Environment variables – Effective Volto – Development tools

Environment variables#

All the environment variables defined at runtime that have the "RAZZLE_" prefix, are available in the browser under window.env. The nodejs server always has access to them, via the process.env runtime variable.

ex: If we start the application with an env variable

RAZZLE_MY_VARIABLE=some_value build/server.js

In the frontend we can access this variable with:


Runtime environment variables#

All the environment variables that are configurable work at runtime, not only at build time. This works since Volto 13 onwards.


Before Volto 13, you'd do:

RAZZLE_API_PATH=https://plone.org yarn build && yarn start:prod

From Volto 13 onwards, you can now do:

yarn build && RAZZLE_API_PATH=https://plone.org yarn start:prod

This brings you a lot of power since you don't have to rebuild on every config change. You can also generate builds on your CI, then deploy them anywhere.

Environment variables reference#


From Volto 14 onwards, Seamless mode is the recommended way of setting up your depoloyments. However, it forces you to upgrade several packages in the backend (plone.restapi and plone.rest) and adjust your web server configuration accordingly.

In case you can't afford or change your deployment, you can still upgrade Volto by using the RAZZLE_LEGACY_TRAVERSE flag.

RAZZLE_LEGACY_TRAVERSE=true yarn start:prod


You can override the robots.txt file with an environment variable called VOLTO_ROBOTSTXT. This is useful when using the same build on multiple websites (for example a test website) to forbid robots from crawling it.

$ VOLTO_ROBOTSTXT="User-agent: *
Disallow: /" yarn start


If you want to use the VOLTO_ROBOTSTXT environment variable, make sure to delete the file public/robots.txt from your project.


It will enable the log several logging points scattered through the Volto code. It uses the volto: namespace.

DEBUG=volto:i18n yarn start


DEBUG=volto:shadowing yarn start


DEBUG=volto:* yarn start


It will allow you to debug the devproxy middleware by setting the http-proxy-middleware logging level to debug.

DEBUG_HPM=1 yarn start

Component Shadowing errors (shadowing)#

It displays the errors of the non-compliant customizations (in server console) if you are experiencing problems with a customization not working.

Internationalization errors (i18n)#

It will enable the log of missing i18n messages (in console).

Use add-ons via the ADDONS environment variable#

You can use the ADDONS environment variable to enable and configure add-ons in your project.

When running your app, the add-ons will be loaded in the following order:

  • the file package.json

  • programmatically set in the file volto.config.js

  • the environment variable ADDONS

In the environment variable ADDONS, you can specify:

  • released (or published) packages that were installed previously in your environment and are already present in the node_modules directory,

  • or addons located in the packages folder of your project, such as Volto's testing packages.

ADDONS can be used to temporarily add an add-on to your build for testing purposes.

yarn add volto-slate
ADDONS=volto-form-block yarn start

ADDONS can also be used to temporarily enable a feature or a set of customizations.

# given a folder './packages/coresandbox', like in vanilla Volto
ADDONS=coresandbox:multilingualFixture yarn start

You can specify multiple add-ons, seperated by commas:

ADDONS=test-addon,test-addon2 yarn start

You can specify profiles for installation:

ADDONS=test-addon:profile1,test-addon2:profile2 yarn start

The following code snippets demonstrate how to configure add-ons. First in package.json:

"addons": [

...next in volto.config.js:

module.exports = {
    addons: ['@eeacms/volto-accordion-block']

...and finally using ADDONS:

yarn add volto-slate
ADDONS=volto-slate:asDefault yarn start

If you need to specify several add-ons, separate them with a semicolon (;):

yarn add volto-slate
ADDONS="volto-form-block;@kitconcept/volto-blocks-grid" yarn start

As a result, your app will load the add-ons in the following order:

  • @kitconcept/volto-blocks-grid

  • @eeacms/volto-accordion-block

  • volto-form-block


The ADDONS key is a Volto specific configuration. Simply setting ADDONS doesn't download the javascript package. This has to be covered by another way, either installing the addon package (with yarn add) or loading it as a development package with mrs-developer.


This is a runtime-only environment variable that directs the build to run Volto from an especific location, other than the default folder build.

BUILD_DIR=dist node dist/server.js