Add operating-system and join-path modules

examples/join-path/README.md

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+# Join path example
+
+This folder shows examples of how to use the [join-path module](/modules/join-path) to create a file path with the 
+proper path separator for the current operating system. 
+
+
+
+
+## How do you run these examples?
+
+1. Install [Terraform](https://www.terraform.io/).
+1. `terraform init`.
+1. `terraform apply`.
+
+
+

examples/join-path/main.tf

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+module "path" {
+  # When using these modules in your own templates, you will need to use a Git URL with a ref attribute that pins you
+  # to a specific version of the modules, such as the following example:
+  # source = "git::git@github.com:gruntwork-io/package-terraform-utilities.git//modules/join-path?ref=v1.0.8"
+  source = "../../modules/join-path"
+
+  path_parts = ["foo", "bar", "baz.txt"]
+}

examples/join-path/outputs.tf

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+output "path" {
+  value = "${module.path.path}"
+}

examples/operating-system/README.md

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+# Operating system example
+
+This folder shows examples of how to use the [operating-system module](/modules/operating-system) to access information
+about the current operating system in Terraform.
+
+
+
+
+## How do you run these examples?
+
+1. Install [Terraform](https://www.terraform.io/).
+1. `terraform init`.
+1. `terraform apply`.
+
+
+

examples/operating-system/main.tf

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+module "os" {
+  # When using these modules in your own templates, you will need to use a Git URL with a ref attribute that pins you
+  # to a specific version of the modules, such as the following example:
+  # source = "git::git@github.com:gruntwork-io/package-terraform-utilities.git//modules/operating-system?ref=v1.0.8"
+  source = "../../modules/operating-system"
+}

examples/operating-system/outputs.tf

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+output "os_name" {
+  value = "${module.os.name}"
+}
+
+output "path_separator" {
+  value = "${module.os.path_separator}"
+}

modules/join-path/README.md

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+# Join Path Module
+
+This is a module that can be used to join a list of given path parts (that is, file and folder names) into a single 
+path with the appropriate path separator (backslash or forward slash) for the current operating system. This is useful
+for ensuring the paths you build will work properly on Windows, Linux, and OS X.
+
+This module uses Python under the hood so, the Python must be installed on the OS. 
+
+
+
+
+## Example code
+
+See the [join-path example](/examples/join-path) for working sample code.
+
+
+
+
+## Usage
+
+Simply use the module in your Terraform code, replacing `<VERSION>` with the latest version from the [releases
+page](https://github.com/gruntwork-io/package-terraform-utilities/releases), and specifying the path parts using the 
+`path_parts` input:
+
+```hcl
+module "path" {
+  source = "git::git@github.com:gruntwork-io/package-terraform-utilities.git//modules/join-path?ref=<VERSION>"
+
+  path_parts = ["foo", "bar", "baz.txt"]
+}
+```
+
+You can now get the joined path using the `path` output:
+
+```hcl
+# Will be set to "foo/bar/baz.txt" on Linux and OS X, "foo\bar\baz.txt" on Windows
+joined_path = "${module.path.path}" 
+```
+

modules/join-path/main.tf

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+module "os" {
+  source = "../operating-system"
+}
+

modules/join-path/outputs.tf

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+output "path" {
+  value = "${join(module.os.path_separator, var.path_parts)}"
+}
+

modules/join-path/vars.tf

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+# ---------------------------------------------------------------------------------------------------------------------
+# REQUIRED MODULE PARAMETERS
+# These variables must be passed in by the operator.
+# ---------------------------------------------------------------------------------------------------------------------
+
+variable "path_parts" {
+  description = "A list of folder and file names to combine into a path, using the proper path separator for the current OS."
+  type        = "list"
+  # Example:
+  # default = ["foo", "bar", "baz.txt"] => outputs "foo/bar/baz.txt" on Linux
+}
+

modules/operating-system/README.md

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+# Operating System Module
+
+This is a module that can be used to figure out what operating system is being used to run Terraform. This may be used
+to modify Terraform's behavior depending on the OS, such as modifying the way you format file paths on Linux vs 
+Windows (see also the [join-path module](/modules/join-path)). 
+
+This module uses Python under the hood so, the Python must be installed on the OS. 
+
+
+
+
+## Example code
+
+See the [operating-system example](/examples/operating-system) for working sample code.
+
+
+
+
+## Usage
+
+Simply use the module in your Terraform code, replacing `<VERSION>` with the latest version from the [releases
+page](https://github.com/gruntwork-io/package-terraform-utilities/releases):
+
+```hcl
+module "os" {
+  source = "git::git@github.com:gruntwork-io/package-terraform-utilities.git//modules/operating-system?ref=<VERSION>"
+}
+```
+
+* You can now get the name of the operating system from the `name` output, which will be set to either `Linux`, 
+  `Darwin`, or `Windows`
+
+* You can also get the path separator for the current OS—backslash for Windows, forward slash everywhere else—from the
+  `path_separator` output.
+
+```hcl
+operating_system_name = "${module.os.name}"
+path_separator        = "${module.os.path_separator}"
+```
+

modules/operating-system/main.tf

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+data "external" "os" {
+  program = ["python", "-c", "import platform; print \"{\\\"platform\\\": \\\"%s\\\"}\" % platform.system()"]
+}

modules/operating-system/outputs.tf

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+output "name" {
+  value = "${data.external.os.result.platform}"
+}
+
+output "path_separator" {
+  value = "${data.external.os.result.platform == "Windows" ? "\\" : "/"}"
+}

test/join_path_test.go

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+package test
+
+import (
+	"github.com/gruntwork-io/terratest"
+	"testing"
+)
+
+func TestJoinPath(t *testing.T) {
+	t.Parallel()
+
+	resourceCollection := createBaseRandomResourceCollection(t)
+	terratestOptions := createBaseTerratestOptions(t, "TestJoinPath", "../examples/join-path", resourceCollection)
+	defer terratest.Destroy(terratestOptions, resourceCollection)
+
+	apply(t, terratestOptions)
+
+	assertOutputEquals(t, "path", "foo/bar/baz.txt", terratestOptions)
+}
+

test/operating_system_test.go

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+package test
+
+import (
+	"github.com/gruntwork-io/terratest"
+	"testing"
+	"runtime"
+	"strings"
+)
+
+func TestOperatingSystem(t *testing.T) {
+	t.Parallel()
+
+	resourceCollection := createBaseRandomResourceCollection(t)
+	terratestOptions := createBaseTerratestOptions(t, "TestOperatingSystem", "../examples/operating-system", resourceCollection)
+	defer terratest.Destroy(terratestOptions, resourceCollection)
+
+	apply(t, terratestOptions)
+
+	assertOutputEquals(t, "os_name", strings.Title(runtime.GOOS), terratestOptions)
+	assertOutputEquals(t, "path_separator", "/", terratestOptions)
+}