diff --git a/puppet/zulip_ops/files/nagios3/commands.cfg b/puppet/zulip_ops/files/nagios4/commands.cfg
similarity index 98%
rename from puppet/zulip_ops/files/nagios3/commands.cfg
rename to puppet/zulip_ops/files/nagios4/commands.cfg
index e7d0e7af73..060a023bf9 100644
--- a/puppet/zulip_ops/files/nagios3/commands.cfg
+++ b/puppet/zulip_ops/files/nagios4/commands.cfg
@@ -34,14 +34,14 @@ define command{
 # 'process-host-perfdata' command definition
 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" >> /var/lib/nagios3/host-perfdata.out
+        command_line    /usr/bin/printf "%b" "$LASTHOSTCHECK$\t$HOSTNAME$\t$HOSTSTATE$\t$HOSTATTEMPT$\t$HOSTSTATETYPE$\t$HOSTEXECUTIONTIME$\t$HOSTOUTPUT$\t$HOSTPERFDATA$\n" >> /var/lib/nagios4/host-perfdata.out
         }
 
 
 # 'process-service-perfdata' command definition
 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" >> /var/lib/nagios3/service-perfdata.out
+        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" >> /var/lib/nagios4/service-perfdata.out
         }
 
 define command{
diff --git a/puppet/zulip_ops/files/nagios3/conf.d/generic-host_nagios2.cfg b/puppet/zulip_ops/files/nagios4/conf.d/generic-host_nagios2.cfg
similarity index 100%
rename from puppet/zulip_ops/files/nagios3/conf.d/generic-host_nagios2.cfg
rename to puppet/zulip_ops/files/nagios4/conf.d/generic-host_nagios2.cfg
diff --git a/puppet/zulip_ops/files/nagios3/conf.d/generic-service_nagios2.cfg b/puppet/zulip_ops/files/nagios4/conf.d/generic-service_nagios2.cfg
similarity index 100%
rename from puppet/zulip_ops/files/nagios3/conf.d/generic-service_nagios2.cfg
rename to puppet/zulip_ops/files/nagios4/conf.d/generic-service_nagios2.cfg
diff --git a/puppet/zulip_ops/files/nagios3/conf.d/hostgroups.cfg b/puppet/zulip_ops/files/nagios4/conf.d/hostgroups.cfg
similarity index 100%
rename from puppet/zulip_ops/files/nagios3/conf.d/hostgroups.cfg
rename to puppet/zulip_ops/files/nagios4/conf.d/hostgroups.cfg
diff --git a/puppet/zulip_ops/files/nagios3/conf.d/services.cfg b/puppet/zulip_ops/files/nagios4/conf.d/services.cfg
similarity index 100%
rename from puppet/zulip_ops/files/nagios3/conf.d/services.cfg
rename to puppet/zulip_ops/files/nagios4/conf.d/services.cfg
diff --git a/puppet/zulip_ops/files/nagios3/conf.d/timeperiods_nagios2.cfg b/puppet/zulip_ops/files/nagios4/conf.d/timeperiods_nagios2.cfg
similarity index 100%
rename from puppet/zulip_ops/files/nagios3/conf.d/timeperiods_nagios2.cfg
rename to puppet/zulip_ops/files/nagios4/conf.d/timeperiods_nagios2.cfg
diff --git a/puppet/zulip_ops/files/nagios3/nagios.cfg b/puppet/zulip_ops/files/nagios4/nagios.cfg
similarity index 88%
rename from puppet/zulip_ops/files/nagios3/nagios.cfg
rename to puppet/zulip_ops/files/nagios4/nagios.cfg
index 2b0a5421d5..fd5d443347 100644
--- a/puppet/zulip_ops/files/nagios3/nagios.cfg
+++ b/puppet/zulip_ops/files/nagios4/nagios.cfg
@@ -2,6 +2,10 @@
 #
 # NAGIOS.CFG - Sample Main Config File for Nagios
 #
+# Read the documentation for more information on this configuration
+# file.  I've provided some comments here, but things may not be so
+# clear without further explanation.
+#
 #
 ##############################################################################
 
@@ -11,19 +15,19 @@
 # for historical purposes.  This should be the first option specified
 # in the config file!!!
 
-log_file=/var/log/nagios3/nagios.log
+log_file=/var/log/nagios4/nagios.log
 
 # Commands definitions
-cfg_file=/etc/nagios3/commands.cfg
+cfg_file=/etc/nagios4/commands.cfg
 
 # Debian also defaults to using the check commands defined by the debian
 # nagios-plugins package
 cfg_dir=/etc/nagios-plugins/config
 
-# Debian uses by default a configuration directory where nagios3-common,
+# Debian uses by default a configuration directory where nagios4-common,
 # other packages and the local admin can dump or link configuration
 # files into.
-cfg_dir=/etc/nagios3/conf.d
+cfg_dir=/etc/nagios4/conf.d
 
 # OBJECT CONFIGURATION FILE(S)
 # These are the object configuration files in which you define hosts,
@@ -32,29 +36,32 @@ cfg_dir=/etc/nagios3/conf.d
 # if you wish (as shown below), or keep them all in a single config file.
 
