Terraform module for Datadog System

This module is responsible for System level alerts. CPU, network, memory, disk, etc... Process performance monitoring (cpu, memory) is not covered in this module. It is possible though to check if specific processes are running.

This module is part of a larger suite of modules that provide alerts in Datadog. Other modules can be found on the Terraform Registry

We have two base modules we use to standardise development of our Monitor Modules:

• generic monitor Used in 90% of our alerts
• service check monitor

Modules are generated with this tool: https://github.com/kabisa/datadog-terraform-generator

Example Usage

module "system" {
  source = "kabisa/system/datadog"

  notification_channel       = "mail@example.com"
  service                    = "ServiceX"
  env                        = "prd"
  filter_str                 = "host:myserver"
  service_check_include_tags = ["host:myserver"]
}

Module Variables

Monitors:

Monitor name	Default enabled	Priority	Query
Bytes Received	False	3	avg(last_30m):avg:system.net.bytes_rcvd{tag:xxx} by {${var.alert_by}} > 5000000
Bytes Sent	False	3	avg(last_30m):avg:system.net.bytes_sent{tag:xxx} by {${var.alert_by}} > 5000000
CPU Stolen	True	3	avg(last_15m):avg:system.cpu.stolen{tag:xxx} by {${var.alert_by}} > 10
CPU	True	2	avg(last_30m):avg:system.cpu.user{tag:xxx} by {${var.alert_by}} + avg:system.cpu.system{tag:xxx} by {${var.alert_by}} > 95
Datadog Agent	True	2	avg(${var.dd_agent_evaluation_period}):avg:datadog.agent.running{${local.dd_agent_filter}} by {${var.alert_by}} < 1
Disk Free Bytes	False	2	avg(last_5m):min:system.disk.free{tag:xxx} by {host,device} < 10000000000
Disk Free Percent	True	2	avg(last_5m):100 * min:system.disk.free{tag:xxx} by {host,device} / min:system.disk.total{tag:xxx} by {host,device} < 10
Disk In Use Percentage	False	2	avg(last_5m):min:system.disk.in_use{tag:xxx} by {${var.alert_by}} * 100 > 90
Disk Iowait	True	3	avg(${var.disk_io_wait_evaluation_period}):avg:system.cpu.iowait{${local.disk_io_wait_filter}} by {${var.alert_by}} > ${var.disk_io_wait_critical}
Memory Free Bytes	False	2	avg(last_5m):min:system.mem.usable{tag:xxx} by {${var.alert_by}} < 1000000000
Memory Free Percent	True	2	avg(last_5m):min:system.mem.pct_usable{tag:xxx} by {${var.alert_by}} * 100 < 10
Memory Usable Percent	False	2	avg(last_5m):100 * min:system.mem.usable{tag:xxx} by {${var.alert_by}} / min:system.mem.total{tag:xxx} by {${var.alert_by}} < 10
Packets In Errors	True	3	avg(last_15m):100 * max:system.net.packets_in.error{tag:xxx} by {${var.alert_by}} / ( max:system.net.packets_in.count{tag:xxx} by {${var.alert_by}} + 1000 ) > 1
Packets Out Errors	True	3	avg(last_15m):100 * max:system.net.packets_out.error{tag:xxx} by {${var.alert_by}} / ( max:system.net.packets_out.count{tag:xxx} by {${var.alert_by}} + 1000 ) > 1
Reboot	True	3	min(last_5m):derivative(max:system.uptime{tag:xxx} by {${var.alert_by}}) < 0
Required Services	True	2	processes('${each.key}').over('tag:xxx').by('host').rollup('count').last('${lookup(each.value, "freshness_duration", var.required_services_default_freshness_duration)}') < ${lookup(each.value, "process_count", 1)}
Swap	True	3	avg(${var.swap_percent_free_evaluation_period}):min:system.swap.pct_free{${local.swap_percent_free_filter}} by {${var.alert_by}} * 100 < ${var.swap_percent_free_critical}

Getting started developing

pre-commit was used to do Terraform linting and validating.

Steps:

• Install pre-commit. E.g. brew install pre-commit.
• Run pre-commit install in this repo. (Every time you clone a repo with pre-commit enabled you will need to run the pre-commit install command)
• That’s it! Now every time you commit a code change (.tf file), the hooks in the hooks: config .pre-commit-config.yaml will execute.

