terraform plan generates corrupt plan

[jonaf]

Terraform Version

$ terraform -v
Terraform v0.9.11

Terraform Configuration Files

Link to gist: https://gist.github.com/jonaf/1878f34bcb6f35a55539d61288ce922b

When I encountered #1497 , I thought it might be related, so I tried changing this line of my configuration:

aliases = ["${split("\n", "${trimspace(file("${path.module}/../data/distributions/hostname_${count.index}.txt"))}")}"]

to this:

aliases = "${split("\n", "${trimspace(file("${path.module}/../data/distributions/hostname_${count.index}.txt"))}")}"

Both of these produce the same plan, but neither of them actually works. Somehow, validate and apply consider the resulting plan to be unparseable.

Debug Output

$ TF_LOG=TRACE terraform validate terraform
2017/07/28 14:04:04 [INFO] Terraform version: 0.9.11
2017/07/28 14:04:04 [INFO] Go runtime version: go1.8.3
2017/07/28 14:04:04 [INFO] CLI args: []string{"/usr/local/Cellar/terraform/0.9.11/bin/terraform", "validate", "terraform"}
2017/07/28 14:04:04 [DEBUG] Detected home directory from env var: /Users/jona.fenocchi
2017/07/28 14:04:04 [DEBUG] Detected home directory from env var: /Users/jona.fenocchi
2017/07/28 14:04:04 [DEBUG] Attempting to open CLI config file: /Users/jona.fenocchi/.terraformrc
2017/07/28 14:04:04 [DEBUG] File doesn't exist, but doesn't need to. Ignoring.
2017/07/28 14:04:04 [DEBUG] Detected home directory from env var: /Users/jona.fenocchi
2017/07/28 14:04:04 [INFO] CLI command args: []string{"validate", "terraform"}
2017/07/28 14:04:04 [DEBUG] plugin: waiting for all plugin processes to complete...
Error loading files Error parsing ./terraform/plan.tf: At 1:7: illegal char

Panic Output

None

Expected Behavior

terraform validate should have come said that the terraform configurations were OK. It does do this before terraform plan is invoked.

Actual Behavior

terraform validate fails with this error after a terraform plan is produced:

Error loading files Error parsing ./terraform/plan.tf: At 1:7: illegal char

However, terraform show ./terraform/plan.tf is able to parse the plan correctly:

Steps to Reproduce

1. terraform plan -out=terraform/plan.tf
2. terraform validate terraform/ (terraform apply will yield the same error)
3. terraform show terraform/plan.tf (works just fine!)

Important Factoids

• Running Terraform 0.9.11 on macOS Sierra 10.12.5 (16F2073), installed via Homebrew.

References

I was unable to find any open or closed GitHub issues with this error message or similar steps to reproduce. #1497 was the closest thing I found.

[apparentlymart]

Hi @jonaf! Sorry for this confusing behavior.

I think what's actually going on here is that you named the plan with a .tf extension and thus Terraform is trying to treat it as a configuration file. The "illegal char" error here is coming from the configuration parser, not the plan parser. I think if you choose a different name for your plan file this problem will go away.

[jonaf]

Oh, interesting. I wonder, what extension should a plan file have? Maybe Terraform shouldn't have such a sharp edge for this (admittedly dense) user error. :)

[jonaf]

Yep, that was it! I changed the file to plan.tfplan and everything is working fine now. Thanks, @apparentlymart !

[apparentlymart]

Hi @jonaf,

Since there's generally only _one_ plan around at a time, I generally just call it tfplan with no extension.

In the forthcoming 0.10.0 release we're introducing (behind an opt-in flag, for the moment) a new workflow that avoids the need to create the temporary plan file when using Terraform interactively in a terminal. This is intended to make this common case smoother:

$ terraform apply -auto-approve=false

The above command prints out the plan, stops to wait for you to type yes in confirmation, and then applies the plan, without the need to ever write the plan file to disk. We're planning to make this the default workflow in a future version, at which point terraform plan -out=tfplan will be used only when running Terraform in some sort of orchestration tool (e.g. a CI system, or Terraform Enterprise) where the plan needs to be stashed somewhere to make it available to a later terraform apply process.

If you're able to use Terraform in an experimental way, you may wish to give the latest release candidate a try to preview the above behavior. The final 0.10.0 release is coming very soon, so it won't be long before this new functionality is available in a stable release.

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