SAP BTP Terraform Provider Bug: Sensitive Fields

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Hey guys! Ever run into a situation where your Terraform deployments for SAP BTP are acting a little... wonky? Specifically, are you seeing those pesky "inconsistent state" errors pop up when dealing with sensitive information, like passwords or client secrets, in your btp_subaccount_destination resources? Let's dive into this frustrating issue, break down what's happening, and explore some possible solutions. We will talk about Terraform provider SAP BTP, Terraform inconsistent state, and sensitive fields.

The Bug: Sensitive Data and Terraform's Memory

So, the core problem lies within the SAP BTP Terraform provider (version 1.18.1, as reported), specifically when creating btp_subaccount_destination resources. These resources are used to define destinations, which are basically connection settings for your applications to reach external services. The issue arises with certain authentication types like BasicAuthentication and OAuth2ClientCredentials that require sensitive information in the additional_configuration block.

What happens is this: Terraform successfully creates the destination resource in SAP BTP. However, when the provider tries to read back the state of the resource after the apply operation, it reports that the sensitive fields (like Password for BasicAuthentication or clientSecret for OAuth2ClientCredentials) are empty. This triggers an "inconsistent state" error, even though the resource was created correctly.

Imagine this: you tell Terraform, "Hey, create this destination, and the password is 'mySecretPassword'." Terraform does its job, the destination is created on the SAP BTP side. But when Terraform checks back, it's like the provider forgot the password and reports it as an empty string. This causes Terraform to think something has changed, even if it hasn't, leading to a frustrating loop of errors.

Let's clarify what we're looking at, including SAP, Terraform, inconsistent state, and sensitive data.

Affected Authentication Types and Fields

The main culprits are:

  • BasicAuthentication: The Password field is the primary source of trouble.
  • OAuth2ClientCredentials: The clientSecret field is the main issue here.
  • Other authentication types: There might be similar issues with other authentication types that also use sensitive credentials.

Expected Behavior vs. Reality

When we run terraform apply, here's what we expect:

  • Successful creation: The resources should be created without any errors, especially those that include sensitive data.
  • Consistent state: The Terraform state should accurately reflect the actual state of the resources in SAP BTP. There should be no discrepancies.

But that's not what is happening. The state is changing and is inconsistent.

Reproducing the Error: Steps to Follow

Here's how you can try to reproduce the issue. To recreate the error, you'll need a couple of files and your Terraform configuration set up correctly. Here's a quick walkthrough:

Scenario 1: Basic Authentication

  1. Create a Configuration File: You'll start by creating a file named terraform.subaccount_destinations.json. Inside this file, you'll define your subaccount destinations using a JSON structure. You'll specify the name, type, proxy_type, url, authentication method, description, and subaccount_id for your destinations. The essential part of this configuration is setting up the additional_configuration to include User and Password credentials. This example shows two destinations: the first one has missing password, which may trigger an error; the second will trigger an inconsistent state error. Here's the sample code to use:

    {
  "subaccount_destinations": {
    "subaccount-01-jkey": {
      "tf-basic-auth-001-jkey": {
        "name": "tf-basic-auth_001",
        "type": "HTTP",
        "proxy_type": "Internet",
        "url": "https://api.authentication.us10.hana.ondemand.com",
        "authentication": "BasicAuthentication",
        "description": "Basic Auth",
        "subaccount_id": "00000000-7a39-4408-9f38-000000000000",
        "additional_configuration": {
          "User": "authorized"
        }      
      },
      "tf-basic-auth-002-jkey": {
        "name": "tf-basic-auth_002",
        "type": "HTTP",
        "proxy_type": "Internet",
        "url": "https://api.authentication.us10.hana.ondemand.com",
        "authentication": "BasicAuthentication",
        "description": "Basic Auth",
        "subaccount_id": "00000000-7a39-4408-9f38-000000000000",
        "additional_configuration": {
          "User": "authorized",
          "Password": "myPass"
        }      
      }
    }
  }
}

  2. Run Terraform: You'll use the command terraform apply with some variables, like globalaccount and the variable file, to create the subaccount destinations in SAP BTP. You will also use the -auto-approve flag to avoid manual confirmation. Make sure to replace <your-ga> with your actual global account ID.

    terraform apply -var "globalaccount=<your-ga>" -var-file="terraform.subaccount_destinations.json" -auto-approve

    Result: The first destination (without a password) may fail, and the second destination (with a password) will likely create successfully but throw an inconsistent state error after it's done.