Bytes Received

Query:

avg(last_30m):avg:system.net.bytes_rcvd{tag:xxx} by {${var.alert_by}} > 5000000

variable	default	required	description
bytes_received_enabled	False	No
bytes_received_warning	4000000	No
bytes_received_critical	5000000	No
bytes_received_evaluation_period	last_30m	No
bytes_received_note	""	No
bytes_received_docs	""	No
bytes_received_filter_override	""	No
bytes_received_alerting_enabled	True	No
bytes_received_priority	3	No	Number from 1 (high) to 5 (low).
bytes_received_notification_channel_override	""	No

Bytes Sent

Query:

avg(last_30m):avg:system.net.bytes_sent{tag:xxx} by {${var.alert_by}} > 5000000

variable	default	required	description
bytes_sent_enabled	False	No
bytes_sent_warning	4000000	No
bytes_sent_critical	5000000	No
bytes_sent_evaluation_period	last_30m	No
bytes_sent_note	""	No
bytes_sent_docs	""	No
bytes_sent_filter_override	""	No
bytes_sent_alerting_enabled	True	No
bytes_sent_priority	3	No	Number from 1 (high) to 5 (low).
bytes_sent_notification_channel_override	""	No

CPU Stolen

Query:

avg(last_15m):avg:system.cpu.stolen{tag:xxx} by {${var.alert_by}} > 10

variable	default	required	description
cpu_stolen_enabled	True	No
cpu_stolen_warning	5	No
cpu_stolen_critical	10	No
cpu_stolen_evaluation_period	last_15m	No
cpu_stolen_note	""	No
cpu_stolen_docs	""	No
cpu_stolen_filter_override	""	No
cpu_stolen_alerting_enabled	True	No
cpu_stolen_priority	3	No	Number from 1 (high) to 5 (low).
cpu_stolen_notification_channel_override	""	No

CPU

Query:

avg(last_30m):avg:system.cpu.user{tag:xxx} by {${var.alert_by}} + avg:system.cpu.system{tag:xxx} by {${var.alert_by}} > 95

variable	default	required	description
cpu_enabled	True	No
cpu_warning	80	No
cpu_critical	95	No
cpu_evaluation_period	last_30m	No
cpu_note	""	No
cpu_docs	""	No
cpu_filter_override	""	No
cpu_alerting_enabled	True	No
cpu_priority	2	No	Number from 1 (high) to 5 (low).
cpu_notification_channel_override	""	No

Datadog Agent Data

Not getting monitoring data could mean anything, best is to assume the host is down and consider this a major event

variable	default	required	description
dd_agent_data_enabled	True	No
dd_agent_data_note	""	No
dd_agent_data_docs	Not getting monitoring data could mean anything, best is to assume the host is down and consider this a major event	No
dd_agent_data_include_tags_override	None	No
dd_agent_data_exclude_tags_override	None	No
dd_agent_data_alerting_enabled	True	No
dd_agent_data_priority	2	No	Number from 1 (high) to 5 (low).
dd_agent_data_notification_channel_override	""	No

Datadog Agent

Not getting monitoring data could mean anything, best is to assume the host is down and consider this a major event

Query:

avg(${var.dd_agent_evaluation_period}):avg:datadog.agent.running{${local.dd_agent_filter}} by {${var.alert_by}} < 1

variable	default	required	description
dd_agent_enabled	True	No
dd_agent_evaluation_period	last_15m	No
dd_agent_note	""	No
dd_agent_docs	Not getting monitoring data could mean anything, best is to assume the host is down and consider this a major event	No
dd_agent_filter_override	""	No
dd_agent_alerting_enabled	True	No
dd_agent_priority	2	No	Number from 1 (high) to 5 (low).
dd_agent_notification_channel_override	""	No

Disk Free Bytes

Query:

avg(last_5m):min:system.disk.free{tag:xxx} by {host,device} < 10000000000

variable	default	required	description
disk_free_bytes_enabled	False	No
disk_free_bytes_warning	20000000000	No
disk_free_bytes_critical	10000000000	No
disk_free_bytes_evaluation_period	last_5m	No
disk_free_bytes_note	""	No
disk_free_bytes_docs	""	No
disk_free_bytes_filter_override	""	No
disk_free_bytes_alerting_enabled	True	No
disk_free_bytes_priority	2	No	Number from 1 (high) to 5 (low).
disk_free_bytes_notification_channel_override	""	No

Disk Free Percent

Query:

avg(last_5m):100 * min:system.disk.free{tag:xxx} by {host,device} / min:system.disk.total{tag:xxx} by {host,device} < 10

variable	default	required	description
disk_free_percent_enabled	True	No
disk_free_percent_warning	20	No
disk_free_percent_critical	10	No
disk_free_percent_evaluation_period	last_5m	No
disk_free_percent_note	""	No
disk_free_percent_docs	""	No
disk_free_percent_filter_override	""	No
disk_free_percent_alerting_enabled	True	No
disk_free_percent_priority	2	No	Number from 1 (high) to 5 (low).
disk_free_percent_notification_channel_override	""	No

