All pods and databases are running successfully
I have a login page, with endpoint /login on the frontend service, but it cannot redirect to the rest-service, can everyone help me to fix the problem (I run it successfully on my local machine manually).

1. This is how I built and deploy my front-end service:

nginx.conf:

worker_processes auto;

events {
    worker_connections 8000;
    multi_accept on;
}

http {
    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    log_format compression '$remote_addr - $remote_user [$time_local] '
                           '"$request" $status $upstream_addr '
                           '"$http_referer" "$http_user_agent"';

    server {
        listen 3000;
        access_log /var/log/nginx/access.log compression;

        root /usr/share/nginx/html;
        index index.html index.htm;

        location / {
            try_files $uri $uri/ /index.html;
        }

        # Proxy API requests to backend
        location /api {
            proxy_pass $REACT_APP_BACKEND_HOST;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection 'upgrade';
            proxy_set_header Host $host;
            proxy_cache_bypass $http_upgrade;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
        }

        # Media: images, icons, video, audio, HTC
        location ~* .(?:jpg|jpeg|gif|png|ico|cur|gz|svg|svgz|mp4|ogg|ogv|webm|htc)$ {
            expires 1M;
            access_log off;
            add_header Cache-Control "public";
        }

        # Javascript and CSS files
        location ~* .(?:css|js)$ {
            try_files $uri =404;
            expires 1y;
            access_log off;
            add_header Cache-Control "public";
        }

        # Any route containing a file extension (e.g. /devicesfile.js)
        location ~ ^.+..+$ {
            try_files $uri =404;
        }
    }
}

Dockerfile:

FROM node:18-alpine as build

WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

FROM nginx:stable-alpine
COPY --from=build /app/build /usr/share/nginx/html
COPY nginx.conf /etc/nginx/nginx.conf
COPY entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh
ENTRYPOINT ["/entrypoint.sh"]
CMD ["nginx", "-g", "daemon off;"]

entrypoint.sh:

envsubst '$REACT_APP_BACKEND_HOST' < /etc/nginx/nginx.conf.template > /etc/nginx/nginx.conf
nginx -g 'daemon off;'

2. And here is my config on Kubernetes:

rest-client-deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: client-frontend
  labels:
    app: client-frontend
spec:
  replicas: 1
  selector:
    matchLabels:
      app: client-frontend
  template:
    metadata:
      labels:
        app: client-frontend
    spec:
      containers:
      - name: client
        image: daniel135dang/client:1.0.0-6
        ports:
        - containerPort: 3000
        envFrom:
          - configMapRef:
              name: app-config
        env:
        - name: REACT_APP_BACKEND_HOST
          valueFrom:
            configMapKeyRef:
              name: app-config
              key: REACT_APP_BACKEND_HOST
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: rest-backend
  labels:
    app: rest-backend
spec:
  replicas: 1
  selector:
    matchLabels:
      app: rest-backend
  template:
    metadata:
      labels:
        app: rest-backend
    spec:
      volumes:
      - name: rest-file
        persistentVolumeClaim:
          claimName: rest-file-pvc
      - name: google-credentials
        secret:
          secretName: google-credentials
      containers:
      - name: rest-backend
        image: daniel135dang/rest:1.0.0-6
        ports:
        - containerPort: 5000
        volumeMounts:
        - name: rest-file
          mountPath: /mnt/rest/files
        - name: google-credentials
          mountPath: /app/google_credentials.json
          subPath: google_credentials.json
          readOnly: true
        env:
          - name: PORT
            value: "5000"
          - name: APP_NAME
            value: "rest"
          - name: HOST
            value: "rest-service"
          - name: RABBITMQ_HOST
            value: "amqp://rabbitmq:5672"
          - name: RABBITMQ_FILE_LOCATION_EXCHANGE
            value: "uploaded_file_location"
          - name: RABBITMQ_OUTPUT_LOCATION_EXCHANGE
            value: "output_location"
          - name: POSTGRES_HOST
            valueFrom:
              configMapKeyRef:
                name: services-config
                key: POSTGRES_HOST
          - name: POSTGRES_USER
            valueFrom:
              configMapKeyRef:
                name: services-config
                key: POSTGRES_USER
          - name: POSTGRES_PASSWORD
            valueFrom:
              configMapKeyRef:
                name: services-config
                key: POSTGRES_PASSWORD
          - name: POSTGRES_DB
            valueFrom:
              configMapKeyRef:
                name: services-config
                key: POSTGRES_DB
          - name: ROOT_DIR
            valueFrom:
              configMapKeyRef:
                name: services-config
                key: ROOT_DIR
          - name: REACT_APP_SERVICE_LIST
            valueFrom:
              configMapKeyRef:
                name: app-config
                key: REACT_APP_SERVICE_LIST
          - name: GUIDELINES_LIST
            value: "chapter_title,format_check,page_count"
          - name: GOOGLE_CLOUD_STORAGE_BUCKET
            valueFrom:
              configMapKeyRef:
                name: services-config
                key: GOOGLE_CLOUD_STORAGE_BUCKET
---
apiVersion: v1
kind: Service
metadata:
  name: client-frontend-service
spec:
  type: LoadBalancer
  selector:
    app: client-frontend
  ports:
    - protocol: TCP
      port: 3000
      targetPort: 3000
---
apiVersion: v1
kind: Service
metadata:
  name: rest-service
spec:
  type: ClusterIP
  selector:
    app: rest-backend
  ports:
    - protocol: TCP
      port: 5000
      targetPort: 5000

app-config.yml:

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  REACT_APP_SERVICE_LIST: "word_frequency,chapter_title,format_check,chapter_summarization,page_count,table_of_content,citation,table_figure_detection"
  REACT_APP_BACKEND_HOST: "http://rest-service:5000"