Docker nginx: [emerg] host not found in upstream “web:3000”

Question

I released my reactJs application. I have code information as below. But I get the error “11 # 11: host not found in upstream”. where could i have made a mistake Could you help ?

I get an upStream error even though my docker, nginx, and docker-compose file is correct. I had run the same codes before but I could not find where I made changes.

I’ve been researching for 2 days, but I get an upstream not found error.

I couldn’t find where I made a mistake. please can you help with the solution ?

I added the screenshot, it gives upstream not found error. I can’t find a solution https://ibb.co/10BH3bv 1

web: I tried ports like 80, 443 but it is not resolved

default.conf

 upstream frontend_server{
      server web:3000;
 }

  server{
   listen 80;
   resolver 127.0.0.11;

   location /.well-known/acme-challenge/ {
       root /var/www/certbot;
   }
   location / {
       return 301 https://$host$request_uri;
   }
  } 
  # SSL
 server {
   listen 443 ssl;
   resolver 127.0.0.11;

   ssl_certificate /usr/share/nginx/certificates/fullchain.pem;
   ssl_certificate_key /usr/share/nginx/certificates/privkey.pem;
   include /etc/ssl-options/options-nginx-ssl.conf;
   ssl_dhparam /etc/ssl-options/ssl-dhparams.pem;

 location / {
   proxy_pass http://frontend_server;
   proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
   proxy_set_header Host $host;
   proxy_redirect off;

   #Websocket support
   proxy_http_version 1.1;
   proxy_set_header Upgrade $http_upgrade;
   proxy_set_header Connection "upgrade";
 }
}

docker-compose.yml


 version: '3'
 services:
   nginxproxy:
     build:
       context: .
       dockerfile: Dockerfile.lets
     container_name: nginxproxy
     networks:
      - nginx_network
     restart: always
     expose:
       - 80
     ports:
       - "443:443"
       - "80:80"
     environment:
       DOMAIN: mySiteaddress.com
       EMAIL: myMail@hotmail.com
       RENEW_INTERVAL: 12h
     volumes:
       - ./certificates:/usr/share/nginx/certificates
       - ./default.conf:/etc/nginx/conf.d/default.conf

   web:
     build:
       context: .
       dockerfile: Dockerfile.dev
     container_name: web
     networks:
      - nginx_network
     expose:
       - 3000
     ports:
        - "3000:3000"
     depends_on:
       - nginxproxy
     volumes:
       - /app/node_modules
       - .:/app
   tests:
     build:
       context: .
       dockerfile: Dockerfile.dev
     container_name: tests
     volumes:
       - /app/node_modules
       - .:/app
     command: ["npm","run","test"]


 networks:
   nginx_network:
     driver: bridge

Dockerfile.dev


 FROM node:alpine
 WORKDIR '/app'
 COPY package.json .
 RUN npm install
 COPY . . 
 EXPOSE 3000
 CMD ["npm", "run", "start"]

Dockerfile.lets


 FROM nginx:1.15-alpine
 RUN apk add inotify-tools certbot openssl ca-certificates
 WORKDIR /opt
 COPY entrypoint.sh nginx-letsencrypt
 COPY certbot.sh certbot.sh
 COPY ssl-options/ /etc/ssl-options
 COPY default.conf /etc/nginx/conf.d/default.conf
 RUN chmod +x nginx-letsencrypt && \
     chmod +x certbot.sh

 EXPOSE 443

 ENTRYPOINT ["./nginx-letsencrypt"]
 CMD ["nginx", "-g", "daemon off;"]