Disk In Use Percentage

Default disabled, only use when disk_free_percent is not giving results

Query:

avg(last_5m):min:system.disk.in_use{tag:xxx} by {${var.alert_by}} * 100 > 90

variable	default	required	description
disk_in_use_percentage_enabled	False	No
disk_in_use_percentage_warning	80	No
disk_in_use_percentage_critical	90	No
disk_in_use_percentage_evaluation_period	last_5m	No
disk_in_use_percentage_note	system.disk.in_use is actually a fraction, we've multiplied it by 100 to make it a percentage	No
disk_in_use_percentage_docs	Default disabled, only use when disk_free_percent is not giving results	No
disk_in_use_percentage_filter_override	""	No
disk_in_use_percentage_alerting_enabled	True	No
disk_in_use_percentage_priority	2	No	Number from 1 (high) to 5 (low).
disk_in_use_percentage_notification_channel_override	""	No

Disk Iowait

The CPU is mainly waiting for data to be written on disk. This means in general that application running on this machine is stalled

Query:

avg(${var.disk_io_wait_evaluation_period}):avg:system.cpu.iowait{${local.disk_io_wait_filter}} by {${var.alert_by}} > ${var.disk_io_wait_critical}

variable	default	required	description
disk_io_wait_enabled	True	No
disk_io_wait_warning	80	No
disk_io_wait_critical	95	No
disk_io_wait_evaluation_period	last_30m	No
disk_io_wait_note	""	No
disk_io_wait_docs	The CPU is mainly waiting for data to be written on disk. This means in general that application running on this machine is stalled	No
disk_io_wait_filter_override	""	No
disk_io_wait_alerting_enabled	True	No
disk_io_wait_priority	3	No	Number from 1 (high) to 5 (low).
disk_io_wait_notification_channel_override	""	No

Memory Free Bytes

Query:

avg(last_5m):min:system.mem.usable{tag:xxx} by {${var.alert_by}} < 1000000000

variable	default	required	description
memory_free_bytes_enabled	False	No	Memory free based on absolute values. Disabled by default to use memory_free_percent
memory_free_bytes_warning	2000000000	No
memory_free_bytes_critical	1000000000	No
memory_free_bytes_evaluation_period	last_5m	No
memory_free_bytes_note	""	No
memory_free_bytes_docs	""	No
memory_free_bytes_filter_override	""	No
memory_free_bytes_alerting_enabled	True	No
memory_free_bytes_priority	2	No	Number from 1 (high) to 5 (low).
memory_free_bytes_notification_channel_override	""	No

Memory Free Percent

Query:

avg(last_5m):min:system.mem.pct_usable{tag:xxx} by {${var.alert_by}} * 100 < 10

variable	default	required	description
memory_free_percent_enabled	True	No
memory_free_percent_warning	20	No
memory_free_percent_critical	10	No
memory_free_percent_evaluation_period	last_5m	No
memory_free_percent_note	""	No
memory_free_percent_docs	""	No
memory_free_percent_filter_override	""	No
memory_free_percent_alerting_enabled	True	No
memory_free_percent_priority	2	No	Number from 1 (high) to 5 (low).
memory_free_percent_notification_channel_override	""	No

Memory Usable Percent

This looks at system.mem.usable, only use this when memory_free_percent doesn't have data

Query:

avg(last_5m):100 * min:system.mem.usable{tag:xxx} by {${var.alert_by}} / min:system.mem.total{tag:xxx} by {${var.alert_by}} < 10

variable	default	required	description
memory_usable_percent_enabled	False	No
memory_usable_percent_warning	20	No
memory_usable_percent_critical	10	No
memory_usable_percent_evaluation_period	last_5m	No
memory_usable_percent_note	""	No
memory_usable_percent_docs	This looks at system.mem.usable, only use this when memory_free_percent doesn't have data	No
memory_usable_percent_filter_override	""	No
memory_usable_percent_alerting_enabled	True	No
memory_usable_percent_priority	2	No	Number from 1 (high) to 5 (low).
memory_usable_percent_notification_channel_override	""	No

Ntp Check

variable	default	required	description
ntp_check_enabled	True	No
ntp_check_alerting_enabled	True	No

Packets In Errors

Packet errors can severely degrade network performance. A good article about it is found here: https://netcraftsmen.com/understanding-interface-errors-and-tcp-performance/

