DB management ENH - SQLite Fallback in all cases

Author: app-generator

apps/__init__.py

@@ -3,6 +3,8 @@
 Copyright (c) 2019 - present AppSeed.us
 """
 
+import os
+
 from flask import Flask
 from flask_login import LoginManager
 from flask_sqlalchemy import SQLAlchemy
@@ -28,7 +30,18 @@ def configure_database(app):
 
     @app.before_first_request
     def initialize_database():
-        db.create_all()
+        try:
+            db.create_all()
+        except Exception as e:
+
+            print('> Error: DBMS Exception: ' + str(e) )
+
+            # fallback to SQLite
+            basedir = os.path.abspath(os.path.dirname(__file__))
+            app.config['SQLALCHEMY_DATABASE_URI'] = SQLALCHEMY_DATABASE_URI = 'sqlite:///' + os.path.join(basedir, 'db.sqlite3')
+
+            print('> Fallback to SQLite ')
+            db.create_all()
 
     @app.teardown_request
     def shutdown_session(exception=None):

apps/config.py

@@ -3,22 +3,57 @@
 Copyright (c) 2019 - present AppSeed.us
 """
 
-import os
+import os, random, string
 
 class Config(object):
 
     basedir = os.path.abspath(os.path.dirname(__file__))
 
+    # Assets Management
+    ASSETS_ROOT = os.getenv('ASSETS_ROOT', '/static/assets')
+
     # Set up the App SECRET_KEY
-    # SECRET_KEY = config('SECRET_KEY'  , default='S#perS3crEt_007')
-    SECRET_KEY = os.getenv('SECRET_KEY', 'S#perS3crEt_007')
+    SECRET_KEY  = os.getenv('SECRET_KEY', None)
+    if not SECRET_KEY:
+        SECRET_KEY = ''.join(random.choice( string.ascii_lowercase  ) for i in range( 32 ))    
 
-    # This will create a file in <app> FOLDER
-    SQLALCHEMY_DATABASE_URI = 'sqlite:///' + os.path.join(basedir, 'db.sqlite3')
-    SQLALCHEMY_TRACK_MODIFICATIONS = False 
+    SQLALCHEMY_TRACK_MODIFICATIONS = False
 
-    # Assets Management
-    ASSETS_ROOT = os.getenv('ASSETS_ROOT', '/static/assets')    
+    DB_ENGINE   = os.getenv('DB_ENGINE'   , None)
+    DB_USERNAME = os.getenv('DB_USERNAME' , None)
+    DB_PASS     = os.getenv('DB_PASS'     , None)
+    DB_HOST     = os.getenv('DB_HOST'     , None)
+    DB_PORT     = os.getenv('DB_PORT'     , None)
+    DB_NAME     = os.getenv('DB_NAME'     , None)
+
+    USE_SQLITE  = True 
+
+    # try to set up a Relational DBMS
+    if DB_ENGINE and DB_NAME and DB_USERNAME:
+
+        try:
+            
+            # Relational DBMS: PSQL, MySql
+            SQLALCHEMY_DATABASE_URI = '{}://{}:{}@{}:{}/{}'.format(
+                DB_ENGINE,
+                DB_USERNAME,
+                DB_PASS,
+                DB_HOST,
+                DB_PORT,
+                DB_NAME
+            ) 
+
+            USE_SQLITE  = False
+
+        except Exception as e:
+
+            print('> Error: DBMS Exception: ' + str(e) )
+            print('> Fallback to SQLite ')    
+
+    if USE_SQLITE:
+
+        # This will create a file in <app> FOLDER
+        SQLALCHEMY_DATABASE_URI = 'sqlite:///' + os.path.join(basedir, 'db.sqlite3') 
 
 class ProductionConfig(Config):
     DEBUG = False
@@ -28,15 +63,6 @@ class ProductionConfig(Config):
     REMEMBER_COOKIE_HTTPONLY = True
     REMEMBER_COOKIE_DURATION = 3600
 
-    # PostgreSQL database
-    SQLALCHEMY_DATABASE_URI = '{}://{}:{}@{}:{}/{}'.format(
-        os.getenv('DB_ENGINE'   , 'mysql'),
-        os.getenv('DB_USERNAME' , 'appseed_db_usr'),
-        os.getenv('DB_PASS'     , 'pass'),
-        os.getenv('DB_HOST'     , 'localhost'),
-        os.getenv('DB_PORT'     , 3306),
-        os.getenv('DB_NAME'     , 'appseed_db')
-    ) 
 
 class DebugConfig(Config):
     DEBUG = True