@netlify/build/lib/core/missing_side_file.js

Netlify build module

import { relative } from 'path';
import { pathExists } from 'path-exists';
import { logMissingSideFile } from '../log/messages/core.js';
// Some files like `_headers` and `_redirects` must be copied to the publishing
// directory to be used in production. When those are present in the repository
// but not in the publish directory, this most likely indicates that the build
// command accidentally forgot to copy those. We then print a warning message.
export const warnOnMissingSideFiles = async function ({ buildDir, netlifyConfig: { build: { publish }, }, logs, }) {
    await Promise.all(SIDE_FILES.map((sideFile) => warnOnMissingSideFile({ logs, sideFile, buildDir, publish })));
};
const SIDE_FILES = ['_headers', '_redirects'];
const warnOnMissingSideFile = async function ({ logs, sideFile, buildDir, publish }) {
    if (!(await pathExists(`${buildDir}/${sideFile}`)) || (await pathExists(`${publish}/${sideFile}`))) {
        return;
    }
    logMissingSideFile(logs, sideFile, relative(buildDir, publish));
};