 # You can specify individual object config files as shown below:
-#cfg_file=/etc/nagios3/objects/commands.cfg
-#cfg_file=/etc/nagios3/objects/contacts.cfg
-#cfg_file=/etc/nagios3/objects/timeperiods.cfg
-#cfg_file=/etc/nagios3/objects/templates.cfg
+#cfg_file=/etc/nagios4/objects/commands.cfg
+#cfg_file=/etc/nagios4/objects/contacts.cfg
+#cfg_file=/etc/nagios4/objects/timeperiods.cfg
+#cfg_file=/etc/nagios4/objects/templates.cfg
+
+# Definitions for monitoring the local (Linux) host
+#cfg_file=/etc/nagios4/objects/localhost.cfg
 
 # Definitions for monitoring a Windows machine
-#cfg_file=/etc/nagios3/objects/windows.cfg
+#cfg_file=/etc/nagios4/objects/windows.cfg
 
 # Definitions for monitoring a router/switch
-#cfg_file=/etc/nagios3/objects/switch.cfg
+#cfg_file=/etc/nagios4/objects/switch.cfg
 
 # Definitions for monitoring a network printer
-#cfg_file=/etc/nagios3/objects/printer.cfg
+#cfg_file=/etc/nagios4/objects/printer.cfg
 
 
 # You can also tell Nagios to process all config files (with a .cfg
 # extension) in a particular directory by using the cfg_dir
 # directive as shown below:
 
-#cfg_dir=/etc/nagios3/servers
-#cfg_dir=/etc/nagios3/printers
-#cfg_dir=/etc/nagios3/switches
-#cfg_dir=/etc/nagios3/routers
+#cfg_dir=/etc/nagios4/servers
+#cfg_dir=/etc/nagios4/printers
+#cfg_dir=/etc/nagios4/switches
+#cfg_dir=/etc/nagios4/routers
 
 
 
@@ -66,7 +73,7 @@ cfg_dir=/etc/nagios3/conf.d
 # directly) in order to prevent inconsistencies that can occur
 # when the config files are modified after Nagios starts.
 
-object_cache_file=/var/cache/nagios3/objects.cache
+object_cache_file=/var/cache/nagios4/objects.cache
 
 
 
@@ -82,7 +89,7 @@ object_cache_file=/var/cache/nagios3/objects.cache
 # Read the documentation section on optimizing Nagios to find our more
 # about how this feature works.
 
-precached_object_file=/var/lib/nagios3/objects.precache
+precached_object_file=/var/cache/nagios4/objects.precache
 
 
 
@@ -95,7 +102,7 @@ precached_object_file=/var/lib/nagios3/objects.precache
 # defined as macros in this file and restrictive permissions (600)
 # can be placed on this file.
 
-resource_file=/etc/nagios3/resource.cfg
+resource_file=/etc/nagios4/resource.cfg
 
 
 
@@ -105,7 +112,7 @@ resource_file=/etc/nagios3/resource.cfg
 # The contents of the status file are deleted every time Nagios
 #  restarts.
 
-status_file=/var/cache/nagios3/status.dat
+status_file=/var/cache/nagios4/status.dat
 
 
 
@@ -146,24 +153,6 @@ check_external_commands=1
 
 
 
-# EXTERNAL COMMAND CHECK INTERVAL
-# This is the interval at which Nagios should check for external commands.
-# This value works of the interval_length you specify later.  If you leave
-# that at its default value of 60 (seconds), a value of 1 here will cause
-# Nagios to check for external commands every minute.  If you specify a
-# number followed by an "s" (i.e. 15s), this will be interpreted to mean
-# actual seconds rather than a multiple of the interval_length variable.
-# Note: In addition to reading the external command file at regularly
-# scheduled intervals, Nagios will also check for external commands after
-# event handlers are executed.
-# NOTE: Setting this value to -1 causes Nagios to check the external
-# command file as often as possible.
-
-#command_check_interval=15s
-command_check_interval=-1
-
-
-
 # EXTERNAL COMMAND FILE
 # This is the file that Nagios checks for external command requests.
 # It is also where the command CGI will write commands that are submitted
@@ -174,17 +163,14 @@ command_check_interval=-1
 # Debian Users: In case you didn't read README.Debian yet, _NOW_ is the
 # time to do it.
 
