> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # Count > This article explores Terraform’s count meta-argument for creating multiple resource instances and discusses issues with modifying the underlying list used with count. In this article, we explore Terraform’s count meta-argument, demonstrating how it can be used to create multiple resource instances and discussing potential issues when modifying the underlying list used with count. This guide covers both static and dynamic count techniques to help you manage resources efficiently. *** ## Creating Multiple Instances with a Static Count One of the simplest ways to create multiple instances of a resource is by using a static count. Below is an example that creates three instances of a local file resource: ```hcl theme={null} resource "local_file" "pet" { filename = var.filename count = 3 } ``` The variable is defined as follows: ```hcl theme={null} variable "filename" { default = "/root/pets.txt" } ``` When you run `terraform plan`, Terraform plans to create three resources: ```bash theme={null} $ terraform plan [Output Truncated] Terraform will perform the following actions: ... # local_file.pet[2] will be created + resource "local_file" "pet" { + directory_permission = "0777" + file_permission = "0777" + filename = "/root/pets.txt" + id = (known after apply) } Plan: 3 to add, 0 to change, 0 to destroy. ``` Each resource is indexed as `pet[0]`, `pet[1]`, and `pet[2]`. Although three resources are created, all instances share the same file name, which means Terraform creates the same file three times rather than three unique files. *** ## Creating Unique Resources by Using a List Variable To generate unique resources, update the variable definition to a list and reference each element using `count.index`. Here is the modified configuration: ```hcl theme={null} resource "local_file" "pet" { filename = var.filename[count.index] count = 3 } ``` Define the list variable as follows: ```hcl theme={null} variable "filename" { default = [ "/root/pets.txt", "/root/dogs.txt", "/root/cats.txt" ] } ``` In this configuration: * The first iteration (index 0) creates `/root/pets.txt`. * The second iteration (index 1) creates `/root/dogs.txt`. * The third iteration (index 2) creates `/root/cats.txt`. After executing `terraform apply`, listing the `/root` directory produces: ```bash theme={null} $ ls /root pets.txt dogs.txt cats.txt ``` This confirms that each resource is now unique. *** ## Dynamically Adjusting the Count with the length() Function A drawback of the previous approach is its fixed count. If you wish to add more file names, the configuration would still create only three resources. To adapt dynamically to the number of elements, use the built-in `length()` function: ```hcl theme={null} resource "local_file" "pet" { filename = var.filename[count.index] count = length(var.filename) } ``` You can now define the variable with any number of file names: ```hcl theme={null} variable "filename" { default = [ "/root/pets.txt", "/root/dogs.txt", "/root/cats.txt", "/root/cows.txt", "/root/ducks.txt" ] } ``` When running `terraform apply`, Terraform will automatically create five resources—one for each element in the list. To revert back to testing with three elements, simply modify the list back to three filenames: ```hcl theme={null} variable "filename" { default = [ "/root/pets.txt", "/root/dogs.txt", "/root/cats.txt" ] } ``` After applying these changes, the `/root` directory will properly contain the three files. *** Modifying a list that drives the count parameter can lead to resource replacements due to index shifts. This may trigger unwanted service interruptions or data loss if the resources are critical. ## A Pitfall: List Element Removal and Resource Replacement When using count with a list, removing an element causes a shift in resource indices. Consider this configuration: ```hcl theme={null} resource "local_file" "pet" { filename = var.filename[count.index] count = length(var.filename) } ``` Initially, the variable is defined with three elements: ```hcl theme={null} variable "filename" { default = [ "/root/pets.txt", "/root/dogs.txt", "/root/cats.txt" ] } ``` After a successful apply, Terraform recognizes three resources: `pet[0]`, `pet[1]`, and `pet[2]`. Now, if you remove the first element (`/root/pets.txt`), the updated variable becomes: ```hcl theme={null} variable "filename" { default = [ "/root/dogs.txt", "/root/cats.txt" ] } ``` Running `terraform plan` now shows: * The resource at index 0 is updated from `/root/pets.txt` to `/root/dogs.txt`. * The resource at index 1 is updated from `/root/dogs.txt` to `/root/cats.txt`. * The resource at index 2 is marked for destruction as there is no corresponding list element. An abbreviated plan output looks like this: ```bash theme={null} $ terraform plan ... # local_file.pet[0] must be replaced -/+ resource "local_file" "pet" { directory_permission = "0777" file_permission = "0777" ~ filename = "/root/pets.txt" -> "/root/dogs.txt" # } # local_file.pet[1] must be replaced -/+ resource "local_file" "pet" { directory_permission = "0777" file_permission = "0777" ~ filename = "/root/dogs.txt" -> "/root/cats.txt" # } # local_file.pet[2] will be destroyed -/+ resource "local_file" "pet" { directory_permission = "0777" -> null file_permission = "0777" -> null ~ filename = "/root/cats.txt" -> null # } ``` This behavior occurs because the resource indices are directly linked to the order of the list elements. Removing an element causes subsequent elements to shift, resulting in the unnecessary replacement or destruction of resources. *** ## Viewing Resource Details It is often useful to confirm resource details created with count. Adding an output variable lets you verify each resource's configuration: ```hcl theme={null} output "pets" { value = local_file.pet } ``` After running `terraform output`, you should see similar details for each resource: ```bash theme={null} $ terraform output Outputs: pets = [ { "directory_permission" = "0777" "file_permission" = "0777" "filename" = "/root/pets.txt" "id" = "da39a3ee5e6b4d3255bef95601890afd80709" }, { "directory_permission" = "0777" "file_permission" = "0777" "filename" = "/root/dogs.txt" "id" = "da39a3ee5e6b4d3255bef95601890afd80709" }, { "directory_permission" = "0777" "file_permission" = "0777" "filename" = "/root/cats.txt" "id" = "da39a3ee5e6b4d3255bef95601890afd80709" }, ] ``` This output confirms that Terraform manages the resources as a list, allowing each element to be accessed individually by its index. *** ## Conclusion In this article, we demonstrated how to use the count meta-argument in Terraform to create multiple resource instances. We examined both static and dynamic count methods using a list variable and the `length()` function, respectively. Additionally, we discussed a common pitfall—removing an element from the list can trigger resource replacements due to index shifting. Practice using the count meta-argument in your Terraform projects to automate resource creation and better manage infrastructure changes. For more detailed information on Terraform and its resource management, refer to the [Terraform Documentation](https://www.terraform.io/docs).