One of the biggest challenges to implementing an end-to-end Continuous Delivery pipeline is making sure adequate test automation is in place. However, even if you have automated across your entire Test Suite, there is a second challenge: How do you manage Test infrastructure and environments without breaking the bank?
If you want to move towards Continuous Delivery, you need to execute a majority of your tests for each code change in a pristine environment that is as close to your production environment as possible. This ensures that code defects are identified immediately and every code change is therefore 'shippable'. However, creating these environments and updating them with each new application version or every time the config changes adds a lot of overhead. If you're testing an application with many tiers or microservices, the complexity increases since each tier might need to be tested indepedently in its own environment against specific versions of other tiers.