Docker Expose Port 302

Expose Port 302 in Docker

docker run -p 302:302 your-image-name
		

This command maps container port 302 to the same port on the host machine.

Dockerfile Example

FROM node:18-alpine
WORKDIR /app
COPY . .
EXPOSE 302
CMD ["npm", "start"]
		

The EXPOSE instruction documents that the container listens on port 302.

EXPOSE vs Publish (-p)

• EXPOSE 302 documents the port inside the container.
• -p 302:302 makes the port accessible from the host.
• Exposed ports are not reachable unless published.

Docker Expose Port 302 Not Working

If Docker expose port 302 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 302 Already in Use

The error “port 302 already in use” means another process is already bound to that port on your host system.

# Find process using port 302
lsof -i :302

# OR use a different host port
docker run -p 8080:302 your-image-name
		

• Ensure your app is listening on port 302 inside the container
• Verify the port is published using -p
• Check firewall or network rules
• Avoid conflicts with existing services

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