# Baselime CDK Alerts

Alerts are used to run a query on a schedule and notify you if a threshold is crossed. Baselime alerts are based on Baselime queries, which gives you you the flexibility to specify alerts on defects or events of interest, and reduce false positives and alert fatigue.

Here’s a sample alert in Baselime CDK that uses all of the supported settings for defining alert in Baselime. Use it to get started creating your own alert.

import { Alert } from "@baselime/cdk";

new Alert("sign-up-errors", {
  // Provide a description for the alert - optional
  description: `Notify me when ever an error happens whilst a user is signing up`,
  // disable the alert - optional
  enabled: true,
  parameters: {
    // run the sign up query - this query can also be inlined
    query: signUpErrorQuery,
    // trigger if the querys calculation is greater than 10
    threshold: threshold.gt(10),
    // run this alert every 30 minutes
    frequency: '30 mins',
    // look back over the last 30 minutes of data
    window: '30 mins',
  },
  // route the alert slack, email or webhook
  channels: [{ targets: ['you@company.com'], type: 'email' }]
});

The description of the alert is a string that provides more information about the alert. It can include details about the conditions being monitored and any other relevant information.

Example:

description: "Notify me whenever an error happens while a user is signing up."

The enabled property is a boolean that indicates whether the alert is enabled or disabled. If set to true, the alert will be active and trigger notifications when thresholds are met. If set to false, the alert will be inactive and no notifications will be sent.

Example:

enabled: true

The parameters of an alert define the query to run, the threshold to evaluate, and the frequency and window for monitoring. query

The query parameter specifies the query to run for monitoring. It can reference an existing query object or include an inline query definition.

Example:

query: {
  filters: [
    eq("LogType", "ERROR"),
    eq("user.action", "SIGN_UP")
  ]
}

With the inline query the calculation defaults to [calc.count()]

or

query: new Query("sign-up-errors", {
  calculation: [calc.count()]
  filters: [
    eq("LogType", "ERROR"),
    eq("Action", "SIGN_UP")
  ]
})

The threshold parameter specifies the condition to evaluate from the query results. It can use helper functions to create comparisons or calculations, such as gt, lt, eq, count, etc.

Example:

threshold: gt(10)

The frequency parameter specifies the frequency at which the alert should run the query and evaluate the threshold. It uses a string representation of the frequency, such as '5 mins', '1 hour', '1 day', etc.

Example:

frequency: '5 mins'

The window parameter specifies the time window to look back for data when evaluating the threshold. It uses a string representation of the time window, such as '10 mins', '1 hour', '1 day', etc.

Example:

window: '10 mins'

The channels property specifies the destinations to send the alert notifications. It is an array of channel objects, where each object defines the channel type and targets.

The type property specifies the type of channel for the alert. Baselime CDK supports various channel types, such as 'email', 'slack', 'webhook', etc.

The targets property specifies the target destinations for the alert notifications. The targets can be specific emails, channels, or URLs depending on the channel type.

Example:

channels: [{ targets: ['baselime-alerts'], type: 'slack' }]

Moreover, you can define a defaultChannel when initialising your Baselime CDK, this channel will be used for all alerts in the service, simplifying your CDK code.

Baselime.init(this, {
  defaultChannel: { targets: ['baselime-alerts'], type: 'slack'}
});