Merge pull request #2601 from nathanielks/feature/docs-environment-variables

Added page documenting useful Environment Variables

website/source/docs/configuration/environment-variables.html.md

@@ -0,0 +1,64 @@
+---
+layout: "docs"
+page_title: "Environment Variables"
+sidebar_current: "docs-config-environment-variables"
+description: |-
+  Terraform uses different environment variables that can be used to configure various aspects of how Terraform behaves. this section documents those variables, their potential values, and how to use them.
+---
+
+# Environment Variables
+
+## TF_LOG
+
+If set to any value, enables detailed logs to appear on stderr which is useful for debugging. For example:
+
+```
+export TF_LOG=1
+```
+
+To disable, either unset it or set it to empty. When unset, logging will default to stderr. For example:
+
+```
+export TF_LOG=
+```
+
+For more on debugging Terraform, check out the section on [Debugging](/docs/internals/debugging.html).
+
+## TF_LOG_PATH
+
+This specifies where the log should persist its output to. Note that even when `TF_LOG_PATH` is set, `TF_LOG` must be set in order for any logging to be enabled. For example, to always write the log to the directory you're currently running terraform from:
+
+```
+export TF_LOG_PATH=./terraform.log
+```
+
+For more on debugging Terraform, check out the section on [Debugging](/docs/internals/debugging.html).
+
+## TF_INPUT
+
+If set to "false" or "0", causes terraform commands to behave as if the `-input=false` flag was specified. This is used when you want to disable prompts for variables that haven't had their values specified. For example:
+
+```
+export TF_INPUT=0
+```
+
+## TF_MODULE_DEPTH
+
+When given a value, causes terraform commands to behave as if the `-module=depth=VALUE` flag was specified. Modules are treated like a black box and terraform commands do not show what resources within the module will be created. By setting this to -1, for example, you enable commands such as [plan](/docs/commands/plan.html) and [graph](/docs/commands/graph.html) to display more detailed information.
+
+```
+export TF_MODULE_DEPTH=-1
+```
+
+For more information regarding modules, check out the section on [Using Modules](/docs/modules/usage.html).
+
+## TF_VAR_name
+
+Environment variables can be used to set variables. The environment variables must be in the format `TF_VAR_name` and this will be checked last for a value. For example:
+
+```
+export TF_VAR_region=us-west-1
+export TF_VAR_ami=ami-049d8641
+```
+
+For more on how to use `TF_VAR_name` in context, check out the section on [Variable Configuration](/docs/configuration/variables.html).

website/source/layouts/docs.erb

@@ -49,6 +49,10 @@
 					<a href="/docs/configuration/atlas.html">Atlas</a>
 					</li>
 
+					<li<%= sidebar_current("docs-config-environment-variables") %>>
+					<a href="/docs/configuration/environment-variables.html">Environment Variables</a>
+					</li>
+
 				</ul>
 				</li>