How to monitor MySQL using Nagios

How to configuring Nagios to monitor your MySQL server. Before we begin, there are a few prerequisites that you have to fulfill


Prerequisites

1. Operating System - CentOS.


2. Nagios Core - Installed and configured.


3. Nagios Plugins should be installed.


4. MySQL server(or MariaDB) should be installed on your server.

MySQL User Creation

1. Log in to your MySQL server with the following command.



# mysql -u root -p



2. Type in the following commands.



mysql> CREATE USER 'nagios'@'localhost' IDENTIFIED BY 'nagiospasswd'; mysql> GRANT ALL PRIVILEGES ON *.* TO 'nagios'@'localhost'; mysql> CREATE USER 'nagios'@'%' IDENTIFIED BY 'nagiospasswd'; mysql> GRANT ALL PRIVILEGES ON *.* TO 'nagios'@'%'; mysql> flush privileges;

These commands create a user "nagios" that can be used by local host as well as remotely. We have also granted all privileges to the user.


Install of the perl-modules DBI and DBD::mysql

Log in to nagios server use the following command to install perl-modules DBI and DBD::mysql

# yum -y install perl-DBI # yum -y install "perl(DBD::mysql)"

MySQL Plugin Installation

1. Run the following command to download the "check_mysql_health-2.2.2.tar.gz" package.



# wget https://labs.consol.de/assets/downloads/nagios/check_mysql_health-2.2.2.tar.gz



2. Extract the downloaded package.



# tar -zxvf check_mysql_health-2.2.2.tar.gz



3. Change into the check_mysql_health-2.2.2 directory.



# cd check_mysql_health-2.2.2



4. Run the following commands to configure and install the plugin.



# ./configure --prefix=/usr/local/nagios --with-nagios-user=nagios --with-nagios-group=nagios --with-perl=/usr/bin/perl # make # make install

Nagios Configuration for MySQL Monitoring

1. "check_mysql_health" Command Definition

The following file contains all the commands pertaining to Nagios. Open it in any text editor of your choice("vi" in this case).



# vi /usr/local/nagios/etc/objects/commands.cfg


Edit the file and add the "check_mysql_health" command block.



define command{ command_name check_mysql_health command_line $USER1$/check_mysql_health -H $ARG1$ --username $ARG2$ --password $ARG3$ --port $ARG4$ --mode $ARG5$ }



2. "check_mysql_health" Service Definition

Open the file "hosttomonitor.cfg" to add the service definition to the host that will be monitored.



# vi /usr/local/nagios/etc/servers/hosttomonitor.cfg


Add the following service blocks of Connection-time, io thread and sql thread. This will perform different tasks.



define service{ use local-service host_name hosttomonitor service_description MySQL connection-time check_command check_mysql_health!192.168.30.10!nagios!nagiospasswd!3306!connection-time! } define service{ use local-service host_name hosttomonitor service_description MySQL slave-io-running check_command check_mysql_health!192.168.30.10!nagios!nagiospasswd!3306!slave-io-running! } define service{ use local-service host_name hosttomonitor service_description MySQL slave-sql-running check_command check_mysql_health!192.168.30.10!nagios!nagiospasswd!3306!slave-sql-running! }



3. Restart the Nagios server.



# service nagios restart

You can configure other MySQL services as well whose information can be found on the website.

https://labs.consol.de/nagios/check_mysql_health/index.html

How to Install Nagios Plugins in CentOS

Prerequisites - Common

These are the common set of packages required for compiling most of the plugins. SNMP and required modules are included here are they are one of the most common types of network monitoring.

CentOS 6.x / 7.x

yum install -y gcc glibc glibc-common make gettext automake autoconf wget openssl-devel net-snmp net-snmp-utils epel-release yum install -y perl-Net-SNMP

Download latest nagios-plugins source and install using following commands

cd /opt wget http://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz tar xzf nagios-plugins-2.2.1.tar.gz cd nagios-plugins-2.2.1

Now compile and install nagios plugins

./configure --with-nagios-user=nagios --with-nagios-group=nagios make make install

Setup the nagios user:

useradd nagios passwd nagios

Plugin Installation Location

The plugins will now be located in /usr/local/nagios/libexec/.

How to Install - Oracle Plugin check_oracle_health (CentOS 6)

Prerequisites

Oracle software

The Oracle database server or instant client must be up and running.