-command_file=/var/lib/nagios3/rw/nagios.cmd
+command_file=/var/cache/nagios4/rw/nagios.cmd
 
 
 
-# EXTERNAL COMMAND BUFFER SLOTS
-# This settings is used to tweak the number of items or "slots" that
-# the Nagios daemon should allocate to the buffer that holds incoming
-# external commands before they are processed.  As external commands
-# are processed by the daemon, they are removed from the buffer.
+# QUERY HANDLER INTERFACE
+# This is the socket that is created for the Query Handler interface
 
-external_command_buffer_slots=4096
+#query_socket=/var/cache/nagios4/rw/nagios.qh
 
 
 
@@ -192,7 +178,7 @@ external_command_buffer_slots=4096
 # This is the lockfile that Nagios will use to store its PID number
 # in when it is running in daemon mode.
 
-lock_file=/var/run/nagios3/nagios3.pid
+lock_file=/var/run/nagios4/nagios4.pid
 
 
 
@@ -202,7 +188,7 @@ lock_file=/var/run/nagios3/nagios3.pid
 # is created, used, and deleted throughout the time that Nagios is
 # running.
 
-temp_file=/var/cache/nagios3/nagios.tmp
+temp_file=/var/cache/nagios4/nagios.tmp
 
 
 
@@ -254,11 +240,11 @@ event_broker_options=-1
 # LOG ROTATION METHOD
 # This is the log rotation method that Nagios should use to rotate
 # the main log file. Values are as follows..
-#       n       = None - don't rotate the log
-#       h       = Hourly rotation (top of the hour)
-#       d       = Daily rotation (midnight every day)
-#       w       = Weekly rotation (midnight on Saturday evening)
-#       m       = Monthly rotation (midnight last day of month)
+#	n	= None - don't rotate the log
+#	h	= Hourly rotation (top of the hour)
+#	d	= Daily rotation (midnight every day)
+#	w	= Weekly rotation (midnight on Saturday evening)
+#	m	= Monthly rotation (midnight last day of month)
 
 log_rotation_method=d
 
@@ -268,7 +254,7 @@ log_rotation_method=d
 # This is the directory where archived (rotated) log files should be
 # placed (assuming you've chosen to do log rotation).
 
-log_archive_path=/var/log/nagios3/archives
+log_archive_path=/var/cache/nagios4/archives
 
 
 
@@ -325,6 +311,15 @@ log_initial_states=0
 
 
 
+# CURRENT STATES LOGGING OPTION
+# If you don't want Nagios to log all current host and service states
+# after log has been rotated to the main log file, you can disable this
+# option by setting this value to 0. Default value is 1.
+
+log_current_states=1
+
+
+
 # EXTERNAL COMMANDS LOGGING OPTION
 # If you don't want Nagios to log external commands, set this value
 # to 0.  If external commands should be logged, set this value to 1.
@@ -368,9 +363,9 @@ log_passive_checks=1
 # at the same time (with no delay between them)!  This is not a
 # good thing for production, but is useful when testing the
 # parallelization functionality.
-#       n       = None - don't use any delay between checks
-#       d       = Use a "dumb" delay of 1 second between checks
-#       s       = Use "smart" inter-check delay calculation
+#	n	= None - don't use any delay between checks
+#	d	= Use a "dumb" delay of 1 second between checks
+#	s	= Use "smart" inter-check delay calculation
 #       x.xx    = Use an inter-check delay of x.xx seconds
 
 service_inter_check_delay_method=s
@@ -409,9 +404,9 @@ service_interleave_factor=s
 # space all host checks out evenly to minimize CPU load.
 # Using the dumb setting will cause all checks to be scheduled
 # at the same time (with no delay between them)!
-#       n       = None - don't use any delay between checks
-#       d       = Use a "dumb" delay of 1 second between checks
-#       s       = Use "smart" inter-check delay calculation
+#	n	= None - don't use any delay between checks
+#	d	= Use a "dumb" delay of 1 second between checks
+#	s	= Use "smart" inter-check delay calculation
 #       x.xx    = Use an inter-check delay of x.xx seconds
 
 host_inter_check_delay_method=s
@@ -466,7 +461,7 @@ max_check_result_reaper_time=30
 # Note: Make sure that only one instance of Nagios has access
 # to this directory!
 
-check_result_path=/var/lib/nagios3/spool/checkresults
+check_result_path=/var/lib/nagios4/spool/checkresults
 
 
 
@@ -594,14 +589,6 @@ auto_rescheduling_window=180
 
 
 
-# SLEEP TIME
-# This is the number of seconds to sleep between checking for system
-# events and service checks that need to be run.
-
-sleep_time=0.25
-
-
-
 # TIMEOUT VALUES
 # These options control how much time Nagios will allow various
 # types of commands to execute before killing them off.  Options
@@ -641,7 +628,7 @@ retain_state_information=1
 # This file is used only if the retain_state_information
 # variable is set to 1.
 
-state_retention_file=/var/lib/nagios3/retention.dat
+state_retention_file=/var/cache/nagios4/retention.dat
 
 
 
@@ -730,14 +717,14 @@ interval_length=60
 # patches to Nagios.  Nagios is critical to you - make sure you keep it in
 # good shape.  Nagios will check once a day for new updates. Data collected
 # by Nagios Enterprises from the update check is processed in accordance
-# with our privacy policy - see http://api.nagios.org for details.
+# with our privacy policy - see https://api.nagios.org for details.
 
 check_for_updates=1
 
 
 
 # BARE UPDATE CHECK
-# This option deterines what data Nagios will send to api.nagios.org when
+# This option determines what data Nagios will send to api.nagios.org when
 # it checks for updates.  By default, Nagios will send information on the
 # current version of Nagios you have installed, as well as an indicator as
 # to whether this was a new installation or not.  Nagios Enterprises uses
@@ -854,8 +841,8 @@ process_performance_data=0
 # Performance data is only written to these files if the
 # enable_performance_data option (above) is set to 1.
 
-#host_perfdata_file=/tmp/host-perfdata
-#service_perfdata_file=/tmp/service-perfdata
+#host_perfdata_file=/var/cache/nagios4/host-perfdata
+#service_perfdata_file=/var/cache/nagios4/service-perfdata
 
 
 
@@ -906,7 +893,7 @@ process_performance_data=0
 
 
 # HOST AND SERVICE PERFORMANCE DATA PROCESS EMPTY RESULTS
-# THese options determine whether the core will process empty perfdata
+# These options determine whether the core will process empty perfdata
 # results or not. This is needed for distributed monitoring, and intentionally
 # turned on by default.
 # If you don't require empty perfdata - saving some cpu cycles
@@ -917,7 +904,6 @@ process_performance_data=0
 #service_perfdata_process_empty_results=1
 
 
-
 # OBSESS OVER SERVICE CHECKS OPTION
 # This determines whether or not Nagios will obsess over service
 # checks and run the ocsp_command defined below.  Unless you're
@@ -1111,10 +1097,10 @@ high_host_flap_threshold=20.0
 # DATE FORMAT OPTION
 # This option determines how short dates are displayed. Valid options
 # include:
-#       us              (MM-DD-YYYY HH:MM:SS)
-#       euro            (DD-MM-YYYY HH:MM:SS)
-#       iso8601         (YYYY-MM-DD HH:MM:SS)
-#       strict-iso8601  (YYYY-MM-DDTHH:MM:SS)
+#	us		(MM-DD-YYYY HH:MM:SS)
+#	euro    	(DD-MM-YYYY HH:MM:SS)
+#	iso8601		(YYYY-MM-DD HH:MM:SS)
+#	strict-iso8601	(YYYY-MM-DDTHH:MM:SS)
 #
 
 date_format=iso8601
@@ -1141,37 +1127,6 @@ date_format=iso8601
 
 
 
-
-# P1.PL FILE LOCATION
-# This value determines where the p1.pl perl script (used by the
-# embedded Perl interpreter) is located.  If you didn't compile
-# Nagios with embedded Perl support, this option has no effect.
-
-p1_file=/usr/lib/nagios3/p1.pl
-
-
-
-# EMBEDDED PERL INTERPRETER OPTION
-# This option determines whether or not the embedded Perl interpreter
-# will be enabled during runtime.  This option has no effect if Nagios
-# has not been compiled with support for embedded Perl.
-# Values: 0 = disable interpreter, 1 = enable interpreter
-
-enable_embedded_perl=1
-
-
-
-# EMBEDDED PERL USAGE OPTION
-# This option determines whether or not Nagios will process Perl plugins
-# and scripts with the embedded Perl interpreter if the plugins/scripts
-# do not explicitly indicate whether or not it is okay to do so. Read
-# the HTML documentation on the embedded Perl interpreter for more
-# information on how this option works.
-
-use_embedded_perl_implicitly=1
-
-
-
 # ILLEGAL OBJECT NAME CHARACTERS
 # This option allows you to specify illegal characters that cannot
 # be used in host names, service descriptions, or names of other
@@ -1187,14 +1142,16 @@ illegal_object_name_chars=`~!$%^&*|'"<>?,()=
 # handlers, etc.  This DOES NOT affect macros used in service or
 # host check commands.
 # The following macros are stripped of the characters you specify:
-#       $HOSTOUTPUT$
-#       $HOSTPERFDATA$
-#       $HOSTACKAUTHOR$
-#       $HOSTACKCOMMENT$
-#       $SERVICEOUTPUT$
-#       $SERVICEPERFDATA$
-#       $SERVICEACKAUTHOR$
-#       $SERVICEACKCOMMENT$
+#	$HOSTOUTPUT$
+#	$LONGHOSTOUTPUT$
+#	$HOSTPERFDATA$
+#	$HOSTACKAUTHOR$
+#	$HOSTACKCOMMENT$
+#	$SERVICEOUTPUT$
+#	$LONGSERVICEOUTPUT$
+#	$SERVICEPERFDATA$
+#	$SERVICEACKAUTHOR$
+#	$SERVICEACKCOMMENT$
 
