What does 'terraform apply' primarily do?

The command 'terraform apply' is primarily used to create or update infrastructure as defined in the Terraform configuration files. When you run this command, Terraform evaluates the current state of your infrastructure—stored in the state file—and compares it with the desired state defined in your configuration files. It then generates an execution plan that shows what actions will be taken to align the actual infrastructure with the desired state.

If there are changes needed, 'terraform apply' will execute the necessary actions, such as creating new resources, modifying existing ones, or deleting resources that are no longer defined in the configuration. This makes it a crucial command for effectively managing and provisioning infrastructure in a declarative way.

In contrast, directly changing the state file, validating configurations only, or destroying infrastructure are not the primary actions associated with this command. Although 'terraform apply' might result in modifying the state file as part of its process, its core function is to apply the desired changes to your infrastructure based on the configurations provided.