I was looking at 12 factor app principle and saw this statement. I believe this statement states that the application must respond to any backing service such database or message broker and connect to them irrespective of what they are. How does it differ from traditional way of connecting? For eg: in my microservice , I was defined database and kafka broker as user provided service in cloud foundry. It just provides the connection parameters as vcap service variables. I still have code to connect to a database and kafka broker which are entirely different. What does this statement signify and how does it differ from what we do in non-cloud environment?
As stated in the below article:
https://12factor.net/backing-services
It states that :
A backing service is any service the app consumes over the network as part of its normal operation. Examples include datastores (such as MySQL or CouchDB), messaging/queueing systems (such as RabbitMQ or Beanstalkd), SMTP services for outbound email (such as Postfix), and caching systems (such as Memcached).
Microservice can connect to any backing service irrespective of the platform. In PCF, you are binding services to your microservices to connect. In other cloud environment, you can point to any backing service like AWS RDS or other services provided by the Platform.
The real difference is this :
Backing services like the database are traditionally managed by the same systems administrators as the app’s runtime deploy. In addition to these locally-managed services, the app may also have services provided and managed by third parties. Resources can be attached and detached to deploys at will. For example, if the app’s database is misbehaving due to a hardware issue, the app’s administrator might spin up a new database server restored from a recent backup. The current production database could be detached, and the new database attached – all without any code changes.