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Environments

Background

Environments are different contexts that your code runs in. The Workers platform allows you to create and manage different environments. Through environments, you can deploy the same project to multiple places under multiple names.

These environments are utilized with the --env or -e flag on wrangler build, wrangler dev, wrangler preview, wrangler publish, and wrangler secret.

Usage

You will likely use environments to deploy Workers to a staging subdomain before your production environment. wrangler publish will determine its destination by the top-level configuration in your wrangler.toml file . You can create other environments beneath the top-level configuration in the wrangler.toml file by adding an [env.name] configuration and specifying additional keys and values. For details on what keys are inherited by environments from the top-level configuration, see wrangler.toml configuration .

The layout of a top-level configuration in a wrangler.toml file is displayed below:

---
filename: wrangler.toml
---
name = "your-worker"
type = "javascript"
account_id = "your-account-id"

# This field specifies that the Worker
# will be deployed to a *.workers.dev domain
workers_dev = true

# -- OR --

# These fields specify that the Worker
# will deploy to a custom domain
zone_id = "your-zone-id"
routes = ["example.com/*"]

Naming

You cannot specify multiple environments with the same name. If this were allowed, publishing each environment would overwrite your previously deployed Worker and the behavior would not be clear.

For this reason, Wrangler appends the environment name to the top-level name to publish a Worker script. For example, a Worker project named my-worker with an environment [env.dev] would become my-worker-dev.

The layout of an example [env.dev] environment is displayed below:

---
filename: wrangler.toml
---
name = "your-worker"
type = "javascript"
account_id = "your-account-id"

[env.dev]
name = "your-worker-dev"
route = "your-custom-route"

Examples

Top-level configuration

Publishing to a custom domain

This wrangler.toml file has no environments defined and will publish my-worker to example.com/*. The workers_dev key is missing from this example, but because a route is specified, the inferred value of workers_dev is false.

---
filename: wrangler.toml
---
type = "webpack"
name = "my-worker"
account_id = "12345678901234567890"

# These fields specify that the Worker
# will deploy to a custom domain
zone_id = "09876543210987654321"
route = "example.com/*"

To deploy this Worker, run the wrangler publish command in your terminal:

~/my-worker $ wrangler publish
✨  Built successfully, built project size is 523 bytes.
✨  Successfully published your script to example.com/*

Publishing to *.workers.dev

Your *.workers.dev subdomain allows you to deploy Workers scripts without attaching a custom domain as a Cloudflare zone. To claim a *.workers.dev subdomain, such as my-subdomain.workers.dev, select the Workers icon on your account home, or Workers then Manage Workers on your zone’s dashboard, and begin setup on the right side of the Workers dashboard under Your subdomain.

This wrangler.toml file has no environments defined and will publish my-worker to my-worker.<your-subdomain>.workers.dev:

---
filename: wrangler.toml
---
type = "webpack"
name = "my-worker"
account_id = "12345678901234567890"

# this field specifies that the worker
# should be deployed to *.workers.dev
workers_dev = true

This example will publish to your *.workers.dev subdomain because workers_dev has been set to true.

Run wrangler publish as normal to deploy your Worker script:

~/my-worker $ wrangler publish
✨  Built successfully, built project size is 523 bytes.
✨  Successfully published your script to https://my-worker.<your-subdomain>.workers.dev

Introducing environments

Environments enable you to write and deploy projects to multiple places.

You can define an environment by specifying an [env.name] block with its own values in your wrangler.toml file. Values within this block may override top-level configuration values with the same key.

The wrangler.toml file below adds two environments, [env.staging] and [env.production], to the wrangler.toml file. If you are deploying to a custom domain, you must provide a route or routes key for each environment.

---
filename: wrangler.toml
---
type = "webpack"
name = "my-worker-dev"
account_id = "12345678901234567890"
zone_id = "09876543210987654321"
route = "dev.example.com/*"
vars = { ENVIRONMENT = "dev" }

[env.staging]
name = "my-worker-staging"
vars = { ENVIRONMENT = "staging" }
route = "staging.example.com/*"

[env.production]
name = "my-worker"
vars = { ENVIRONMENT = "production" }
routes = [
  "example.com/foo/*",
  "example.com/bar/*"
]

In order to use environments with this configuration, you can pass the name of the environment via the --env flag.

With this configuration, Wrangler will behave in the following manner:

~/my-worker $ wrangler publish
✨  Built successfully, built project size is 523 bytes.
✨  Successfully published your script to dev.example.com/*

~/my-worker $ wrangler publish --env staging
✨  Built successfully, built project size is 523 bytes.
✨  Successfully published your script to staging.example.com/*

~/my-worker $ wrangler publish --env production
✨  Built successfully, built project size is 523 bytes.
✨  Successfully published your script to example.com/*

Any defined environment variables (the vars key) are exposed as global variables to your Worker.

