I have a node.js express (server-side rendering) frontend app that calls java backend endpoints. I use Axios to call the java endpoints. I need to set a header named "agent-id" into every request express makes to java, the value of that header comes from the express session (req.session).

My Axios code is on another module. I'm importing that module and calling my APIs.

Currently my Axios module code is setup like so:

const axiosClient = axios.create({
 baseURL: '...',
 httpsAgent: null,
 proxy: false,
 timeout: 60000,
});

axiosClient.interceptors.request.use(request => {
 console.log(`Starting:${request.baseURL}${request.url}`);

 // HOW DO I SET HEADER FROM EXPRESS SESSION HERE //

 return request;
}, error => Promise.reject(error));

axiosClient.interceptors.response.use(response => {
 console.log(`Received from:${response.config.baseURL}${response.config.url}`);
 return response;
}, error => Promise.reject(error));

module.exports = axiosClient;

and I call my APIs from frontend express app like so:

import api from 'my-api-module';

const { data = {} } = await api.someName();

What I've tried

I tried updating req.headers using a app.use middleware but I could not find that header within the axios interceptor.

Ideally I dont want to change my entire API calling structure by passing req obj on every existing API calls, so is there anyway I can globally set the header using express session value for every Java request ?