How to access NodeJS server that is running in the same pod?

Question

I am trying to deploy an app to Kubernetes. I have 2 containers: Angular app, hosted by nginx, and Node.js server. I run those containers in the same pod. The issue is that Angular app can't access the Node.js api. Here is my nginx's default.conf:

server {
    listen 80;
    server_name localhost;

    location / {
        root /usr/share/nginx/html;
        try_files $uri $uri/ /index.html;
        index index.html;
    }

    location /api/ {
        proxy_pass http://localhost:3000;
        proxy_http_version 1.1;
    }
}

Here is my Dockerfile for the Angular app:

FROM node:lts-alpine AS build

WORKDIR /app
COPY . .

RUN npm install

RUN npm run build:prod

FROM nginx:stable-alpine

COPY nginx/default.conf /etc/nginx/conf.d/default.conf
COPY --from=build /app/dist/mag-ui /usr/share/nginx/html

Here is my deploy.yml that I run on a Kubernetes cluster:

kind: Namespace
metadata:
  name: mag
---
apiVersion: apps/v1
kind: Deployment
metadata:
  namespace: mag
  name: mag
  labels:
    app: mag
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mag
  minReadySeconds: 10
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
      maxSurge: 1
  template:
    metadata:
      labels:
        app: mag
    spec:
      terminationGracePeriodSeconds: 10
      containers:
      - name: mag-api
        image: mag-api
        imagePullPolicy: "Always"
        ports:
        - containerPort: 3000
      - name: mag-ui
        image: mag-ui
        imagePullPolicy: "Always"
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  namespace: mag
  name: mag-svc
  labels:
    app: mag
spec:
  ports:
  - port: 80
    name: ui
    targetPort: 80
  selector:
    app: mag

So when I deploy this to my local cluster (and forward port 8080:80 of service/mag-svc) and browse localhost:8080, the ui app tries to query data from Node.js server and fails with: GET http://localhost:3000/api/mag/models net::ERR_CONNECTION_REFUSED .

However , if I connect to Angular app container's shell and curl the localhost:3000/api/mag/models , it works fine and I get the expected response.

Looks like it tries to access localhost of my host vm, instead of localhost of a container where the Angular app is running. So, how to make the Angular app call Node.js api, that runs in the same pod?

Answer 1

angular runs in your browser so the connections to http://localhost:3000 from the app running in your browser are to your PC's localhost:3000 .

You can create a Service for the nodejs container:

apiVersion: v1
kind: Service
metadata:
  namespace: mag
  name: mag-svc-api
  labels:
    app: mag
spec:
  ports:
  - port: 3000
    name: mag-api
    targetPort: 3000
  selector:
    app: mag

... then forward traffic for localhost:3000 to the Service : kubectl port-forward -n mag mag-svc-api 3000:3000 . Connections from the app running in your browser to http://localhost:3000 would be forwarded to the Service -> container running in Kubernetes .