Dynamic monitor creation

Create monitors dynamically with the Checkly CLI by looping over lists of targets in TypeScript or JavaScript, managing checks at scale without duplication.

The Checkly CLI enables you to code your entire monitoring setup taking full advantage of the flexibility of TypeScript/JavaScript. Reusing language constructs that you are already familiar with, you will be able to create a MaC setup that neatly fits your unique use cases and workflows.

This page shows a few examples.

Similar checks from a list of targets

Iterating through lists of target URLs is an easy way to manage checks at scale while avoiding code duplication.

__checks__/api.check.ts

import { ApiCheck } from 'checkly/constructs'

const publicResources = ['/public-stats', '/v1/runtimes']

for (const publicResource of publicResources) {
  new ApiCheck(`public-resource_${publicResource}`, {
    name: `Public Resource ${publicResource}`,
    request: {
      url: `https://api.checkly.com${publicResource}`,
      method: 'GET',
      followRedirects: true,
      skipSsl: false,
      assertions: [ AssertionBuilder.statusCode().equals(200) ]
    }
  })
}

Asynchronous operations are supported by exporting an async function from your check files, too.

__checks__/api.check.ts

import { ApiCheck } from 'checkly/constructs'
import { getPublicResources } from './helpers'

// an exported async function to signal that
// this check file performs asynchronous operations
export default async function createApiChecks() {
  const publicResources = await getPublicResources();

  for (const publicResource of publicResources) {
    new ApiCheck(`public-resource_${publicResource}`, {
      name: `Public Resource ${publicResource}`,
      request: {
        url: `https://api.checkly.com${publicResource}`,
        method: 'GET',
        followRedirects: true,
        skipSsl: false,
        assertions: [ AssertionBuilder.statusCode().equals(200) ]
      }
    })
  }
}

Separate groups for prod and pre-prod

Iterating through target environments (like preview and production) linked to Group resources allows you to reuse existing Check definitions.

__checks__/browser.check.ts

import fs from 'fs'
import { BrowserCheck } from 'checkly/constructs'
import { groupProd, groupPreview } from './groups.check'

// This reads a directory and extracts all file paths containing '.spec.ts'
const files = fs.readdirSync('__checks__/')
const specFiles = files.filter((filename) => {
  return filename.includes('.spec.ts')
})

// This is the list of environments and their matching group; it can be extended easily
const environments = [
  { name: 'preview', group: groupPreview },
  { name: 'production', group: groupProd },
]

// Here we create a new browser check for each environment x testspec combination
// Checks are added to the right groups - the group will set the right env variable for the target URL
environments.forEach((environment) => {
  for (const specFile of specFiles) {
    new BrowserCheck(`${specFile}${environment.name}`, {
      name: `${specFile} [${environment.name}]`,
      tags: [`${environment.name}`],
      group: environment.group,
      code: {
        entrypoint: specFile,
      },
    })
  }
})

You can handle potential differences between target environments via group-level environment variables, which are made available to all checks within a group.

__checks__/group.check.ts

import { CheckGroupV2 } from 'checkly/constructs'
import { smsChannel, emailChannel } from '../alert-channels'
const alertChannels = [smsChannel, emailChannel]

export const groupPreview = new CheckGroupV2('group-browser-preview', {
  name: 'WebShop - Preview',
  activated: true,
  muted: false,
  runtimeId: '2025.04',
  locations: ['us-east-1', 'eu-west-1'],
  tags: ['mac', 'preview'],
  // You can use group-level environment vars to point each group's checks to the right target URL
  environmentVariables: [ { key: 'TARGET_URL', value: 'https://preview.mywebsite.com' }],
  apiCheckDefaults: {},
  concurrency: 100,
  alertEscalationPolicy: 'global',
  alertChannels
})

export const groupProd = new CheckGroupV2('group-browser-prod', {
  name: 'WebShop - Production',
  activated: true,
  muted: false,
  runtimeId: '2025.04',
  locations: ['us-east-1', 'eu-west-1'],
  tags: ['mac', 'production'],
  // You can use group-level environment vars to point each group's checks to the right target URL
  environmentVariables: [ { key: 'TARGET_URL', value: 'https://www.mywebsite.com' }],
  apiCheckDefaults: {},
  concurrency: 100,
  alertEscalationPolicy: 'global',
  alertChannels
})