CentOS packages

yum -y install cpan sharutils

Perl packages

Find out the absolute path of ORACLE_HOME and set the Oracle environment.
This is required for the installation of DBD::Oracle.

if Oracle 11gR2 server installated

export ORACLE_HOME=/u01/app/oracle/product/11.2.0/db_1 export LD_LIBRARY_PATH=$ORACLE_HOME/lib

if Oracle Instantclient installated

export ORACLE_HOME=/usr/lib/oracle/11.2/client64 export LD_LIBRARY_PATH=$ORACLE_HOME/lib

Install Perl DBD::Oracle module

wget http://www.cpan.org/modules/by-module/DBD/DBD-Oracle-1.74.tar.gz tar zxvf DBD-Oracle-1.74.tar.gz cd DBD-Oracle-1.74 perl Makefile.PL -l make && make test make install

Download and install the check_oracle_health plugin

Check for the latest version at http://labs.consol.de/lang/en/nagios/check_oracle_health/, scroll down to "Download".

cd /tmp wget https://labs.consol.de/assets/downloads/nagios/check_oracle_health-3.1.0.3.tar.gz tar xzf check_oracle_health-3.1.0.3.tar.gz cd /tmp/check_oracle_health-* ./configure make make install cp /usr/local/nagios/libexec/check_oracle_health /usr/lib64/nagios/plugins/

Set up the Oracle user "nagios" in target server

# as root: su - oracle sqlplus / as sysdba CREATE USER nagios IDENTIFIED BY oradbmon; GRANT CREATE SESSION TO nagios; GRANT SELECT any dictionary TO nagios; GRANT SELECT ON V_$SYSSTAT TO nagios; GRANT SELECT ON V_$INSTANCE TO nagios; GRANT SELECT ON V_$LOG TO nagios; GRANT SELECT ON SYS.DBA_DATA_FILES TO nagios; GRANT SELECT ON SYS.DBA_FREE_SPACE TO nagios; exit # leave SQL*Plus exit # back to root

Test locally

Please replace the path to ORACLE_HOME and the connect string as appropriate. In the following example,
the connect string refers to the alias in $ORACLE_HOME/network/admin/tnsnames.ora if your install server version
if you install instantclient connect string refers to the alias in /etc/tnsnames.ora

/usr/local/nagios/libexec/check_oracle_health --connect XE --user nagios --password oradbmon --environment ORACLE_HOME=/u01/app/oracle/product/11.2.0/xe --mode tablespace-usage

Now you have to configure the check command in nagios. For the command to work, it needs to have the oracle client paths added to the environment variables – ORACLE_HOME, LD_LIBRARY_PATH,PATH. To avoid all sorts of issues in passing environment variables in nagios and altering the startup script of nagios to set them (as described on the author’s site), just pass the variables directly in the command. The latest version of check_oracle_health allows that.

Define command in /usr/local/nagios/etc/objects/command.cfg

vi /usr/local/nagios/etc/objects/command.cfg

# Oracle Database check health command # check_oracle_health    !  SID  !  USER  !  Pass  !  Warn  !  crit  !  mode define command {         command_name check_oracle_health         command_line $USER1$/check_oracle_health --environment PATH=$PATH:$ORACLE_HOME/bin --environment LD_LIBRARY_PATH=$ORACLE_HOME/lib --connect $ARG1$ --user $ARG2$ --password $ARG3$ --mode $ARG4$         } # Oracle Check Tablespace per name # check_oracle_health_tbs_name    !  SID  !  USER  !  Pass  !  Warn  !  crit  !  mode  ! tbs_name define command {         command_name check_oracle_health_tbs_name         command_line $USER1$/check_oracle_health --environment PATH=$PATH:$ORACLE_HOME/bin --environment LD_LIBRARY_PATH=$ORACLE_HOME/lib --connect $ARG1$ --user $ARG2$ --password $ARG3$ --mode $ARG4$ --name $ARG5$         }

Define service in /usr/local/nagios/etc/servers/oracledbtest.cfg

define host{ use                                     linux-server host_name                               oracledbtest alias                                   oracledbtest address                                 192.168.xx.yy max_check_attempts                      5 check_period                            24x7 notification_interval                   30 notification_period                     24x7 } ### Change last argument to the different modes ### tns-ping , process-usage , sga-shared-pool-free define service {         use                             local-service         host_name                       oracledbtest         service_description             Oracle Connection Time         check_command                   check_oracle_health!XE!nagios!oradbmon!connection-time         notifications_enabled           1 } define service {         use                             local-service         host_name                       oracledbtest         service_description             Oracle Connected Users         check_command                   check_oracle_health!XE!nagios!oradbmon!connected-users         notifications_enabled           1 } ### Change last argument to the different tablespace ### users, undotbs define service {         use                             local-service         host_name                       oracledbtest         service_description             Oracle Tablespace Usage Users         check_command                   check_oracle_health_tbs_name!XE!nagios!oradbmon!tablespace-usage!users         notifications_enabled           1 }

You can add all the modes you want. You can manually test the command like so. It’s very important that the ORACLE_HOME and other variables are set. They can be passed to the command directly, this way you don’t need to modify your nagios startup script to set the vars in the nagios user enviornment.

