为什么我的 Nginx 别名指令不起作用？

我在 CentOS 7 上使用 Nginx 和 Ruby on Rails / Puma。我希望 RoR 跳过某些文件路径并直接由 Nginx 提供服务。我在我的网站的“服务器”块中创建了这个

location /assets/lib/ {
    alias /home/rails/myproject_production/app/assets/javascripts/lib/;
    autoindex off;
}

但是，当我调用类似的资产时http://www.mydomein.com/assets/lib/myfile.js，我得到一个 404。这就是我的日志中出现的内容

2018/05/11 15:21:47 [error] 242#0: *1 open() "/home/rails/myproject_production/public/assets/lib/myfile.js" failed (2: No such file or directory), client: 50.240.135.5, server: www.mydomein.com, request: "GET /assets/lib/myfile.js HTTP/1.1", host: "www.mydomein.com"

从日志中，似乎根本没有调用别名。我在上面缺少什么？我的完整配置如下

upstream myproject {
  server unix:///home/rails/myproject_production/shared/sockets/puma.sock;
}

# Listener for Apex Domain
server {
  listen 80;
  server_name www.mydomein.com;
  root /home/rails/myproject_production/public; # I assume your app is located at this location

  location / {
    proxy_pass http://myproject; # match the name of upstream directive which is defined above
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

    if ($request_uri ~* "(\/image\/.*)|(.*\.(ico|gif|jpe?g|png)$)") {
      expires 60d;
      access_log off;
      add_header Pragma public;
      add_header Cache-Control "public";
      break;
    }
  }

  location /assets/lib/ {
        alias /home/rails/myproject_production/app/assets/javascripts/lib/;
        autoindex off;
  }

  location /cable {
    proxy_pass http://myproject;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
  }

  location ~* ^/assets/ {
    # Per RFC2616 - 1 year maximum expiry
    expires 1y;
    add_header Cache-Control public;

    # Some browsers still send conditional-GET requests if there's a
    # Last-Modified header or an ETag header even if they haven't
    # reached the expiry date sent in the Expires header.
    add_header Last-Modified "";
    add_header ETag "";
    break;
  }

}