL_VIP_IPADDR='@CENTRAL_VIP_IPADDR@'
CENTRAL_VIP_IFNAME='@CENTRAL_VIP_IFNAME@'
CENTRAL_VIP_CIDR_NETMASK='@CENTRAL_VIP_CIDR_NETMASK@'
CENTRAL_VIP_BROADCAST_IPADDR='@CENTRAL_VIP_BROADCAST_IPADDR@'
MYSQL_VIP_IPADDR='@DB_VIP_IPADDR@'
MYSQL_VIP_IFNAME='@DB_VIP_IFNAME@'
MYSQL_VIP_CIDR_NETMASK='@DB_VIP_CIDR_NETMASK@'
MYSQL_VIP_BROADCAST_IPADDR='@DB_VIP_BROADCAST_IPADDR@'
To make sure that the last steps have been done correctly, and that the correct names, logins and passwords have been entered in the configuration file, run the command :
/usr/share/centreon-ha/bin/mysql-check-status.sh
The expected outcome is:
Connection Status '@DB_MASTER_NAME@' [OK]
Connection Status '@DB_SLAVE_NAME@' [OK]
Slave Thread Status [KO]
Error reports:
No slave (maybe because we cannot check a server).
Position Status [SKIP]
!Error reports:
Skip because we can't identify a unique slave.
What is important to check is that the first two connection tests are OK
.
Switching to read-onlyβ
Now that everything is set up properly, we need to enable read_only mode on both servers by uncommenting (ie. remove the #
at the beginning of the line) this statement in the /etc/my.cnf.d/server.cnf
file:
- Main node
[server]
server-id=1
read_only
log-bin=mysql-bin
- Secondary node
[server]
server-id=2
read_only
log-bin=mysql-bin
Then apply this change by restarting MySQL on both nodes:
systemctl restart mariadb
Authorization of centreon and mysql accountsβ
For the scripts to run correctly through the ssh connections via the centreon and mysql accounts, they must be given additional rights
For the centreon account, edit the file /etc/sudoers.d/centreon-cluster
and add the following lines:
CENTREON ALL = NOPASSWD: /usr/bin/systemctl reload centreon
CENTREON ALL = NOPASSWD: /usr/bin/systemctl restart centreon
CENTREON ALL = NOPASSWD: /usr/bin/systemctl stop centreon
CENTREON ALL = NOPASSWD: /usr/bin/systemctl start centreon
CENTREON ALL = NOPASSWD: /usr/bin/nmcli
For the mysql account, edit the file /etc/sudoers.d/centreon-cluster-db
and add the following line:
MYSQL ALL = NOPASSWD: /usr/bin/nmcli
Synchronize databases and start MySQL replicationβ
To synchronize the databases, stop the mysql
service on the secondary node to overwrite its data with that of the main server.
So you need to run the following command on the secondary node :
systemctl stop mariadb
In some cases systemd may fail to stop the mysql
service, to be sure, check that the following command returns no lines:
ps -ef | grep mysql[d]
If a mysqld
process is still running, then the following command should be run to stop it (and provide the mysql root password when prompted):
mysqladmin -p shutdown
Once the service is stopped on the secondary node, run the synchronization script from the main node :
/usr/share/centreon-ha/bin/mysql-sync-bigdb.sh
This script does the following:
- verify that mysql is stopped on the secondary node
- stop mysql on the primary node
- mount an LVM snapshot on the volume group that supports the /var/lib/mysql partition
- start mysql on the primary node
- store the current position in the binary logs
- disable the MySQL global variable
read_only
on the master node (ie. the master node is now allowed to write to its database) - synchronize all data files (excluding the
mysql
system database) by overwriting the files on the secondary node - unmount the LVM snapshot
- create the replication thread that will keep the data updated on the secondary node
This script is very verbose, and not everything that is displayed is understandable, but to make sure that it has run to completion, just make sure that the end looks like :
Umount and Delete LVM snapshot
Logical volume "dbbackupdatadir" successfully removed
Start MySQL Slave
OK
Start Replication
Id User Host db Command Time State Info Progress
3 @MYSQL_REPL_USER@ @DB_MASTER_NAME@:33084 NULL Query 0 init show processlist 0.000
If all went well, then the mysql-check-status.sh
command should return an error-free result:
/usr/share/centreon-ha/bin/mysql-check-status.sh
Expected outcome:
Connection Status '@DB_MASTER_NAME@' [OK]
Connection Status '@DB_SLAVE_NAME@' [OK]
Slave Thread Status [OK]
Position Status [OK]
Creating the MySQL VIPβ
The VIP will be added to the @DB_VIP_IFNAME@
interface configuration on the database master node:
nmcli con mod "@DB_VIP_IFNAME@" +ipv4.addresses "@DB_VIP_IPADDR@/@DB_VIP_CIDR_NETMASK@"
nmcli connection up "@DB_VIP_IFNAME@"
Then run the following script on one of the two MySQL nodes to verify if the VIP is correctly mounted on the MySQL master server (this script can be run on either of the two nodes, it will detect by itself which is the master):
/usr/share/centreon-ha/bin/move-mysql-vip-to-mysql-master.sh
The result should be like this, if not the script move the VIP in correct place:
The VIP address is already at the right place. Nothing to do.