 illegal_macro_output_chars=`~$&|'"<>
 
@@ -1265,13 +1222,16 @@ use_large_installation_tweaks=0
 # This option determines whether or not Nagios will make all standard
 # macros available as environment variables when host/service checks
 # and system commands (event handlers, notifications, etc.) are
-# executed.  Enabling this option can cause performance issues in
-# large installations, as it will consume a bit more memory and (more
-# importantly) consume more CPU.
-# Values: 1 - Enable environment variable macros (default)
-#         0 - Disable environment variable macros
+# executed.
+# Enabling this is a very bad idea for anything but very small setups,
+# as it means plugins, notification scripts and eventhandlers may run
+# out of environment space. It will also cause a significant increase
+# in CPU- and memory usage and drastically reduce the number of checks
+# you can run.
+# Values: 1 - Enable environment variable macros
+#         0 - Disable environment variable macros (default)
 
-enable_environment_macros=1
+enable_environment_macros=0
 
 
 
@@ -1309,10 +1269,10 @@ enable_environment_macros=1
 # Values:
 #          -1 = Everything
 #          0 = Nothing
-#          1 = Functions
+#	   1 = Functions
 #          2 = Configuration
 #          4 = Process information
-#          8 = Scheduled events
+#	   8 = Scheduled events
 #          16 = Host/service checks
 #          32 = Notifications
 #          64 = Event broker
@@ -1339,7 +1299,7 @@ debug_verbosity=1
 # DEBUG FILE
 # This option determines where Nagios should write debugging information.
 
-debug_file=/var/log/nagios3/nagios.debug
+debug_file=/var/cache/nagios4/nagios.debug
 
 
 
@@ -1352,4 +1312,49 @@ debug_file=/var/log/nagios3/nagios.debug
 
 max_debug_file_size=1000000
 
+
+
+# Should we allow hostgroups to have no hosts, we default this to off since
+# that was the old behavior
+
 allow_empty_hostgroup_assignment=1
+
+
+
+# Normally worker count is dynamically allocated based on 1.5 * number of cpu's
+# with a minimum of 4 workers.  This value will override the defaults
+
+#check_workers=3
+
+
+
+# DISABLE SERVICE CHECKS WHEN HOST DOWN
+# This option will disable all service checks if the host is not in an UP state
+#
+# While desirable in some environments, enabling this value can distort report
+# values as the expected quantity of checks will not have been performed
+
+#host_down_disable_service_checks=0
+
+
+
+# EXPERIMENTAL load controlling options
+# To get current defaults based on your system issue a command to
+# the query handler. Please note that this is an experimental feature
+# and not meant for production use. Used incorrectly it can induce
+# enormous latency.
+# #core loadctl
+#   jobs_max - The maximum amount of jobs to run at one time
+#   jobs_min - The minimum amount of jobs to run at one time
+#   jobs_limit - The maximum amount of jobs the current load lets us run
+#   backoff_limit - The minimum backoff_change
+#   backoff_change - # of jobs to remove from jobs_limit when backing off
+#   rampup_limit - Minimum rampup_change
+#   rampup_change - # of jobs to add to jobs_limit when ramping up
+# NOTE: The backoff_limit and rampup_limit are NOT used by anything currently,
+#       so if your system is under load nothing will actively modify the jobs
+#       even if you have these options enabled, they are for external
+#       connector information only.  However, if you change the jobs_max or
+#       jobs_min manually here or through the query handler interface that
+#       WILL affect your system
+#loadctl_options=jobs_max=100;backoff_limit=10;rampup_change=5
diff --git a/puppet/zulip_ops/files/nagios3/resource.cfg b/puppet/zulip_ops/files/nagios4/resource.cfg
similarity index 100%
rename from puppet/zulip_ops/files/nagios3/resource.cfg
rename to puppet/zulip_ops/files/nagios4/resource.cfg
diff --git a/puppet/zulip_ops/files/nagios3/zuliprc b/puppet/zulip_ops/files/nagios4/zuliprc
similarity index 100%
rename from puppet/zulip_ops/files/nagios3/zuliprc
rename to puppet/zulip_ops/files/nagios4/zuliprc
diff --git a/puppet/zulip_ops/manifests/profile/nagios.pp b/puppet/zulip_ops/manifests/profile/nagios.pp
index 7b8c57533a..9a2420fe4d 100644
--- a/puppet/zulip_ops/manifests/profile/nagios.pp
+++ b/puppet/zulip_ops/manifests/profile/nagios.pp
@@ -3,7 +3,7 @@ class zulip_ops::profile::nagios {
   include zulip_ops::apache
 
