Terraform: `-backup` option for `terraform state mv` seems not to work correctly

[kamatama41]

I'm not sure it's a spec or bug, but I think this behavior is different from document's specification.
https://www.terraform.io/docs/commands/state/mv.html#_backup_path

Terraform Version

Terraform v0.8.7

Affected Resource(s)

• My example is aws_vpc but I think it's core issue.

Terraform Configuration Files

provider "aws" {
  region = "us-east-1"
  max_retries = 3
}

resource "aws_vpc" "example" {
  cidr_block = "10.1.0.0/16"
  tags { Name = "example" }
}
# I want to move the above resource to the module
# module "vpc" {
#  source = "./vpc"
#}

Debug Output

sishimura% TF_LOG=debug terraform state mv -backup=mybackup.tfstate aws_vpc.example module.vpc.aws_vpc.example                                                                                                                               [kamatama-test](master)
2017/02/22 12:44:55 [INFO] Terraform version: 0.8.7  c1df88ac4633b61b83802bbb10c343c20d3035b5
2017/02/22 12:44:55 [INFO] CLI args: []string{"/Users/shinichi/IdeaProjects/tfenv/versions/0.8.7/terraform", "state", "mv", "-backup=mybackup.tfstate", "aws_vpc.example", "module.vpc.aws_vpc.example"}
2017/02/22 12:44:55 [DEBUG] Detected home directory from env var: /Users/shinichi
2017/02/22 12:44:55 [DEBUG] Detected home directory from env var: /Users/shinichi
2017/02/22 12:44:55 [DEBUG] Attempting to open CLI config file: /Users/shinichi/.terraformrc
2017/02/22 12:44:55 [DEBUG] File doesn't exist, but doesn't need to. Ignoring.
2017/02/22 12:44:55 [DEBUG] Detected home directory from env var: /Users/shinichi
2017/02/22 12:44:55 [DEBUG] plugin: waiting for all plugin processes to complete...
Moved aws_vpc.example to module.vpc.aws_vpc.example

Panic Output

No panic

Expected Behavior

terraform.tfstate should be updated and mybackup.tfstate should be generated as a backup file.

Actual Behavior

mybackup.tfstate was generated as a new state file and mybackup.tfstate.1487735095.backup was generated as a backup file

Steps to Reproduce

1. terraform apply
2. terraform state mv -backup=mybackup.tfstate aws_vpc.example module.vpc.aws_vpc.example

Important Factoids

Nothing

References

Nothing

[mitchellh]

This isn't intended. Working on a fix now.

[mitchellh]

Fix is in a PR. Thank you for reporting this!

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