DevOps Classroom Series – 11/Jul/2020

Nagios configuration, templates and Inheritance

  • Nagios main configuration file has cfg_file with commands
###############################################################################
# COMMANDS.CFG - SAMPLE COMMAND DEFINITIONS FOR NAGIOS 4.4.5
#
#
# NOTES: This config file provides you with some example command definitions
#        that you can reference in host, service, and contact definitions.
#
#        You don't need to keep commands in a separate file from your other
#        object definitions.  This has been done just to make things easier to
#        understand.
#
###############################################################################



################################################################################
#
# SAMPLE NOTIFICATION COMMANDS
#
# These are some example notification commands.  They may or may not work on
# your system without modification.  As an example, some systems will require
# you to use "/usr/bin/mailx" instead of "/usr/bin/mail" in the commands below.
#
################################################################################

define command {

    command_name    notify-host-by-email
    command_line    /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\nHost: $HOSTNAME$\nState: $HOSTSTATE$\nAddress: $HOSTADDRESS$\nInfo: $HOSTOUTPUT$\n\nDate/Time: $LONGDATETIME$\n" | /bin/mail -s "** $NOTIFICATIONTYPE$ Host Alert: $HOSTNAME$ is $HOSTSTATE$ **" $CONTACTEMAIL$
}



define command {

    command_name    notify-service-by-email
    command_line    /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\n\nService: $SERVICEDESC$\nHost: $HOSTALIAS$\nAddress: $HOSTADDRESS$\nState: $SERVICESTATE$\n\nDate/Time: $LONGDATETIME$\n\nAdditional Info:\n\n$SERVICEOUTPUT$\n" | /bin/mail -s "** $NOTIFICATIONTYPE$ Service Alert: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ **" $CONTACTEMAIL$
}



################################################################################
#
# SAMPLE HOST CHECK COMMANDS
#
################################################################################

# This command checks to see if a host is "alive" by pinging it
# The check must result in a 100% packet loss or 5 second (5000ms) round trip
# average time to produce a critical error.
# Note: Five ICMP echo packets are sent (determined by the '-p 5' argument)

define command {

    command_name    check-host-alive
    command_line    $USER1$/check_ping -H $HOSTADDRESS$ -w 3000.0,80% -c 5000.0,100% -p 5
}



################################################################################
#
# SAMPLE SERVICE CHECK COMMANDS
#
# These are some example service check commands.  They may or may not work on
# your system, as they must be modified for your plugins.  See the HTML
# documentation on the plugins for examples of how to configure command definitions.
#
# NOTE:  The following 'check_local_...' functions are designed to monitor
#        various metrics on the host that Nagios is running on (i.e. this one).
################################################################################

define command {

    command_name    check_local_disk
    command_line    $USER1$/check_disk -w $ARG1$ -c $ARG2$ -p $ARG3$
}



define command {

    command_name    check_local_load
    command_line    $USER1$/check_load -w $ARG1$ -c $ARG2$
}



define command {

    command_name    check_local_procs
    command_line    $USER1$/check_procs -w $ARG1$ -c $ARG2$ -s $ARG3$
}



define command {

    command_name    check_local_users
    command_line    $USER1$/check_users -w $ARG1$ -c $ARG2$
}



define command {

    command_name    check_local_swap
    command_line    $USER1$/check_swap -w $ARG1$ -c $ARG2$
}



define command {

    command_name    check_local_mrtgtraf
    command_line    $USER1$/check_mrtgtraf -F $ARG1$ -a $ARG2$ -w $ARG3$ -c $ARG4$ -e $ARG5$
}



