health configuration reference - hilbix/netdata GitHub Wiki

Stock netdata health configuration is in /usr/lib/netdata/conf.d/health.d. These files can be overwritten by copying them and editing them in /etc/netdata/health.d (run /etc/netdata/edit-config to edit them).

In /etc/netdata/health.d you can also put any number of files (in any number of sub-directories) with a suffix .conf to have them processed by netdata.

Health configuration can be reloaded at any time, without restarting netdata. Just send netdata the SIGUSR2 signal, like this:

killall -USR2 netdata

Reloading health configuration will re-do the actions of the alarms (i.e. will re-send emails for warning and critical alarms).

There are 2 entities:

1. alarms, which are attached to specific charts, and

2. templates, which define rules that should be applied to all charts having a specific context. You can use this feature to apply alarms to all disks, all network interfaces, all mysql databases, all nginx web servers, etc.

Both of these entities have exactly the same format and feature set. The only difference is the label alarm or template.

netdata supports overriding templates with alarms. For example, when a template is defined for a set of charts, an alarm with exactly the same name attached to the same chart the template matches, will have higher precedence (i.e. netdata will use the alarm on this chart and prevent the template from being applied to it).

The following lines are parsed.

This line starts an alarm or alarm template.

alarm: NAME

or

template: NAME

This line has to be first on each alarm or template. NAME is anything you would like to name it (the only symbols allowed are . and _).

This line defines the data the alarm should be attached to.

For alarms:

on: CHART

For CHART you can use a chart id or name of the chart, as shown on the dashboard.

For alarm templates:

on: CONTEXT

CONTEXT is the template of a chart. For example the charts mysql_local.net and mysql_server2.net have the same context: mysql.net. So, you can use this to apply alarms to all mysql.net charts.

To find the CONTEXT of a chart download the latest netdata.conf, find the chart you are interested and you will see its context in its configuration section. You can also find it if you fetch http://your.netdata:19999/api/v1/charts (again search for the chart and you will find its context).

This alarm or template will be used only if the O/S of the host loading it, matches this pattern list. The value is a space separated list of simple patterns (use * as wildcard, prefix with ! for a negative match, order is important).

os: linux freebsd macos

This alarm or template will be used only if the hostname of the host loading it, matches this pattern list. The value is a space separated list of simple patterns (use * as wildcard, prefix with ! for a negative match, order is important).

hosts: server1 server2 database* !redis3 redis*

The above says: use this alarm on all hosts named server1, server2, database*, and all redis* except redis3.

This line is only used in alarm templates. It filters the charts. So, if you need to create an alarm template for a few of a kind of chart (a few of your disks, or a few of your network interfaces, or a few your mysql servers, etc), you can create an alarm template that would normally be applied to all of them, and filter them by family.

The format is:

families: SIMPLE PATTERN LIST

Simple patterns list is a lists of space separated patterns. Use * as wildcard and ! for a negative match. Processing is left to right, and on the first hit (positive or negative), processing stops.

So. families: * means, match anything, while families: !bad*pattern* * means anything except bad*pattern* (where * is a wildcard to match any sequence of characters).

This lines makes a database lookup to find a value. This value is the available as $this.

The format is:

lookup: METHOD AFTER [at BEFORE] [every DURATION] [OPTIONS] [of DIMENSIONS]

Everything is the same with badges. In short:

• METHOD is one of average, min, max, sum, incremental-sum. This is required.

• AFTER is a relative number of seconds, but it also accepts a single letter for changing the units, like -1s = 1 second in the past, -1m = 1 minute in the past, -1h = 1 hour in the past, -1d = 1 day in the past. You need a negative number (i.e. how far in the past to look for the value). This is required.

• at BEFORE is by default 0 and is not required. Using this you can define the end of the lookup. So data will be evaluated between AFTER and BEFORE.

• every DURATION sets the updated frequency of the lookup (supports single letter units as above too).

• OPTIONS is a space separated list of percentage, absolute, min2max, unaligned, match-ids, match-names. Check the badges documentation for more info.

• of DIMENSIONS is optional and has to be the last parameter. Dimensions have to be separated by , or |. The space characters found in dimensions will be kept as-is (a few dimensions have spaces in their names). This accepts netdata simple patterns and the match-ids and match-names options affect the searches for dimensions.

  The result of the lookup will be available as $this and $NAME in expressions. The timestamps of the timeframe evaluated by the database lookup is available as variables $after and $before (both are unix timestamps).

This expression is evaluated just after the lookup (if any). Its purpose is to apply some calculation before using the value looked up from the db.

You can also have an expression without a lookup, using other variables that are available.

