How to back up v3 Docker container data for v4 migration?

Setup and configuration
1

I’m running ChirpStack v3 in a Docker container. I’d like to migrate to v4, and I’d like to back up the existing v3 data before doing so. My skills with Docker are basically limited to the start, stop, pull, and ps commands. I know even less about Postgres.

Using small words and exact commands, can someone please explain how to create a back up?

2

Have you looked at this doc?

https://www.chirpstack.io/docs/v3-v4-migration.html

3

Yes, I did. And it says absolutely nothing in relation to Chirpstack running in a Docker container.