Setting up the Centreon clusterβ
Note: unless otherwise noted, each of the following steps must be performed on the two center nodes.
Configuring the Synchronization Serviceβ
The centreon-central-sync
service requires that we define for each node in /etc/centreon-ha/centreon_central_sync.pm
the IP address of its correspondent:
So for the server @CENTRAL_MASTER_NAME@
we must have :
our %centreon_central_sync_config = (
peer_addr => "@CENTRAL_SLAVE_IPADDR@"
);
1;
And for the server @CENTRAL_SLAVE_NAME@
we must have :
our %centreon_central_sync_config = (
peer_addr => "@CENTRAL_MASTER_IPADDR@"
);
1;
Removing cronsβ
Scheduled cron tasks are executed directly by the gorgone process in the highly available architecture. This ensures that they do not compete with each other on the central nodes. It is therefore necessary to delete them manually:
rm -f /etc/cron.d/centreon
rm -f /etc/cron.d/centstorage
rm -f /etc/cron.d/centreon-auto-disco
Changing rightsβ
The directories /var/log/centreon-engine and /tmp/centreon-autodisco are shared between several processes. It is necessary to modify the rights of the directories and files to ensure the proper functioning of file replication and automatic discovery of services:
chmod 775 /var/log/centreon-engine/
mkdir /var/log/centreon-engine/archives
chown centreon-engine: /var/log/centreon-engine/archives
chmod 775 /var/log/centreon-engine/archives/
chmod 664 /var/log/centreon-engine/*
chmod 664 /var/log/centreon-engine/archives/*
mkdir /tmp/centreon-autodisco/
chown apache: /tmp/centreon-autodisco/
chmod 775 /tmp/centreon-autodisco/
Stop and disable servicesβ
The Centreon application services will no longer be launched at the server startup as it is the case for a standard installation, the clustering services will take care of it. It is therefore necessary to stop and disable these services.
On the central servers:
- Alma / RHEL / Oracle Linux 8
systemctl stop centengine snmptrapd centreontrapd gorgoned cbd httpd php-fpm centreon
systemctl disable centengine snmptrapd centreontrapd gorgoned cbd httpd php-fpm centreon centreon-central-sync cbd-sql
Redefine service startup rulesβ
Some services should only be started on one node, but for others, it's okay or even desirable to start them on both nodes. We'll start with these services.
PHP serviceβ
The php-fpm.service
service does not need to be modified, but must be enabled so that it is started automatically when the central servers are started.
