👀 Views: 18 💬 Answers: 1 📅 Created: 2025-06-11

Docker Ubuntu Networking bash

I'm collaborating on a project where I'm currently experiencing a frustrating networking scenario with Docker on my Ubuntu 22.04 server. I have a Docker container that needs to connect to an external API, but I keep receiving the behavior `curl: (7) Failed to connect to api.example.com port 80: Network is unreachable` when I attempt to access it from within the container. I've verified the external API is accessible from the host machine, and I can curl the endpoint without any problems: ```bash curl http://api.example.com ``` This returns the expected response. However, within the Docker container, I've tried using both the default bridge network and a custom bridge network with the following configuration: ```bash docker network create my-custom-network ``` Then I run the container with: ```bash docker run --rm -it --network my-custom-network my-docker-image /bin/sh ``` Inside the container, I've tried pinging both the external API and the host itself: ```bash ping api.example.com ping host.docker.internal ``` The ping command to the external API fails with the same 'Network is unreachable' behavior, while the ping to the host seems to work. I've also checked the DNS configuration within the container and it appears to be set correctly. I suspect there might be an scenario with the way Docker is handling network routes, especially since I recently configured UFW to allow traffic on specific ports. I ran the following commands to configure UFW: ```bash sudo ufw allow 80/tcp sudo ufw allow 443/tcp sudo ufw enable ``` Could this UFW configuration be interfering with Docker’s networking? What steps can I take to debug this scenario further or resolve the network connectivity question from within my container? This is happening in both development and production on Ubuntu 20.04. Could this be a known issue?