When managing APIs with Azure API Management and Terraform, syncing your OpenAPI schema can follow two distinct paths. One approach prioritizes rapid development and iteration, while the other emphasizes stability and version control. Choosing between them depends on your development goals and how you intend to manage changes to your API over time.

A common pattern is to use the openapi-link method to import your OpenAPI specification directly from a URL. At first glance, this seems straightforward—point your Terraform resource to a hosted JSON file and let it do the rest. However, this setup has a major caveat: Terraform will not detect changes to the document unless the URL itself changes.

This means that if you update your OpenAPI spec at the same URL, Terraform will not recognize the difference. The state remains unchanged, and Terraform will not trigger any updates in Azure API Management. To force Terraform to detect the update, you’d have to change the URL — typically by versioning it, such as bumping from /openapi/v1.json to /openapi/v2.json. However, this introduces its own complications.

If your goal is to push frequent, iterative updates to your API while it’s still under heavy development, this pattern quickly becomes unwieldy. Updating the OpenAPI URL requires coordinated changes in your application code to serve the new versioned file and corresponding changes in your infrastructure code to reference the new URL. It also adds complexity if you aren’t ready to support multiple versions of your API yet.

Here’s what not to do in that case:

resource "azurerm_api_management_api" "main" {
  name                = "file-upload"
  resource_group_name = var.api_management.resource_group
  api_management_name = var.api_management.name

  display_name          = "file-upload"
  protocols             = ["https"]
  subscription_required = false
  revision              = "1"
  path                  = "file-upload"

  import {
    content_format = "openapi-link"
    content_value  = "${var.endpoint}/openapi/v1.json"
  }
}

This approach works best when you are managing stable, versioned APIs and want to explicitly define and deploy different API versions. If you’re already on a versioning strategy and need strong control over long-term schema stability, this may be the right path.

A Better Option for Rapid Development

If you’re still in the early stages of API development — pre-1.0, where your schema is undergoing frequent and significant changes — you’ll want a faster, more flexible workflow. Instead of using openapi-link, you can use Terraform’s http data source to fetch the OpenAPI document content directly and perform content-based diffs.

The key advantage here is that Terraform retrieves the actual contents of the OpenAPI JSON file and compares them during each plan and apply cycle. If there are any changes in the API schema, Terraform will detect them — even if the URL stays the same. This provides a tight feedback loop between your OpenAPI changes and your infrastructure without requiring you to version URLs or modify application code just to push updates.

Here’s the recommended pattern for rapid iteration:

data "http" "openapi" {
  url = "${var.endpoint}/openapi/v1.json"
}

resource "azurerm_api_management_api" "main" {
  name                = "file-upload"
  resource_group_name = var.api_management.resource_group
  api_management_name = var.api_management.name

  display_name          = "file-upload"
  protocols             = ["https"]
  subscription_required = false
  revision              = "1"
  path                  = "file-upload"

  import {
    content_format = "openapi+json"
    content_value  = data.http.openapi.response_body
  }
}

In this setup, the OpenAPI document is retrieved as raw JSON and injected into the API Management resource. Because the data.http block exposes the content directly, Terraform can detect and react to changes instantly. There’s no need to version the URL unless you’re also managing versioned endpoints in your application logic.

Choosing the Right Strategy

These two approaches represent different philosophies of API lifecycle management. If you’re developing an API that’s still evolving rapidly, using http to inject the raw OpenAPI content gives you immediate feedback and the flexibility to iterate quickly.

Once your API stabilizes and you’re ready to manage multiple versions or enforce strict versioning discipline, switching to openapi-link with versioned URLs may be the better long-term strategy.

Understanding the trade-offs between these options can help you tailor your infrastructure to fit your API’s stage of maturity, whether you’re moving fast or building for the long haul.

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