Scenario 2: OAuth2 Client Credentials

  1. Configure the JSON File: In a similar fashion, create a terraform.subaccount_destinations.json file. This configuration will define destinations, including NoAuthentication and OAuth2ClientCredentials with varying configurations. You'll specify name, type, proxy_type, url, authentication, and subaccount_id, along with additional_configuration. Be sure to set up the additional_configuration to include clientId, clientSecret, tokenServiceURL, and tokenServiceURLType. This configuration will set up three destinations: one using NoAuthentication, one using OAuth2ClientCredentials without a clientSecret, and another with a clientSecret. Below is the sample code:

    {
  "subaccount_destinations": {
    "subaccount-01-jkey": {
      "tf-http-basic-destination-jkey": {
        "name": "tf-http-basic-destination",
        "type": "HTTP",
        "proxy_type": "Internet",
        "url": "https://myservice.example.com",
        "authentication": "NoAuthentication",
        "description": "Subaccount-level destination with additional configuration",
        "subaccount_id": "00000000-7a39-4408-9f38-000000000000"
      },
      "tf-xsuaa-apiaccess-clientId-jkey": {
        "name": "tf-xsuaa-apiaccess-no-secret",
        "type": "HTTP",
        "proxy_type": "Internet",
        "url": "https://api.authentication.us10.hana.ondemand.com",
        "authentication": "OAuth2ClientCredentials",
        "description": "Destination for XSUAA apiaccess plan",
        "subaccount_id": "00000000-7a39-4408-9f38-000000000000",
        "additional_configuration": {
          "clientId": "clientId",
          "tokenServiceURL": "https://XXXXXXXXtrial.authentication.us10.hana.ondemand.com/oauth/token",
          "tokenServiceURLType": "Dedicated"
        }
      },
      "tf-xsuaa-apiaccess-clientId-clientSecret-jkey": {
        "name": "tf-xsuaa-apiaccess-clientId-clientSecret",
        "type": "HTTP",
        "proxy_type": "Internet",
        "url": "https://api.authentication.us10.hana.ondemand.com",
        "authentication": "OAuth2ClientCredentials",
        "description": "Destination for XSUAA apiaccess plan",
        "subaccount_id": "00000000-7a39-4408-9f38-000000000000",
        "additional_configuration": {
          "clientId": "sb-na-2e2cc4ef-f29b-4618-bdf7-00000000000000000000",
          "clientSecret": "fee19c27-bdec-4929-a4bf-7aecdcee5a0f$wI_AWfR7vVuDegWS8ghXXXXXXXXXXXXXXXXXXXXXXXXX",
          "tokenServiceURL": "https://XXXXXXXXtrial.authentication.us10.hana.ondemand.com/oauth/token",
          "tokenServiceURLType": "Dedicated"
        }
      }
    }
  }
}

  2. Run Terraform: Execute terraform apply with the specified variables. Substitute your global account ID where needed. For the variable, use the command below:

    terraform apply -var "globalaccount=XXXXXXXXtrial-ga" -var-file="terraform.subaccount_destinations.json" -auto-approve

    Result: The initial destinations (without secret keys) should be created without errors. But the last destination (with the clientSecret key) will likely throw the same inconsistent state error, showing the value of clientSecret as "" instead of the actual key.

The Error Messages

Here are some examples of the error messages you might see:

  • Scenario 1: The error will be something along the lines of the provider producing an inconsistent result after apply, and it'll show that the Password has changed from the actual value to an empty string.