The result of the calculation will be available as $this in warning and critical expressions (overwriting the lookup one).

Format:

calc: EXPRESSION

Check Expressions below for more information.

Sets the update frequency of this alarm. This is the same to the every DURATION given in the lookup lines.

Format:

every: DURATION

DURATION accepts s for seconds, m is minutes, h for hours, d for days.

Set the green and red thresholds of a chart. Both are available as $green and $red in expressions. If multiple alarms define different thresholds, the ones defined by the first alarm will be used. These will eventually visualized on the dashboard, so only one set of them is allowed. If you need multiple sets of them in different alarms, use absolute numbers instead of $red and $green.

Format:

green: NUMBER
red: NUMBER

These expressions should evaluate to true or false (alternatively non-zero or zero). They trigger the alarm. Both are optional.

Format:

warn: EXPRESSION
crit: EXPRESSION

Check Expressions below for more information.

This will be the first parameter of the script to be executed when the alarm switches status. Its meaning is left up to the exec script.

The default exec script, alarm-notify.sh, uses this field as a space separated list of roles, which are then consulted to find the exact recipients per notification method.

Format:

to: ROLE1 ROLE2 ROLE3 ...

The script that will be executed when the alarm changes status.

Format:

exec: SCRIPT

The default SCRIPT is netdata's alarm-notify.sh, which supports all the notifications methods netdata supports, including custom hooks.

This is used to provide optional hysteresis settings for the notifications, to defend against notification floods. These settings do not affect the actual alarm - only the time the exec script is executed.

Format:

delay: [[[up U] [down D] multiplier M] max X]

• up U defines the delay to be applied to a notification for an alarm that raised its status (i.e. CLEAR to WARNING, CLEAR to CRITICAL, WARNING to CRITICAL). For example, up 10s, the notification for this event will be sent 10 seconds after the actual event. This is used in hope the alarm will get back to its previous state within the duration given. The default U is zero.

• down D defines the delay to be applied to a notification for an alarm that moves to lower state (i.e. CRITICAL to WARNING, CRITICAL to CLEAR, WARNING to CLEAR). For example, down 1m will delay the notification by 1 minute. This is used to prevent notifications for flapping alarms. The default D is zero.

• mutliplier M multiplies U and D when an alarm changes state, while a notification is delayed. The default multiplier is 1.0.

• max X defines the maximum absolute notification delay an alarm may get. The default X is max(U * M, D * M) (i.e. the max duration of U or D multiplied once with M).

  Example:

  delay: up 10s down 15m multiplier 2 max 1h

  The time is 00:00:00 and the status of the alarm is CLEAR.

  time of event	new status	delay	notification will be sent	why
  00:00:01	WARNING	up 10s	00:00:11	first state switch
  00:00:05	CLEAR	down 15m x2	00:30:05	the alarm changes state while a notification is delayed, so it was multiplied
  00:00:06	WARNING	up 10s x2 x2	00:00:26	multiplied twice
  00:00:07	CLEAR	down 15m x2 x2 x2	00:45:07	multiplied 3 times.

  So:

  • U and D are multiplied by M every time the alarm changes state (any state, not just their matching one) and a delay is in place.
  • All are reset to their defaults when the alarm switches state without a delay in place.

netdata has an internal infix expression parser. This parses expressions and creates an internal structure that allows fast execution of them.

These operators are supported +, -, *, /, <, <=, <>, !=, >, >=, &&, ||, !, AND, OR, NOT. Boolean operators result in either 1 (true) or 0 (false).

The conditional evaluation operator ? is supported too. Using this operator IF-THEN-ELSE conditional statements can be specified. The format is: (condition) ? (true expression) : (false expression). So, netdata will first evaluate the condition and based on the result will either evaluate true expression or false expression. Example: ($this > 0) ? ($avail * 2) : ($used / 2). Nested such expressions are also supported (i.e. true expression and false expression can contain conditional evaluations).

Expressions also support the abs() function.

Expressions can have variables. Variables start with $. Check below for more information.

There are two special values you can use:

• nan, for example $this != nan will check if the variable this is available. A variable can be nan if the database lookup failed. All calculations (i.e. addition, multiplication, etc) with a nan result in a nan. netdata will log an error if any calc, warn or crit expressions result in nan.

• inf, for example $this != inf will check if this is not infinite. A value or variable can be infinite if divided by zero. All calculations (i.e. addition, multiplication, etc) with a inf result in a inf. netdata will log an error if any calc, warn or crit expressions result in inf.

A common (but not necessarily obvious) use of the conditional evaluation operator is to provide hysteresis around the critical or warning thresholds. This usage helps to avoid bogus messages resulting from small variations in the value when it is varying regularly but staying close to the threshold value, without needing to delay sending messages at all.

