How to Deploy MockServer to Azure using Terraform and Docker

Deploying applications using Terraform and Docker makes it extremely quick and easy to setup software in Azure. In this tutorial I use the MockServer docker image to deploy an application that can be used to mock REST API calls during development phases. Checkout the MockServer docs for more information.

Prerequisites

To run terraform we need to download the terraform executable from the Hashicorp website. Extract the zip to a known location and add that location to your PATH variable so that you can execute in a command line terminal.

Also, ensure you have the Azure CLI tools installed. We will use the az login command from the terminal which will redirect to a browser for you to login as well as to setup the initial Azure resources.

Storing the Terraform State

We will store the state remotely in an Azure Storage Blob which makes it easier to manage the resources for continuous delivery scenarios. First we use the az command mentioned above to create a resource group, storage account and blob container:

az login

$RESOURCE_GROUP_NAME='unstacked-mockserver-rg-dev'
$STORAGE_ACCOUNT_NAME="tfstatestorage$(Get-Random)" 
$CONTAINER_NAME='tfstate'
#
# Create resource group
#
az group create --name $RESOURCE_GROUP_NAME --location ukwest
#
# Create storage account
#
az storage account create --resource-group $RESOURCE_GROUP_NAME --name $STORAGE_ACCOUNT_NAME --location uksouth --sku Standard_LRS
#
# Create blob container
#
az storage container create --name $CONTAINER_NAME --account-name $STORAGE_ACCOUNT_NAME --verbose

The state will be stored in a file called terraform.tfstate inside the container tfstatestorageXXX in the specified resource group.

As of version 4 of the azurerm terraform provider we are now required to provide the Azure Subscription ID. Use the az show command to find the Subscription ID and export it as an environment variable:

# Read Subscription ID
az account show

# Export the id as an evnironment variable
$env:ARM_SUBSCRIPTION_ID = "<azure-subscription-id>"

Creating the Infrastructure

The full Terraform code for deploying the MockServer is shown below. Save the content to a file locally called main.tf :

terraform {
  required_providers {
    azurerm = {
      source  = "hashicorp/azurerm"
      version = "~> 4.16.0"
    }
  }
  backend "azurerm" {
    resource_group_name  = "unstacked-mockserver-rg-dev"
    storage_account_name = "tfstatestorage1718258922"
    container_name       = "tfstate"
    key                  = "terraform.tfstate"
  }
}

provider "azurerm" {
  features {}
}

data "azurerm_resource_group" "rg" {
  name = "unstacked-mockserver-rg-dev"
}

resource "azurerm_service_plan" "mockapi_plan" {
  name                = "unstacked-mockserver-asp-dev"
  resource_group_name = data.azurerm_resource_group.rg.name
  location            = data.azurerm_resource_group.rg.location
  os_type             = "Linux"
  sku_name            = "B1"
}

resource "azurerm_linux_web_app" "mockapi_app" {
  name                = "unstacked-mockserver-app-dev"
  resource_group_name = data.azurerm_resource_group.rg.name
  location            = data.azurerm_resource_group.rg.location
  service_plan_id     = azurerm_service_plan.mockapi_plan.id
  https_only          = true

  site_config {
    minimum_tls_version = "1.2"
    application_stack {
      docker_registry_url = "https://index.docker.io"
      docker_image_name   = "mockserver/mockserver:latest"
    }
  }

  app_settings = {
    "WEBSITES_PORT" = "1080"
  }

  identity {
    type = "SystemAssigned"
  }
}

In the code above the backend section sets up the configuration for the remote Terraform state ensuring that the state file is stored in Azure and not locally. Also, we actually store the MockServer resources in the same resource group that we created for the Terraform file by using a Terraform Data Source.

With the above code saved to file we now ready to use the Terraform CLI executable downloaded in the first step to create the MockServer resources. Open a command line terminal and CD to where you saved main.tf. The basic Terraform commands are:

Note you can use set-alias in PowerShell to create a shorter form of the terraform command - less typing!

Run the following commands to create the MockServer in an Azure Web App resource in your subscription:

set-alias ter terraform

ter init
ter plan
ter apply -auto-approve

The commands take sometime to run through, but at the end of the apply operation the new resources will be created in the Azure Portal.

Using MockServer

If you browse to the mockserver/dashboard path of your deployed MockServer you can see the dashboard outlining the status of any expectations created and requests made:

Its possible to create a variety of expectations and responses, MockServer is very configurable and has some great documentation:

• Clients

• Request Property Matchers

• Response Actions

I particularly like the detailed logging which explains why an incoming request does not match a particular expectation - extremely useful for debugging: