Generate Terraform files for existing resources

You may find yourself in a position where a resource already exists in your cloud environment but was created in the respective provider’s GUI rather than in Terraform. You may feel a bit overwhelmed at first, but there are a few ways to generate Terraform files for existing resources, and we’re going to talk about the various ways today. This is also not an exhaustive list; if you have any other suggestions, please leave a comment and I’ll be sure to update this post.

Method 1 – Manual

Be warned, the manual method takes a little more time, but is not restricted to certain resource types. I prefer this method because it means that you’ll be able to see every setting that is already set on your resource with your own two eyes, which is good for sanity checking.

First, you’re going to want to create a .tf file with just the outline of the resource type you’re trying to import or generate.

For example, if I wanted to create the Terraform for a resource group called example-resource-group that had several tags attached to it, I would do:

resource "azurerm_resource_group" "example-resource-group" {
}

and then save it.

Next, I would go to the Azure GUI, find and open the resource group, and then open the ‘Properties’ section from the blade.

I would look for the Resource ID, for example /subscriptions/54ba8d50-7332-4f23-88fe-f88221f75bb3/resourceGroups/example-resource-group and copy it.

I would then open up a command prompt / terminal and import the state by running: terraform import azurerm_resource_group.example-resource-group /subscriptions/54ba8d50-7332-4f23-88fe-f88221f75bb3/resourceGroups/example-resource-group

Finally, and this is the crucial part, I would immediately run terraform plan. There may be required fields that you will need to fill out before this comamnd works, but in general, this will compare the existing state that you just imported to the blank resource in the .tf file, and show you all of the differences which you can then copy into your new Terraform file, and be confident that you have imported all of the settings.

Example:

# azurerm_resource_group.example-resource-group will be updated in-place
   ~ resource "azurerm_resource_group" "example-resource-group" {
         id       = "/subscriptions/54ba8d50-7332-4f23-88fe-f88221f75bb3/resourceGroups/example-resource-group"
         location = "centralus"
         name     = "example-resource-group"
       ~ tags     = {
           ~ "environment" = "dev" -> null
           ~ "owner"       = "example.person" -> null
           ~ "product"     = "internal" -> null
         }
     }

A shortcut I’ve found is to just copy the entire resource section, and then replace all of the tildes (~) with spaces, and then find and remove all instances of -> null.

Method 2 – Az2tf (Azure only)

Andy Thomas (Microsoft employee) put together a tool called Az2tf which iterates over your entire subscription, and generates .tf files for most of the common types of resources, and he’s adding more all the time. Requesting a specific resource type is as simple as opening an issue and explaining which resource is missing. In my experience, he’s responded within a few hours with a solution.

Method 3 – Terraforming (AWS only)

Daisuke Fujita put together a tool called Terraforming that with a little bit of scripting can generate Terraform files for all of your AWS resources.

Method 4 – cf-terraforming (Cloudflare only)

Cloudflare put together a fantastic tool called cf-terraforming which rips through your Cloudflare tenant and generates .tf files for everything Cloudflare related. The great thing about cf-terraforming is that because it’s written by the vendor of the original product, they treat it as a first class citizen and keep it very up-to-date with any new resources they themselves add to their product. I wish all vendors would do this.

To sum things up, there are plenty of ways to generate Terraform files for existing resources. Some are more time consuming than others, but they all have the goal of making your environment less brittle and your processes more repeatable, which will save time, money, and most importantly stress, when an inevitable incident takes place.

Do you know of any other tools for these or other providers that can assist in bringing previously unmanaged resources under Terraform management? Leave a comment and we’ll add them to this page as soon as possible!

Add your AWS API key info in a Key Vault for Terraform

EDIT: Updated on July 10, 2019; modified second- and third-last paragraphs to show the correct process of retrieving the AWS_SECRET_ACCESS_KEY from the Key Vault and setting it as a protected environment variable

Our primary cloud is in Azure which makes building DevOps pipelines with automation scoped to a particular subscription very easy, but what happens when we want to deploy something in AWS, since storing keys in source control is A Very Bad Idea™?

Simple, we use Azure Key Vault.

First, we created a Key Vault specifically for this purpose called company-terraform which will specifically be used to store the various secrets for Terraform-based deployments. When you tie a subscription from Azure DevOps to an Azure subscription, it creates an “application” in the Azure Enterprise Applications list, so give that application Get and List permissions to this vault.

Next, we created a secret called AmazonAPISecretKey and then set the secret’s content to the actual API key you are presented when you enable programmatic access to an account in the AWS IAM console.

In our Azure DevOps Terraform build and release pipelines, we then added an Azure Key Vault step, selecting the appropriate subscription and Key Vault. Once selected, we added a Secrets filter AmazonAPISecretKey meaning that it will only ever fetch that secret on run; if you will be adding multiple secrets which will all be used in this particular pipeline, add them to this filter list.

Finally, we can now use the string $(AmazonAPISecretKey) in any shellexec or other pipeline task to authenticate against AWS, while never having to commit the actual key to a viewable source.

Since one of the methods the Terraform AWS provider can use to authenticate is by using the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables, we will set them up so that DevOps can use them in its various tasks.

First, open your Build or Release pipeline and select the Variables tab. Create a new variable called AWS_ACCESS_KEY_ID and set the value to your access key ID (usually something like AK49FKF4034F42DZV2VRMD). Then create a second variable called AWS_SECRET_ACCESS_KEY which you can leave blank, but click the padlock icon next to it, to tell DevOps that its contents are secret and shouldn’t be shared.

Now create a shellexec task and add the following command to it, which will set the AWS_SECRET_ACCESS_KEY environment variable to the contents of the Key Vault entry we created earlier:

echo "##vso[task.setvariable variable=AWS_SECRET_ACCESS_KEY;]$(AmazonAPISecretKey)"

And there you have it! You can now reference your AWS accounts from within your Terraform structure without ever actually exposing your keys to prying eyes!