With this configuration, the ENVIRONMENT variable can be used to call specific code depending on the given environment:

if (ENVIRONMENT === 'staging') {
  // staging-specific code
} else if (ENVIRONMENT === 'production') {
  // production-specific code
}

Staging Environment with workers.dev

In order to deploy your code to your *.workers.dev subdomain, include workers_dev = true in the desired environment. Your wrangler.toml file may look like this:

---
filename: wrangler.toml
---
name = "my-worker"
type = "webpack"
account_id = "12345678901234567890"
zone_id = "09876543210987654321"
route = "example.com/*"

[env.staging]
workers_dev = true

With this configuration, Wrangler will behave in the following manner:

~/my-worker $ wrangler publish
✨  Built successfully, built project size is 523 bytes.
✨  Successfully published your script to example.com/*

~/my-worker $ wrangler publish --env staging
✨  Built successfully, built project size is 523 bytes.
✨  Successfully published your script to https://my-worker-staging.<your-subdomain>.workers.dev

workers.dev as a first-class target

If you want to connect multiple environments to your *.workers.dev subdomain, you must assign a different name per environment. This allows your Worker to be uploaded as different scripts, each given its own set of environment variables , secrets, and KV namespaces. Configure your wrangler.toml file like the example below:

---
filename: wrangler.toml
---
name = "my-worker-dev"
type = "webpack"
account_id = "12345678901234567890"
workers_dev = true

[env.production]
name = "my-worker"

[env.staging]
name = "my-worker-staging"

With this configuration, deploy each environment by attaching a --env or -e flag and the name of the environment like the examples below:

~/my-worker $ wrangler publish
✨  Built successfully, built project size is 523 bytes.
✨  Successfully published your script to https://my-worker-dev.<your-subdomain>.workers.dev

~/my-worker $ wrangler publish --env staging
✨  Built successfully, built project size is 523 bytes.
✨  Successfully published your script to https://my-worker-staging.<your-subdomain>.workers.dev

~/my-worker $ wrangler publish --env production
✨  Built successfully, built project size is 523 bytes.
✨  Successfully published your script to https://my-worker.<your-subdomain>.workers.dev

Custom webpack configurations

You can specify different webpack configurations for different environments.

---
filename: wrangler.toml
---
name = "my-worker-dev"
type = "webpack"
account_id = "12345678901234567890"
workers_dev = true
webpack_config = "webpack.dev.js"

[env.production]
name = "my-worker"
webpack_config = "webpack.config.js"

[env.staging]
name = "my-worker-staging"

Your default wrangler build, wrangler preview, and wrangler publish commands will all build with webpack.dev.js. Any commands tied to the staging environment will also use this configuration; for example, wrangler build -e staging, wrangler preview -e staging, and wrangler publish -e staging.

The build commands wrangler build -e production, wrangler preview -e production, and wrangler publish -e production would all use your webpack.config.js file.

Invalid configurations

Multiple types

You cannot specify multiple type values. The type must be specified at the top level of your wrangler.toml file.

---
filename: wrangler.toml
---
name = "my-worker"
type = "webpack"
account_id = "12345678901234567890"
zone_id = "09876543210987654321"
route = "example.com/*"
workers_dev = true

[env.staging]
type = "rust"

With this configuration, no errors will be thrown. However, only type = "webpack" will be used, even in an --env staging setting.

Same name for multiple environments

You cannot specify multiple environments with the same name. If this were allowed, publishing each environment would overwrite your previously deployed Worker, and the behavior would not be clear.

---
filename: wrangler.toml
---
name = "my-worker"
type = "webpack"
account_id = "12345678901234567890"
zone_id = "09876543210987654321"
route = "example.com/*"

[env.staging]
name = "my-worker"
workers_dev = true

~/my-worker $ wrangler publish
Error: ⚠️  Each name in your `wrangler.toml` must be unique, this name is duplicated: my-worker

~/my-worker $ wrangler publish --env staging
Error: ⚠️  Each name in your `wrangler.toml` must be unique, this name is duplicated: my-worker

Defining workers_dev and route 

name = "my-worker"
type = "webpack"
account_id = "12345678901234567890"
zone_id = "09876543210987654321"
route = "example.com/*"
workers_dev = true

[env.staging]
workers_dev = true
route = "staging.example.com/*"

Wrangler will fail to deploy when both workers_dev = true and route (or routes) are defined. If you are trying to deploy to a *.workers.dev domain, remove the route or routes value.

~/my-worker $ wrangler publish
Error: ⚠️  Your environment should only include `workers_dev` or `route`. If you are trying to publish to workers.dev, remove `route` from your wrangler.toml, if you are trying to publish to your own domain, remove `workers_dev`.

~/my-worker $ wrangler publish --env staging
Error: ⚠️  Your environment should only include `workers_dev` or `route`. If you are trying to publish to workers.dev, remove `route` from your wrangler.toml, if you are trying to publish to your own domain, remove `workers_dev`.