the shipped terraform is not used when the installer is called via PATH lookup

[steveej]

I ran into this issue trying to destroy a libvirt cluster:

$ tectonic destroy --dir=test1

Error:
Terraform doesn't allow running any operations against a state
that was written by a future Terraform version. The state is
reporting it is written by Terraform '0.11.7'

Please run at least that version of Terraform to continue.

Between create and destroy, I have installed terraform to my PATH.
I suspect there is something odd in the logic to find the terraform binary, as removing it from PATH makes the error go away and succeed in destroying the cluster.

[steveej]

/assign
/kind bug

[steveej]

After figuring out the conditions that lead to the situation here's something interesting I learned. Running from PATH gives the following - unhelpful in our case - argument list:

execve("/home/steveej/src/openshift/installer/scripts/testing/../../tectonic-dev/installer/tectonic", ["tectonic", "destroy", "--dir=test1"], 0x7ffdb3769080 /* 89 vars */) = 0

This results in filepath.Abs(filepath.Dir(os.Args[0])) evaluating to CWD. This defeats my expectation of the terraform from the installer's directory being used.

In my case terraform was also not in CWD but was instead looked up from PATH.
Appending the installer path to PATH instead of prepending it caused the installer to use my user's terraform version, which is of course not version controlled by the bazel instructions.

I'm not sure if or what to do about this situation. It might happen to someone else in the future and might cause other issues than the one I've hit, which could be more subtle and harder to debug due to some change in terraform behavior.

I suggest to introduce a runtime version check and assert for >= the version that's shipped with bazel.

[wking]

I suggest to introduce a runtime version check and assert for >= the version that's shipped with bazel.

We ship a terraform binary. I think we want to always use that one, instead of doing version comparisons. We always recommend prepending to PATH:

$ git grep PATH= 44bedfef
44bedfef:Documentation/dev/libvirt-howto.md:export PATH="${PWD}/installer:${PATH}"
44bedfef:README.md:    export PATH="${PWD}/installer:${PATH}"
44bedfef:modules/tectonic/resources/tectonic.sh:ASSETS_PATH="$2"
44bedfef:tests/run.sh:export PATH="${PWD}/tectonic-dev/installer:${PATH}"

but not everyone follows directions ;). Should we make our tarball self-extracting by adding a #!/bin/sh-based prefix? Then we can have that script ensure we always invoke the bundled terraform.