Install Oracle Instant Client on Linux CentOS

The installation of an Oracle client on a server is always a tedious task and although you have done it many times, there are always things to review.

In this case we are going to install an Oracle InstantClient of version 11 for the CentOS operating system.

As we also want to be able to compile applications that will be used by Oracle libraries, we will also have to install the header files.


Download installation packages

The installation files can be found at this URL:

https://www.oracle.com/technetwork/topics/linuxx86-64soft-092277.html

The client version to be used is 11.2.0.4.0

The packages to download are:

oracle-instantclient11.2-basic-11.2.0.4.0–1.x86_64.rpm oracle-instantclient11.2-devel-11.2.0.4.0–1.x86_64.rpm oracle-instantclient11.2-sqlplus-11.2.0.4.0–1.x86_64.rpm

The package with sqlplus is only needed to check that the installation was correct


Installing the RPM files

We proceed to the installation of previously downloaded packages

$ sudo yum localinstall -y oracle-instantclient11.2-basic-11.2.0.4.0–1.x86_64.rpm $ sudo yum localinstall -y oracle-instantclient11.2-devel-11.2.0.4.0-1.x86_64.rpm $ sudo yum localinstall -y oracle-instantclient11.2-sqlplus-11.2.0.4.0-1.x86_64.rpm

Environment Variables

We will need to define some environment variables for the Oracle client to work correctly

$ export ORACLE_HOME=/usr/lib/oracle/11.2/client64 $ export TNS_ADMIN=$ORACLE_HOME/network/admin $ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$ORACLE_HOME/lib $ export PATH=$PATH:$ORACLE_HOME/bin

To be able to work with the tnsnames.ora file, we will have to copy it to the directory defined in the environment variable

$ sudo mkdir -p /usr/lib/oracle/11.2/client64/network/admin

Create new /usr/lib/oracle/11.2/client64/network/admin/tnsnames.ora like this:

TEST =   (DESCRIPTION =     (ADDRESS_LIST =         (ADDRESS =                  (PROTOCOL = TCP)           (Host = testdboracle)           (Port = 1521)         )     )     (CONNECT_DATA = (SID = ORCL)     )   )

Installation test

To verify that the installation was correct, we will open a sqlplus session against one of our databases

Connect to Your database with:

$ sqlplus scott/tiger@TEST

You can also use the Easy Connect connection string format (does not use TNSNAMES):

$ sqlplus scott/tiger@testdboracle:1521/ORCL

Monitor ssh on non-default port with Nagios

In ssh pluging config /usr/local/nagios/etc/objects/commands.cfg, there an alias named check_ssh_port.
if it not existe you may define it like above:

define command{ command_name check_ssh_port command_line $USER1$/check_ssh  -p $ARG1$ $HOSTADDRESS$ }

in the service file /usr/local/nagios/etc/servers/hosttomonitor.cfg, define you ssh service to monitor like this:

define host{ use                                 linux-server host_name                           hosttomonitor.localnet alias                               hosttomonitor address                             10.10.10.19 max_check_attempts                  5 check_period                        24x7 notification_interval               30 notification_period                 24x7 } define service {         use                         generic-service         host_name                   hosttomonitor.localnet         service_description         SSH2         check_command               check_ssh_port!1422         notifications_enabled       0         }

replace 1422 by you default ssh port and server by your target.

finally restart nagios service

How to solve the problem "caching_sha2_password" problem

How to solve the problem "caching_sha2_password" problem ?

if you log in to MySQL and find an error like below

[root@localhost ~]# mysql -h 127.0.0.1 -P 3306 -u root -p Enter password: ERROR 2059 (HY000): Authentication plugin 'caching_sha2_password' cannot be loaded: /usr/lib64/mysql/plugin/caching_sha2_password.so: cannot open shared object file: No such file or directory

So I found the reason for that error message (at least for my case). It's because MySQL as of version 8.04 and onwards uses caching_sha2_password as default authentication plugin where previously mysql_native_password has been used.

This obviously causes compatibility issues with older services that expect mysql_native_password authentication.

