Docker Expose Port 84

Expose Port 84 in Docker

docker run -p 84:84 your-image-name
		

This command maps container port 84 to the same port on the host machine.

Dockerfile Example

FROM node:18-alpine
WORKDIR /app
COPY . .
EXPOSE 84
CMD ["npm", "start"]
		

The EXPOSE instruction documents that the container listens on port 84.

EXPOSE vs Publish (-p)

• EXPOSE 84 documents the port inside the container.
• -p 84:84 makes the port accessible from the host.
• Exposed ports are not reachable unless published.

Docker Expose Port 84 Not Working

If Docker expose port 84 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 84 Already in Use

The error “port 84 already in use” means another process is already bound to that port on your host system.

# Find process using port 84
lsof -i :84

# OR use a different host port
docker run -p 8080:84 your-image-name
		

• Ensure your app is listening on port 84 inside the container
• Verify the port is published using -p
• Check firewall or network rules
• Avoid conflicts with existing services

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