Vitrage Templates Format - Version 2¶
Note: Consider using the newer template format version_3
Overview¶
In Vitrage we use configuration files, called templates, to express rules
regarding raising deduced alarms, setting deduced states, and detecting/setting
RCA links.
This page describes the format of the Vitrage templates, with some examples and
open questions on extending this format. Additionally, a short guide on adding
templates is presented.
Note: This document refers to Vitrage templates version 2. The documentation of version 1 can be found here
Template Structure¶
- The template is written in YAML language, with the following structure:
metadata: version: <template version> name: <unique template identifier> type: <one of: standard, definition, equivalence> description: <what this template does> definitions: entities: - entity: ... - entity: ... relationships: - relationship: ... - relationship: ... includes: - name: <name as stated in the metadata of a definition template> - name: ... scenarios: - scenario: condition: <if statement true do the action> actions: - action: ...
The template is divided into four main sections:
metadata: Contains general information about the template.
version - the version of the template format. The default is 1.
name - the name of the template
type - the type of the template. Should be one of: standard, definition, equivalence
description - a brief description of what the template does (optional)
definitions: This section is mandatory unless an include section is specified in the template (see below). This section contains the atomic definitions referenced later on, for entities and relationships.
entities – describes the resources and alarms which are relevant to the template scenario (conceptually, corresponds to a vertex in the entity graph)
relationships – the relationships between the entities (conceptually, corresponds to an edge in the entity graph)
includes: This section is optional. If included, it must contain a list of names of definition templates as they appear in the metadata section of said templates. If only definitions from included definition templates are used to create scenarios within the template, then the definitions section is optional.
scenarios: A list of if-then scenarios to consider. Each scenario is comprised of: - condition – the condition to be met. This condition will be phrased referencing the entities and relationships previously defined. - action(s) – a list of actions to execute when the condition is met.
Definition Template Structure¶
These are separate files, which contain only definitions and can be included under the includes section in regular templates. The definition templates are written in YAML language, with the following structure:
metadata: version: 2 name: <unique definition template identifier. Used in the includes section of regular templates> type: definition description: <what definitions this template contains> definitions: entities: - entity: ... - entity: ... relationships: - relationship: ... - relationship: ...
A definition template is in same format as a regular template - except it does not contain a scenarios or an includes section. Once included in a template, the definition template’s entities and relationships can be used within the template they are included to create scenarios.
Condition Format¶
The condition which needs to be met will be phrased using the entities and relationships previously defined. An expression is either a single entity, or some logical combination of relationships. Expression can be combined using the following logical operators:
“and” - indicates both expressions must be satisfied in order for the condition to be met.
“or” - indicates at least one expression must be satisfied in order for the condition to be met (non-exclusive or).
“not” - indicates that the expression must not be satisfied in order for the condition to be met.
parentheses “()” - clause indicating the scope of an expression.
The following are examples of valid expressions, where X, Y and Z are relationships:
X
X and Y
X and Y and Z
X and not Y
X and not (Y or Z)
X and not X
A few restrictions regarding the condition format:
A condition can not be entirely “negative”, i.e. it must have at least one part that does not have a “not” in front of it.
- For example, instead of:
not alarm_on_instance
- use:
instance and not alarm_on_instance
There must be at least one entity that is common to all “or” clauses.
- For example, this condition is illegal:
alarm1_on_host or alarm2_on_instance
- This condition is legal:
alarm1_on_instance or alarm2_on_instance
For more information, see the ‘Calculate the action_target’ section in External Actions Spec
Template validation status codes¶
Examples¶
Example 1: Basic RCA and Deduced Alarm/State¶
The following template demonstrates
How to raise a deduced alarm. Specifically, if there is high CPU load on a host, raise alarm indicating CPU performance problems on all contained instances.
How to link alarms for purposes of root cause analysis (RCA). Specifically, if there is high CPU load on the host and CPU performance problems on the hosted instances, we link them with a “causes” relationship.
How to use a single template for several different scenarios.
metadata: version: 2 name: host_high_mem_load_to_instance_mem_suboptimal type: standard description: when there is high memory on the host, show implications on the instances definitions: entities: - entity: category: ALARM name: host_high_mem_load template_id: host_alarm # some string - entity: category: ALARM name: instance_mem_performance_problem template_id: instance_alarm - entity: category: RESOURCE type: nova.host template_id: host - entity: category: RESOURCE type: nova.instance template_id: instance relationships: - relationship: source: host_alarm # source and target from entities section target: host relationship_type: on template_id : alarm_on_host - relationship: source: instance_alarm target: instance relationship_type: on template_id : alarm_on_instance - relationship: source: host target: instance relationship_type: contains template_id : host_contains_instance scenarios: - scenario: condition: alarm_on_host and host_contains_instance # condition uses relationship ids actions: - action: action_type: raise_alarm properties: alarm_name: instance_mem_performance_problem severity: warning action_target: target: instance # entity template_id - action: action_type: set_state properties: state: suboptimal action_target: target: instance # entity template_id - scenario: condition: alarm_on_host and alarm_on_instance and host_contains_instance actions: - action: action_type: add_causal_relationship action_target: source: host_alarm target: instance_alarm
Example 2: Deduced state based on alarm¶
The following template will change the state of a resource to “ERROR” if there is any alarm of severity “CRITICAL” on it.
