This can be achieved by defining Deduplication Rules for each Service in Squadcast. When these rules evaluate true for an incoming incident, alerts will get deduplicated.

## Prerequisites

• The User Role associated with the user in the Team must have required permissions to manage Services (ability to manage Deduplication Rules).
• Integrate with an Alert Source and ensure that the Alert Source has started sending alerts to Squadcast before setting up Deduplication Rules.
Important Deduplication Rules work only on incidents in either the Triggered or Acknowledged states.

## Create a Deduplication Rule

To create a Deduplication Rule:
1. 1.
Navigate to Services -> Service Overview -> select or search for your desired service.
2. 2.
In the extreme right, expand the accordion -> In Automation section, View All
3. 3.
In the Automation Rules section, Add Deduplication Rules
4. 4.
Select an Alert Source from the drop down -> Add New Rule
5. 5.
Deduplication Rules can be added in two ways:

### A. UI-based Rule Builder (Beginner-friendly)

1. 1.
On the right, you can view the payload of the latest alert for the chosen Alert Source
2. 2.
The drop-downs in the Rule Builder contain values from the payload on the right. You can use them to easily create your Deduplication Rules
3. You can add more than 1 condition for a rule by selecting Add Condition (a logical AND is performed between all the conditions -> the entire Deduplication Rule will evaluate to True only if all the conditions evaluate to True)
Next, choose the Deduplication Time Window. You can deduplicate incidents for a maximum of 48 hours.
Time Window
During the set time window, incidents that occur are compared against all incidents that come in during that time period, and will then get deduplicated against the first incident that it matches with.
4. Click on Save
Note: The search option under payload is not a free search, we have to search by JSON format, for example, type in payload.annotations to get annotations.
We also have an option for click-to search, wherein you can click on the keys in the payload to get their required values.

### B. Raw String Method

Important
Once you opt for the Raw String method, you cannot revert to the UI-based Rule Builder method for that rule.
1. 1.
On the right, you can view the payload of the latest alert for the chosen Alert Source
2. 2.
Click on Edit to enable the Raw String method
Supported Rules
The rule engine supports expressions with parameters, arithmetic, logical, and string operations.
Basic Expressions
$10 > 0, 1+2, 100/3$
Parameterized Expressions
$past.metric == current.metric$
The available parameters are past, current and event_count + past: This parameter contains the JSON payload of the previous incident which the current event is compared with + current: This parameter contains the JSON payload of the incoming event which will be compared with the past incidents’ JSON payload + event_count: This denotes the number of deduplicated events for a given incident
Use-case for event_count:
This can be used in scenarios where you do not want to deduplicate more than n number of alerts to a particular incident.
Regular Expressions
This can be used to check if a particular JSON payload field matches a regular expression.
$re(payload.metric, "disk.*")$
Parse JSON content within the payload using jsonPath
General Format
jsonPath(<the JSON string that should be parsed for JSON content>, <"the parameter that needs to be picked from the parsed JSON object">)
Example
{
"MessageId": "5966c484-5b37-58df",
"TopicArn": "arn:aws:sns:us-east-1:51:Test",
"Message": "{\"AlarmName\":\"Squadcast Testing - Ignore\",\"AlarmDescription\":\"Created from EC2 Console\"}"
}
}
This will pick out the value AlarmName from the Message object in the payload, based on which, you can de-duplicate incidents.
We can see alert payloads of past events from different alert sources for the Service by selecting the respective alert source from the dropdown in the right-half side.
Since the payload format is fixed for a given alert source, it is usually preferable to have Deduplication Rules on a per-alert source basis. This can be done by making use of the source field which lets you know the alert source that triggered the incoming event. For example, if you want to have a Deduplication Rule for a Service, only for alerts coming for grafana alert source, then the corresponding rule would look something like: source == 'grafana' && (<your_deduplication_rule>)
Example
Below is an example payload for demonstration:
{
"event_count": 5,
"past": {
"issue_description": "bug - 2",
"issue_id": "10029",
"issue_key": "HYD-30",
"issue_labels": [],
"issue_priority": "Medium",
"issue_summary": "bug - 2",
"issue_type": "Bug",
"project_id": "10000",
"project_key": "HYD",
"project_name": "hydra"
},
"source": "grafana"
}
To deduplicate any incoming alert when:
• The metric matches the regular expression ^disk.*
• The past incident metric and the current event metric are the same
• The past incident host and the current event host are the same
• The current disk usage value is less than 60%
• The context value tag is same
Deduplication Rule:
past.metric == current.metric &&
re(current.metric, "^disk.*") &&
past.host == current.host &&
current.value < 60 &&
jsonPath(past.tags, "context.value") ==
jsonPath(current.tags, "context.value");

## Viewing Deduplicated Incidents

From the Incidents page, you can view which incidents have deduplicated events when there is a +<number> next to the Incident ID like in the screenshot below.
The number indicates how many alerts were deduplicated against this incident.
Clicking on such an incident will take you to its Incident Details page where, by clicking on Deduped Events, you will be able to see the following:
• Number of deduplicated events
• Time when they reached Squadcast
• Message and Payload of the event
Clicking on any of the deduplicated events will display will all the information that is sent for that alert from the monitoring tool, including the Deduplication Reason (which Deduplication Rule got executed).

## FAQs

(1) Will I get notified of the duplicate alerts that come in for an incident in a Triggered state?
No, nobody is notified of the duplicate alerts that come in for an incident in the Triggered or Acknowledged state.
(2) Will I get notified of the duplicate alerts that come in for an incident in the Resolved state?
Yes, Incident Deduplication will not take place for an incident when it is in the Resolved state. Squadcast triggers a fresh incident for such an alert and notifies the right people.
(3) Why can’t I deduplicate incidents for more than 48 hours?
Most organizations across the world follow a best practice of resolving critical incidents within 48 hours of their creation. This is also the reason why Squadcast allows you to deduplicate incidents for a maximum of 48 hours.
(4) Can I create OR rules?
Yes, you can. The evaluation between different Deduplication Rules is OR.
(5) What kind of regex can be used to write custom rules?
The rule engine supports expressions with parameters, arithmetic, logical, and string operations. You can also check this out to get an idea of all the expression types accepted in Squadcast. Please do your regex here against Golang flavour as shown in the screenshot below and then, set them up in Squadcast:
(6) Do the Deduplication Rules have priority?
Yes, you can specify Execution Rule Priority for the rules defined by moving them Up or Down the list of rules.
(7) While adding a Deduplication Rule, is the search string in the rule case sensitive?