Markus Eisele - Modernizing Enterprise Java

The differences between public clouds, private clouds, hybrid clouds, and multi clouds were once easily defined by location and ownership. Today, these two are no longer the only relevant drivers for the classification of clouds. Lets start with a more comprehensive definition of the different target environments and why they are used.

A public cloud environment is usually created from resources not owned by the end-user that can be redistributed to other tenants. Private cloud environments solely dedicate their resources to the end-user, usually within the users firewall, data-center, or sometimes on-premises. Multiple cloud environments with some degree of workload portability, orchestration, and management are called hybrid clouds. Decoupled, independent, and not connected clouds are commonly referred to as multi clouds. Hybrid and multi cloud approaches are mutually exclusive; you cant have both simultaneously because the clouds will either be interconnected (hybrid cloud) or not (multi cloud).

Deploying applications to a cloud, regardless of the type of cloud, is becoming more common across enterprises as they seek to improve security and performance through an expanded portfolio of environments. But security and performance are only two of many reasons to move workloads into hybrid or multi cloud environments. The primary motivation for many is the pay-for-what-you-use model. Instead of investing in costly on-premises hardware that is hard and expensive to scale out, clouds offer resources when you need them. You dont have to invest in facilities, utilities, or building out your own data center. You do not even need dedicated IT teams to handle your cloud data center operations, as you can enjoy the expertise of your cloud providers staff.

For developers, the cloud is about self-service and flexibility. You dont have to wait for environments to be promoted and you cant choose infrastructure components (e.g., databases, message brokers, etc.) as a need arises to free you from unnecessary wait times and ultimately speed up development cycles. Beyond these primary advantages, you can also find custom features for developers in some cloud environments. OpenShift, for example, has an integrated development console that provides developers with direct edit access to all details of their application topology. Cloud-based IDEs (e.g., Eclipse Che) provide browser-based access to development workspaces and eliminate local environment configuration for teams.

Additionally, cloud infrastructures encourage you to automate your deployment processes. Deployment automation enables you to deploy your software to testing and production environments with the push of a button a mandatory requirement for agile development and DevOps teams. Youve seen a need for 100% automation already when youve read about microservices architectures. But automation goes well beyond the application parts. It extends to the infrastructure and downstream systems. Ansible, Helm, and Kubernetes Operators help you. We talk more about automation in chapter four, and youll use an Operator in chapter seven.