Cookie not being set in browser

I am trying to set a cookie which has my auth token in it. I can see it being returned in the response header set-cookie: xxxxxx but for whatever reason, the browser is not storing the cookie.

On my react front end http://app1.dev:3001 I am making an POST api call as such:

return axios.get(
  `${apiUrl}/info`,
  { withCredentials: true }
)
.then(res => res.data)
.catch(console.error)

And I have a simple Koa server running on http://localhost:3000

const Koa = require("koa")
const Router = require("koa-router")
const bodyParser = require("koa-bodyparser")
const cors = require("@koa/cors")
const axios = require("axios")
const env = require("./env")
const KeyGrip = require("keygrip")

const app = new Koa()
const router = new Router()
const port = env("port")

const keyList = ["xxxxxxx",]
app.keys = new KeyGrip(keyList, "sha256")

router.get("/info", ctx => {
  console.log('req', ctx.req)
  ctx.cookies.set("token", "test_token", { signed: true, httpOnly: true })
  ctx.body = { ok: true }
})

const corsOptions = {
  origin: ctx => ctx.request.header.origin,
  credentials: true
}

app
  .use(cors(corsOptions))
  .use(bodyParser())
  .use(router.routes())
  .use(router.allowedMethods())

app.listen(port, () => console.info(`Listening on port ${port}`))

I suspect it is not being set because it is cross domain. when I use http://localhost:3001 for my front end the cookie gets set fine.

Why are the cookies not being set in browser? Any help would be greatly appreciated.

Solution

When you use http://localhost:3001 for the frontend, your frontend and backend servers share the same domain (even being on different ports), so you can see the cookie set by a request to your backend server (and so linked to backend server domain).

When you use different domains, you just can't see the cookie as dev tools are attached to a page that belongs to another domain. But the cookie is saved and will be sent back with subsequent requests.