updating readme

README.md

@@ -42,6 +42,44 @@ uvicorn valis.wsgi:app --reload
 ```
 This will start a local web server at `http://localhost:8000/valis/`.  The API documentation will be located at `http://localhost:8000/valis/docs`.  Or to see the alternate documentation, go to `http://localhost:8000/valis/redoc/`
 
+### Database Connection
+
+Valis uses the `sdssdb` package for all connections to databases.  The most relevant database for the API is the `sdss5db` on `pipelines.sdss.org`.  The easiest way to connect is through a local SSH tunnel. To set up a tunnel,
+
+1. Add the following to your `~/.ssh/config`. Replace `unid` with your Utah unid.
+
+```
+Host pipe
+        HostName pipelines.sdss.org
+        User [unid]
+        ForwardX11Trusted yes
+        ProxyCommand ssh -A [unid]@mwm.sdss.org nc %h %p
+```
+1. In a terminal, create an ssh tunnel to the pipelines database localhost port 5432, to a some local port. E.g. this maps the remote db localhost port 5432 to local machine on port 6000.
+```
+    ssh -L 6000:localhost:5432 pipe
+```
+2. Optionally, update your `~/.pgass` file with the following lines. Replace `port`, `unid`, and `password`, with your tunneled port, Utah unid, and db password, respectively. Alternatively, just set the VALIS_DB_PASS environment variable with your database password.
+```
+localhost:[port]:*:[unid]:[password]
+host.docker.internal:[port]:*:[unid]:[password]
+```
+3. Set the following environment variables.
+
+- export VALIS_DB_PORT=6000
+- export VALIS_DB_USER={unid}
+- export VALIS_DB_PASS={password} (if skipped step 2.)
+
+or optionally add them to the `~/.config/sdss/valis.yaml` configuration file.
+
+```
+allow_origin: ['http://localhost:3000']
+db_remote: true
+db_port: 6000
+db_user: {unid}
+```
+
+
 ## Deployment
 ### Deploying at Utah in api.sdss.org docker
 - Login to `lore` or `manga` machines