Problem

As a user installing the Service Binding Operator, I have very little value that is provided out of the box, as no services are providing bindable metadata. 

In order to increase adoption of SBO, we would like to remove the barrier of getting services that are compatible by making the SBO able to bind a set of popular services.

Description

As a user, I'd like to bind services to my application without having to alter the CR or CRD of the services so that I can have a simpler experience and bindable services available out of the box.

There are two sources of bindable metadata that SBO should be able to look for:

• certain annotations or labels that commonly used to describe certain services. For example, a database will always have a URL and other parameters. SBO should be able to look for those and leverage them to do the projection. 
• a catalog of "known services", where SBO will know exactly where to look for the bindable metadata. 

Acceptance Criteria

• We should look at building a library of "bindings source" for popular services. We should start simple, but making the list public so that other developers can eventually contribute to that library for services.
• We should have documentation that is explicit about which services SBO "work with" out of the box. 

Initial Targeted Services

Based on Managed Operator statistic, the state of Kubernetes report from Datadog and our "Let's do the number" session, here is the list of services we would like to initially start with (bold have the highest priority):

• Databases
  1. Redis
  2. MongoDB
  3. MySQL
  4. Postgres
  5. CockroachDB
  6. Elasticsearch
• Logging
  1. Jaeger
  2. Grafana
  3. Dynatrace
  4. Datadog
• Other Services
  1. NGINX
  2. IBM Cert Manager
  3. Kafka
  4. RabbitMQ
  5. Vault