Web app works well inside docker container but can not access from host

Docker Desktop
,
1
  • OS Version/build: Windows 10 22H2
  • App version: Docker version 20.10.17, build 100c701
  • Steps to reproduce:
  1. install Docker Desktop for Windows
  2. a Hello World Ruby on Rails app in Dockerfile (copy&paste this from somewhere on the internet) , this issue happen with every helloworl docker app on my machine like django, nodejs etc…
FROM ruby:2.7
WORKDIR /app
RUN apt-get update; \
    apt-get upgrade -y; \
    apt-get install -y build-essential libssl-dev libreadline-dev libyaml-dev \
      default-libmysqlclient-dev gnupg2 nodejs
RUN gem install rails --no-document; rails new .
ENV RAILS_ENV="development"
EXPOSE 3000
CMD ["bundle", "exec", "rails", "server"]
  1. build and run it with port 3000 mapping
docker build - < Dockerfile -t demo01:1.0 
docker run -p 3000:3000 demo01:1.0
  1. try to access from http://localhost:3000 and failed
error screenshot

localhost:3000 failed

image
image1858×1072 20.1 KB

  1. check with docker exec and curl to verify if the app working inside container
docker ps
docker exec -it my-container-id-here /bin/sh
curl localhost:3000

the curl inside container return the proper html content so the app is working well inside containter

curl result 
> docker exec -it 287f8b720a90 /bin/sh
# curl localhost:3000
<!DOCTYPE html>
<html>
<head>
  <title>Ruby on Rails 7.0.4.2</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <link rel="icon" href="data:image/svg+xml;base64,PHN2ZyB3aWR0aD0iMzIwcHgiIGhlaWdodD0iMzIwcHgiIHZpZXdCb3g9IjAgMCAzMjAgMzIwIiB2ZXJzaW9uPSIxLjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyIgeG1sbnM6eGxpbms9Imh0dHA6Ly93d3cudzMub3JnLzE5OTkveGxpbmsiPgogICAgPHRpdGxlPkljb248L3RpdGxlPgogICAgPGcgaWQ9Ikljb24iIHN0cm9rZT0ibm9uZSIgc3Ryb2tlLXdpZHRoPSIxIiBmaWxsPSJub25lIiBmaWxsLXJ1bGU9ImV2ZW5vZGQiPgogICAgICAgIDxnIGlkPSJSdWJ5LU9uLVJhaWxzLUxvZ28iIHRyYW5zZm9ybT0idHJhbnNsYXRlKDUuMDAwMDAwLCAyMC4wMDAwMDApIiBmaWxsPSIjRDgxRTAwIj4KICAgICAgICAgICAgPHBhdGggZD0iTTIxLjkzMzA3MDYsMjg1IEwxNjguMTc1NDI2LDI4NSBDMTQ3Ljk0MDg1OCwxNTAuNjkxNzA2IDE5Ni44ODIzODMsNjYuMzE0MjkwMiAzMTUsMzEuODY3NzUzNiBDMzE1LDIxLjc4NTEyODQgMzE1LDMxLjg2Nzc1MzYgMzE1LDIxLjc4NTEyODQgQzE2MS4yNTI4MywyNC45MTE2Mjc4IDYzLjU2Mzg1MzMsMTEyLjY0OTkxOCAyMS45MzMwNzA2LDI4NSBaIiBpZD0iUGF0aCIvPgogICAgICAgICAgICA8cG9seWdvbiBpZD0iUGF0aCIgcG9pbnRzPSI0MC40MDgyNjQzIDE4NS45MTU3MSAxMi43MzI2NDk0IDE3NC40MDE2NjMgLTEuNDIxMDg1NDdlLTE0IDIwNS40NDI3MSAyOS41NzExOTY2IDIxNi42NDcxMTUiLz4KICAgICAgICAgICAgPHBvbHlnb24gaWQ9IlBhdGgiIHBvaW50cz0iMTgwLjQ3MzEwMiAyNjguMDczNjQzIDIwNC45MzYwMTYgMjc2LjQxMDk2NiAyMDQuOTM2MDE2IDI1NC41MDg2NzMgMTgwLjQ4OTY0NCAyNDQuMzM4MTA3Ii8+CiAgICAgICAgICAgIDxwb2x5Z29uIGlkPSJQYXRoIiBwb2ludHM9IjEwMC41ODk1MTkgOTcuMjI4NzYwNiA3Ni42ODQwMTU2IDc5LjE2ODcwMjEgNTUuMjQ0MDc5MSAxMDAuMTgzMTA1IDgxLjUxNDMyMzkgMTE3LjQzMzcyNSIvPgogICAgICAgICAgICA8cG9seWdvbiBpZD0iUGF0aCIgcG9pbnRzPSIxODQuNTc1Njc5IDE4NC44OTYyOTUgMjA3Ljk1MjAzIDIwMC4yNDY2MSAyMTEuNzI3NzI5IDE4MS4yMDUyNjYgMTg5Ljg2MzY1MyAxNjQuNjg3NDYiLz4KICAgICAgICAgICAgPHBvbHlnb24gaWQ9IlBhdGgiIHBvaW50cz0iMjYxLjczNDAxIDY1Ljg5NTk0NDYgMjY5LjM1NDIzNCA4Mi4zMjk1NCAyODUuMzE4MjU2IDcyLjcwNDg1OTYgMjc4LjMxMDEyOSA1Ni45ODI5ODk1Ii8+CiAgICAgICAgICAgIDxwb2x5Z29uIGlkPSJQYXRoIiBwb2ludHM9IjI2MS45MTM3IDE2LjE4NDU0NzMgMjU1LjU5ODQ3OSA3LjEwNTQyNzM2ZS0xNSAyMzIuNzk2MDIgMy40ODg5NjMyMyAyNDAuNDYzODczIDIwLjAyNTI3MjUiLz4KICAgICAgICAgICAgPHBvbHlnb24gaWQ9IlBhdGgiIHBvaW50cz0iMjExLjkzNDExOSAxMTEuNTgwNjc1IDIyNi43MjI1NDcgMTI3Ljc5MjYwMSAyMzguMDIzOTI1IDExMy45MDM3MTUgMjIzLjQ2ODM3NSA5Ni41NDY4Njg1Ii8+CiAgICAgICAgICAgIDxwb2x5Z29uIGlkPSJQYXRoIiBwb2ludHM9IjE3OS42ODY4NTggMzguNDk1MjIxOCAxNjQuNjQxOTMxIDIwLjAyNTI3MjUgMTM5Ljg0NzYyIDMyLjU1NTI5OTIgMTU2LjYwMTMyNCA1MC45MjE2NzUzIi8+CiAgICAgICAgPC9nPgogICAgPC9nPgo8L3N2Zz4=" />

