Add better comments for all the variables

modules/join-path/vars.tf

@@ -8,5 +8,5 @@ variable "path_parts" {
   type        = list(string)
 
   # Example:
-  # default = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
+  # path_parts = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
 }

modules/prepare-pex-environment/variables.tf

@@ -2,19 +2,19 @@ variable "python2_pex_path_parts" {
   description = "Parts of the path (folders and files names) to the PEX executable for python 2 as a list of strings."
   type        = list(string)
   # Example:
-  # default = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
+  # python2_pex_path_parts = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
 }
 
 variable "python3_pex_path_parts" {
   description = "Parts of the path (folders and files names) to the PEX executable for python 3 as a list of strings."
   type        = list(string)
   # Example:
-  # default = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
+  # python3_pex_path_parts = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
 }
 
 variable "pex_module_path_parts" {
   description = "Parts of the path (folders and file names) to the python package directory housing the pex file."
   type        = list(string)
   # Example:
-  # default = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
+  # pex_module_path_parts = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
 }

modules/run-pex-as-data-source/variables.tf

@@ -2,21 +2,21 @@ variable "python2_pex_path_parts" {
   description = "Parts of the path (folders and files names) to the PEX executable for python 2 as a list of strings."
   type        = list(string)
   # Example:
-  # default = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
+  # python2_pex_path_parts = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
 }
 
 variable "python3_pex_path_parts" {
   description = "Parts of the path (folders and files names) to the PEX executable for python 3 as a list of strings."
   type        = list(string)
   # Example:
-  # default = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
+  # python3_pex_path_parts = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
 }
 
 variable "pex_module_path_parts" {
   description = "Parts of the path (folders and file names) to the python package directory housing the pex file."
   type        = list(string)
   # Example:
-  # default = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
+  # pex_module_path_parts = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
 }
 
 variable "script_main_function" {
@@ -27,7 +27,9 @@ variable "script_main_function" {
 variable "command_args" {
   description = "The arguments to pass to the command as a string"
   type        = string
-  default     = ""
+
+  # We don't use null here because this is interpolated into the python script.
+  default = ""
 }
 
 variable "command_query" {

modules/run-pex-as-resource/variables.tf

@@ -27,5 +27,7 @@ variable "script_main_function" {
 variable "command_args" {
   description = "The arguments to pass to the command as a string"
   type        = string
-  default     = ""
+
+  # We don't use null here because this is interpolated into the python script.
+  default = ""
 }