fix: enable login on selfhosted instances

[zolfariot]

Allow the user to define a main custom domain for self-hosting, under the DOMAIN environment variable,
this custom domain will be recognized by the middleware when run in production (local, non vercel) mode.

Secure cookies are used when a custom domain is set, thus requiring papermark to be served on https.

Finally, sender addresses can be customized with the RESEND_SENDER_SYSTEM and RESEND_SENDER_VERIFY environment variables, to be able to deliver emails from domains allowed in the instance RESEND api key.

Fixes #1353

[vercel]

@zolfariot is attempting to deploy a commit to the mftsio Team on Vercel.

A member of the Team first needs to authorize it.

[mpadronm90]

@zolfariot Adding your changes manually still having this issue:

Something I found is that the custom domain you set in these variables gets blocked.

NEXTAUTH_URL=http://localhost:3000
NEXT_PUBLIC_BASE_URL=http://localhost:3000

So weird!

[zolfariot]

Hello, are you hosting on your server or deploying to your Vercel account? And do you have https enabled for your custom domain url?

I could not reproduce on a minimal production-like test:

Preparation:

1. Deploy a fresh Debian 12 VPS
2. Install certbot, postgres, nginx
3. certbot: create a letsencrypt certificate for papermark.$YOUR_DOMAIN
4. postgres: create a user papermark with password $DB_PASS
5. postgres: create a db papermark owned by user papermark
6. nginx: replace the location block in the default https server statement with:

location / {
    proxy_pass              http://localhost:3000;
    proxy_set_header        Host $host;
    proxy_set_header        Connection "Upgrade";
    proxy_set_header        Upgrade $http_upgrade;
}

Papermark setup

As unprivileged user

1. Install node22 lts with nvm (https://nodejs.org/en/download)
2. Clone PR

git clone -b fix/enable_login_selfhosted https://github.com/zolfariot/papermark

3. Enter papermark and copy .env.example to .env, then modify only the following entries of .env (replacing $YOUR_DOMAIN, $DB_PASS and $YOUR_RESEND_API_KEY):

NEXTAUTH_URL=https://papermark.$YOUR_DOMAIN
NEXT_PUBLIC_BASE_URL=https://papermark.$YOUR_DOMAIN
DOMAIN=papermark.$YOUR_DOMAIN
POSTGRES_PRISMA_URL="postgres://papermark:$DB_PASS@localhost:5432/papermark"
POSTGRES_PRISMA_URL_NON_POOLING="postgres://papermark:$DB_PASS@localhost:5432/papermark"
RESEND_API_KEY=$YOUR_RESEND_API_KEY
RESEND_SENDER_SYSTEM="papermark@$YOUR_DOMAIN"
RESEND_SENDER_VERIFY="papermark@$YOUR_DOMAIN"

4. Install and build papermark

npm i
npm run build 

5. Run the server (eventually in a screen/tmux or as a systemd unit)

npm run start