  <style type="text/css">
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      align-items: center;
      background-color: #F0E7E9;
      background-image: url(data:image/svg+xml;base64,PHN2ZyBoZWlnaHQ9IjEwMjQiIHZpZXdCb3g9IjAgMCAxNDQwIDEwMjQiIHdpZHRoPSIxNDQwIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjxwYXRoIGQ9Im0xNDQwIDUxMC4wMDA2NDh2LTUxMC4wMDA2NDhoLTE0NDB2Mzg0LjAwMDY0OGM0MTcuMzExOTM5IDEzMS4xNDIxNzkgODkxIDE3MS41MTMgMTQ0MCAxMjZ6IiBmaWxsPSIjZmZmIi8+PC9zdmc+);
      background-position: center center;
      background-repeat: no-repeat;
      background-size: cover;
      color: #261B23;
      display: flex;
      flex-direction: column;
      font-family: Sans-Serif;
      font-size: calc(0.9em + 0.5vw);
      font-style: normal;
      font-weight: 400;
      justify-content: center;
      line-height: 1.25;
      min-height: 100vh;
      text-align: center;
    }

    nav {
      font-size: 0;
      height: 20vw;
      line-height: 0;
      max-height: 280px;
      max-width: 280px;
      min-height: 86px;
      min-width: 86px;
      width: 20vw;
    }

    nav a {
      background: #D30001;
      border-radius: 100%;
      display: flex;
      transition: background 0.25s cubic-bezier(0.33, 1, 0.68, 1);
    }

    nav a:hover {
      background: #261B23;
    }

    nav a img {
      height: auto;
      max-width: 100%;
      width: 100%;
      cursor: pointer;
    }

    ul {
      bottom: 0;
      left: 0;
      list-style: none;
      margin: 0 2rem 2rem 2rem;
      position: absolute;
      right: 0;
    }
  </style>
</head>

<body>
  <nav>
    <a href="https://rubyonrails.org" target="_blank">
      <img alt="" src="data:image/svg+xml;base64,<svg height="112" viewBox="0 0 112 112" width="112" xmlns="http://www.w3.org/2000/svg"><path d="m100.082357 48.9995403v4.1135034h-7.3003388v1.89854h3.6840717c1.9725091 0 4.0725341 1.4664311 4.1979971 3.9665124l.005913.2373977v1.5821167c-.087824 3.007959-2.5431211 4.1390018-4.0715389 4.2011773l-.1323712.0027328h-7.3907451v-4.0909018l7.4811518-.0226016v-1.9889467h-3.4806567c-1.7752583 0-4.0818321-1.3389153-4.2199942-3.9549201l-.0065176-.24899v-1.423905c0-2.6982402 2.2782129-4.182853 4.065464-4.2678491l.1610478-.003866zm-18.691579 0v11.8658752h6.1702551v4.1361051h-10.7357919v-16.0019803zm-6.4414751 0v16.0019803h-4.5881385v-16.0019803zm-15.210922 0h4.4073251l.187724.0066812c.0338609.0022735.0689457.0051499.1051601.0086643l.2300875.0290178c1.2913829.1985476 3.5463816 1.1213816 3.6751708 3.9068587l.0057677.2526881v11.7980702h-4.2717151v-2.8252084h-4.1361051v2.8252084h-4.4073251v-11.7980702c0-1.3184306 1.0040826-4.0468495 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fill="#fff"/></svg>" />
    </a>
  </nav>

  <ul>
    <li><strong>Rails version:</strong> 7.0.4.2</li>
    <li><strong>Ruby version:</strong> ruby 2.7.7p221 (2022-11-24 revision 168ec2b1e5) [x86_64-linux]</li>
  </ul>
</body>

</html>

Then, could you please give me any advice about how to check and fix this issue?

2

Typically, people experience this behavior, because the application inside the container either binds to localhost or 127.0.0.1, listens on a different port or requires the udp protocol. In order for the port mapping you specified (`-p 3000:3000) to work, the application needs to bind to 0.0.0.0 (=all interfaces) and listen on port 3000/tcp.

2 Likes
3

Right. With Rails 4.2 or later rails server binds to local host by default. To bind to 0.0.0.0 you can run rails server -b 0.0.0.0, or you can add a few lines of code to config/boot.rb as documented in a StackOver post’s answers.

2 Likes
4

New to docker so I could be wrong. Your Dockerfile only contains detail of one port in the EXPOSE section. Should there not be two as in 3000:3000 ?

5

No, that would be syntactically incorrect. You can’t define port forward in a Dockerfile as you can’t tell if that port will be available on the machine where the image is used.

https://docs.docker.com/engine/reference/builder/#expose