Cannot reach web server inside Docker

I’m doing some recapitulation of my Docker knowledge but have run into a problem that I don’t understand.

I created a simple web server in Go and have no problems running it inside a Docker container. But I cannot reach it from outside.

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  • Since I thought that perhaps something is blocking access to Docker containers, I tried running an SSHd container. That works fine; I can reach it and log in using SSH.

    You can see my Dockerfile and my small Go code in this gist:

    Why can’t I reach the small web server?

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  • Docker will be the best open platform for developers and sysadmins to build, ship, and run distributed applications.