    Error: Provider produced inconsistent result after apply
When applying changes to btp_subaccount_destination.this["subaccount-01-jkey,tf-basic-auth-002-jkey"], 
provider "provider["registry.terraform.io/sap/btp"]" produced an unexpected new value: 
.additional_configuration: was cty.StringVal("{"Password":"myPass","User":"authorized"}"), 
but now cty.StringVal("{"Password":"","User":"authorized"}").
This is a bug in the provider, which should be reported in the provider's own issue tracker.

  • Scenario 2: The error message will indicate that the clientSecret has been changed from its original value to an empty string.

    Error: Provider produced inconsistent result after apply
When applying changes to btp_subaccount_destination.this["subaccount-01-jkey,tf-xsuaa-apiaccess-clientId-clientSecret-jkey"], 
provider "provider["registry.terraform.io/sap/btp"]" produced an unexpected new value: 
.additional_configuration: was cty.StringVal("{"clientId":"sb-na-2e2cc4ef-f29b-4618-bdf7-00000000000000000000",
"clientSecret":"fee19c27-bdec-4929-a4bf-7aecdcee5a0f$wI_AWfR7vVuDegWS8ghXXXXXXXXXXXXXXXXXXXXXXXXX",
"tokenServiceURL":"https://XXXXXXXXtrial.authentication.us10.hana.ondemand.com/oauth/token","tokenServiceURLType":"Dedicated"}"), 
but now cty.StringVal("{"clientId":"sb-na-2e2cc4ef-f29b-4618-bdf7-00000000000000000000","clientSecret":"",
"tokenServiceURL":"https://XXXXXXXXtrial.authentication.us10.hana.ondemand.com/oauth/token","tokenServiceURLType":"Dedicated"}").
This is a bug in the provider, which should be reported in the provider's own issue tracker.

Terraform Configuration Example

Here's a snippet of the Terraform configuration to help you define a btp_subaccount_destination resource. This is a crucial part of the setup, as it demonstrates how to handle the additional_configuration block, where the sensitive credentials live. Take note of how the jsonencode function is used to convert the configuration into a JSON string, which the BTP provider expects.

resource "btp_subaccount_destination" "this" {
  for_each = local.subaccount_destinations_map

  name           = each.value.name
  type           = each.value.type
  proxy_type     = each.value.proxy_type
  url            = each.value.url
  authentication = each.value.authentication
  subaccount_id  = each.value.subaccount_id

  description         = each.value.description
  service_instance_id = each.value.service_instance_id

  additional_configuration = (
    each.value.additional_configuration != null
    ? jsonencode(each.value.additional_configuration)
    : null
  )
}

What's Causing the Problem?

It appears the SAP BTP provider isn't correctly handling sensitive data when reading back the state after an apply operation. It's likely that the provider is either not storing the sensitive values in the state or is intentionally masking them, which causes the subsequent comparison to fail.

Potential Workarounds & Solutions

Unfortunately, as this is a provider issue, there aren't many workarounds. But here are a few things you can try:

  1. Provider Updates: Keep an eye on updates to the SAP BTP Terraform provider. SAP is likely working on a fix, so updating to the latest version might resolve the issue.
  2. State Management: If you are using remote state, ensure your state backend is configured correctly and has the necessary permissions. A misconfigured backend can sometimes cause state discrepancies, though it's less likely to be the root cause in this specific scenario.
  3. Manual Intervention (Not Recommended): In extreme cases, you could manually modify the Terraform state file. But be warned, this is highly discouraged because it can lead to further inconsistencies and is prone to errors. Only do this as a last resort and with extreme caution.
  4. Issue Reporting: Report the bug to the provider's issue tracker. Providing detailed steps to reproduce the issue will help the developers find and fix the problem. You can find the issue tracker on the provider's GitHub page or SAP's support channels.

The Bottom Line

This bug is a real pain, but understanding the root cause helps to prepare for it. The inconsistent state error is a result of the Terraform provider not correctly handling sensitive information when reading the state. The best course of action is to report the bug, monitor provider updates, and hope for a fix. Keep a close eye on your Terraform deployments and be ready to adapt as the provider evolves. Hopefully, a fix is on the way.