Docker Expose Port 304

Expose Port 304 in Docker

docker run -p 304:304 your-image-name
		

This command maps container port 304 to the same port on the host machine.

Dockerfile Example

FROM node:18-alpine
WORKDIR /app
COPY . .
EXPOSE 304
CMD ["npm", "start"]
		

The EXPOSE instruction documents that the container listens on port 304.

EXPOSE vs Publish (-p)

• EXPOSE 304 documents the port inside the container.
• -p 304:304 makes the port accessible from the host.
• Exposed ports are not reachable unless published.

Docker Expose Port 304 Not Working

If Docker expose port 304 is not working, it is usually due to incorrect port publishing, an application not listening on the expected port, or a port conflict on the host machine.

Port 304 Already in Use

The error “port 304 already in use” means another process is already bound to that port on your host system.

# Find process using port 304
lsof -i :304

# OR use a different host port
docker run -p 8080:304 your-image-name
		

• Ensure your app is listening on port 304 inside the container
• Verify the port is published using -p
• Check firewall or network rules
• Avoid conflicts with existing services

Related Docker Expose Port Guides