Terraform: data source from local file without interpolation

[shantanugadgil]

Terraform Version

Terraform v0.9.6

Affected Resource(s)

Please list the resources as a list, for example:

• template_file

I want to use a shell script as-is and later use its "rendered" value at multiple places. So I did

data "template_file" "setup" {
  template = "${file("config/setup.sh")}"
}

My script "setup.sh" contains a line:

hostname -b ${host_name}

When I do plan, Terraform complains:

Error refreshing state: 1 error(s) occurred:

* data.template_file.setup: 1 error(s) occurred:

* data.template_file.setup: data.template_file.setup: failed to render : 10:29: unknown variable accessed: host_name

Can I tell Terraform not to perform interpolation for this data source?
OR
Is there any other data source that I can use?

Regards,
Shantanu

[apparentlymart]

Hi @shantanugadgil!

Recently we added a local provider, which so far just had a resource for writing a local file, but when it was added we anticipated having a data source for reading at some later point... it just didn't get done yet, unfortunately.

In the mean time, a trick you can do with the existing data source is to load the file into a template _variable_ instead, and then set the template itself to just insert that variable and nothing else. A file loaded into an element of the vars map won't be processed as a template.

[shantanugadgil]

Yes, I had noticed the "local" provider with the file-writing capabilities.
Awesome trick with the variable!!! 😃
_Though would be very confusing to the next person reading the code!_

Is the simple data source planned any time soon?

I think my options are:

• start using the variable trick from now on. (confusing, but will work.)
• change references of ${myvar} to $myvar is shell scripts. (not recommended)

Regards,
Shantanu

[apparentlymart]

@shantanugadgil the local_file data source is not something the Terraform team at Hashicorp has on the short-term list right now, but I'd be happy to review a PR for it if someone had the time and motivation to do it.

Otherwise, it's currently on my "rainy day list", as a quick thing that should be easy to get done if I find myself with a spare moment, :grin: but other stuff is unfortunately a higher priority right now.

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