Document how to connect to postgresql

README.md

@@ -218,6 +218,17 @@ If any step of the instructions does not work for you, please open an issue and
 describe the problem you're having, as it is important to us that onboarding is
 super easy :)
 
+### Connecting to the PostgreSQL database
+
+If you need to connect to your development PostgreSQL database, you should
+install `psql` locally. The port 5432 is already forwarded, so you can connect with:
+  
+```
+psql -h localhost -U obs -d obs
+```
+
+The password is `obs` as well.
+  
 ## License
   
     Copyright (C) 2020-2021 OpenBikeSensor Contributors

deployment/README.md

@@ -402,3 +402,26 @@ exporting that with an exclusion pattern instead of an explicit list.
 
 And then, please test your backup and restore strategy before going live, or at
 least before you need it!
+
+
+### Connecting to the PostgreSQL database
+
+Here are the quick steps for connecting to your PostgreSQL database, should you
+need that:
+
+* Add the `gateway` network to your `postgres` service.
+* Add a port forwarding to your `postgres` service:
+  ```yaml
+     ports:
+       - 127.0.0.1:25432:5432
+  ```
+* Run `docker-compose up -d postgres` again
+* You can now connect from your server to the PostgreSQL service with:
+
+  ```
+  psql -h localhost -U obs -d obs -p 25432
+  ```
+  
+  You will need your database password for the connection.
+* If you do not want to install `psql` outside your container, you can use an
+  SSH tunnel from your local machine to your server and run `psql` locally.