An example of such usage from the default CPU usage alarms bundled with netdata is:

warn: $this > (($status >= $WARNING)  ? (75) : (85))
crit: $this > (($status == $CRITICAL) ? (85) : (95))

Translated to simple English, this becomes:

• If the alarm is currently a warning, then the threshold for being considered a warning is 75, otherwise it's 85.
• If the alarm is currently critical, then the threshold for being considered critical is 85, otherwise it's 95.

Which in turn, results in the following behavior:

• While the value is rising, it will trigger a warning when it exceeds 85, and a critical alert when it exceeds 95.
• While the value is falling, it will return to a warning state when it goes below 85, and a normal state when it goes below 75.
• If the value is constantly varying between 80 and 90, then it will trigger a warning the first time it goes above 85, but will remain a warning until it goes below 75 (or goes above 85).
• If the value is constantly varying between 90 and 100, then it will trigger a critical alert the first time it goes above 95, but will remain a critical alert goes below 85 (at which point it will return to being a warning).

netdata supports 3 new internal indexes for variables that will be used in health monitoring:

• chart local variables. All the dimensions of the chart are exposed as local variables. All chart alarms are exposed too.

charts define a few special variables:

• last_collected_t is the unix timestamp of the last data collection
• collected_total_raw is the sum of all the dimensions (their last collected values)
• update_every is the update frequency of the chart
• green and red the threshold defined in alarms (these are per chart - the charts inherits them from the the first alarm that defined them)

dimensions define their last calculated (i.e. interpolated) value, exactly as shown on the charts, but also a variable with their name and suffix _raw that resolves to the last collected value - as collected and another with suffix _last_collected_t that resolves to unix timestamp the dimension was last collected (there may be dimensions that fail to be collected while others continue normaly).

• family variables. Families are used to group charts together. For example all eth0 charts, have family = eth0. This index includes all local variables, but if there are overlaping variables, only the first are exposed.

• host variables. All the dimensions of all charts, including all alarms, in fullname. Fullname is CHART.VARIABLE, where CHART is either the chart id or the chart name (both are supported).

There are also a few special variables:

• this, which is resolved to the value of the current alarm.
• status, which is resolved to the current status of the alarm (the current = the last status, i.e. before the current database lookup and the evaluation of the calc line). This values can be compared with $REMOVED, $UNINITIALIZED, $UNDEFINED, $CLEAR, $WARNING, $CRITICAL. These values are incremental, ie. $status > $CLEAL works as expected.
• now, which is resolved to current unix timestamp.

You can find all the variables that can be used for a given chart, using http://your.netdata.ip:19999/api/v1/alarm_variables?chart=NAME. This will dump all the indexes from the chart's perspective. Example: variables for the system.cpu chart of the registry.

The exec line in health configuration defines an external script that will be called once the alarm is triggered. The default script is alarm-notify.sh. You can change the default script by editing /etc/netdata/netdata.conf (if you installation is old, you may need to download a fresh copy of it from netdata using the url http://your.netdata:19999/netdata.conf).

alarm-notify.sh is capable of:

1. sending emails
2. sending pushover.net notifications (push notification to your mobile)
3. sending pushbullet.com notifications (push notifications to all devices linked within pushbullet account)
4. sending messages to slack.com channels
5. sending messages to Discord channels

It uses roles. For example sysadmin, webmaster, dba, etc.

Each alarm is assigned to one or more roles, using the to line of the alarm configuration. Then alarm-notify.sh uses its own configuration file /etc/netdata/health_alarm_notify.conf the default is here (to edit it on your system run /etc/netdata/edit-config health_alarm_notify.conf) to find the destination address of the notification for each method. Each role may have one or more destinations.

So, for example the sysadmin role may send:

1. emails to [email protected] and [email protected]
2. pushover.net notifications to USERTOKENS A, B and C.
3. pushbullet.com push notifications to [email protected] and [email protected]
4. messages to slack.com channel #alarms and #systems.
5. messages to Discord channels #alarms and #systems.

Alarms can have the following statuses:

• REMOVED - the alarm has been deleted (this happens when a SIGUSR2 is sent to netdata to reload health configuration)
• UNINITIALIZED - the alarm is not initialized yet
• UNDEFINED - the alarm failed to be calculated (i.e. the database lookup failed, a division by zero occurred, etc)
• CLEAR - the alarm is not armed / raised (i.e. is OK)
• WARNING - the warning expression resulted in true or non-zero
• CRITICAL - the critical expression resulted in true or non-zero

The external script will be called for all status changes.