systemctl enable php-fpm
RRD Broker serviceβ
The "broker-rrd" process is started via the cbd.service
. The latter is by default driven by centreon.service
but in this configuration, it must be detached by modifying its definition on the two central nodes:
cat > /usr/lib/systemd/system/cbd.service <<"EOF"
[Unit]
Description=Centreon Broker watchdog
After=syslog.target network.target
[Service]
ExecStart=/usr/sbin/cbwd /etc/centreon-broker/watchdog.json
ExecReload=/bin/kill -HUP $MAINPID
Type=simple
User=centreon-broker
UMask=0002
[Install]
WantedBy=multi-user.target
EOF
Then start it and activate it:
systemctl start cbd
systemctl enable cbd
Creating the Centreon VIPβ
The VIP will be added to the @CENTRAL_VIP_IFNAME@
interface configuration on central master node:
nmcli con mod "@CENTRAL_VIP_IFNAME@" +ipv4.addresses "@CENTRAL_VIP_IPADDR@/@CENTRAL_VIP_CIDR_NETMASK@"
nmcli connection up "@CENTRAL_VIP_IFNAME@"
Httpd serviceβ
The httpd.service
service is by default independent of centreon.service
but in this configuration, it must be attached to it by modifying its definition on the two central nodes:
- Alma / RHEL / Oracle Linux 8
cat > /usr/lib/systemd/system/httpd.service <<"EOF"
[Unit]
Description=The Apache HTTP Server
PartOf=centreon.service
ReloadPropagatedFrom=centreon.service
After=centreon.service
[Service]
Type=notify
Environment=LANG=C
ExecStart=/usr/sbin/httpd $OPTIONS -DFOREGROUND
ExecReload=/usr/sbin/httpd $OPTIONS -k graceful
ExecStop=/usr/sbin/httpd $OPTIONS -k graceful-stop
# Send SIGWINCH for graceful stop
KillSignal=SIGCONT
KillMode=mixed
PrivateTmp=true
[Install]
WantedBy=centreon.service
EOF
Gorgone serviceβ
The gorgoned.service
service is by default independent of centreon.service
but in this configuration, it must be attached to it by modifying its definition on the two central nodes:
- Alma / RHEL / Oracle Linux 8
cat > /etc/systemd/system/gorgoned.service <<"EOF"
[Unit]
Description=Centreon Gorgone
PartOf=centreon.service
After=httpd.service
ReloadPropagatedFrom=centreon.service
[Service]
EnvironmentFile=/etc/sysconfig/gorgoned
ExecStart=/usr/bin/perl /usr/bin/gorgoned $OPTIONS
Type=simple
User=centreon-gorgone
[Install]
WantedBy=centreon.service
EOF
Centreon-central-sync serviceβ
This service is specific to Centreon HA. Its function is to replicate configuration changes, add images via the interface, etc.
cat > /usr/lib/systemd/system/centreon-central-sync.service <<"EOF"
[Unit]
Description=Centreon Central Sync (failover only)
PartOf=centreon.service
ReloadPropagatedFrom=centreon.service
After=gorgoned.service
[Service]
EnvironmentFile=/etc/sysconfig/centreon_central_sync
ExecStart=/usr/share/centreon-ha/bin/centreon_central_sync $OPTIONS
ExecReload=/bin/kill -HUP $MAINPID
Type=simple
User=centreon
[Install]
WantedBy=centreon.service
EOF
Broker SQL serviceβ
cat > /usr/lib/systemd/system/cbd-sql.service <<"EOF"
[Unit]
Description=Centreon SQL Broker service
PartOf=centreon.service
ReloadPropagatedFrom=centreon.service
After=centreon-central-sync.service
[Service]
EnvironmentFile=/etc/sysconfig/cbd_sql
ExecStart=/usr/sbin/cbd $OPTIONS
ExecReload=/bin/kill -HUP $MAINPID
Type=simple
User=centreon-broker
UMask=0002
[Install]
WantedBy=centreon.service
EOF
Centengine serviceβ
cat > /usr/lib/systemd/system/centengine.service <<"EOF"
[Unit]
Description=Centreon Engine
PartOf=centreon.service
ReloadPropagatedFrom=centreon.service
After=cbd-sql.service
[Service]
ExecStart=/usr/sbin/centengine /etc/centreon-engine/centengine.cfg
ExecReload=/bin/kill -HUP $MAINPID
Type=simple
User=centreon-engine
[Install]
WantedBy=centreon.service
EOF
Centreontrapd serviceβ
cat > /usr/lib/systemd/system/centreontrapd.service <<"EOF"
[Unit]
Description=Centreon Trapd Daemon is a Centreon program that manage traps
PartOf=centreon.service
After=centreon.service
ReloadPropagatedFrom=centreon.service
[Service]
EnvironmentFile=/etc/sysconfig/centreontrapd
ExecStart=/usr/share/centreon/bin/centreontrapd $OPTIONS
ExecReload=/bin/kill -HUP $MAINPID
Type=simple
User=centreon
[Install]
WantedBy=centreon.service
EOF
Snmptrapd serviceβ
cat > /usr/lib/systemd/system/snmptrapd.service <<"EOF"
[Unit]
Description=Simple Network Management Protocol (SNMP) Trap Daemon.