metadata: id: deduced_state_for_all_with_alarm description: deduced state for all resources with alarms definitions: entities: - entity: category: RESOURCE template_id: a_resource # entity ids are any string - entity: category: ALARM severity: critical template_id: high_alarm # entity ids are any string relationships: - relationship: source: high_alarm target: a_resource relationship_type: on template_id : high_alarm_on_resource scenarios: - scenario: condition: high_alarm_on_resource actions: - action: action_type : set_state properties: state: error action_target: target: a_resource
Example 3: Deduced alarm based on state¶
This template will cause an alarm to be raised on any Host in state “ERROR”
Note that in this template, there are no relationships. The condition is just that the entity exists. Also note that the states and severity are case-insensitive.
metadata: version: 2 name: deduced_alarm_for_all_host_in_error type: standard description: raise deduced alarm for all hosts in error definitions: entities: - entity: category: RESOURCE type: nova.host state: error template_id: host_in_error scenarios: - scenario: condition: host_in_error actions: - action: action_type: raise_alarm properties: alarm_name: host_in_error_state severity: critical action_target: target: host_in_error
Example 4: Deduced Alarm triggered by several options¶
This template will raise a deduced alarm on an instance, which can be caused by an alarm on the hosting zone or an alarm on the hosting host.
metadata: version: 2 name: deduced_alarm_two_possible_triggers type: standard description: deduced alarm using or in condition definitions: entities: - entity: category: ALARM name: zone_connectivity_problem template_id: zone_alarm - entity: category: ALARM name: host_connectivity_problem template_id: host_alarm - entity: category: RESOURCE type: nova.zone template_id: zone - entity: category: RESOURCE type: nova.host template_id: host - entity: category: RESOURCE type: nova.instance template_id: instance relationships: - relationship: source: zone_alarm target: zone relationship_type: on template_id : alarm_on_zone - relationship: source: zone_alarm target: zone relationship_type: on template_id : alarm_on_host - relationship: source: zone target: host relationship_type: contains template_id : zone_contains_host - relationship: source: host target: instance relationship_type: contains template_id : host_contains_instance scenarios: - scenario: condition: (alarm_on_host and host_contains_instance) or (alarm_on_zone and zone_contains_host and host_contains_instance) actions: - action: action_type : raise_alarm properties: alarm_name: instance_connectivity_problem severity: critical action_target: target: instance
Usage¶
Adding/removing a template¶
Ensure all the templates you wish to use are placed here: <vitrage folder>/templates.
Restart vitrage-graph.
The template will be validated before loading. Validation errors are written to the log. Templates with validation errors are skipped.
Common properties and their acceptable values - for writing templates¶
block |
key |
supported values |
comments |
|---|---|---|---|
entity |
category |
ALARM RESOURCE |
|
entity (ALARM) |
type |
any string |
|
entity (RESOURCE) |
type |
openstack.cluster, nova.zone, nova.host, nova.instance, cinder.volume, switch |
These are for the datasources that come with vitrage by default. Adding datasources will add more supported types, as defined in the datasource transformer |
action |
action_type |
raise_alarm, set_state, add_causal_relationship, mark_down, execute_mistral |
Using regular expressions in an entity definition¶
All properties within an entity definition can be made to include regular expressions. To do this, simply add “.regex” to their key. For example, as Zabbix supports regular expressions and a Zabbix alarm contains a “rawtext” field which is a regular expression, a Zabbix alarm entity defined in the template may contain a “rawtext.regex” field that is also defined by a regular expression:
- entity:
category: ALARM
type: zabbix
rawtext.regex: Interface ([_a-zA-Z0-9'-]+) down on {HOST.NAME}
template_id: zabbix_alarm
Using parameters¶
On version 2, some properties in the template definition can be defined as parameters and assigned with actual values upon template creation. This allows easy reuse of a similar template structure for different alarm types.
For example, the following two templates can be written using a single template with parameters:
a high CPU load on a host causes high CPU load on the instances
insufficient memory on a host causes insufficient memory on the instances
To use parameters, add a parameters section to the template. This section
defines all parameters that are used in the template. Each parameter can have
two optional properties:
description: explanation on the purpose of the parameterdefault: default value for the parameter
Using a parameter inside the template is done by calling the get_param()
function. For example:
name: get_param(alarm_name)
Note: In order to be able to create multiple templates from the parametrized template, the template name must also be defined as a parameter.
