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Lab description

This lab will cover the very basic terraform workflow for the updating of resources in Azure.

The terraform Core Workflow is still:

Day 2 operation (update)

Setup

Make sure you are in the correct folder:

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cd ~/terraform-labs

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cd ~/terraform-labs

If you were unable to complete the last lab, you can find a copy of the files in the solutions folder

1. Write

  1. Open main.tf on the editor and add a tag by making the below change within contoso_rg resource

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     tags = {
   cost_center = "contoso research"
 }

    It should look something like below:

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     resource "azurerm_resource_group" "contoso_rg" {
   name     = "contoso_rg"
   location = "UK South"
    
   tags = {
     cost_center = "contoso research"
   } 
 }

  2. Save main.tf

Note: we are not doing an init this time because the .terraform folder and azure provider plugin is already available from our previous run. When running in a CI / CD pipeline, this step may be required.

2. Plan

  1. Do a terraform plan but this time we are also storing the output in a separate .tfplan file

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     terraform plan -out contoso.tfplan

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     terraform plan -out contoso.tfplan

  2. Take a look at the plan file that’s been created using show command as before.

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     terraform show contoso.tfplan

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     terraform show contoso.tfplan

    You should see something like below

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     azurerm_resource_group.contoso_rg: Refreshing state... [id=/subscriptions/b857908d-3f5c-4477-91c1-0fbd08df4e88/resourceGroups/contoso_rg]
    
 Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
   ~ update in-place
    
 Terraform will perform the following actions:
    
   # azurerm_resource_group.contoso_rg will be updated in-place
   ~ resource "azurerm_resource_group" "contoso_rg" {
         id         = "/subscriptions/b857908d-3f5c-4477-91c1-0fbd08df4e88/resourceGroups/contoso_rg"
         name       = "contoso_rg"
       ~ tags       = {
           + "cost_center" = "contoso research"
         }
         # (2 unchanged attributes hidden)
     }
    
 Plan: 0 to add, 1 to change, 0 to destroy.
    
 ───────────────────────────────────────────────────────────────────────
    
 Saved the plan to: contoso.tfplan
    
 To perform exactly these actions, run the following command to apply:
     terraform apply "contoso.tfplan"

  3. Add to .gitignore file

    Much like, .tfstate, .tfplan files can also contain sensitive information and should be kept as secure as possible. It is also in .gitignore of this repo.

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     Add-Content .gitignore "$([Environment]::NewLine)contoso.tfplan"

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     echo "contoso.tfplan" >> .gitignore

    See: https://developer.hashicorp.com/terraform/cli/commands/plan#out-filename

3. Apply

Pass the plan file to terraform apply and this time, we also do an -auto-approve, so we are not prompted for approval.

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terraform apply -auto-approve "contoso.tfplan"

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terraform apply -auto-approve "contoso.tfplan"

The terminal output should state something like below

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azurerm_resource_group.contoso_rg: Modifying... [id=/subscriptions/b857908d-3f5c-4477-91c1-0fbd08df4e88/resourceGroups/contoso_rg]
azurerm_resource_group.contoso_rg: Modifications complete after 1s [id=/subscriptions/b857908d-3f5c-4477-91c1-0fbd08df4e88/resourceGroups/contoso_rg]

Apply complete! Resources: 0 added, 1 changed, 0 destroyed.

4. Verify

Verify that cost_center tag has been created on our resource group.

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az group show --name "contoso_rg"

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az group show --name "contoso_rg"

Take a quick look at the state file as well.

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terraform show terraform.tfstate

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terraform show terraform.tfstate

5. Version control your code

  1. Add main.tf to git

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     cd ~/terraform-labs
    
 git add .
 git commit -m "Added tags to resource group"

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     cd ~/terraform-labs
    
 git add .
 git commit -m "Added tags to resource group"

  2. You are welcome to push your changes to your own remote if you prefer.

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