In Cloud Assembly, tags express capabilities and constraints that determine how and where resources are allocated to provisioned deployments during the provisioning process.
Cloud Assembly uses a specific order and hierarchy of operations in resolving tags to create provisioned deployments. Understanding the basics of this process will help you to implement tags efficiently to create predictable deployments.
The following list summarizes the high level operations and sequence that Cloud Assembly uses to resolve tags and define a deployment:
- Cloud zones are filtered by several criteria, including availability and profiles; tags in profiles for the region the zone belongs to are matched at this point.
- Zone and compute capability tags are used to filter the remaining cloud zones by hard constraints.
- Out of the filtered zones, priority is used to select a cloud zone. If there are several cloud zones with the same priority, they are sorted by matching soft constraints, using a combination of the cloud zone and compute capabilities.
- After a cloud zone is selected, a host is selected by matching a series of filters, including hard & soft constraints as expressed in cloud templates.