################################################################################
# NOTE:  The following 'check_...' commands are used to monitor services on
#        both local and remote hosts.
################################################################################

define command {

    command_name    check_ftp
    command_line    $USER1$/check_ftp -H $HOSTADDRESS$ $ARG1$
}



define command {

    command_name    check_hpjd
    command_line    $USER1$/check_hpjd -H $HOSTADDRESS$ $ARG1$
}



define command {

    command_name    check_snmp
    command_line    $USER1$/check_snmp -H $HOSTADDRESS$ $ARG1$
}



define command {

    command_name    check_http
    command_line    $USER1$/check_http -I $HOSTADDRESS$ $ARG1$
}



define command {

    command_name    check_ssh
    command_line    $USER1$/check_ssh $ARG1$ $HOSTADDRESS$
}



define command {

    command_name    check_dhcp
    command_line    $USER1$/check_dhcp $ARG1$
}



define command {

    command_name    check_ping
    command_line    $USER1$/check_ping -H $HOSTADDRESS$ -w $ARG1$ -c $ARG2$ -p 5
}



define command {

    command_name    check_pop
    command_line    $USER1$/check_pop -H $HOSTADDRESS$ $ARG1$
}



define command {

    command_name    check_imap
    command_line    $USER1$/check_imap -H $HOSTADDRESS$ $ARG1$
}



define command {

    command_name    check_smtp
    command_line    $USER1$/check_smtp -H $HOSTADDRESS$ $ARG1$
}



define command {

    command_name    check_tcp
    command_line    $USER1$/check_tcp -H $HOSTADDRESS$ -p $ARG1$ $ARG2$
}



define command {

    command_name    check_udp
    command_line    $USER1$/check_udp -H $HOSTADDRESS$ -p $ARG1$ $ARG2$
}



define command {

    command_name    check_nt
    command_line    $USER1$/check_nt -H $HOSTADDRESS$ -p 12489 -v $ARG1$ $ARG2$
}



################################################################################
#
# SAMPLE PERFORMANCE DATA COMMANDS
#
# These are sample performance data commands that can be used to send performance
# data output to two text files (one for hosts, another for services).  If you
# plan on simply writing performance data out to a file, consider using the
# host_perfdata_file and service_perfdata_file options in the main config file.
#
################################################################################

define command {

    command_name    process-host-perfdata
    command_line    /usr/bin/printf "%b" "$LASTHOSTCHECK$\t$HOSTNAME$\t$HOSTSTATE$\t$HOSTATTEMPT$\t$HOSTSTATETYPE$\t$HOSTEXECUTIONTIME$\t$HOSTOUTPUT$\t$HOSTPERFDATA$\n" >> /usr/local/nagios/var/host-perfdata.out
}



define command {

    command_name    process-service-perfdata
    command_line    /usr/bin/printf "%b" "$LASTSERVICECHECK$\t$HOSTNAME$\t$SERVICEDESC$\t$SERVICESTATE$\t$SERVICEATTEMPT$\t$SERVICESTATETYPE$\t$SERVICEEXECUTIONTIME$\t$SERVICELATENCY$\t$SERVICEOUTPUT$\t$SERVICEPERFDATA$\n" >> /usr/local/nagios/var/service-perfdata.out
}
  • The commands defined over here can be used in host and service checks.
  • The variables used such as $USER1$ is defined in resources.cfg
###########################################################################
#
# RESOURCE.CFG - Sample Resource File for Nagios 4.4.5
#
#
# You can define $USERx$ macros in this file, which can in turn be used
# in command definitions in your host config file(s).  $USERx$ macros are
# useful for storing sensitive information such as usernames, passwords,
# etc.  They are also handy for specifying the path to plugins and
# event handlers - if you decide to move the plugins or event handlers to
# a different directory in the future, you can just update one or two
# $USERx$ macros, instead of modifying a lot of command definitions.
#
# The CGIs will not attempt to read the contents of resource files, so
# you can set restrictive permissions (600 or 660) on them.
#
# Nagios supports up to 256 $USERx$ macros ($USER1$ through $USER256$)
#
# Resource files may also be used to store configuration directives for
# external data sources like MySQL...
#
###########################################################################

# Sets $USER1$ to be the path to the plugins
$USER1$=/usr/local/nagios/libexec

# Sets $USER2$ to be the path to event handlers
#$USER2$=/usr/local/nagios/libexec/eventhandlers

# Store some usernames and passwords (hidden from the CGIs)
#$USER3$=someuser
#$USER4$=somepassword
  • Lets try to create a new file called as mycommands.cfg with new command. For coming up with command refer here. For comand object definition refer here
# 10 ICMP echo packets are sent and aggresive turn around times are expected

define command {
    command_name    check-host-upto-speed
    command_line    $USER1$/check_ping -H $HOSTADDRESS$ -w 1000.0,10% -c 2000.0,20%   -p 10
}