PartOf=centreon.service
After=centreontrapd.service
[Service]
Type=notify
Environment=OPTIONS="-Lsd"
EnvironmentFile=-/etc/sysconfig/snmptrapd
ExecStart=/usr/sbin/snmptrapd $OPTIONS -f
ExecReload=/bin/kill -HUP $MAINPID
[Install]
WantedBy=centreon.service
EOF
Initial launch of all servicesβ
Installation of the Centreon virtual IP addressβ
Normally the VIP has already been mounted previously. Check that this is the case on the primary server defined above (normally @CENTRAL_MASTER_NAME@
)
ip a
You should see the virtual IP @CENTRAL_VIP_IPADDR@
attached to the @CENTRAL_VIP_IFNAME@
interface appear in the return of the ip a
command.
If this is not the case, the virtual IP address must be mounted, for example on @CENTRAL_MASTER_NAME@
:
nmcli con mod "@CENTRAL_VIP_IFNAME@" +ipv4.addresses "@CENTRAL_VIP_IPADDR@/@CENTRAL_VIP_CIDR_NETMASK@"
nmcli con up "@CENTRAL_VIP_IFNAME@"
Taking into account the changes made to the servicesβ
To take into account all the previous modifications, and to activate the services (so that the start of the centreon.service
service starts them all) it is necessary to launch these commands on the two central nodes:
- Alma / RHEL / Oracle Linux 8
systemctl daemon-reload
systemctl enable cbd httpd gorgoned centreon-central-sync cbd-sql centengine centreontrapd snmptrapd
And finally start them all via the centreon.service
on the node where the VIP was mounted:
systemctl start centreon
Then check the status of all services:
- Alma / RHEL / Oracle Linux 8
systemctl status cbd httpd gorgoned centreon-central-sync cbd-sql centengine centreontrapd snmptrapd
After this step, all resources must be active in the same place, and the platform must be functional and redundant. If not, refer to the troubleshooting guide in the next paragraph.
Standard manual HA operationβ
Switch Centreon services from one node to anotherβ
This script can be run from any Centreon node, but you must (for now) specify the target node. For example to change the active node from @CENTRAL_MASTER_NAME@
to @CENTRAL_SLAVE_NAME@
:
/usr/share/centreon-ha/bin/set-centreon-master.sh @CENTRAL_SLAVE_NAME@
The expected outcome is:
Stopping centreon.service on @CENTRAL_MASTER_NAME@...
Unmounting VIP on @CENTRAL_MASTER_NAME@...
Adding vip to @CENTRAL_SLAVE_NAME@...
Starting centreon.service on @CENTRAL_SLAVE_NAME@...
If we try to switch to the node that is already active, we will get :
Host @CENTRAL_MASTER_NAME@ is already the current master :-)
Reverse MySQL SLAVE/MASTER rolesβ
This script can be launched from any database node, this time we do not specify the name of the target server:
/usr/share/centreon-ha/bin/mysql-switch-slave-master.sh
The expected outcome is:
Locking master database on @DB_SLAVE_NAME@
Waiting Relay log bin to finish proceed (TIMEOUT = 60sec)
Removing slave thread on @DB_MASTER_NAME@
Recording binlog file and position from @DB_MASTER_NAME@
Unlocking databases on @DB_MASTER_NAME@
Setting and starting slave thread on @DB_SLAVE_NAME@
We have to move the VIP address
Checking database synchronizationβ
The status of MySQL replication can be checked at any time with the command mysql-check-status.sh
:
/usr/share/centreon-ha/bin/mysql-check-status.sh
The expected outcome is:
Connection Status '@DB_MASTER_NAME@' [OK]
Connection Status '@DB_SLAVE_NAME@' [OK]
Slave Thread Status [OK]
Position Status [OK]
Integrating pollersβ
You can now add your Pollers and start monitoring!