Consider splitting azurerm_iothub resource into several smaller ones

[maxbog]

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Description

Right now, all endpoints and routes for IoTHub must be known at the moment of IoTHub creation. In my case, this causes unwanted coupling, which I'd like to eliminate. It's best to show an example.

Let's say we have two terraform modules:

• iothub - this one contains (among other things) the iothub configuration
• reporting - this one has some resources which will be used to process the messages from IoTHub.

I want IoTHub to have several routes which forward messages to different Event Hubs. Right now, I would have to define all of those event hubs in the iothub module, so that I can pass the connection string to the azurerm_iothub resource. However, what I'd like to be able to do is to define IoTHub only in the iothub module and configure endpoints and routing in the reporting module.

New or Affected Resource(s)

• azurerm_iothub
• azurerm_iothub_route
• azurerm_iothub_fallback_route
• azurerm_iothub_endpoint_eventhub
• azurerm_iothub_endpoint_storage_container
• azurerm_iothub_endpoint_servicebus_queue
• azurerm_iothub_endpoint_servicebus_topic

Potential Terraform Configuration

resource "azurerm_iothub" "example" {
  resource_group_name = "example"
  location = "East US"

  name = "example"

  sku {
    capacity = 1
    name = "S1"
    tier = "Standard"
  }
}

resource "azurerm_iothub_endpoint_eventhub" "example_endpoint1" {
  resource_group_name = "${azurerm_iothub.example.resource_group_name}"
  iothub_name = "${azurerm_iothub.example.name}"

  connection_string = "..."
  name = "example-endpoint1"
}

resource "azurerm_iothub_endpoint_storage_container" "example_endpoint2" {
  resource_group_name = "${azurerm_iothub.example.resource_group_name}"
  iothub_name = "${azurerm_iothub.example.name}"

  connection_string = "..."
  batch_frequency_in_seconds = 60
  container_name = "example"
  file_name_format = "{iothub}/{partition}/{YYYY}/{MM}/{DD}/{HH}/{mm}"
  encoding = "avro"
  max_chunk_size_in_bytes = 10485760
  name = "example-endpoint2"
}

resource "azurerm_iothub_route" "example_route1" {
  resource_group_name = "${azurerm_iothub.example.resource_group_name}"
  iothub_name = "${azurerm_iothub.example.name}"
  enabled = true
  endpoint_names = [ "${azurerm_iothub_endpoint.example_endpoint1.name}"]
  name = "example-route1"
  source = "DeviceMessages"
  condition = "message-type = 'type1'"
}

resource "azurerm_iothub_route" "example_route2" {
  resource_group_name = "${azurerm_iothub.example.resource_group_name}"
  iothub_name = "${azurerm_iothub.example.name}"
  enabled = true
  endpoint_names = [ "${azurerm_iothub_endpoint.example_endpoint2.name}"]
  name = "example-route2"
  source = "DeviceMessages"
  condition = "message-type = 'type2'"
}

I am willing to work on this if you think it's in line with how the azurerm provider is developing.

References

• Feature Request: Set azurerm_iothub shared access policies #2201

[maxbog]

Have you had any time to think about this issue? Like I said, I am willing to implement the change, so the only thing needed right now is an OK/nope from the core team with some possible comments :)

[maxbog]

ping

[tombuildsstuff]

hey @maxbog

Thanks for opening this issue / apologies for the delayed response here.

Taking a look into this, I think splitting this out would make sense - from what I can see I think this'd be simplest to start with the endpoint field/resource. Since the only API endpoint available for IoTHubs appears to be the one we're currently using (and I can't find a Data Plane SDK/API we could use to make a more granular API call) - we'll have to fake this in several ways:

1. We'll need to use Locks inside the IoTHub resources, to ensure that they're not being modified at the same time (example)
2. We'll also need to build/fake a Resource ID for the IoTHub child resources (example) - since all of the information we require to look it up must be available in the ID (at Import time)
3. Finally we'll need to deprecate the built-in endpoints and route blocks (and make them Computed) so that we can replace them with the new resources, and then remove them in 2.0.

WDYT?

Thanks!

[maxbog]

Hi, thanks for the response!

I agree with you on all the points and this is actually how I planned to proceed.

However, I'd like to make one clarification before I proceed. Currently, there is a single field named endpoint in the azurerm_iothub resource, which is actually used to define 4 different types of endpoints (Storage Container, Service Bus Queue, Service Bus Topic and Event Hub). I was thinking about splitting it into 4 resources, one for each of the types, as each of them has different mandatory fields. They would of course share the majority of the code underneath, but I think having separate resources with their own, simpler documentation would be beneficial for the user.

What do you think?

Either way, please expect some PRs in the coming weeks :)

[tombuildsstuff]

@maxbog yep, totally agree on splitting those out into the 4 sub-resources 👍 (sorry I should have clarified that)

Thanks!

[tombuildsstuff]

Closing since #3679 has been merged via #4965

[ghost]

This has been released in version 1.38.0 of the provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading. As an example:

provider "azurerm" {
    version = "~> 1.38.0"
}
# ... other configuration ...

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. If you feel I made an error 🤖 🙉 , please reach out to my human friends 👉 [email protected]. Thanks!