  • Its a best practice to have objects grouped into folders, so we would create folders for

    • commands
    • timeperiods
    • contacts
    • contactgroups
    • hosts
    • hostgroups
    • services
    • servicegroups Preview

  • The sample nagios configuration will have following contacts

###############################################################################
# CONTACTS.CFG - SAMPLE CONTACT/CONTACTGROUP DEFINITIONS
#
#
# NOTES: This config file provides you with some example contact and contact
#        group definitions that you can reference in host and service
#        definitions.
#
#        You don't need to keep these definitions in a separate file from your
#        other object definitions.  This has been done just to make things
#        easier to understand.
#
###############################################################################



###############################################################################
#
# CONTACTS
#
###############################################################################

# Just one contact defined by default - the Nagios admin (that's you)
# This contact definition inherits a lot of default values from the
# 'generic-contact' template which is defined elsewhere.

define contact {

    contact_name            nagiosadmin             ; Short name of user
    use                     generic-contact         ; Inherit default values from generic-contact template (defined above)
    alias                   Nagios Admin            ; Full name of user
    email                   nagios@localhost ; <<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******
}



###############################################################################
#
# CONTACT GROUPS
#
###############################################################################

# We only have one contact in this simple configuration file, so there is
# no need to create more than one contact group.

define contactgroup {

    contactgroup_name       admins
    alias                   Nagios Administrators
    members                 nagiosadmin
}
  • Now lets add more contacts as per our folder structure as per object definitions mentioned over here
  • Now create a contact for your admins, create a file in contacts folder with anyname.cfg
define contact {
    contact_name                        khaja
    alias                               khaja
    host_notifications_enabled          1
    service_notifications_enabled       1
    host_notification_period            24x7
    service_notification_period         24x7
    host_notification_options           d,u,r
    service_notification_options        w,u,c,r
    email                               khaja@learningthoughts.in
    can_submit_commands                 1
}
define contact {
    contact_name                        ibrahim
    alias                               ibrahim
    host_notifications_enabled          1
    service_notifications_enabled       1
    host_notification_period            24x7
    service_notification_period         24x7
    host_notification_options           d,u,r
    service_notification_options        w,u,c,r
    email                               ibrahim@learningthoughts.in
    can_submit_commands                 1
}
  • If you look at contacts, most of the options are redundant, Is there any way in nagios to make object defintions reusable. Answer is yes, we have templates
  • Template helps us in creating reusable configurations, every template will have a register with 0 value which tells nagios that it is a template Preview.
  • Lets add a new folder for templates and create templates for contacts
define contact {
    contact_name                    admin-contact
    service_notification_period     24x7
    host_notification_period        24x7
    service_notification_options    w,u,c,r,f,s
    host_notification_options       d,u,r,f,s
    host_notification_commands      notify-host-by-email
    register                        0

}

define contact {
    contact_name                    non-admin-contact
    service_notification_period     24x7
    host_notification_period        24x7
    service_notification_options    c,r
    host_notification_options       d,r
    host_notification_commands      notify-host-by-email
    register                        0

}
  • Now lets change our actual contacts file to have 2 admins and 2 non admins
define contact {
    contact_name            admin
    alias                   admin
    use                     admin-contact
    email                   admin@learningthoughts.in
}

define contact {
    contact_name            khaja
    alias                   khaja
    use                     admin-contact
    email                   khaja@learningthoughts.in
}

define contact {
    contact_name            ibrahim
    alias                   ibrahim
    use                     non-admin-contact
    email                   ibrahim@learningthoughts.in
}

define contact {
    contact_name            satish
    alias                   satish
    use                     non-admin-contact
    email                   satish@learningthoughts.in
}
  • Now lets add contact groups in the contact groups folder
define contactgroup {

    contactgroup_name       admins
    alias                   Nagios Administrators
    members                 admin,khaja
}

define contactgroup {
    contactgroup_name        nonadmins
    alias                    Normal Users
    members                  ibrahim,satish
}
  • Lets retain the default time periods in the timeperiods folder Refer Here

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