Feature Flags allow you to enable and test experimental features. You can also use it to switch temporarily back to legacy and deprecated behavior. This can allow more time to modify applications to stop using them before they’re removed.
The following list contains all of the experimental and legacy features. They’re also listed in the
com.vaadin.experimental.FeatureFlags (Javadoc) class.
Feature flags can be managed in different ways: by using Vaadin Developer Tools; by editing the feature flags properties file; or by setting Java system properties. Each of these methods is described in the sub-sections that follow. However, remember that system properties always have the highest priority. Since they’re not written into the feature flags properties file, they’re valid only for a single execution.
It’s easy to manage feature flags using Vaadin Developer Tools. When running your browser in development mode, click the Vaadin Developer Tools icon button in your application — it’s located at bottom right corner.
Next, open the Feature Flags tab and then click the toggle buttons to enable or disable features.
When you’re finished, restart the application for your changes to take effect.
As mentioned, you can also manage feature flags by editing the properties file. To do so by this method, edit the
src/main/resources/vaadin-featureflags.properties file in your application folder — or create the file if it doesn’t already exist.
When you have that file open, add a line for each feature in the format of
com.vaadin.experimental.<FEATURE_NAME>=true. Here’s an example of how this might look:
To disable a feature, remove the corresponding line or set its value to
When you’re finished enabling or disabling feature flags, save the properties file and restart the application.
The last method for managing feature flags is to set the Java system properties. From the command-line, use the IDE launch configuration or a tool configuration — such as, Spring Boot Maven plugin — to set a system property for each feature flag to be enabled or disabled.
The property name should be in the format
vaadin.<FEATURE_NAME>, like so:
To temporarily disable a feature, set its property value to
false, like this: