Fix SQLite support (#210)

SQLite DB was not writable because it was always located in
/usr/src/shynet/, which is owned by root and not writable by
appuser. SQLite needs the parent directory containing the DB file to be
writable by the running user.

The applied fix is to place the DB file in /var/local/shynet/db and to
create that directory in the Docker image with the right permissions.

SQLite setup is now documented in README as an alternative to Postgres.

Dockerfile

@@ -37,7 +37,9 @@ RUN apk --purge del .build-deps && \
 	rm -rf /var/lib/apt/lists/* && \
 	rm /var/cache/apk/* && \
 	addgroup --system -g $GF_GID appgroup && \
-	adduser appuser --system --uid $GF_UID -G appgroup
+	adduser appuser --system --uid $GF_UID -G appgroup && \
+	mkdir -p /var/local/shynet/db/ && \
+	chown -R appuser:appgroup /var/local/shynet
 
 # Install Shynet
 COPY shynet .

GUIDE.md

@@ -32,7 +32,11 @@ Before continuing, please be sure to have the latest version of Docker installed
 
 1. Pull the latest version of Shynet using `docker pull milesmcc/shynet:latest`. If you don't have Docker installed, [install it](https://docs.docker.com/get-docker/).
 
-2. Have a PostgreSQL server ready to go. This can be on the same machine as the deployment, or elsewhere. You'll just need a username, password, host, and port. (For info on how to setup a PostgreSQL server on Ubuntu, follow [this guide](https://www.digitalocean.com/community/tutorials/how-to-install-and-use-postgresql-on-ubuntu-18-04)).
+2. For database you can use either PostgreSQL or SQLite:
+
+    2.1 To use PostgreSQL you need a server ready to go. This can be on the same machine as the deployment, or elsewhere. You'll need a username, password, host, and port, set in the appropriate `DB_` environment variables (see next). (For info on how to setup a PostgreSQL server on Ubuntu, follow [this guide](https://www.digitalocean.com/community/tutorials/how-to-install-and-use-postgresql-on-ubuntu-18-04)).
+
+    2.2 SQLite doesn't need a server, just a file. Set `SQLITE=True` in the environment file and create a Docker volume to hold the persistent DB with `docker volume create shynet_db`. Then whenever you run the container include `-v shynet_db:/var/local/shynet/db:rw` to mount the volume into the container. See the [Docker documentation on volumes](https://docs.docker.com/storage/volumes/).
 
 3. Configure an environment file for Shynet, using [this file](/TEMPLATE.env) as a template. (This file is typically named `.env`.) Make sure you set the database settings, or Shynet won't be able to run. Also consider setting `ALLOWED_HOSTS` inside the environment file to your deployment's domain for better security.
 

TEMPLATE.env

@@ -9,6 +9,10 @@ DB_PASSWORD=shynet_db_user_password
 DB_HOST=db
 DB_PORT=5432
 
+# Database settings (SQLite) - comment PostgreSQL settings
+# SQLITE=True
+# DB_NAME=/var/local/shynet/db
+
 # Email settings (optional)
 EMAIL_HOST_USER=example
 EMAIL_HOST_PASSWORD=example_password

shynet/shynet/settings.py

@@ -100,13 +100,13 @@ WSGI_APPLICATION = "shynet.wsgi.application"
 
 
 # Database
-# https://docs.djangoproject.com/en/2.2/ref/settings/#databases
+# https://docs.djangoproject.com/en/3.2/ref/settings/#databases
 
 if os.getenv("SQLITE", "False") == "True":
     DATABASES = {
         "default": {
             "ENGINE": "django.db.backends.sqlite3",
-            "NAME": os.path.join(BASE_DIR, "db.sqlite3"),
+            "NAME": os.environ.get("DB_NAME", "/var/local/shynet/db/db.sqlite3"),
         }
     }
 else: