POST https://localhost:3008/v1/login net::ERR_CONNECTION_REFUSED

I had a setup to deploy a React app and a nodejs server with their services. https://github.com/Binomi0/gbpd/tree/develop/pods/gbpd

I can start all without errors but:
If runs kubectl exec -it "gbpd-front-xxxxx" -- /bin/bash and then curl https://gbpd-api No answer
If runs kubectl exec -it "gbpd-front-xxxxx" -- /bin/bash and then curl gbpd-api No answer
If runs kubectl exec -it "gbpd-front-xxxxx" -- /bin/bash and then curl https://gbpd-api:3008 Gets this answer:

curl: (60) SSL certificate problem: self signed certificate
More details here: https://curl.haxx.se/docs/sslcerts.html

curl performs SSL certificate verification by default, using a "bundle"
 of Certificate Authority (CA) public keys (CA certs). If the default
 bundle file isn't adequate, you can specify an alternate file
 using the --cacert option.
If this HTTPS server uses a certificate signed by a CA represented in
 the bundle, the certificate verification probably failed due to a
 problem with the certificate (it might be expired, or the name might
 not match the domain name in the URL).
If you'd like to turn off curl's verification of the certificate, use
 the -k (or --insecure) option.

As far as I know, with lastone it gets a response so why getting the title error in web?

What manage to get working with docker-compose file

I got a docker-compose file https://github.com/Binomi0/gbpd/blob/develop/docker-compose.yml that runs ok.

...
args:
  REACT_APP_API_URL: https://localhost:3008

Then I can run docker-compose up and get everything connecting OK.

What I can see:

Project needs to be built with then ENV var set before build process?.
Then if i set environment: - foo=bar it goes to container but the app misses it. So we can't use environment vars in this kind of setup?
When runs docker-compose up we are building the image and passing as args to Dockerfile ARG and setting the right ENV vars before building.

#Dockerfile

FROM node:12

WORKDIR /usr/src/app/front

ARG REACT_APP_API_URL
RUN echo $REACT_APP_API_URL

ENV REACT_APP_API_URL=$REACT_APP_API_URL

COPY package*.json ./

RUN npm install

COPY . .

RUN npm run build

RUN npm install -g serve

EXPOSE 3000

CMD ["serve", "-s", "build", "-l", "3000"]

I'm lost in how to connect front to back with this setup, so will be very appreciated if someone can show some light on it. Why can't connect using localhost like in development or deploying with compose? Why even creating build passing gbpd-api it gets refused?

I can give more feedback if needed.
Thx in advance!!