Terraform-provider-azurerm: Provider authentication to blob using Azure AD

[omerlh]

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Description

Azure Storage now supports authentication using Azure AD, in addition to authentication with a SAS token or access keys. The provider also supports authentication with Azure AD service principal, but look like it's using the credentials to get access keys, and then use them to access the storage. I noticed that when I tried to use SP credentials and encountered the following error:

Error retrieving keys for Storage Account "<>": storage.AccountsClient#ListKeys: Failure responding to request: StatusCode=403

It happened because I granted the SP contributor role to the blob, not to the storage (least privilege!). It was solved once I granted it a contributor role to the entire storage account.

Please consider support authentication with AD credentials.

[tombuildsstuff]

hey @omerlh

Thanks for opening this issue :)

I'm currently working on replacing/writing our own Storage SDK we use to communicate with the Storage API's - so that we can move forward on some other issues; a side-effect of this is that this SDK now supports authenticating using Azure AD instead; which we'll be using in future versions of the Provider. Whilst I don't have a timeline for this, this should form a part of the 2.0 release for the Storage Services which support authenticating using Azure AD; as the other storage services switch to supporting this in the future I expect we'll also migrate them over to using AzureAD for authentication too

Thanks!

[omerlh]

Looking forward to try it out!

[mud5150]

@tombuildsstuff Our developers use a read only service principal when running plan locally. We are also running into this issue since these SPs don't have access to the storage account keys. This is intentional as I wouldn't want to grant these accounts access to retrieve credentials for every storage account. Is there a use case that requires listkeys during the plan phase?

[tombuildsstuff]

@mud5150 running terraform plan means that Terraform is going to refresh the state of the resource; which since this resource exposes the keys means the refresh will load those (hence this error).

In addition Azure counts the List Account Keys operation as a Write operation, which means these fail when users only have Read permissions (upstream issue)

Whilst Terraform /could/ return empty strings if the user doesn't have permission to the Access Keys - it currently doesn't; but it may make sense to do this - if you're looking for this functionality would you mind opening a new issue specifically for that?

Thanks!

[tombuildsstuff]

👋

After spending some time with Azure AD authentication for Storage - chatting internally we believe this would make sense as an optional toggle rather than something the provider defaults to (instead continuing to default to using a SharedKey for authentication).

This is primarily since it requires non-standard permissions (e.g. users with the Owner/Contributor roles are unable to access this data, which is confusing) - as such we believe an optional toggle of some sort (either in the config, or an environment variable) is the best way to allow both mechanisms to co-exist.

Thanks!

[mud5150]

@tombuildsstuff Thanks. I created #4138 to address the access issue.

[drdamour]

couldn't this be fall thru behaviour similar to the portal.. try keys first, ad next?

[tombuildsstuff]

@drdamour unfortunately that's harder than it may first appear due to the way the API/SDK works - given these permissions haven't been granted retroactively, I believe a toggle is the best way to approach this in the interim (at least until these permissions are more widespread). In addition attempting to obtain the keys prior to AAD would show as a failed event in the Azure (Security) Events system which isn't ideal when we could instead try AAD/Key auth directly

[hashibot[bot]]

This has been released in version 1.44.0 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 = "~> 1.44.0"
}
# ... other configuration ...

[drdamour]

@tombuildsstuff should this work with remote state too?

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