I was working on a Dockerfile deploy that was setup to listen on port 8844. I wanted to add ssl and couldn't figure out why adding the ssl cert didn't making things 'just work'. Since the `proxy:ports-add` step I discuss in this commit is run both `under the hood` and `sometimes`, I thought it might be worth issuing a PR for.
When configuring domains/ssl certificates, the port mappings for an application may be automatically set. This can cause issues for applications which will use non-standard ports - ie. for Dockerfile deploys.
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