Query:

avg(last_15m):100 * max:system.net.packets_in.error{tag:xxx} by {${var.alert_by}} / ( max:system.net.packets_in.count{tag:xxx} by {${var.alert_by}} + 1000 ) > 1

variable	default	required	description
packets_in_errors_enabled	True	No
packets_in_errors_warning	0.5	No
packets_in_errors_critical	1	No
packets_in_errors_evaluation_period	last_15m	No
packets_in_errors_note	""	No
packets_in_errors_docs	Packet errors can severely degrade network performance. A good article about it is found here: https://netcraftsmen.com/understanding-interface-errors-and-tcp-performance/	No
packets_in_errors_filter_override	""	No
packets_in_errors_alerting_enabled	True	No
packets_in_errors_priority	3	No	Number from 1 (high) to 5 (low).
packets_in_errors_notification_channel_override	""	No

Packets Out Errors

Packet errors can severely degrade network performance. A good article about it is found here: https://netcraftsmen.com/understanding-interface-errors-and-tcp-performance/

Query:

avg(last_15m):100 * max:system.net.packets_out.error{tag:xxx} by {${var.alert_by}} / ( max:system.net.packets_out.count{tag:xxx} by {${var.alert_by}} + 1000 ) > 1

variable	default	required	description
packets_out_errors_enabled	True	No
packets_out_errors_warning	0.5	No
packets_out_errors_critical	1	No
packets_out_errors_evaluation_period	last_15m	No
packets_out_errors_note	""	No
packets_out_errors_docs	Packet errors can severely degrade network performance. A good article about it is found here: https://netcraftsmen.com/understanding-interface-errors-and-tcp-performance/	No
packets_out_errors_filter_override	""	No
packets_out_errors_alerting_enabled	True	No
packets_out_errors_priority	3	No	Number from 1 (high) to 5 (low).
packets_out_errors_notification_channel_override	""	No

Reboot

Query:

min(last_5m):derivative(max:system.uptime{tag:xxx} by {${var.alert_by}}) < 0

variable	default	required	description
reboot_enabled	True	No
reboot_note	""	No
reboot_docs	""	No
reboot_filter_override	""	No
reboot_alerting_enabled	True	No
reboot_priority	3	No	Number from 1 (high) to 5 (low).
reboot_notification_channel_override	""	No

Required Services

Query:

processes('${each.key}').over('tag:xxx').by('host').rollup('count').last('${lookup(each.value, "freshness_duration", var.required_services_default_freshness_duration)}') < ${lookup(each.value, "process_count", 1)}

variable	default	required	description
required_services_enabled	True	No
required_services_config	{}	No
required_services_default_freshness_duration	5m	No
required_services_default_note	""	No
required_services_default_docs	""	No
required_services_filter_override	""	No
required_services_alerting_enabled	True	No
required_services_default_priority	2	No	Number from 1 (high) to 5 (low).
required_services_notification_channel_override	""	No

Swap

Query:

avg(${var.swap_percent_free_evaluation_period}):min:system.swap.pct_free{${local.swap_percent_free_filter}} by {${var.alert_by}} * 100 < ${var.swap_percent_free_critical}

variable	default	required	description
swap_percent_free_enabled	True	No
swap_percent_free_warning	15	No
swap_percent_free_critical	10	No
swap_percent_free_evaluation_period	last_5m	No
swap_percent_free_note	""	No
swap_percent_free_docs	""	No
swap_percent_free_filter_override	""	No
swap_percent_free_alerting_enabled	True	No
swap_percent_free_priority	3	No	Number from 1 (high) to 5 (low).
swap_percent_free_notification_channel_override	""	No

Module Variables

variable	default	required	description
env		Yes
filter_str		Yes
service		Yes	Service name of what you're monitoring. This also sets the service: tag on the monitor
service_display_name	None	No
notification_channel		Yes	Channel to which datadog sends alerts, will be overridden by alerting_enabled if that's set to false
additional_tags	[]	No	Additional tags to set on the monitor. Good tagging can be hard but very useful to make cross sections of the environment. Datadog has a few default tags. https://docs.datadoghq.com/getting_started/tagging/ is a good place to start reading about tags
name_prefix	""	No	Can be used to prefix to the Monitor name
name_suffix	""	No	Can be used to suffix to the Monitor name
restricted_roles	[]	No	A list of unique role identifiers to define which roles are allowed to edit the monitor
service_check_include_tags	None	No	List of tags for the "over" part of the query. Can be either key:value tags or boolean tags.
service_check_exclude_tags	None	No	List of tags for the "exclude" part of the query. Can be either key:value tags or boolean tags.
priority_offset	0	No	For non production workloads we can +1 on the priorities
alert_by	host	No	This determines if you want an alert for each value of a tag, ex: by {host} -> generates an alert per host