@netlify/config/lib/headers.js

Netlify config module

import { resolve } from 'path';
import { parseAllHeaders } from '@netlify/headers-parser';
import { warnHeadersParsing, warnHeadersCaseSensitivity } from './log/messages.js';
// Retrieve path to `_headers` file (even if it does not exist yet)
export const getHeadersPath = function ({ build: { publish } }) {
    return resolve(publish, HEADERS_FILENAME);
};
const HEADERS_FILENAME = '_headers';
// Add `config.headers`
export const addHeaders = async function ({ config: { headers: configHeaders, ...config }, headersPath, logs }) {
    const { headers, errors } = await parseAllHeaders({
        headersFiles: [headersPath],
        configHeaders,
        minimal: true,
    });
    warnHeadersParsing(logs, errors);
    warnHeadersCaseSensitivity(logs, headers);
    return { ...config, headers };
};