First lets check out the terraform state CLI command, it comes with 7 subcommands:

• list - list all resources within the state file
• mv - move an item within the state file
• pull - pull the current state file and output it to our terminal
• push - update remote state from a local state file
• replace-provider - replace a provider within the state file
• rm - remove a resource from our state file
• show - show a single resource within the state file

Generally I use list and show fairly frequently to interrogate what’s in the state file, especially if it is a new codebase that I am looking at.

The rm subcommand can also be very useful if someone has been unkind enough to remove a resource (e.g. from the Azure portal). This allows us to remove that reference in state so that Terraform won’t complain, although if we don’t also remove it from the code Terraform will try to create on next apply.

This is actually pretty common during the development phase with larger projects. Let’s say you’ve built an entire cloud environment but you want to recreate a network. taint allows us to do this, otherwise we might need to delete the resource manually or comment the code out, neither are good solutions.

# Find the resource in state
terraform state list

# Inspect the resource
terraform state show azurerm_virtual_network.this

# Taint the resource
terraform taint azurerm_virtual_network.this

On the next terraform apply the azurerm_virtual_network.this will be recreated. If you change your mind and no longer require the resource to be tainted then you can use the aptly named untaint command.

terraform untaint azurerm_virtual_network.this

Sometimes we define all of our resources in our Terraform code but for some reason the resource is manually created. This leaves us in a state where Terraform can see the resource on the remote end and in its code but not in state. In order to fix that we need to import the resource into state this is where the import command comes into play.

terraform import azurerm_virtual_network.this /subscriptions/00000000-0000-0000-0000-000000000000/resourceGroups/Resource_Group/providers/Microsoft.Network/virtualNetworks/Virtual Network 

This happens as our Terraform code grows, we might start with a single instance of something and then move to multiple instance through the use of the for expression or through creation of a module. To tell Terraform that we want to move our currently existing resource into one of those constructs we can either use the moved block or the Terraform mv command. Let’s take a look at an example.

# `for` expression
terraform mv azurerm_virtual_network.this azurerm_virtual_network.this["primary"]

# Module
terraform mv azurerm_virtual_network.this module.virtual_networks.azurerm_virtual_network.this

terraform refresh