   $nagios_packages = [# Packages needed for Nagios
-                      'nagios3',
+                      'nagios4',
                       # For sending outgoing email
                       'msmtp',
                       ]
@@ -32,15 +32,15 @@ class zulip_ops::profile::nagios {
   $hosts_fullstack = split(zulipconf('nagios', 'hosts_fullstack', undef), ',')
   $hosts_smokescreen = split(zulipconf('nagios', 'hosts_smokescreen', undef), ',')
 
-  file { '/etc/nagios3/':
+  file { '/etc/nagios4/':
     recurse => true,
     purge   => false,
-    require => Package[nagios3],
+    require => Package[nagios4],
     owner   => 'root',
     group   => 'root',
     mode    => '0644',
-    source  => 'puppet:///modules/zulip_ops/nagios3/',
-    notify  => Service['nagios3'],
+    source  => 'puppet:///modules/zulip_ops/nagios4/',
+    notify  => Service['nagios4'],
   }
 
   file { '/etc/apache2/sites-available/nagios.conf':
@@ -64,71 +64,71 @@ class zulip_ops::profile::nagios {
     port        => '3000',
   }
 
-  file { '/etc/nagios3/conf.d/contacts.cfg':
-    require => Package[nagios3],
+  file { '/etc/nagios4/conf.d/contacts.cfg':
+    require => Package[nagios4],
     owner   => 'root',
     group   => 'root',
     mode    => '0644',
-    content => template('zulip_ops/nagios3/contacts.cfg.template.erb'),
-    notify  => Service['nagios3'],
+    content => template('zulip_ops/nagios4/contacts.cfg.template.erb'),
+    notify  => Service['nagios4'],
   }
-  file { '/etc/nagios3/conf.d/hosts.cfg':
-    require => Package[nagios3],
+  file { '/etc/nagios4/conf.d/hosts.cfg':
+    require => Package[nagios4],
     owner   => 'root',
     group   => 'root',
     mode    => '0644',
-    content => template('zulip_ops/nagios3/hosts.cfg.template.erb'),
-    notify  => Service['nagios3'],
+    content => template('zulip_ops/nagios4/hosts.cfg.template.erb'),
+    notify  => Service['nagios4'],
   }
-  file { '/etc/nagios3/conf.d/localhost.cfg':
-    require => Package[nagios3],
+  file { '/etc/nagios4/conf.d/localhost.cfg':
+    require => Package[nagios4],
     owner   => 'root',
     group   => 'root',
     mode    => '0644',
-    content => template('zulip_ops/nagios3/localhost.cfg.template.erb'),
-    notify  => Service['nagios3'],
+    content => template('zulip_ops/nagios4/localhost.cfg.template.erb'),
+    notify  => Service['nagios4'],
   }
 
-  file { '/etc/nagios3/cgi.cfg':
-    require => Package[nagios3],
+  file { '/etc/nagios4/cgi.cfg':
+    require => Package[nagios4],
     owner   => 'root',
     group   => 'root',
     mode    => '0644',
-    content => template('zulip_ops/nagios3/cgi.cfg.template.erb'),
-    notify  => Service['nagios3'],
+    content => template('zulip_ops/nagios4/cgi.cfg.template.erb'),
+    notify  => Service['nagios4'],
   }
 
-  service { 'nagios3':
+  service { 'nagios4':
     ensure => running,
   }
 
   file { [
-    '/etc/nagios3/conf.d/extinfo_nagios2.cfg',
-    '/etc/nagios3/conf.d/services_nagios2.cfg',
-    '/etc/nagios3/conf.d/contacts_nagios2.cfg',
-    '/etc/nagios3/conf.d/hostgroups_nagios2.cfg',
-    '/etc/nagios3/conf.d/localhost_nagios2.cfg',
+    '/etc/nagios4/conf.d/extinfo_nagios2.cfg',
+    '/etc/nagios4/conf.d/services_nagios2.cfg',
+    '/etc/nagios4/conf.d/contacts_nagios2.cfg',
+    '/etc/nagios4/conf.d/hostgroups_nagios2.cfg',
+    '/etc/nagios4/conf.d/localhost_nagios2.cfg',
   ]:
     ensure     => absent,
   }
 
-  file { '/etc/nagios3/conf.d/zulip_nagios.cfg':
+  file { '/etc/nagios4/conf.d/zulip_nagios.cfg':
     ensure => file,
     mode   => '0644',
     owner  => 'root',
     group  => 'root',
     source => '/usr/local/share/zulip/integrations/nagios/zulip_nagios.cfg',
-    notify => Service['nagios3'],
+    notify => Service['nagios4'],
   }
 
