No, Railway doesn’t let you attach an old volume to a new Postgres service. Volumes are tied to the service they were created with. If you want to reuse the data, you’ll need to spin up a new Postgres service and restore from a backup or dump, not by reattaching the volume.

Just delete the old volume and create a new postgres service. It'll come up with a new volume. If you have nothing in that volume, you can just delete it.

Yeah. Sure you can.

Instead of selecting Database > Postgres, select Docker Image. Just type in ghcr.io/railwayapp-templates/postgres-ssl:16 .

Once you've got that service, mount the volume. Easy.

To do this correctly however, you're going to want to copy paste the environmental variables from the Postgres template before deploying this image. I've attached the default values below for your convenience. Make sure you mount your old volume at /var/lib/postgresql/data.

Make sure to do this before you deploy for the first time.

DATABASE_PUBLIC_URL="postgresql://${{PGUSER}}:${{POSTGRES_PASSWORD}}@${{RAILWAY_TCP_PROXY_DOMAIN}}:${{RAILWAY_TCP_PROXY_PORT}}/${{PGDATABASE}}"
DATABASE_URL="postgresql://${{PGUSER}}:${{POSTGRES_PASSWORD}}@${{RAILWAY_PRIVATE_DOMAIN}}:5432/${{PGDATABASE}}"
PGDATA="/var/lib/postgresql/data/pgdata"
PGDATABASE="${{POSTGRES_DB}}"
PGHOST="${{RAILWAY_PRIVATE_DOMAIN}}"
PGPASSWORD="${{POSTGRES_PASSWORD}}"
PGPORT="5432"
PGUSER="${{POSTGRES_USER}}"
POSTGRES_DB="railway"
POSTGRES_PASSWORD=""
POSTGRES_USER="postgres"
RAILWAY_DEPLOYMENT_DRAINING_SECONDS="60"
SSL_CERT_DAYS="820"

You can also create a new postgres service, remove the volume it attaches by default and then attach your old volume at the same path. But since the option for postgres only creates a service like any other, the result will be essentially the same as what loudbook posted.

I was actually not able to remove it without deleting the service itself.

It seems you're right! I definitely remember this was possible through the right click menu before (you can see what I mean on a non-database service) since I did it while manually migrating some databases to Metal before that was automatic, but it's not possible for the database ones anymore. Not sure what's up with that, but you're totally right!

I apprecate the great response. Attempted to do this and the service did come up with the old volume but I could not authenticate. (I added a TCP proxy as well.) In the env vars, do I need to put the correct "old" password for POSTGRES_PASSWORD or leave it blank (or create a new one)?

Yeah, this was a potential issue. You're going to want to replicate the exact same configuration as the old one. If you can remember it.

There's always the option of SSHing in and dealing with this manually, too. You'll likely need the old password.

If this isn't an option for you, there is definitely a way to extract the data without the original login. It will take a bit of effort though.

Ok, looks like I might be in business! I did use this container: ghcr.io/railwayapp-templates/postgres-ssl:16
Password had to match the original DB.
I'll keep looking at it, but I believe this is a feasible workflow. Thanks loudbrook!

You’re welcome

People kept deleting volumes from Postgres and losing data, so our database templates now have a requirement for the volume that prevents you from deleting the volume, or mounting it to the wrong location.