AWS Terraform IAM user with assume role for S3 back end

Question

To store the Terraform state file in S3 bucket, I have used admin account credentials and configured. Now I have created IAM user and trying to use assume role. Assume role has the administrator policy attached.

I have tested this AIM user setup with aws sts assume-role --role-arn commands. I was able to get the token and using the token able access the S3 bucket using aws s3 ls command.

Now trying to use the IAM user access/secret key with assume role for terraform. when I run terraform refresh command its giving below errors.

provider code:

provider "aws" {
  region  = "us-west-2"
  max_retries = 1
  assume_role {
    role_arn = var.assume_role_arn
  }

}

Error

 Error: Error acquiring the state lock
│
│ Error message: 2 errors occurred:
│       * AccessDeniedException: User: arn:aws:iam::xxxxxxxx:user/deploy is not authorized to perform: dynamodb:PutItem on resource:
│ arn:aws:dynamodb:us-west-2:xxxxxxxx:table/terraform-state-lock
│       status code: 400, request id: CV4J3JN1LD0KPDGHAOA9UL13ONVV4KQNSO5AEMVJF66Q9ASUAAJG
│       * AccessDeniedException: User: arn:aws:iam::xxxxxxxx:user/deploy is not authorized to perform: dynamodb:GetItem on resource:
│ arn:aws:dynamodb:us-west-2:xxxxxxxx:table/terraform-state-lock
│       status code: 400, request id: BISQQDU4659LLI3CEDP26T8RJ7VV4KQNSO5AEMVJF66Q9ASUAAJG
│
│
│
│ 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.

Why this is not working in Terraform How to fix this error?

Thanks SR

Answer 1

It does not seem like it's even assuming the role, otherwise the error would show up as an assumed-role/deploy identity.

I'd suggest you try exporting the AWS_SECRET_ACCESS_KEY and AWS_ACCESS_KEY_ID variables in the command line and then run Terraform again.

I tried this few days back using Terraform Cloud with the terraform user credentials there, which is not exactly your case, but it should behave in the same way.