Environment Variables

Environment variables are useful when:

  • Values are different across developer machines.
  • Values are different across multiple environments: (dev, staging, qa, prod)
  • Values change frequently and are highly dynamic.

Environment variables can be changed easily - especially when running in CI.

Instead of hard coding this in your tests:

cy.request('https://api.acme.corp') // this will break on other environments

We can move this into a Cypress environment variable:

cy.request(Cypress.env('EXTERNAL_API')) // points to a dynamic env var

Setting

There are different ways to set environment variables. Each has a slightly different use case.

To summarize you can:

Don't feel obligated to pick just one method. It is common to use one strategy for local development but another when running in CI.

When your tests are running, you can use the Cypress.env function to access the values of your environment variables.

Option #1: configuration file

Any key/value you set in your configuration file (cypress.json by default) under the env key will become an environment variable.

{
  "projectId": "128076ed-9868-4e98-9cef-98dd8b705d75",
  "env": {
    "login_url": "/login",
    "products_url": "/products"
  }
}

Test file

Cypress.env() // {login_url: '/login', products_url: '/products'}
Cypress.env('login_url') // '/login'
Cypress.env('products_url') // '/products'

Overview

Option #2: cypress.env.json

You can create your own cypress.env.json file that Cypress will automatically check. Values in here will overwrite conflicting environment variables in your configuration file (cypress.json by default).

This strategy is useful because if you add cypress.env.json to your .gitignore file, the values in here can be different for each developer machine.

{
  "host": "veronica.dev.local",
  "api_server": "http://localhost:8888/api/v1/"
}

From test file

Cypress.env() // {host: 'veronica.dev.local', api_server: 'http://localhost:8888/api/v1'}
Cypress.env('host') // 'veronica.dev.local'
Cypress.env('api_server') // 'http://localhost:8888/api/v1/'

An Overview

Option #3: CYPRESS_*

Any OS-level environment variable on your machine that starts with either CYPRESS_ or cypress_ will automatically be added to Cypress' environment variables and made available to you.

Conflicting values will override values from your configuration file (cypress.json by default) and cypress.env.json files.

Cypress will strip off the CYPRESS_ when adding your environment variables.

Export cypress env variables from the command line

export CYPRESS_HOST=laura.dev.local

export cypress_api_server=http://localhost:8888/api/v1/

In test file

In your test file you should omit CYPRESS_ or cypress_ prefix

Cypress.env() // {HOST: 'laura.dev.local', api_server: 'http://localhost:8888/api/v1'}
Cypress.env('HOST') // 'laura.dev.local'
Cypress.env('api_server') // 'http://localhost:8888/api/v1/'

Overview:

Option #4: --env

You can pass in environment variables as options when using the CLI tool.

Values here will overwrite all other conflicting environment variables.

You can use the --env argument for cypress run.

From the command line or CI

cypress run --env host=kevin.dev.local,api_server=http://localhost:8888/api/v1

Test file:

Cypress.env() // {host: 'kevin.dev.local', api_server: 'http://localhost:8888/api/v1'}
Cypress.env('host') // 'kevin.dev.local'
Cypress.env('api_server') // 'http://localhost:8888/api/v1/'

Overview -

Option #5: Plugins

Instead of setting environment variables in a file, you can use plugins to dynamically set them with Node code. This enables you to do things like use fs and read off configuration values and dynamically change them.

For example, if you use the dotenv package to read the .env file, you could then grab the needed environment variables from the process.env object and place them into config.env to make available in the tests:

// .env file
USER_NAME=aTester

// plugins/index.js
require('dotenv').config()

module.exports = (on, config) => {
  // copy any needed variables from process.env to config.env
  config.env.username = process.env.USER_NAME

  // do not forget to return the changed config object!
  return config
}

// integration/spec.js
it('has username to use', () => {
  expect(Cypress.env('username')).to.be.a('string')
})

We've fully documented how to do this here.

Overview

Option #6: Test Configuration

You can set environment variables for specific suites or tests by passing the env values to the test configuration.

Suite of test configuration

// change environment variable for single suite of tests
describe(
  'test against Spanish site',
  {
    env: {
      language: 'es',
    },
  },
  () => {
    it('displays Spanish', () => {
      cy.visit(`https://docs.cypress.io/${Cypress.env('language')}/`)
      cy.contains('¿Por qué Cypress?')
    })
  }
)

Single test configuration

// change environment variable for single test
it(
  'smoke test develop api',
  {
    env: {
      api: 'https://dev.myapi.com',
    },
  },
  () => {
    cy.request(Cypress.env('api')).its('status').should('eq', 200)
  }
)

// change environment variable for single test
it(
  'smoke test staging api',
  {
    env: {
      api: 'https://staging.myapi.com',
    },
  },
  () => {
    cy.request(Cypress.env('api')).its('status').should('eq', 200)
  }
)

Overview

Overriding Configuration

If your environment variables match a standard configuration key, then instead of setting an environment variable they will instead override the configuration value.

Change the baseUrl configuration value / not set env var in Cypress.env()

export CYPRESS_BASE_URL=http://localhost:8080

'foo' does not match config / sets env var in Cypress.env()

export CYPRESS_FOO=bar

You can read more about how environment variables can change configuration here.

See also