AWS::ApplicationSignals::ServiceLevelObjective

Creates or updates a service level objective (SLO), which can help you ensure that your critical business operations are meeting customer expectations. Use SLOs to set and track specific target levels for the reliability and availability of your applications and services. SLOs use service level indicators (SLIs) to calculate whether the application is performing at the level that you want.

Create an SLO to set a target for a service or operation’s availability or latency. CloudWatch measures this target frequently you can find whether it has been breached.

The target performance quality that is defined for an SLO is the attainment goal. An attainment goal is the percentage of time or requests that the SLI is expected to meet the threshold over each time interval. For example, an attainment goal of 99.9% means that within your interval, you are targeting 99.9% of the periods to be in healthy state.

When you create an SLO, you specify whether it is a period-based SLO or a request-based SLO. Each type of SLO has a different way of evaluating your application's performance against its attainment goal.

• A period-based SLO uses defined periods of time within a specified total time interval. For each period of time, Application Signals determines whether the application met its goal. The attainment rate is calculated as the number of good periods/number of total periods.

  For example, for a period-based SLO, meeting an attainment goal of 99.9% means that within your interval, your application must meet its performance goal during at least 99.9% of the time periods.

• A request-based SLO doesn't use pre-defined periods of time. Instead, the SLO measures number of good requests/number of total requests during the interval. At any time, you can find the ratio of good requests to total requests for the interval up to the time stamp that you specify, and measure that ratio against the goal set in your SLO.

After you have created an SLO, you can retrieve error budget reports for it. An error budget is the amount of time or amount of requests that your application can be non-compliant with the SLO's goal, and still have your application meet the goal.

• For a period-based SLO, the error budget starts at a number defined by the highest number of periods that can fail to meet the threshold, while still meeting the overall goal. The remaining error budget decreases with every failed period that is recorded. The error budget within one interval can never increase.

  For example, an SLO with a threshold that 99.95% of requests must be completed under 2000ms every month translates to an error budget of 21.9 minutes of downtime per month.

• For a request-based SLO, the remaining error budget is dynamic and can increase or decrease, depending on the ratio of good requests to total requests.

When you call this operation, Application Signals creates the AWSServiceRoleForCloudWatchApplicationSignals service-linked role, if it doesn't already exist in your account. This service- linked role has the following permissions:

• xray:GetServiceGraph

• logs:StartQuery

• logs:GetQueryResults

• cloudwatch:GetMetricData

• cloudwatch:ListMetrics

• tag:GetResources

• autoscaling:DescribeAutoScalingGroups

You can easily set SLO targets for your applications that are discovered by Application Signals, using critical metrics such as latency and availability. You can also set SLOs against any CloudWatch metric or math expression that produces a time series.

You cannot change from a period-based SLO to a request-based SLO, or change from a request-based SLO to a period-based SLO.

For more information about SLOs, see Service level objectives (SLOs).

Syntax

To declare this entity in your AWS CloudFormation template, use the following syntax:

JSON

{
  "Type" : "AWS::ApplicationSignals::ServiceLevelObjective",
  "Properties" : {
      "Description" : String,
      "Goal" : Goal,
      "Name" : String,
      "RequestBasedSli" : RequestBasedSli,
      "Sli" : Sli,
      "Tags" : [ Tag, ... ]
    }
}

YAML

Type: AWS::ApplicationSignals::ServiceLevelObjective
Properties:
  Description: String
  Goal: 
    Goal
  Name: String
  RequestBasedSli: 
    RequestBasedSli
  Sli: 
    Sli
  Tags: 
    - Tag

Properties

Description

An optional description for this SLO.

Required: No

Type: String

Minimum: 1

Maximum: 1024

Update requires: No interruption

Goal

This structure contains the attributes that determine the goal of an SLO. This includes the time period for evaluation and the attainment threshold.

Required: No

Type: Goal

Update requires: No interruption

Name

A name for this SLO.

Required: Yes

Type: String

Pattern: ^[0-9A-Za-z][-._0-9A-Za-z ]{0,126}[0-9A-Za-z]$

Update requires: Replacement

RequestBasedSli

A structure containing information about the performance metric that this SLO monitors, if this is a request-based SLO.

Required: No

Type: RequestBasedSli

Update requires: No interruption

Sli

A structure containing information about the performance metric that this SLO monitors, if this is a period-based SLO.

Required: No

Type: Sli

Update requires: No interruption

Tags

A list of key-value pairs to associate with the SLO. You can associate as many as 50 tags with an SLO. To be able to associate tags with the SLO when you create the SLO, you must have the cloudwatch:TagResource permission.

Tags can help you organize and categorize your resources. You can also use them to scope user permissions by granting a user permission to access or change only resources with certain tag values.

Required: No

Type: Array of Tag

Minimum: 1

Maximum: 200

Update requires: No interruption

Return values

Ref

When you pass the logical ID of this resource to the intrinsic Ref function, Ref returns the ARN of the SLO. For example, arn:aws:cloudwatch:us-west-1:123456789012:slo:my-slo-name

Fn::GetAtt

Arn

The ARN of this SLO.

CreatedTime

The date and time that this SLO was created.

EvaluationType

Displays whether this is a period-based SLO or a request-based SLO.

LastUpdatedTime

The time that this SLO was most recently updated.