package.json


 {
    "name": "customer_Flow",
    "version": "1.0.0",
    "description": "Customer flow",
    "copyright": "Copyright 2019",
    "license": "MIT",
    "private": true,
    "repository": {
    "type": "git",
         "url": "git@github.com:coreui/coreui-free-react-admin-template.git"
   },
   "dependencies": {
     "@coreui/coreui": "^2.1.16",
     "@coreui/coreui-plugin-chartjs-custom-tooltips": "^1.3.1",
     "@coreui/icons": "0.3.0",
     "@coreui/react": "^2.5.7",
     "@date-io/date-fns": "^2.6.1",
     "@devexpress/dx-react-chart": "^2.6.2",
     "@devexpress/dx-react-chart-material-ui": "^2.6.2",
     "@devexpress/dx-react-core": "^2.6.2",
     "@devexpress/dx-react-grid": "^2.6.0",
     "@devexpress/dx-react-grid-material-ui": "^2.6.0",
     "@devexpress/dx-react-scheduler": "^2.6.0",
     "@devexpress/dx-react-scheduler-material-ui": "^2.6.0",
     "@material-ui/core": "^4.9.8",
     "@material-ui/icons": "^4.9.1",
     "bootstrap": "^4.4.1",
     "chart.js": "^2.9.2",
     "classnames": "^2.2.6",
     "core-js": "^3.6.4",
     "cors": "^2.8.5",
     "corsproxy": "^1.5.0",
     "date-fns": "^2.12.0",
     "dotenv": "^8.2.0",
     "enzyme": "^3.11.0",
     "enzyme-adapter-react-16": "^1.15.2",
     "flag-icon-css": "^3.4.6",
     "font-awesome": "^4.7.0",
     "http-proxy-middleware": "^0.20.0",
     "jquery": "^3.4.1",
     "jwt-decode": "^2.2.0",
     "moment": "^2.24.0",
     "node-sass": "^4.13.1",
     "nodemon": "^2.0.2",
     "prettier": "^1.18.2",
     "prop-types": "^15.7.2",
     "react": "^16.13.1",
     "react-alert": "^6.0.1",
     "react-alert-template-basic": "^1.0.0",
     "react-app-polyfill": "^1.0.6",
     "react-chartjs-2": "^2.9.0",
     "react-dom": "^16.13.1",
     "react-notifications-component": "^2.4.0",
      "react-redux": "^7.2.0",
     "react-router-config": "^5.1.1",
     "react-router-dom": "^5.1.2",
     "react-test-renderer": "^16.13.1",
     "reactstrap": "^8.4.1",
     "redux": "^4.0.5",
     "redux-devtools-extension": "^2.13.8",
     "redux-persist": "^6.0.0",
     "redux-thunk": "^2.3.0",
     "simple-line-icons": "^2.4.1",
     "typescript": "^3.8.3"
   },
   "devDependencies": {
     "react-scripts": "^3.4.1"
   },
   "scripts": {
     "start": "react-scripts start",
     "build": "react-scripts build",
     "test": "react-scripts test",
     "test:cov": "npm test -- --coverage --watchAll=false",
     "test:debug": "react-scripts --inspect-brk test --runInBand",
     "eject": "react-scripts eject"
   },
   "bugs": {
     "url": "https://github.com/coreui/coreui-free-react-admin-template/issues"
   },
   "eslintConfig": {
     "extends": "react-app"
   },
   "browserslist": [
     ">0.2%",
     "not dead",
     "not ie <= 9",
     "not op_mini all"
    ],
   "jest": {
     "collectCoverageFrom": [
       "src/**/*.{js,jsx}",
       "!**/*index.js",
       "!src/serviceWorker.js",
       "!src/polyfill.js"
     ]
   },
  "engines": {
     "node": ">=8.10",
     "npm": ">=6"
   }
 }
``

Clay Herendeen · Answer

@pkraak , It could be possible that the containers you are trying to link may not be on the same network. You could try putting them all on the same network: services: example_service_1: image: example_service_1/image container_name: example_service_1 ... ... networks: - example-net example_service_2: image: example_service_2/image container_name: example_service_2 ... ... networks: - example-net nginx: image: nginx container_name: nginx ports: - 80:80 - 443:443 ... ... networks: - example-net networks: example-net: external: true

Peter Kraak · Answer

I am having nearly identical issue. If you connect to the nginx container you will find that you cannot resolve external URL from within, it is not using your host DNS. I connect with $docker exec -it container_name /bin/bash

I have not been able to find a way to use docker-compose networking (i.e. linking between containers, depends_on) AND set DNS to access external hosts.

has anyone else solved this?

Bobby Iliev · Answer

Hi there @turkdoktoru , I believe that the problem is caused by the depends_on directive, currently, your web service depends on the Nginx service, but it has to be the other way around. You need to have your web service up and running first before bringing up your Nginx service otherwise the Nginx service would fail as it would not find the web service. Let me know how it goes!Regards,Bobby

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