Duplicate variables in tfvars should warn or error

[lopopolo]

Terraform Version

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$ terraform -v
Terraform v0.9.10

Terraform Configuration Files

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Debug Output

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Panic Output

If Terraform produced a panic, please provide a link to a GitHub Gist containing the output of the crash.log.

Expected Behavior

Terraform should error when there are duplicate variable definitions in a *.tfvars file like it does for duplicate variable definitions in *.tf files.

Actual Behavior

No error, no warning. The last definition wins.

Steps to Reproduce

Please list the steps required to reproduce the issue, for example:

1. terraform apply

Important Factoids

Are there anything atypical about your accounts that we should know? For example: Running in EC2 Classic? Custom version of OpenStack? Tight ACLs?

References

Are there any other GitHub issues (open or closed) or Pull Requests that should be linked here? For example:

• provider/aws: Fix issue when changing map-public-ip in Subnets #1234

[apparentlymart]

Hi @lopopolo! Sorry for the long silence here.

I've verified that as of Terraform v0.12.0-alpha1 -- a prerelease version of the forthcoming v0.12.0 major release -- Terraform will now produce an error if the same variable is assigned a value multiple times in the same tfvars file.

It is intentional that assignments in separate files (or separate assignments directly from the command line using -var=) have a "last assignment wins" rule, since that allows the user to "layer" variable values, such as by having a file with values that are used in most cases and then another separate file that selectively overrides it e.g. for special deployment environments.

We have also updated the documentation for setting variables in an attempt to be clearer about the override behavior and the value precedence when using overrides. This is not visible on the website yet since it is still showing the v0.11.10 documentation, but the changes will be published in conjunction with the v0.12.0 final release.

Since the duplicate-checking behavior is now present on master and will be included in the final release, I'm going to close this out. Thanks for reporting this, and sorry again for the delay in getting back to you about it.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

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