Solutions:

1. Check for an updated version of the client service you are using (most recent workbench for instance).


2. Downgrade the MySQL Server to a version below that change.


3. Change the authentication plugin on a per user basis (I didn't find a global option, maybe there exists one though).

Now regarding option 3 this is as simple as altering the user:

mysql> ALTER USER root IDENTIFIED WITH mysql_native_password BY 'password';

or when creating the user:

mysql> CREATE USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';

How to FIX ORA-00257: archiver error. Connect internal only, until freed.

How to FIX ORA-00257: archiver error. Connect internal only, until freed.


Cause: The archiver process received an error while trying to archive a redo log. If the problem is not resolved soon, the database will stop executing transactions. The most likely cause of this message is the destination device is out of space to store the redo log file.

ORA-00257 is a common error in Oracle. You will usually see ORA-00257 upon connecting to the database because you have encountered a maximum in the flash recovery area (FRA), or db_recovery_file_dest_size .

First, make sure your automatic archiving is enabled. To check the archive lo made, try:

SQL> archive log list; Database log mode Archive Mode Automatic archival Enabled Archive destination USE_DB_RECOVERY_FILE_DEST Oldest online log sequence 2671 Next log sequence to archive 2676 Current log sequence 2676

Now, note that you can find archive destinations if you are using a destination of USE_DB_RECOVERY_FILE_DEST by:

SQL> show parameter db_recovery_file_dest; NAME                                 TYPE        VALUE ------------------------------------ ----------- ------------------------------ db_recovery_file_dest                string      /oracle/fast_recovery_area db_recovery_file_dest_size           big integer 32G

The next step in resolving ORA-00257 is to find out what value is being used for db_recovery_file_dest_size, use:

SQL> SELECT * FROM V$RECOVERY_FILE_DEST; NAME                                     SPACE_LIMIT SPACE_USED SPACE_RECLAIMABLE NUMBER_OF_FILES ---------------------------------------- ----------- ---------- ----------------- ---------------    /oracle/fast_recovery_area                3.8174E+10 3.8174E+10                 0             327

You may find that the SPACE_USED is the same as SPACE_LIMIT,

The first step to fixing this issue would be to log into your server and see if you have run out of physical space on one of your disks or mounts. If you have run out of physical space you have a few options.

You can backup your archivelogs and delete input, or

# rman target / RMAN> BACKUP ARCHIVELOG ALL DELETE ALL INPUT;

you can just delete the archivelogs if you won’t need them to restore your database.

# rman target /     RMAN> DELETE NOPROMPT ARCHIVELOG ALL;

you can Increase db_recovery_file_dest_size

SQL> alter system set db_recovery_file_dest_size=64g scope=both;

After all you can restart database

SQL> shutdown immediate; SQL> startup

Setting up NSQ as a Service on CentOS 7 (SystemD)

In this tutorial I will give an example of making nsqlookup, nsqd and nsqadmin run as service in centos 7 (systemD)

first create a configuration file for each of these services and all configurations are placed in the /etc/nsq directory


for the nsqlookupd configuration file it is nsqlookupd.conf and make it like the file below

# cd /etc/nsq # vi nsqlookupd.conf

## log verbosity level: debug, info, warn, error, or fatal log-level = "info" ## <addr>:<port> to listen on for TCP clients tcp_address = "0.0.0.0:4160" ## <addr>:<port> to listen on for HTTP clients http_address = "0.0.0.0:4161" ## address that will be registered with lookupd (defaults to the OS hostname) broadcast_address = "main" ## duration of time a producer will remain in the active list since its last ping inactive_producer_timeout = "300s" ## duration of time a producer will remain tombstoned if registration remains tombstone_lifetime = "45s"

