We previously did not copy the sticky flag if the load-balancer
method validation failed, causing enabled stickiness to be dropped in
case of a validation error (which, technically, for us is the same as a
load-balancer configuration without an explicitly set method). This
change fixes that.
A few refactorings and improvements along the way:
- Move the frontend and backend configuration steps into separate
methods/functions for better testability.
- Include the invalid method name in the error value and avoid log
duplication.
- Add tests for the backend configuration part.
For the two existing health check parameters (path and interval), we add
support for Marathon labels.
Changes in detail:
- Extend the Marathon provider and template.
- Refactor Server.loadConfig to reduce duplication.
- Refactor the healthcheck package slightly to accommodate the changes
and allow extending by future parameters.
- Update documentation.
