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The main role of this feature is to allow users to have in one "indicator" the aggregation of other states. This indicator can provide a unique view for users playing focused on different roles.
Typical roles:
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Let's take a simple example of a service delivery role for an ERP application. It mainly consists in of the following IT components:
- 2 databases, in high availability, so with one database active, the service is considered to be up
- 2 web servers, in load sharing, so with one web server active, the service is considered to be up
- 2 load balancers, again in high availability
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With business rules, you can have an "indicator" representing the "aggregated service" state for the ERP service! Shinken Enterprise already checks all of the IT components one by one including processing for root cause analysis from a host and service perspective.
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The X of: expression may be configured with different values depending on the needs. The supported expressions are described below:
- A positive integer, which means "at least X host should be up"
- A positive percentage, which means "at least X percents of hosts should be up". This percentage expression may be combined with Groupping expression expansion to build expressions such as "95 percents of the web front ends shoud be up". This way, adding hosts in the web frontend hostgroup is sufficient, and the QoS remains the same.
- A negative integer, which means "at most X host may be down"
- A negative percentage, which means "at most X percents of hosts should may be down". This percentage expression may be combined with Groupping expression expansion to build expressions such as "5 percents of the web front ends may be down". This way, adding hosts in the web frontend hostgroup is sufficient, and the QoS remains the same.
Example:
| Code Block |
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(srv-oracle-1 | srv-oracle-2) & (srv-loadbalancer-1 | srv-loadbalancer-2) & 95% of: g:frontend |
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The NOT rule
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You can define a not state rule. It can be useful for active/passive setups for example. You just need to add a ! before your element name.
Example:
::
define service{
use generic-service
host_name servicedelivery
service_description Cluster_state
check_command bp_rule!(h1,database1 & !h2,database2)
}
| Code Block |
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(srv-oracle-1 & !srv-oracle-2) |
Aggregated state will be ok if database1 is ok and database2 is warning or critical (stopped).
Manage degraded status
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For this you can use the extended operator *X,Y,Zof:*
X: number min of OK to get an overall OK state
Y: number min of WARNING to get an overall WARNING state
Z: number min of CRITICAL to get an overall CRITICAL state
State processing will be done the following order:
is Ok possible?
is critical possible?
is warning possible?
if none is possible, set OK.
Here are some example for business rules about 5 services A, B, C, D and E. Like 5,1,1of:A|B|C|D|E
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===== ===== ===== ===== =====
**A***B***C***D***E**
Warn Ok Ok Ok Ok
===== ===== ===== ===== =====
Rules and overall states:
4of: --> Ok
5,1,1of: --> Warning
5,2,1of: --> Ok
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===== ===== ===== ===== =====
**A***B***C***D***E**
Warn Warn Ok Ok Ok
===== ===== ===== ===== =====
Rules and overall states:
4of: --> Warning
3of: --> Ok
4,1,1of: --> Warning
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===== ===== ===== ===== =====
**A***B***C***D***E**
Crit Crit Ok Ok Ok
===== ===== ===== ===== =====
Rules and overall states:
4of: --> Critical
3of: --> Ok
4,1,1of: --> Critical
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===== ===== ===== ===== =====
**A***B***C***D***E**
Warn Crit Ok Ok Ok
===== ===== ===== ===== =====
Rules and overall states:
4of: --> Critical
4,1,1of: --> Critical
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===== ===== ===== ===== =====
**A***B***C***D***E**
Warn Warn Crit Ok Ok
===== ===== ===== ===== =====
Rules and overall states:
2of: --> Ok
4,1,1of: --> Critical
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===== ===== ===== ===== =====
**A***B***C***D***E**
Warn Crit Crit Ok Ok
===== ===== ===== ===== =====
Rules and overall states:
2of: --> Ok
2,4,4of: --> Ok
4,1,1of: --> Critical
4,1,2of: --> Critical
4,1,3of: --> Warning
Classic cases
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Let's look at some classic setups, for MAX elements.
ON/OFF setup: MAXof: <=> MAX,MAX,MAXof:
Warning as soon as problem, and critical if all criticals: MAX,1,MAXof:
Worse state: MAX,1,1
Grouping expression expansion
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UP and database2 DOWN.
Grouping expression expansion
Sometimes, you do not want to specify explicitly the hosts /services contained in a business rule, but prefer using use a grouping expression such as *hosts from the hostgroup xxx*, *services holding lablel yyyor *hosts which name matches regex zzz*.
To do so, it is possible to use a *grouping expression which expressionwhich is expanded into hosts or services. The supported expressions use the following syntax:::
| Code Block |
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flag:expression |
The flag is a single character qualifying the expansion type. The supported types (and associated flags) are described in the table below.
Host flags
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| Flag | Expansion | Example | Equivalent to |
|---|---|---|---|
| g | Content of the hostgroup | g:webs | web-srv1 & web-srv2 & ... |
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| r | Hosts which name matches regex | r:^web | web-srv1 & web-srv2 & ... |
| t | Hosts which are holding |
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| a host template | t:http | web-srv1 & web-srv2 & ... |
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Check flags
| Flag | Expansion | Example | Equivalent to |
|---|---|---|---|
| r | Checks which description matches regex | regex r:^HTTPS? | web-srv1,HTTP & db-srv2,HTTPS & ... |
| t |
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| Checks which are holding |
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| templates | t:http | web-srv1,HTTP & db-srv2,HTTPS & ... |
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**Labels*are arbitrary names which may be set on any host or service using the ``label`` directive.
**Tags*are the template names inherited by hosts or services, generally coming from packs.
It is possible to combine both **host*and **service*expansion expression to build complex business rules.
.. note:: A business rule expression always has to be made by a host expression (selector if you prefer)
AND a service expression (still selector) separated by a coma when looking at service status.
If not so, there is no mean to distinguish a host status from a service status in the expression.
In servicegroup flag case, as you do not want to apply any filter on the host (you want ALL services which are member of the XXX service group, whichever host they are bound to),
you may use the host selector expression. The correct expression syntax should be:
``bp_rule!*,g:my-servicegroup``
The same rule applies to other service selectors (l, r, t, and so on).
Examples of combined expansion expression
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You want to build a business rule including all web servers composing the application frontend.::
| Code Block |
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l:front,r:HTTPS? |
which is equivalent to:
| Code Block |
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web-srv1,HTTP & web-srv3,HTTPS |
You may obviously combine expression expansion with standard expressions.::
| Code Block |
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l:front,h:HTTPS? & db-srv1,MySQL |
which is equivalent to:
| Code Block |
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(web-srv1,HTTP & web-srv3,HTTPS) & db-srv1,MySQL |