terraform-s3-dir | Terraform config upload a directory of files | Cloud Storage library

There are similar questions about how to install golang with vagrant provision or how to set $GOPATH environment variable, such that it will be available on boot.

However, this question is about how you can set $GOPATH, etc, such that the variable is available during later steps of the provisioning script (and everything else important about golang is in-place for that matter). I'm using an ubuntu image.

Specifically, I want to run these steps in my_provision.sh:

go get github.com/saymedia/terraform-s3-dir
go install github.com/saymedia/terraform-s3-dir

such that when I run the following command after vagrant ssh, it will just work:

terraform-s3-dir

When the go get/install commands run in my_provision.sh, it outputs one of two things: silence, or complaints that the GOPATH var is not set. Either way, when I boot in, terraform-s3-dir is not a recognised command.

I've tried setting the GOPATH, GOROOT and PATH variables in several different ways:

Setting them in my_provision.sh directly (with and without export), echoing export commands into .bashrc. echoing exporting commands to /etc/profile.d/gopath.sh. These all results in "$GOPATH not set".

running exports in an inline provisioning script, prior to my_provision.sh. This resulted in silent failure, unless I try to run the go get/install commands with sudo, in which case it has the $GOPATH error, too.

If I echo the GOPATH variable in my_provision.sh immediately before the go get/install commands, the variables show that they are set as expected.

If I run the go get/install commands manually from the shell after vagrant ssh, then it installs successfully.

What is different about the vagrant ssh context, vs the provisioning script context, where the go get/install commands get the desired result in the former, but not the latter?