run-pex-as-data-source

Run PEX as Data Source

This module runs the provided PEX binary in a portable manner that works with multiple platforms and python versions, to be used as an external data source in Terraform.

This module uses prepare-pex-environment under the hood. See What is PEX? for more details on what is a PEX file and how to construct one for use with this module.

How do you use this module?

• See the pex example for example usage.
• See variables.tf for all the variables you can set on this module.
• See outputs.tf for all the variables that are outputed by this module.

Data Source vs Resource

Terraform provides two escape hatches where a first-class Terraform provider is not more appropriate. The escape hatches allow you to call out to arbitrary binaries available on the operator machine. These are:

• External Data Source, where you can run the binary as a data source.
• local-exec Provisioners, where you can run the binary to provision a resource.

This module uses the data source approach (you can see the run-pex-as-resource module for running it as a data source). Which approach to use depends on your needs:

• Data sources are calculated every time a terraform state needs to be refreshed. This includes all plan and apply calls, even if the data source isn't explicitly changed.
• Data sources are useful if the logic can be used to determine if a resource needs to be changed.
• Data sources can output values that can be used in other parts of the Terraform code. You cannot do this with the provisioner approach.
• There are limitations with Data Sources and dependencies. See this terraform issue comment for example.
• Provisioners with a null_resource implements the standard resource life cycle (create, destroy, etc).
• Provisioners with a null_resource have explicit controls on when to trigger.