JHipster/Microservices frontend development hot reload - docker-compose

Question

I have created a JHipster microservices application and want to do some frontend development on it. Launching the whole microservices stack in the ./docker-compose/ directory with docker-compose up -d works as expected. Registry shows all microservices, the gateway and an UAA instance with status 'up'. No exceptions thrown. Login to http://localhost:8080 works as expected.
Launching yarn start in the gateway project directory launches the development server via webpack and browsersync. Hot reload works as expected when pointing the browser at http://localhost:9000.
Now to my problem/question: logging into http://localhost:9000 as user/user doesn't work, as the account cannot be retrieved. The thrown exception is irrelevant because it just states that the account is null:
webpack-internal:///…fesm5/core.js:16064 ERROR Error: Uncaught (in promise):
TypeError: Cannot read property 'langKey' of null
TypeError: Cannot read property 'langKey' of null
at LoginService.setPreferredLanguage (webpack-internal:///…
login.service.ts:34)
....
But when I point the browser back to http://localhost:8080, I'm logged in as 'user'. Which means that the login on the backend worked.
Being new to docker and microservices, I'm suspecting that I'm conceptually missing something (networks/ports/etc..). Any ideas that could point to finding a solution? Or what is the suggested setup/practices for developing the frontend in a JHipster/microservices configuration.

Answer 1

There has been an error in the webpack.dev.js configuration file and because UAA was added later to the project, the UAA module was missing in the contexts to be proxies:
devServer: {
contentBase: './build/www',
proxy: [{
context: [
'/microservice1',
'/microservice2',
'/microserviceuaa', /* !!! was missing !!! */
/* jhipster-needle-add-entity-to-webpack - JHipster will add entity api paths here */
'/api',
'/management',
'/swagger-resources',
'/v2/api-docs',
'/h2-console',
'/auth'
],
target: `http${options.tls ? 's' : ''}://127.0.0.1:8080`,
secure: false,
changeOrigin: options.tls,
headers: { host: 'localhost:9000' }
}],