Terraform failed to acquire state lock: 403: Access denied., forbidden

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Terraform failed to acquire state lock: 403: Access denied., forbidden

2022-11-17

Problem

We stored Terraform state in gcs. For some reasons, we got this error randomly when running on BitBucket pipelines:

╷
│ Error: Error acquiring the state lock
│ 
│ Error message: 2 errors occurred:
│ 	* writing
│ "gs://bucket/path/to/default.tflock"
│ failed: googleapi: Error 403: Access denied., forbidden
│ 	* storage: object doesn't exist
│ 
│ 
│ 
│ Terraform acquires a state lock to protect the state from being written
│ by multiple users at the same time. Please resolve the issue above and try
│ again. For most commands, you can disable locking with the "-lock=false"
│ flag, but this is not recommended.
╵

It can be successful after re-running 3, 4 times.

Troubleshooting

I tried to reproduce this issue on my local, but I cannot. Please notice that if the state has been locked by other pipeline, we will get something different:

│ Error: Error acquiring the state lock
│ 
│ Error message: writing
│ "gs://bucket/path/to/default.tflock"
│ failed: googleapi: Error 403: Access denied., forbidden
│ Lock Info:
│   ID:        1668249141203541
│   Path:      gs://bucket/path/to/default.tflock
│   Operation: OperationTypePlan
│   Who:       root@de3c91cdae61
│   Version:   1.4.0
│   Created:   2022-11-12 10:32:21.161498675 +0000 UTC
│   Info:

And if the service account do not have permission on that bucket, we will get another error:

╷
│ Error: Error acquiring the state lock
│
│ Error message: 2 errors occurred:
│ 	* writing "gs://bucket/path/to/default.tflock" failed: googleapi: Error 403:
│ username@project.iam.gserviceaccount.com does not have storage.objects.create access to the Google Cloud Storage object. Permission 'storage.objects.create' denied
│ on resource (or it may not exist)., forbidden
│ 	* googleapi: got HTTP response code 403 with body: <?xml version='1.0' encoding='UTF-8'?><Error><Code>AccessDenied</Code><Message>Access
│ denied.</Message><Details>username@project.iam.gserviceaccount.com does not have storage.objects.get access to the Google Cloud Storage object. Permission
│ 'storage.objects.get' denied on resource (or it may not exist).</Details></Error>

Moreover, I cannot think of a reason why a service account don’t have permission randomly.

By re-reading the documentation, I pay attention to this:

IAM Changes to buckets are eventually consistent and may take upto a few minutes to take effect. Terraform will return 403 errors till it is eventually consistent.

I suspected that something changed IAM permissions but our DevOps team confirmed that there is no such cron job.

Here are the other things I tried, but it didn’t help:

turn on debug by using TF_LOG=DEBUG
update terraform to the latest version 1.3.4

I tried to take a deeper look at the source code::

and add some debug code to print the credential:

	credential, err := google.FindDefaultCredentials(context.Background())
	if err != nil {
		return nil, err
	}
	log.Printf("[TRACE] google-api-go-client/storage/v1: doRequest: credential: %+v", credential)
	log.Printf("[TRACE] google-api-go-client/storage/v1: doRequest: credential.JSON: %s", string(credential.JSON))
	var data map[string]interface{}
	if err := json.Unmarshal(credential.JSON, &data); err == nil {
		log.Printf("[TRACE] google-api-go-client/storage/v1: doRequest: credential: %v", data)
	}

and I know that our runners are running on Google Compute Engine.

By re-reading documentation one more time:

If you are running terraform on Google Cloud, you can configure that instance or cluster to use a Google Service Account. This will allow Terraform to authenticate to Google Cloud without having to bake in a separate credential/authentication file. Make sure that the scope of the VM/Cluster is set to cloud-platform.

I found out that one of our runners does not have that access scope:

    "scopes": [
      "https://www.googleapis.com/auth/devstorage.read_only",
      "https://www.googleapis.com/auth/logging.write",
      "https://www.googleapis.com/auth/monitoring.write",
      "https://www.googleapis.com/auth/servicecontrol",
      "https://www.googleapis.com/auth/service.management.readonly",
      "https://www.googleapis.com/auth/trace.append"
    ]
  }

Solution

Edit the VM and make sure that it has cloud-platform scope:

    "scopes": [
      "https://www.googleapis.com/auth/cloud-platform",
      "https://www.googleapis.com/auth/devstorage.read_only",
      "https://www.googleapis.com/auth/logging.write",
      "https://www.googleapis.com/auth/monitoring.write",
      "https://www.googleapis.com/auth/service.management.readonly",
      "https://www.googleapis.com/auth/servicecontrol",
      "https://www.googleapis.com/auth/trace.append"
    ]

Happy debugging!

Tags: terraform gcs golang

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