Add database docs

DATABASE.md

@@ -0,0 +1,56 @@
+** Database Setup **
+
+Due to our reliance on the Postgres JSON field, a local Postgres installation
+is required to run the app and its tests locally. We recommend that you follow
+the [Heroku instructions](https://devcenter.heroku.com/articles/heroku-postgresql#local-setup) for local Postgres installation. Postgres 9.4 is run in production, and this is the version that
+is recommended for local development. To install this version, go to the
+potgres.app page [for installing legacy versions](https://postgresapp.com/documentation/all-versions.html)
+and download the installer for Postgres 9.4. Other useful resources are a postgres
+[installation video](https://www.youtube.com/watch?v=xaWlS9HtWYw) and the [Postgres.app installation documentation](http://postgresapp.com/documentation/install.html).
+
+PolicyBrain has not been tested on newer versions of Postgres. Thus, we cannot
+help you if you run into problems on a new version of Postgres. Older versions
+of Postgres (< 9.4) do not have as much support for operations on the JSON
+field. Thus, we cannot guarantee that the PolicyBrain will work with older
+versions.
+
+The default behavior is to work off of a local Postgres database
+`policybrain_local_database`, and in `webapp_env.sh`, the Django database url
+environment variable `DATABASE_URL` is set to `postgresql://localhost/policybrain_local_database`.
+However, after running `source webapp_env.sh` you can update this variable
+to point to other Postgres databases such as some other database named
+`my_other_postgres_database`. Then, you update the database url to be
+`postgresql://localhost/my_other_postgres_database`. This is useful if you
+want to run some tests on the production or test app database, for example.
+
+
+** Database Migrations **
+
+- Be very careful with data related to the results column
+- Do a monthly database back up and keep the previous two months of production
+  backups and one month of testing backups
+- Examine the python migration code created by Django
+- Examine the SQL migration code created by Django
+- Always back up your data before running a migration
+- Check that you can roll back your migrations
+- Check how long it will take to run a migration (most of ours are fairly
+  quick)
+
+
+** Database Backup Policy **
+
+Heroku keeps a back up of our databases for up to five days. We should be able to roll back 
+further if needed. Below is the procedure that we should use to maintain at least one
+accurate, uncorrupted (if not up to date) database:
+- Production database stays up and is the production database until it needs to be rolled back
+- Back-up 1 is the previous version of the database where a version is defined by the
+  database schema. If the schema is changed (i.e. migrations are run), the version is bumped up.
+- Back-up 2 is the version preceding Back-up 1. 
+
+The Production database and the Back-up 1 database are stored on Heroku. In order to keep costs down
+Back-up 2 is stored at a separate location. I am actively exploring different options for storage. 
+
+This procedure is not completely infallible. We could realize that the data is corrupted four versions
+after a change was made. However, this procedure gives us a at least a month or two to realize that
+something is wrong. Further, versions that precede large scale or complex migrations are saved for 
+longer periods of time. For example, the databases from before [#738]([https://github.com/OpenSourcePolicyCenter/PolicyBrain/pull/738) and [#822](https://github.com/OpenSourcePolicyCenter/PolicyBrain/pull/822) were both stored.

README.md

@@ -21,7 +21,8 @@ Local Deployment Setup
 
 First, if you plan on contributing to PolicyBrain, then fork PolicyBrain and work off of that fork.  If you do not plan to contribute, then you can clone the main repo.
 
-Open a terminal window and run the following commands:
+Make sure that the local Postgres Server is running. Then, open a terminal
+window and run the following commands using bash:
 ```
 # swap out YOURUSERNAME with OpenSourcePolicyCenter if you did not fork this project and
 # your user name if you did
@@ -31,13 +32,14 @@ git remote add upstream https://github.com/OpenSourcePolicyCenter/PolicyBrain
 pushd deploy
 ./install_taxbrain_server.sh
 popd
+export DATABASE_USER=YOUR_POSTGRES_USERNAME DATABASE_PW=YOUR_POSTGRES_PASSWORD
 source activate aei_dropq && source webapp_env.sh
 python manage.py collectstatic
 python manage.py migrate
 python manage.py runserver
 ```
 Now, the Django app should be up and running.  You can access the local instance of https://www.ospc.org/ at http://localhost:8000.  Next, set up Redis, Flask, and Celery.  This step allows you to submit and run jobs.
-In another terminal, run the following commands
+In another terminal, run the following commands using bash:
 ```
 # Go to the PolicyBrain directory
 cd PolicyBrain/
@@ -53,3 +55,18 @@ gunzip -c puf.csv.gz > puf.csv
 supervisord -c supervisord_local.conf
 
 ```
+
+Now, that the server has been installed, you can start it up simply by running:
+
+```
+export DATABASE_USER=YOUR_POSTGRES_USERNAME DATABASE_PW=YOUR_POSTGRES_PASSWORD
+source activate aei_dropq && source webapp_env.sh
+python manage.py runserver
+```
+
+and in another terminal window, run:
+
+```
+source activate aei_dropq && source webapp_env.sh
+cd deploy/taxbrain_server && supervisord -c supervisord_local.conf
+```

webapp/settings.py

@@ -110,7 +110,7 @@
         'ENGINE': 'django.db.backends.postgresql_psycopg2',
         'USER': os.environ.get('DATABASE_USER', 'postgres'),
         'NAME': 'test_db',
-        'PASSWORD': os.environ.get('TESTDBPASSWORD', ''),
+        'PASSWORD': os.environ.get('DATABASE_PW', ''),
     }
 }
 if os.environ.get('DATABASE_URL', None): # DATABASE_URL var is set
@@ -122,7 +122,7 @@
             'ENGINE': 'django.db.backends.postgresql_psycopg2',
             'NAME': 'taxcalc',
             'USER': os.environ.get('DATABASE_USER', 'postgres'),
-            'PASSWORD': os.environ.get('TESTDBPASSWORD', ''),
+            'PASSWORD': os.environ.get('DATABASE_PW', ''),
             'HOST': 'localhost',
             'PORT': '5432',
         }