Hi Brian,
This is what I understand from building and deploying web apps via Docker in Wappler.
When deploying a project in Docker (locally or remotely), the node modules are installed via the package.json file. Basically, everytime a project is deployed via Docker, it installs the packages.
There are two files that drive this process: docker-compose.yml and Dockerfile. Both files are available here .wappler > targets > target_name > docker-compose.yml and .wappler > targets > target_name > web > Dockerfile.
I don't think this is related to Docker or the absence of node_modules folder. I have come across this issue where the extension was installed correctly, but it didn't add any npm modules and files in the extensions/server_connect_modules folder that were needed to run this extension. I had to manually copy the files and add the npm module in the package.json file before re-deploying the docker project.
At the time, I thought it was something wrong with my setup, but it seems it may be an issue or a bug with the installation of extensions itself.