举个例子，如果服务器绑定在IP地址和端口号上，当然是能运行HTTPS的：

let options = {
    key: fs.readFileSync("key.pem"),
    cert: fs.readFileSync("cert.pem")
};

https.createServer(options, (req, res) => {
    console.log("Request received");
    res.writeHead(200);
    res.end("hello world\n");
}).listen(50000, "127.0.0.1");
console.log("HTTPS server started.");

setTimeout(() => {
    https.request({
        host: "127.0.0.1",
        port: 50000,
        rejectUnauthorized: false
    }).end();
}, 1000);

但一旦绑定的是Unix socket，就不能运行HTTPS了，说self signed certificate error：

let options = {
    key: fs.readFileSync("key.pem"),
    cert: fs.readFileSync("cert.pem")
};

https.createServer(options, (req, res) => {
    console.log("Request received");
    res.writeHead(200);
    res.end("hello world\n");
}).listen("/Users/zzz/test-unix-socket/socket.sock");
console.log("HTTPS server started.");

setTimeout(() => {
    https.request({
        socketPath: "/Users/zzz/test-unix-socket/socket.sock",
        rejectUnauthorized: false
    }).end();
}, 1000);

key.pem和cert.pem是用OpenSSL生成的自签名证书：

openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 7300 -nodes

这难道是Node的bug？