Unity cloud build hook for build downloading with nginx lua

nginx-lua-unity-cloud-build.conf

server {
	listen 443 ssl;
	ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
	ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
	server_name example.com;
	root /var/www/example/httpdocs/;
	include /etc/nginx/vhost-common.conf;
	
	index index.html index.html index.php;
	client_max_body_size 100m;
	access_log /var/www/example/_logs/access.log;
	error_log /var/www/example/_logs/error.log;


	location / {
		try_files $uri $uri/ =404;
	}
	
	location /server {
		try_files $uri =404;
		auth_basic "Password required";
		auth_basic_user_file /var/www/example/server.htpasswd;
	}
	
	location /unity-cloud-build {
		content_by_lua_block {
			local json = require "cjson"
			ngx.req.read_body()
			
			local res = json.decode(ngx.req.get_body_data())
			if not res then
				ngx.log(ngx.ERR, "Invalid body", ngx.req.get_body_data())
				return
			end
			local function fetch(_, url, saveTo) 
				local http = require "resty.http"
				local httpc = http.new()
				local io = require "io"
				local scheme, host, port, path = unpack(httpc:parse_uri(url, true))
				httpc:set_timeouts(10000, 60 * 60 * 1000, 60 * 60 * 1000)
				-- reverse proxy downloads since the s3 unity uses is super slow to our particular network for some reason
				-- config is available here if you need to host it on your own infrastructure: https://gist.github.com/imerr/7fb5ca8a03f7d81838be0f641bc5c956
				local c, cerr httpc:connect("proxy.example.com", 443)
				local handshakeOk, handshakeErr = httpc:ssl_handshake(nil, "proxy.example.com", true)
				if not handshakeOk then
					ngx.log(ngx.ERR, "SSL Handshake failed with rproxy.dl.je:" , handshakeErr)
					return
				end
				local rpath = "/i/"
				if scheme == "https" then
					rpath = "/s/"
				end
				rpath = rpath .. host .. path
				ngx.log(ngx.ERR, rpath)
				local resp, rerr = httpc:request({
					path = rpath,
					version = 1.1,
					method = "GET",
					headers = {
						["Host"] = "proxy.example.com",
						["User-Agent"] = "resty-http"
					},
				})

				if not resp then
					ngx.log(ngx.ERR, "failed to request: ", rerr)
					return
				end

				-- Now we can use the body_reader iterator, to stream the body according to our desired chunk size.
				local reader = resp.body_reader

				local f, ierr = io.open("/var/www/example/httpdocs/" .. saveTo , "wb")
				if f==nil then
					ngx.log(ngx.ERR, "Couldn't open file: "..ierr)
					return
				end
				repeat
					local chunk, err = reader(8192)
					if err then
					  ngx.log(ngx.ERR, err)
					  break
					end

					if chunk then
					  f:write(chunk)
					end
				until not chunk
				f:close()
				httpc:close()
			end
			if res.buildStatus == "success" and res.buildTargetName == "My Build Name" then
				local ok, err = ngx.timer.at(0, fetch, res.links.artifacts[1].files[1].href, "path_to_save_to/build_" .. res.buildNumber .. ".zip")
				if not ok then
					ngx.log(ngx.ERR, "failed to create timer: ", err)
					return
				end
			end
		}
	}
}