通过Dockerfile修改Nginx默认首页后，运行容器仍显示默认页的问题

Let's break down the most likely issues and fixes here — this is a super common snag with Nginx Docker setups, so we'll get it sorted quickly!

1. Nginx Doesn't Know to Load welcome.html by Default #

This is the #1 reason for this problem. The official Nginx image is configured to look for index.html (or index.htm) as the default landing page — it has no idea about your welcome.html file unless you explicitly tell it to prioritize it.

Fixes for this: #

• Simplest fix: Rename your file to index.html
  Just rename your local HTML file to index.html, then update your Dockerfile to copy it:

  FROM nginx:latest
  WORKDIR /usr/share/nginx/html
  COPY index.html index.html
  

  Rebuild your image (docker image build -t html_nginx .) and rerun the container — this should immediately load your custom page.

• Customize Nginx's configuration to use welcome.html
  If you want to keep the filename as welcome.html, create a custom Nginx config file (let's call it default.conf) with the following content:

  server {
      listen       80;
      listen  [::]:80;
      server_name  localhost;
  
      location / {
          root   /usr/share/nginx/html;
          index  welcome.html index.html index.htm; # Add welcome.html as the first priority
      }
  
      error_page   500 502 503 504  /50x.html;
      location = /50x.html {
          root   /usr/share/nginx/html;
      }
  }
  

  Then update your Dockerfile to copy this config into the Nginx config directory:

  FROM nginx:latest
  WORKDIR /usr/share/nginx/html
  COPY welcome.html welcome.html
  COPY default.conf /etc/nginx/conf.d/default.conf
  

  Rebuild and rerun the container — Nginx will now prioritize your welcome.html over the default index.html.

• Temporary fix: Override Nginx's index at runtime
  If you don't want to rebuild the image, you can pass a custom Nginx command when starting the container:

  docker container run -p 80:80 --rm html_nginx nginx -g "daemon off; index welcome.html;"
  

2. Verify welcome.html Was Actually Copied to the Image #

Sometimes the issue is that your welcome.html file wasn't copied into the image at all. Let's check:

• Run a temporary container to inspect the image's contents:

  docker run --rm -it html_nginx /bin/bash
  

  Once inside, navigate to /usr/share/nginx/html and list the files with ls. If welcome.html isn't there:
  • Double-check that you're running docker build from the same directory where welcome.html is stored.
  • Make sure there's no typo in the filename (case sensitivity matters! e.g., Welcome.html vs welcome.html).
  • Check your build logs for errors like COPY failed: no source files were specified — this means Docker couldn't find the file.

3. (Less Likely) Port Conflict or Cached Image #

• Port conflict: If another service is using port 80 on your host, you might be hitting a different Nginx instance. Check with netstat -tulpn | grep 80 (Linux/macOS) or netstat -ano | findstr ":80" (Windows) to see what's listening on port 80.
• Cached image: Docker might be using an old cached version of your image. Rebuild with the --no-cache flag to force a fresh build:

  docker image build --no-cache -t html_nginx .
  

内容的提问来源于stack exchange，提问作者Venkat