   $hosts = zulipconf_nagios_hosts()
-  file { '/etc/nagios3/conf.d/zulip_autossh.cfg':
+  file { '/etc/nagios4/conf.d/zulip_autossh.cfg':
     ensure  => file,
     mode    => '0644',
     owner   => 'root',
     group   => 'root',
     content => template('zulip_ops/nagios_autossh.template.erb'),
-    notify  => Service['nagios3'],
+    notify  => Service['nagios4'],
   }
 
   file { '/var/lib/nagios/msmtprc':
@@ -141,14 +141,14 @@ class zulip_ops::profile::nagios {
   }
 
   exec { 'fix_nagios_permissions':
-    command => 'dpkg-statoverride --update --add nagios www-data 2710 /var/lib/nagios3/rw',
-    unless  => 'bash -c "ls -ld /var/lib/nagios3/rw | grep ^drwx--s--- -q"',
-    notify  => Service['nagios3'],
+    command => 'dpkg-statoverride --update --add nagios www-data 2710 /var/lib/nagios4/rw',
+    unless  => 'bash -c "ls -ld /var/lib/nagios4/rw | grep ^drwx--s--- -q"',
+    notify  => Service['nagios4'],
   }
   exec { 'fix_nagios_permissions2':
-    command => 'dpkg-statoverride --update --add nagios nagios 751 /var/lib/nagios3',
-    unless  => 'bash -c "ls -ld /var/lib/nagios3 | grep ^drwxr-x--x -q"',
-    notify  => Service['nagios3'],
+    command => 'dpkg-statoverride --update --add nagios nagios 751 /var/lib/nagios4',
+    unless  => 'bash -c "ls -ld /var/lib/nagios4 | grep ^drwxr-x--x -q"',
+    notify  => Service['nagios4'],
   }
 
   # TODO: Install our API
diff --git a/puppet/zulip_ops/templates/nagios3/cgi.cfg.template.erb b/puppet/zulip_ops/templates/nagios4/cgi.cfg.template.erb
similarity index 98%
rename from puppet/zulip_ops/templates/nagios3/cgi.cfg.template.erb
rename to puppet/zulip_ops/templates/nagios4/cgi.cfg.template.erb
index 0dbbc0b48e..86de828a43 100644
--- a/puppet/zulip_ops/templates/nagios3/cgi.cfg.template.erb
+++ b/puppet/zulip_ops/templates/nagios4/cgi.cfg.template.erb
@@ -10,7 +10,7 @@
 # The CGIs will read the main and host config files for any other
 # data they might need.
 
-main_config_file=/etc/nagios3/nagios.cfg
+main_config_file=/etc/nagios4/nagios.cfg
 
 
 
@@ -19,7 +19,7 @@ main_config_file=/etc/nagios3/nagios.cfg
 # value is used to locate the logo images needed by the statusmap
 # and statuswrl CGIs.
 
-physical_html_path=/usr/share/nagios3/htdocs
+physical_html_path=/usr/share/nagios4/htdocs
 
 
 
@@ -31,7 +31,7 @@ physical_html_path=/usr/share/nagios3/htdocs
 # http://www.myhost.com/nagios, this value should be '/nagios'
 # (without the quotes).
 
-url_html_path=/nagios3
+url_html_path=/nagios4
 
 
 
@@ -68,7 +68,7 @@ use_pending_states=1
 # have to be tweaked a bit, as different versions of the plugin
 # use different command line arguments/syntaxes.
 
-nagios_check_command=/usr/lib/nagios/plugins/check_nagios /var/cache/nagios3/status.dat 5 '/usr/sbin/nagios3'
+nagios_check_command=/usr/lib/nagios/plugins/check_nagios /var/cache/nagios4/status.dat 5 '/usr/sbin/nagios4'
 
 
 # AUTHENTICATION USAGE
diff --git a/puppet/zulip_ops/templates/nagios3/contacts.cfg.template.erb b/puppet/zulip_ops/templates/nagios4/contacts.cfg.template.erb
similarity index 100%
rename from puppet/zulip_ops/templates/nagios3/contacts.cfg.template.erb
rename to puppet/zulip_ops/templates/nagios4/contacts.cfg.template.erb
diff --git a/puppet/zulip_ops/templates/nagios3/hosts.cfg.template.erb b/puppet/zulip_ops/templates/nagios4/hosts.cfg.template.erb
similarity index 100%
rename from puppet/zulip_ops/templates/nagios3/hosts.cfg.template.erb
rename to puppet/zulip_ops/templates/nagios4/hosts.cfg.template.erb
diff --git a/puppet/zulip_ops/templates/nagios3/localhost.cfg.template.erb b/puppet/zulip_ops/templates/nagios4/localhost.cfg.template.erb
similarity index 100%
rename from puppet/zulip_ops/templates/nagios3/localhost.cfg.template.erb
rename to puppet/zulip_ops/templates/nagios4/localhost.cfg.template.erb
diff --git a/puppet/zulip_ops/templates/nagios_apache_site.conf.template.erb b/puppet/zulip_ops/templates/nagios_apache_site.conf.template.erb
index a1f6545c41..4db0cbe435 100644
--- a/puppet/zulip_ops/templates/nagios_apache_site.conf.template.erb
+++ b/puppet/zulip_ops/templates/nagios_apache_site.conf.template.erb
@@ -4,22 +4,22 @@
     Header add Strict-Transport-Security "max-age=15768000"
     Header add X-Frame-Options DENY
 