for the nsqd configuration file it is nsqd.conf and make it like the file below

# vi nsqd.conf

## log verbosity level: debug, info, warn, error, or fatal #log-level = "info" ## unique identifier (int) for this worker (will default to a hash of hostname) # id = 5150 ## <addr>:<port> to listen on for TCP clients tcp_address = "0.0.0.0:4150" ## <addr>:<port> to listen on for HTTP clients http_address = "0.0.0.0:4151" ## <addr>:<port> to listen on for HTTPS clients # https_address = "0.0.0.0:4152" ## address that will be registered with lookupd (defaults to the OS hostname) broadcast_address = "127.0.0.1" ## cluster of nsqlookupd TCP addresses nsqlookupd_tcp_addresses = [     "127.0.0.1:4160" ] ## duration to wait before HTTP client connection timeout http_client_connect_timeout = "2s" ## duration to wait before HTTP client request timeout http_client_request_timeout = "5s" ## path to store disk-backed messages data_path = "/var/lib/nsq" ## number of messages to keep in memory (per topic/channel) mem_queue_size = 10000 ## number of bytes per diskqueue file before rolling max_bytes_per_file = 104857600 ## number of messages per diskqueue fsync sync_every = 2500 ## duration of time per diskqueue fsync (time.Duration) sync_timeout = "2s" ## duration to wait before auto-requeing a message msg_timeout = "60s" ## maximum duration before a message will timeout max_msg_timeout = "15m" ## maximum size of a single message in bytes max_msg_size = 1024768 ## maximum requeuing timeout for a message max_req_timeout = "1h" ## maximum size of a single command body max_body_size = 5123840 ## maximum client configurable duration of time between client heartbeats max_heartbeat_interval = "60s" ## maximum RDY count for a client max_rdy_count = 2500 ## maximum client configurable size (in bytes) for a client output buffer max_output_buffer_size = 65536 ## maximum client configurable duration of time between flushing to a client (time.Duration) max_output_buffer_timeout = "1s" ## UDP <addr>:<port> of a statsd daemon for pushing stats # statsd_address = "127.0.0.1:8125" ## prefix used for keys sent to statsd (%s for host replacement) statsd_prefix = "nsq.%s" ## duration between pushing to statsd (time.Duration) statsd_interval = "60s" ## toggle sending memory and GC stats to statsd statsd_mem_stats = true ## the size in bytes of statsd UDP packets # statsd_udp_packet_size = 508 ## message processing time percentiles to keep track of (float) e2e_processing_latency_percentiles = [     1.0,     0.99,     0.95 ] ## calculate end to end latency quantiles for this duration of time (time.Duration) e2e_processing_latency_window_time = "10m" ## path to certificate file tls_cert = "" ## path to private key file tls_key = "" ## set policy on client certificate (require - client must provide certificate, ##  require-verify - client must provide verifiable signed certificate) # tls_client_auth_policy = "require-verify" ## set custom root Certificate Authority # tls_root_ca_file = "" ## require client TLS upgrades tls_required = false ## minimum TLS version ("ssl3.0", "tls1.0," "tls1.1", "tls1.2") tls_min_version = "" ## enable deflate feature negotiation (client compression) deflate = true ## max deflate compression level a client can negotiate (> values == > nsqd CPU usage) max_deflate_level = 6 ## enable snappy feature negotiation (client compression) snappy = true

for the nsqadmin configuration file it is nsqadmin.conf and make it like the file below

# vi  nsqadmin.conf

## log verbosity level: debug, info, warn, error, or fatal log-level = "info" ## <addr>:<port> to listen on for HTTP clients http_address = "0.0.0.0:4171" ## graphite HTTP address graphite_url = "" ## proxy HTTP requests to graphite proxy_graphite = false ## prefix used for keys sent to statsd (%s for host replacement, must match nsqd) statsd_prefix = "nsq.%s" ## format of statsd counter stats statsd_counter_format = "stats.counters.%s.count" ## format of statsd gauge stats statsd_gauge_format = "stats.gauges.%s" ## time interval nsqd is configured to push to statsd (must match nsqd) statsd_interval = "60s" ## HTTP endpoint (fully qualified) to which POST notifications of admin actions will be sent notification_http_endpoint = "" ## nsqlookupd HTTP addresses nsqlookupd_http_addresses = [     "127.0.0.1:4161" ] ## nsqd HTTP addresses (optional) #nsqd_http_addresses = [ #    "127.0.0.1:4151" #]

let's make a service for all nsq service

• nsqlookupd



# cd /etc/systemd/system # vim nsqlookupd.service




[Unit] Description=nsqlookup daemon Service After=network.target [Service] PrivateTmp=yes ExecStart=/usr/local/nsq/bin/nsqlookupd -config /etc/nsq/nsqlookupd.conf Restart=always [Install] WantedBy=multi-user.target



• nsqd



# vim nsqd.service




[Unit] Description=Realtime distributed messaging (nsqd) After=network.target [Service] PrivateTmp=yes ExecStart=/usr/local/nsq/bin/nsqd -config /etc/nsq/nsqd.conf Restart=always [Install] WantedBy=multi-user.target



• nsqadmin



v# vim nsqadmin.service




[Unit] Description=nsqadmin daemon Service (nsqadmin) After=network.target [Service] PrivateTmp=yes ExecStart=/usr/local/nsq/bin/nsqadmin -config /etc/nsq/nsqadmin.conf Restart=always [Install] WantedBy=multi-user.target

enable all nsq service

# systemctl enable nsqlookupd.service Created symlink from /etc/systemd/system/multi-user.target.wants/nsqlookupd.service to /etc/systemd/system/nsqlookupd.service.

