State is a set of Kong configuration which is the source of truth. decK will take the state and make Admin API calls to Kong to match configuration stored in Kong’s database with the state. This is also referred to as the target state or desired state.
State is a single file or a set of files in JSON or YAML format, which hold the entire or a sub-set of configuration for Kong. The files respect Kong’s native declarative configuration format.
Sync is a process of taking current configuration of Kong and making it same as the state.
Diff is a process of doing a dry-run sync process. It doesn’t perform any changes to Kong’s database but provides a plan of entities that will be created, deleted or updated.
Select-tag is a common tag in Kong’s entity which is used to filter and group related configuration when performing configuration changes.