This is an ok way of doing things but you don't need Caddy server (or similar), you can put all the http servers on different localhost ip addresses eg 127.0.0.1, 127.0.0.2, etc. They can all use port 80 but on different ip addresses.
A possible disadvantage is that specifying a single ip to listen on means the http server won't listen on your LAN ip address, which you might want.
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