Cors policy error inside template node but not in http request node

General
1

Hello,
I have a template node that is trying to retrieve data with a post request (fetch), I have a CORS policy error that I don't manage to fix.

Access to fetch at 'https://example-elasticsearch/index_3/_search' from origin 'https://mysite.com' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

this is my javascript (in the template node code) :

const userAction = async () => {
  console.info('in');
  const myBody = {"query": {"bool": {"must": [ { "match": { "My": 4000 }}]}}};
  const username = 'hidden';
  const password = 'hidden';
  const response = await fetch('https://example-elasticsearch/index_3/_search', {
    method: 'POST',
    body: myBody, // string or object
    headers: {
      'Content-Type': 'application/json',
      "Authorization": 'Basic ' + btoa(username + ":" + password)
    }
  });
  
const myJson = await response.json(); //extract JSON from the http response
console.info(myJson);
}

I tried to add this line in the header without any success :
'Access-Control-Allow-Origin': '*'

In my opinion it's not a problem on the server where I retrieve the data because when I try to retrieve the data using an http request node it is working.

Does someone have any idea how I can fix that?

Thanks a lot

2

When the HTTP request operates, it is FROM your node-red server.

When the fetch operates, it is from the clients browser.

These are different.

NOTE: CORS control is set by the endpoint server not the requester

I can only assume https://example-elasticsearch/index_3/_search is on the same box as node-red and that the browser is on a separate machine?

3

I believe you are right, I guess that I need to change some configuration in the elastic server.
Thanks for the help this is really helpful.