Periodically refreshing an allowlist in njs

[Tom Hall]

Hi

I am looking to replace some lua scripting we have to do an allowlist,
I found  https://medium.com/geekculture/building-a-simple-bot-protection-with-nginx-javascript-module-njs-and-typescript-386b2207ba90
and it seems to give me a good idea how to port my lua

const fs = require('fs');
const badReputationIPs = loadFile('/var/lib/njs/ips.txt');

function loadFile(file: string): string[] {
    let data: string[] = [];
    try {
        data = fs.readFileSync(file).toString().split('\n');
    } catch (e) {
        // unable to read file
    }
    return data;
}

function verifyIP(r: NginxHTTPRequest): void {
    if (badReputationIPs.some((ip: string) => ip === r.remoteAddress)) {
        r.return(302, '/block.html');
        return;
    }

    r.internalRedirect('@pages');
}

export default { verifyIP };

except I have the lua reloading every 60s by calling ngx.timer.at(60,
helpers.load_json) in a init_worker_by_lua

Is there an equivalent in njs? It seems not if you are starting a new
lightweight VM for every request.
Is the answer to do a subrequest and cache it or something?

Thanks,
Tom