[FIXED] Docker - I have a NodeJs Server and a Flask Server that are dockerized. Fetch request from NodeJs to Flask doesn't work, but in Postman it does

Issue

So i have this flask app which trains a model for sentiment analysis and this is how I start the app.

if __name__ == '__main__':
    app.run(debug=False, host="0.0.0.0", port=5000)

The docker file is the following:

FROM python:3.9-slim-buster

WORKDIR /python-docker

COPY requirements.txt requirements.txt
COPY good_words.txt good_words.txt
COPY bad_words.txt bad_words.txt
COPY imdb_labelled.txt imdb_labelled.txt
COPY amazon_cells_labelled.txt amazon_cells_labelled.txt
COPY yelp_labelled_good.txt yelp_labelled_good.txt
RUN pip3 install -r requirements.txt

COPY . .

EXPOSE 5000

CMD [ "python3", "main.py", "-h", "0.0.0.0", "-p", "5000"]

I have this Node JS app from which I make a POST request to the flask server in order to analyse some data.

  const paragraphs = await Promise.all(
    result.paragraphs.map(async (paragraph) => {
      try {
        const response = await axios.post(
          url,
          JSON.stringify({ text: paragraph }),
          {
            headers: {
              "Content-Type": "application/json",
            },
          }
        );
        const sentimentResponse = parseFloat(response.data);
        if (sentimentResponse > threshold.positive) {
          return { paragraph: paragraph, sentiment: "Positive" };
        } else if (sentimentResponse < threshold.negative) {
          return { paragraph: paragraph, sentiment: "Negative" };
        } else {
          return { paragraph: paragraph, sentiment: "Neutral" };
        }
      } catch (error) {
        throw new AppError("Failed to retrieve Sentiments", 500);
      }
    })
  );
  return paragraphs;
};

The url is basically http://127.0.0.1:5000/sentiment which is the URL I am using in the flask app to listen to requests.

The interesting is that if i run this request from outside the NodeJS app, e.g. Postman, it works, but from the axios request it doesn't.

What can i do?

Solution

backend:
#other configurations
   networks:
            app_net:
                ipv4_address: 172.16.238.2
frontend:
#other configurations
    networks:
            app_net:
                ipv4_address: 172.16.238.3

flask:
    #other configurations
    networks:
            app_net:
                ipv4_address: 172.16.238.4

networks:
    app_net:
        ipam:
            driver: default
            config:
            - subnet: "172.16.238.0/24"

Answered By - Ștefan Jiroveanu