Did you try this property? At least in Maven it works.

  <properties>
    <vaadin.frontend.hotdeploy.dependencies>../moduleB</vaadin.frontend.hotdeploy.dependencies>
  </properties>

The property frontendHotdeployDependencies is not available in a gradle project

Did you try this property? At least in Maven it works.

../moduleB

vaadin.frontend.hotdeploy.dependencies is expected to be provided as a Java system property.

Setting the path to module B to system property vaadin.frontend.hotdeploy.dependencies should work.

We need to document this property as it was created exactly for such use cases - it tells Vite dev server HMR what module to watch.

Additional observations:

I just tried the system property -Dvaadin.frontend.hotdeploy.dependencies=“../project-components” and the frontendHotdeploy worked for project-components, but not for the project-main. I tried to include the project-main additionally via : or ;. However, this did not work =”../project-components;../project-main”

We have to test and be sure that this property works consistently.

Tried this just now and got it working with a few minor changes. I'm not exactly sure what you're using to run the app, I was using Jetty via Gretty plugin.

First issue is that Gradle does not forward system properties to the Jetty process it starts so I had to add a line for that in Gretty section of the root project's build.gradle file:

gretty {
	contextPath = "/"
	servletContainer = 'jetty11'
	systemProperties = System.getProperties() // <- This line!
}

If you're using e.g. Spring I think there's a similar way to pass the system properties to that process as well.

Second issue is the separator for multiple paths, which is actually , - so the parameter I used when starting the app is:

-Dvaadin.frontend.hotdeploy.dependencies='./components,./components2'

Do also note the ' instead of ", although this might depend on the OS or shell used.

Please try it out and let me know if you still have issues.

Note to Flow team: we most likely need to update documentation about how to do this.

Another thing to consider internally is that if the Flow Gradle Plugin would have frontendHotdeployDependencies as a plugin configuration property, one would not need to do the system property forwarding since the plugin would pick it up from its configuration in build.gradle.

I'm not exactly sure what you're using to run the app, I was using Jetty via Gretty plugin.

There is

Application Server (if applicable): Wildfly V35

Mentioned in the issue description.

Application Server (if applicable): Wildfly V35

Mentioned in the issue description.

Thanks, missed that. Maybe I'll wait for more info or test results from the author. Quickly searching I could not find a Wildfly plugin for Gradle (well there was something last updated 2018), so not sure how to run it in dev mode with Wildfy+Gradle combination.

@nico-fri Could you please check if the comments here help you at all? Additionally, it would help my testing if you could provide information on your setup to run the dev mode using WIldfly+Gradle. Thank you!

Separated by a comma, the system property works
=> -Dvaadin.frontend.hotdeploy.dependencies='../project-components,../project-components-2,../project-main'.
Unfortunately only for the project-components and the project-components-2 project. However, frontendHotdeploy does not work for the main project (project-main).

The project consists of two Vaadin Gradle Starter templates (https://github.com/vaadin/base-starter-gradle) with the customizations from the initial request (Minimal reproducible example). It is started with the default Wildfly (https://www.wildfly.org/downloads/) and the VM options (-Dvaadin.frontend.hotdeploy.dependencies).

And to the other addition: It would be very helpful if the Flow Gradle plugin would have frontendHotdeployDependencies as a configuration property.

Tried my project with latest Wildfly with the same result: both the root project and the two sub-project hotdeploy works correctly. I probably have something set up differently than you do, but right now I can't see it. I'll attach my project here so you can take a look at what is the difference.

Please note the root build.gradle contains Gretty config so that can be run from command line. For Wildfly I deployed and started using IDEA.

GradleTest.zip

The difference between our projects is that the frontend folder of the main project is under src/main/frontend. In my project, it is located under src/main/resources/META-INF/resources/frontend, just like in the components projects. The reason for this is that the main project is also only a part of another overall project.

As a comparison in our example, we can say that the individual “components” projects can be started alone for development purposes with development routes to display/develop the components in isolation. In this case, the frontendHotdeploy does not work (provided, of course, that frontendHotdeploy = true is set in the build.gradle of the components project).

Setting the frontendDirectory in build.gradle did not help either:
frontendDirectory = new File(project.projectDir, “src/main/resources/META-INF/resources/frontend”)

Related Docs issue: vaadin/docs#2412