如何使用njs模块将js文件中的变量值传递给nginx config

Question

我试图使用njs使用nginx进行链式请求，下面的问题是我的javascript文件，我的场景是我有两个API。我想请求第一个api并得到它的响应，然后追加第一个api的响应(云是JSON属性)，第二个api的头

async function chain(r) {
  r.headersOut["Content-Type"] = "application/json";
  var result = await r.subrequest("/validation", { method: "POST" });
  var json = JSON.parse(result.responseText);

  headers = json.fullName;// where to put this header and append it to second request header ?
  var result1 = await r.subrequest("/persistance");

  r.return(result1.status, result1.responseBody);

}

function getHeaders() {
  return headers;
}

export default { chain, getHeaders };

和我的nginx配置文件

js_import http.js;
js_set $headers http.getHeaders; // here am trying to get headers from variable in http.js but is it alwat null and undefended
server {
    listen       80;
    listen  [::]:80;
    server_name  localhost;
       
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }
       
    location ~ ^/.*$ {
      js_content http.chain;
    }

    location = /persistance {
       proxy_set_header accountId $headers; //it is always undefined, I think it is because declared on the top of file and it is nginx directives
       proxy_pass http://192.168.2.76:5001/academicyear/list;      
    }
     
    location = /validation {
       proxy_pass http://192.168.2.76:8088/v1/user/validation;
    }

}

我使用子请求和，然后使用--这是同一个问题

Answer 1

这个评论可能就是答案。

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nginx不支持其变量处理程序中的异步操作(它与JavaScript中的异步关键字无关)。当nginx想要某个变量(比如$x_js_log)的值时，它会找到它并调用它的处理程序(js_log)。Nginx不能阻止这里，并且想马上得到结果。r.subrequest()本质上是一个异步操作。

https://github.com/nginx/njs/issues/287#issuecomment-584247289