# systemctl enable nsqd.service Created symlink from /etc/systemd/system/multi-user.target.wants/nsqd.service to /etc/systemd/system/nsqd.service.

# systemctl enable nsqadmin.service Created symlink from /etc/systemd/system/multi-user.target.wants/nsqadmin.service to /etc/systemd/system/nsqadmin.service.

here we go start the service

# systemctl start nsqlookupd # systemctl start nsqd # systemctl start nsqadmin

to check service run or not

# systemctl status nsqlookupd ● nsqlookupd.service - nsqlookup daemon Service    Loaded: loaded (/etc/systemd/system/nsqlookupd.service; enabled; vendor preset: disabled)    Active: active (running) since Tue 2019-04-09 03:38:40 EDT; 1h 41min ago  Main PID: 5193 (nsqlookupd)    CGroup: /system.slice/nsqlookupd.service            └─5193 /usr/local/nsq/bin/nsqlookupd -config /etc/nsq/nsqlookupd.c... Apr 09 05:18:06 main.coba.net nsqlookupd[5193]: [nsqlookupd] 2019/04/09 05:1...) Hint: Some lines were ellipsized, use -l to show in full.

# systemctl status nsqd ● nsqd.service - Realtime distributed messaging (nsqd)    Loaded: loaded (/etc/systemd/system/nsqd.service; enabled; vendor preset: disabled)    Active: active (running) since Tue 2019-04-09 04:58:21 EDT; 22min ago  Main PID: 5234 (nsqd)    CGroup: /system.slice/nsqd.service            └─5234 /usr/local/nsq/bin/nsqd -config /etc/nsq/nsqd.conf Apr 09 04:58:21 main.coba.net nsqd[5234]: [nsqd] 2019/04/09 04:58:21.319327 ...0 Hint: Some lines were ellipsized, use -l to show in full.

# systemctl status nsqadmin ● nsqadmin.service - nsqadmin daemon Service (nsqadmin)    Loaded: loaded (/etc/systemd/system/nsqadmin.service; enabled; vendor preset: disabled)    Active: active (running) since Tue 2019-04-09 04:59:13 EDT; 21h ago  Main PID: 5249 (nsqadmin)    CGroup: /system.slice/nsqadmin.service            └─5249 /usr/local/nsq/bin/nsqadmin -config /etc/nsq/nsqadmin.conf Apr 09 04:59:13 main.coba.net systemd[1]: Started nsqadmin daemon Service (n.... Apr 09 04:59:13 main.coba.net nsqadmin[5249]: [nsqadmin] 2019/04/09 04:59:13...) Hint: Some lines were ellipsized, use -l to show in full

That all's

NSQ messaging Installation

Installation

This is pretty quick for your local setup
Untar the tarball into ~/bin folder Upon untarring ensure that the ~/bin folder has all the files named nsq_

$ wget https://s3.amazonaws.com/bitly-downloads/nsq/nsq-0.2.31.darwin-amd64.go1.3.1.tar.gz $ tar xvfz nsq-0.2.31.darwin-amd64.go1.3.1.tar.gz $ sudo mkdir -p /usr/local/nsq/bin $ sudo mv nsq-0.2.31.darwin-amd64.go1.3.1/bin/* /usr/local/nsq/bin

Setup NSQ and PATH environment variables with root privileges:

# echo 'export NSQROOT=/usr/local/nsq' | tee -a /etc/profile # echo 'export PATH=$PATH:/usr/local/nsq/bin' | tee -a /etc/profile

Start the following daemons

$ source /etc/profile $ nsqlookupd & $ nsqd --lookupd-tcp-address=127.0.0.1:4160 $ nsqadmin --lookupd-http-address=127.0.0.1:4161

If done successfully you will be able to view a web UI that looks like this:

nsqadmin is a Web UI to view aggregated cluster stats in realtime and perform various administrative tasks.

requires the golang for the next step, if there is no golang on your system you can install with the tutorial at the following link


Writing Your Go Program

I like creating the consumer first so I can see the handler in action after pushing a message with a producer (see next section).

please create directory src in your home directory and in src directory create consumer and producer directory