-    ScriptAlias /cgi-bin/nagios3 /usr/lib/cgi-bin/nagios3
-    ScriptAlias /nagios3/cgi-bin /usr/lib/cgi-bin/nagios3
+    ScriptAlias /cgi-bin/nagios4 /usr/lib/cgi-bin/nagios4
+    ScriptAlias /nagios4/cgi-bin /usr/lib/cgi-bin/nagios4
 
     # Where the stylesheets (config files) reside
-    Alias /nagios3/stylesheets /etc/nagios3/stylesheets
+    Alias /nagios4/stylesheets /etc/nagios4/stylesheets
 
     # Where the HTML pages live
-    Alias /nagios3 /usr/share/nagios3/htdocs
+    Alias /nagios4 /usr/share/nagios4/htdocs
 
     <Location "/">
         Require all granted
     </Location>
 
-    RedirectMatch ^/?$ https://nagios.teleport.<%= @default_host_domain %>/cgi-bin/nagios3/status.cgi?host=all
+    RedirectMatch ^/?$ https://nagios.teleport.<%= @default_host_domain %>/cgi-bin/nagios4/status.cgi?host=all
 
-    <DirectoryMatch (/usr/share/nagios3/htdocs|/usr/lib/cgi-bin/nagios3|/etc/nagios3/stylesheets)>
+    <DirectoryMatch (/usr/share/nagios4/htdocs|/usr/lib/cgi-bin/nagios4|/etc/nagios4/stylesheets)>
         Options FollowSymLinks
 
         DirectoryIndex index.php index.html
@@ -28,7 +28,7 @@
         Allow From All
     </DirectoryMatch>
 
-    <Directory /usr/share/nagios3/htdocs>
+    <Directory /usr/share/nagios4/htdocs>
         Options +ExecCGI
     </Directory>
 
@@ -36,5 +36,5 @@
     # See http://apan.sourceforge.net/download.html for more info
     # It allows you to see a clickable list of all hostgroups in the
     # left pane of the Nagios web interface
-    ScriptAlias /nagios3/side.html /usr/lib/cgi-bin/nagios3/grouplist.cgi
+    ScriptAlias /nagios4/side.html /usr/lib/cgi-bin/nagios4/grouplist.cgi
 </VirtualHost>
diff --git a/templates/zerver/integrations/nagios.md b/templates/zerver/integrations/nagios.md
index 1c184a2349..50673fa31d 100644
--- a/templates/zerver/integrations/nagios.md
+++ b/templates/zerver/integrations/nagios.md
@@ -7,7 +7,7 @@
 
 1.  Next, open `integrations/nagios/zuliprc.example` in your favorite
     editor, and change the following lines to specify the email address
-    and API key for your Nagios bot, saving it to `/etc/nagios3/zuliprc`
+    and API key for your Nagios bot, saving it to `/etc/nagios4/zuliprc`
     on your Nagios server:
 
     ```
@@ -17,12 +17,12 @@
     site = {{ api_url }}
     ```
 
-1.  Copy `integrations/nagios/zulip_nagios.cfg` to `/etc/nagios3/conf.d`
+1.  Copy `integrations/nagios/zulip_nagios.cfg` to `/etc/nagios4/conf.d`
     on your Nagios server.
 
 1.  Finally, add `zulip` to the `members` list for one or more of the
     contact groups in the `CONTACT GROUPS` section of
-    `/etc/nagios3/conf.d/contacts.cfg`, doing something like:
+    `/etc/nagios4/conf.d/contacts.cfg`, doing something like:
 
     ```
     define contactgroup {
@@ -33,11 +33,11 @@
     ```
 
 1.  Once you’ve done that, reload your Nagios configuration using
-    `/etc/init.d/nagios3 reload`.
+    `/etc/init.d/nagios4 reload`.
 
 1.  When your Nagios system makes an alert, you’ll see a message like the
     following, to the stream `nagios` (to change this, edit the arguments
-    to `nagios-notify-zulip` in `/etc/nagios3/conf.d/zulip_nagios.cfg`)
+    to `nagios-notify-zulip` in `/etc/nagios4/conf.d/zulip_nagios.cfg`)
     with a topic indicating the service with an issue.
 
 {!congrats.md!}
@@ -58,7 +58,7 @@ on your Nagios instance.
 
 You can confirm whether you’ve correctly configured Nagios to run the
 Zulip plugin by looking for `SERVICE NOTIFICATION` lines mentioning
-zulip in `/var/log/nagios3/nagios.log`. You can confirm whether you’ve
+zulip in `/var/log/nagios4/nagios.log`. You can confirm whether you’ve
 configured the Zulip plugin code correctly by running
 `/usr/local/share/zulip/integrations/nagios/nagios-notify-zulip`
 directly.