reverse-proxy-caddyfile/conf/github.caddyfile

(communal) {
	header_down -Strict-Transport-Security
	header_down -Content-Security-Policy
	header_down -Set-Cookie
	header_down -x-pjax-url
	header_down -Referrer-Policy
	header_up Accept-Encoding identity
}

github.example.com {
	import log github.example.com
	import common
	import ratelimit
	import geoblock

	replace {
		https://raw.githubusercontent.com https://github-raw.example.com
		https://github.com https://github.example.com
		https://github.githubassets.com https://github-assets.example.com
		https://api.github.com https://github-api.example.com
	}

	@downloads path_regexp ^/[^/]+/[^/]+/releases/download/.*$
	redir @downloads https://github-download.example.com{re.0}

	@archives path_regexp ^/[^/]+/[^/]+/archive/.*$
	redir @archives https://github-archive.example.com{re.0}

	@artifacts path_regexp ^/[^/]+/[^/]+/suites/[^/]+/artifacts/.*$
	redir @artifacts https://github-download.example.com{re.0}

	reverse_proxy https://github.com {
		import communal
		header_up Host github.com
		header_up Referer https://github.com/
		header_up Origin https://github.com
	}
}

github-assets.example.com {
	import log github-assets.example.com
	import common
	import ratelimit
	import geoblock

	reverse_proxy https://github.githubassets.com {
		import communal
		header_up Host github.githubassets.com
	}
}

github-codeload.example.com {
	import log github-codeload.example.com
	import common
	import ratelimit
	import geoblock

	reverse_proxy https://codeload.github.com {
		import communal
		header_up Host github.com
	}
}

github-download.example.com {
	import log github-download.example.com
	import common
	import ratelimit
	import geoblock

	@archives path_regexp ^/[^/]+/[^/]+/archive/.*$
	redir @archives https://github-archive.example.com{re.0}

	@downloads path_regexp ^/[^/]+/[^/]+/releases(/latest)?/download/.*$
	reverse_proxy @downloads https://github.com {
		import communal
		header_up Host github.com
	}

	@artifacts path_regexp ^/[^/]+/[^/]+/suites/[^/]+/artifacts/.*$
	reverse_proxy @artifacts https://github.com {
		import communal
		header_up Host github.com
	}
}

github-raw.example.com {
	import log github-raw.example.com
	import common
	import ratelimit
	import geoblock

	replace https://raw.githubusercontent.com https://github-raw.example.com

	reverse_proxy https://raw.githubusercontent.com {
		import communal
		header_up Host raw.githubusercontent.com
	}
}

github-api.example.com {
	import log github-api.example.com
	import common
	import ratelimit
	import geoblock

	replace {
		https://github.com https://github.example.com
		https://raw.githubusercontent.com https://github-raw.example.com
		https://api.github.com https://github-api.example.com
	}

	reverse_proxy https://api.github.com {
		import communal
		header_up Host api.github.com
	}
}

github-archive.example.com {
	import log github-archive.example.com
	import common
	import ratelimit
	import geoblock

	@downloads path_regexp ^/[^/]+/[^/]+/releases(/latest)?/download/.*$
	redir @downloads https://github-download.example.com{re.0}

	@artifacts path_regexp ^/[^/]+/[^/]+/suites/[^/]+/artifacts/.*$
	redir @artifacts https://github-download.example.com{re.0}

	@archives path_regexp ^/[^/]+/[^/]+/archive/.*$
	reverse_proxy @archives https://github.com {
		import communal
		header_up Host github.com
	}
}