$ mkdir src $ cd src $ mkdir consumer producer

Get  go client library

$ go get -u -v github.com/bitly/go-nsq $ go get -u -v github.com/nsqio/go-nsq

Creating a consumer

create file like below in ~/src/consumer/consumer01.go

package main import (     "log"     "sync"     "github.com/nsqio/go-nsq" ) func main() {     wg := &sync.WaitGroup{}     wg.Add(1)     decodeConfig := nsq.NewConfig()     c, err := nsq.NewConsumer("NSQ_Topic", "NSQ_Channel", decodeConfig)     if err != nil {         log.Panic("Could not create consumer")     }     //c.MaxInFlight defaults to 1     c.AddHandler(nsq.HandlerFunc(func(message *nsq.Message) error {         log.Println("NSQ message received:")         log.Println(string(message.Body))         return nil     }))     err = c.ConnectToNSQD("127.0.0.1:4150")     if err != nil {         log.Panic("Could not connect")     }     log.Println("Awaiting messages from NSQ topic \"NSQ Topic\"...")     wg.Wait() }

Now run this consumer program:

$ go run consumer01.go

You’ll get this output:

2019/04/08 03:41:33 INF    1 [NSQ_Topic/NSQ_Channel] (127.0.0.1:4150) connecting to nsqd 2019/04/08 03:41:33 Awaiting messages from NSQ topic "NSQ Topic"...

This should hang there waiting to receive a NSQ message from a topic you specify. Nothing will happen just yet since there aren’t any queued up messages for this particular topic.
Leave this program running in a terminal window for now. In the next step we’ll push a message to it.

Creating a Producer

You can publish a message with a producer with some simple code like this:

create file like below in ~/src/producer/producer01.go

package main import (   "log"   "github.com/nsqio/go-nsq" ) func main() {     config := nsq.NewConfig()     p, err := nsq.NewProducer("127.0.0.1:4150", config)     if err != nil {         log.Panic(err)     }     err = p.Publish("NSQ_Topic", []byte("sample NSQ message"))     if err != nil {         log.Panic(err)     } }

Now run this publisher program:

$ go run producer01.go

In this terminal window, you’ll only see this message indicating your message was published to NSQ:

go run producer01.go 2019/04/08 03:43:35 INF    1 (127.0.0.1:4150) connecting to nsqd

If you look at your consumer terminal window that you left running from the previous step, you’ll now see this additional output:

2019/04/08 03:41:33 Awaiting messages from NSQ topic "NSQ Topic"... 2019/04/08 03:43:35 NSQ message received: 2019/04/08 03:43:35 sample NSQ message topic

Dont  forget add  firewall rule

# firewall-cmd --zone=public --add-port=4171/tcp # firewall-cmd --zone=public --add-port=4171/tcp --permanent # firewall-cmd --zone=public --add-port=4150/tcp # firewall-cmd --zone=public --add-port=4150/tcp --permanent # firewall-cmd --zone=public --add-port=4151/tcp # firewall-cmd --zone=public --add-port=4151/tcp --permanent # firewall-cmd --zone=public --add-port=4160/tcp # firewall-cmd --zone=public --add-port=4160/tcp --permanent # firewall-cmd --zone=public --add-port=4161/tcp # firewall-cmd --zone=public --add-port=4161/tcp --permanent

Congrats - you just pushed and received your first NSQ message!

If you go back to your web UI console you’ll see your newly-created topic. If you drill into this topic, you can also see the channel that you consumed the message to, with the message counter at 1:

Check CPU Nagios Using SNMP on Centos

SNMP stands for simple network management protocol. It is a way that servers can share information about their current state, and also a channel through which an administer can modify pre-defined values. While the protocol itself is very simple, the structure of programs that implement SNMP can be very complex.

If you still didn’t install Nagios Core , check the following articles. How to Install and Configure Nagios on CentOS

In this article we will show you how to install and configure SNMP in the remote server and how to add the host to Nagios Core.

Scenario

In this tutorial i am going to use two systems as mentioned below.

Nagios server (host):

Operating system : CentOS 6 minimal server IP Address       : 192.168.1.150/24

Nagios client (remote):

Operating System : CentOS 6 minimal server IP Address       : 192.168.1.152/24

Installing SNMP Agent on remote machine

1. Install SNMP and SNMP Utilities



yum -y install net-snmp net-snmp-utils



2. Add a Basic Configuration



mv /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.orig cp /dev/null /etc/snmp/snmpd.conf vim /etc/snmp/snmpd.conf


