hello! I'm learning nextjs and the app router and im trying to figure out how to run something when the server starts.

in express, i can do something like

app.get("/", function (req, res) {
fs.readFile("foo.tsxt")

run some operation, (in this case reading a large txt file) and then use another endpoint to get information from that txt file.

app.get("/testendpoint", function (req, res) {

So that i dont have to open the filestream everytime i call said endpoint.

Trying to replicate this behavior entirely on nodejs with the app-router, im a little lost. in testendpoint/route.tsx i have

export async function GET() {

but where should i read the txt file so that i can retrieve some of its contents via this endpoint? Am i simply thinking in a completely incorrect paradigm here?

thank you so much