Actual values for the parameters must be given upon template creation, for example:
vitrage template add --path template_with_params.yaml --params template_name='High CPU load on host' alarm_type='High CPU load'
In the example below, vitrage template add should be called with parameters:
template_name
host_alarm_name
instance_alarm_name
instance_alarm_severity (optional)
metadata:
version: 2
name: get_name(template_name)
type: standard
description: host alarm affects its instances
parameters:
template_name:
host_alarm_name:
description: the name of the zabbix alarm that is reported on the host
instance_alarm_name:
description: the name of the vitrage deduced alarm to raise on the instance
instance_alarm_severity:
description: the severity of the vitrage deduced alarm to raise on the instance
default: WARNING
definitions:
entities:
- entity:
category: ALARM
type: zabbix
rawtext: get_param(host_alarm_name)
template_id: host_alarm
- entity:
category: RESOURCE
type: nova.host
template_id: host
- entity:
category: RESOURCE
type: nova.instance
template_id: instance
relationships:
- relationship:
source: host_alarm
target: host
relationship_type: on
template_id : alarm_on_host
- relationship:
source: host
target: instance
relationship_type: contains
template_id : host_contains_instance
scenarios:
- scenario:
condition: alarm_on_host and host_contains_instance
actions:
- action:
action_type : raise_alarm
properties:
alarm_name: get_param(instance_alarm_name)
severity: get_param(instance_alarm_severity)
action_target:
target: instance
Using functions in an action definition¶
Some properties of an action can be defined using functions. On version 2, one function is supported: get_attr, and it is supported only for execute_mistral action.
Note: Functions are supported from version 2 and on.
get_attr¶
This function retrieves the value of an attribute of an entity that is defined in the template.
Usage¶
get_attr(template_id, attr_name)
Example¶
scenario:
condition: alarm_on_host_1
actions:
action:
action_type: execute_mistral
properties:
workflow: demo_workflow
input:
host_name: get_attr(host_1,name)
retries: 5
get_param¶
See Using parameters
Supported Actions¶
raise_alarm¶
- Raise a deduced alarm on a target entity
action: action_type : raise_alarm properties: alarm_name: some problem # mandatory; string that is valid variable name severity: critical # mandatory; should match values in "vitrage.yaml" action_target: target: instance # mandatory. entity (from the definitions section) to raise an alarm on. Should not be an alarm.
set_state¶
- Set state of specified entity. This will directly affect the state as seen in vitrage, but will not impact the state at the relevant datasource of this entity.
action: action_type : set_state properties: state: error # mandatory; should match values in the relevant datasource_values YAML file for this entity. action_target: target: host # mandatory. entity (from the definitions section) to change state
add_causal_relationship¶
- Add a causal relationship between alarms.
action: action_type : add_causal_relationship action_target: source: host_alarm # mandatory. the alarm that caused the target alarm (name from the definitions section) target: instance_alarm # mandatory. the alarm that was caused by the source alarm (name from the definitions section)
mark_down¶
Set an entity marked_down field. This can be used along with nova notifier to call force_down for a host
action:
action_type : mark_down
action_target:
target: host # mandatory. entity (from the definitions section, only host) to be marked as down
execute_mistral¶
Execute a Mistral workflow. If the Mistral notifier is used, the specified workflow will be executed with its parameters.
action:
action_type: execute_mistral
properties:
workflow: demo_workflow # mandatory. The name of the workflow to be executed
input: # optional. A list of properties to be passed to the workflow
farewell: Goodbye and Good Luck!
employee: John Smith
Future support & Open Issues¶
Inequality¶
Consider a template that has two entities of the same category+type, say E1 and E2 both are instances like this:
metadata: version: 2 name: two_similar_instances type: standard definitions: entities: - entity: category: RESOURCE type: nova.host template_id: host - entity: category: RESOURCE type: nova.instance template_id: instance1 - entity: category: RESOURCE type: nova.instance template_id: instance2 ... relationships: - relationship: source: host target: instance1 relationship_type: contains template_id: link1 - relationship: source: host target: instance2 relationship_type: contains template_id: link2 ...
There are three options of how to interpret this template:
instance1 == instance2. This option is not a reasonable one, as in this case the template can be written with only instance1
instance1 != instance2.
instance1 != instance2 or instance1 == instance2. In other words, either option is fine.
Thus, we need a way to distinguish between options 2 & 3 (as option 1 can be expressed by using only instance1). This can be done in two ways: 1. Introducing another logical operator “neq”, to be used between expressions:
condition: (instance1 neq instance2) and...
Using this as a relationship type “neq”:
relationship: source: instance1 target: instance2 relationship_type: neq
Cardinality¶
To support cardinality, for example to express we want a host to have two instances on it, we could take different approaches.
1. One approach would rely on the “neq” relationship described above. Similar to the example given in the previous section, stating that the two instances on the host are not equal is equivalent to a cardinality of two. 2. A different approach would be to expand the definition of the “relationship” clause. By default cardinality=1 (which will support backward compatibility)
For example, we might use the one of the following formats
- relationship: # option A
source: host
target: instance
target_cardinality: 2 # two instances, but only one host
relationship_type: contains
template_id: host_contains_two_instances_A
- relationship: # option B, same as option A but split into two lines
source: host
target: instance
cardinality_for: target
cardinality: 2
relationship_type: contains
template_id: host_contains_two_instances_B