Insert the following text into the new /etc/snmp/snmpd.conf



# Map 'idv90we3rnov90wer' community to the 'ConfigUser' # Map '209ijvfwer0df92jd' community to the 'AllUser' #       sec.name        source          community com2sec ConfigUser      default         idv90we3rnov90wer com2sec AllUser         default         209ijvfwer0df92jd # Map 'ConfigUser' to 'ConfigGroup' for SNMP Version 2c # Map 'AllUser' to 'AllGroup' for SNMP Version 2c #                       sec.model       sec.name group   ConfigGroup     v2c             ConfigUser group   AllGroup        v2c             AllUser # Define 'SystemView', which includes everything under .1.3.6.1.2.1.1 (or .1.3.6.1.2.1.25.1) # Define 'AllView', which includes everything under .1 #                       incl/excl       subtree view    SystemView      included        .1.3.6.1.2.1.1 view    SystemView      included        .1.3.6.1.2.1.25.1.1 view    AllView         included        .1 # Give 'ConfigGroup' read access to objects in the view 'SystemView' # Give 'AllGroup' read access to objects in the view 'AllView' #                       context model   level   prefix  read            write   notify access  ConfigGroup     ""      any     noauth  exact   SystemView      none    none access  AllGroup        ""      any     noauth  exact   AllView         none    none


Exit vim, and restart the SNMP service to reload the new configuration file:

on Centos 6.x



service snmpd restart


on Centos 7.x



systemctl restart snmpd


Configure SNMP to start when the server boots:

on Centos 6.x



chkconfig snmpd on


on Centos 7.x



systemctl enable snmpd



3. Test the SNMP Configuration

from localhost on remote



snmpwalk -v 2c -c 209ijvfwer0df92jd -O e 127.0.0.1


from nagios host



snmpwalk -v 2c -c 209ijvfwer0df92jd -O e 192.168.1.152

Configure Nagios To Monitor The Linux Host

1. Install plugins check_cpu for snmp download from below



https://exchange.nagios.org/directory/Plugins/Operating-Systems/Solaris/check_cpu/details


Put check_cpu into your Nagios libexec directory
(e.g. /usr/local/Nagios/libexec, or wherever Nagios is installed on your server)

Create the symbolic links, being careful not to overwrite any files by the same name already there



ln -s check_cpu check_load ln -s check_cpu check_ram ln -s check_cpu check_swap


(these symlinks dictate how the script is run, as it can check CPU, RAM, load and swap, depending on how it is invoked)


2. Insert the following text into /usr/local/nagios/etc/objects/commands.conf



#snmp check_cpu define command{ command_name check_cpu command_line $USER1$/check_cpu -H $HOSTADDRESS$ -w $ARG1$ -c $ARG2$ -p $ARG3$ } define command{ command_name check_swap command_line $USER1$/check_swap -H $HOSTADDRESS$ -w $ARG1$ -c $ARG2$ -p $ARG3$ } define command{ command_name check_ram command_line $USER1$/check_ram -H $HOSTADDRESS$ -w $ARG1$ -c $ARG2$ -p $ARG3$ -o $ARG4$ } define command{ command_name check_load command_line $USER1$/check_load -H $HOSTADDRESS$ -w $ARG1$ -c $ARG2$ -p $ARG3$ }



3. Insert the following text into /usr/local/nagios/etc/servers/hostname.cfg



define host{ use                             linux-server host_name                       hostname alias                           hostname address                         192.168.10.70 max_check_attempts              5 check_period                    24x7 notification_interval           30 notification_period             24x7 } # Check CPU with check_cpu snmpd define service{         use                             local-service         ; Name of service template to use         host_name                       hostname         service_description             Check CPU         check_command                   check_cpu!70%!80%!209ijvfwer0df92jd         } define service{         use                             local-service         ; Name of service template to use         host_name                       hostname         service_description             Check Swap Memory         check_command                   check_swap!70!90!209ijvfwer0df92jd         } define service{         use                             local-service         ; Name of service template to use         host_name                       hostname         service_description             Check Memory         check_command                   check_ram!70!90!209ijvfwer0df92jd         } define service{         use                             local-service         ; Name of service template to use         host_name                       hostname         service_description             Check Load Average         check_command                   check_load!60,70,80!70,80,90!209ijvfwer0df92jd         }



4. Restart Nagios

Next, verify Nagios Configuration files for any errors.



/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg Total Warnings: 0 Total Errors:   0


Finally, restart Nagios.

On Centos 6.x



service nagios restart


On Centos 7.x



systemctl restart nagios


Log into the web interface via : http://[SERVER_IP]/nagios , enter your login information and check for new Linux hosts added in nagios core service.
That’s all.

Congratulations! Enjoy your Monitoring platform Nagios Core.