2_Azure_WebApp.md

Build an Azure Web App

For this project, we'll deploy an Azure App Service, with its corresponding App Service Plan, using Terraform. Then we'll deploy an app using the Deployment Center feature in the App Service page in the Portal.

The Project

• First, we'll create the Terraform file, which will contain the resources to be deployed.
• This is my main.tf file.
• In the video, Michael didn't include in his file the creation of the resource group. I included it. As you can see from my file, the first resource block is a resource group.
• Two other files accompany the main.tf: variables.tf and terraform.tfvars.
  • variables.tf is where we define the variables we'll use throughout our configuration file.
  • terraform.tfvars is the file where we actually specify the values for the variables.
• This is my variables.tf:

variable "app_service_plan_name" {
  type = string
}

variable "location" {
  type = string
}

variable "resource_group_name" {
  type = string
}

variable "app_service_name" {
  type = string
}

• And this is my terraform.tfvars:

app_service_plan_name = "cloudskillssp"
location              = "westeurope"
resource_group_name   = "cloudskillsapp-rg"
app_service_name      = "cloudskillsradapp"

• The terraform.tfvars file is usually included in the .gitignore file, so it wouldn't normally be in source control. This file is likely to contain sensitive and confidential information, such as passwords and credentials.
• To execute the configuration, we first need to make sure we're in the same directory as the main.tf.
• We then run terraform init to initialize the working directory. This is the first command that should be run after writing a new Terraform configuration.
• The second command we run is terraform plan. This will create an execution plan. This command is a convenient way to check whether the execution plan for a set of changes matches your expectations without making any changes to real resources or to the state.
• The third command is terraform apply and this one will actually apply the changes required to reach the desired state described in the configuration file.
• After running these commands, we can see the resources are now present.
• The next step is to deploy our app to App Service. For this, we'll use the Deployment Center feature. Deployment Center offers a quick and easy way to implement CI/CD.
• The UX we see on the video is different than the one I used. I found this new experience interesting because it's streamlined in a single page. It also automatically creates a GitHub Actions workflow.
• We'll deploy a JavaScript sample app, which I forked from Michael's GitHub repo.This is my repository.
• My GitHub account was already authorized in the Azure Portal, so I immediately saw my organization and my repositories.
• For Workflow Option, if you select Add a workflow, Azure will automatically create a GitHub Action for you. This is a great feature!
• When you click on save, you'll be taken to the Logs tab, where you can see the progress of the current commit, and the previous commits.
• After a considerable time had passed, the build and deploy succeeded!
• And this is the app running.
• After confirming everything is working, I ran terraform destroy to tear down the resources we built.

Conclusion

• In the first iteration of my Terraform configuration, I used the same value for the resource_group_name parameter in all 3 resource blocks present in the configuration, which was var.resource_group_name. This references the variables.tf file. When I first ran terraform apply, it gave me an error during the creation of the app service and app service plan, that stated that the resource group couldn't be found. A second terraform apply immediately afterwards succeeded in the creation of these resources.
• Patrick Loftus, from the community, helped me spot my mistake. I have to reference the subsequent resources, the ones which depend on the creation of a previous resource to exist, with interpolation. Like that, we're creating an implicit dependency. Otherwise, we need to use the depends_on argument. This should be used only when Terraform can't automatically infer the dependency, or when there are hidden dependencies.
• After updating my code, the resource_group_name parameter under the azurerm_app_service_plan and the azurerm_app_service resource blocks looked like this: resource_group_name = azurerm_resource_group.azurerg.name
• The dependencies between resources is something we must pay attention to. By using interpolation, Terraform will be able to figure out the dependencies most of the time.
• More detailed information about the depends_on can be found here.