website: docs for null_resource

website/source/docs/provisioners/null_resource.html.markdown

@@ -0,0 +1,60 @@
+---
+layout: "docs"
+page_title: "Provisioners: null_resource"
+sidebar_current: "docs-provisioners-null-resource"
+description: |-
+  The `null_resource` is a resource allows you to configure provisioners that
+  are not directly associated with a single exiting resource.
+---
+
+# null\_resource
+
+The `null_resource` is a resource that allows you to configure provisioners
+that are not directly associated with a single existing resource.
+
+A `null_resource` behaves exactly like any other resource, so you configure
+[provisioners](/docs/provisioners/index.html), [connection
+details](/docs/provisioners/connection.html), and other meta-parameters in the
+same way you would on any other resource.
+
+This allows fine-grained control over when provisioners run in the dependency
+graph.
+
+## Example usage
+
+```
+# Bootstrap a cluster after all its instances are up
+resource "aws_instance" "cluster" {
+  count = 3
+  // ...
+}
+
+resource "null_resource" "cluster" {
+  # Changes to any instance of the cluster requires re-provisioning
+  triggers {
+    cluster_instance_ids = "${join(",", aws_instance.cluster.*.id)}"
+  }
+
+  # Bootstrap script can run on any instance of the cluster
+  # So we just choose the first in this case
+  connection {
+    host = "${element(aws_instance.cluster.*.public_ip, 0)}"
+  }
+
+  provisioner "remote-exec" {
+    # Bootstrap script called with private_ip of each node in the clutser
+    inline = [
+      "bootstrap-cluster.sh ${join(" ", aws_instance.cluster.*.private_ip}"
+    ]
+  }
+}
+```
+
+## Argument Reference
+
+In addition to all the resource configuration available, `null_resource` supports the following specific configuration options:
+
+ * `triggers` - A mapping of values which should trigger a rerun of this set of
+   provisioners. Values are meant to be interpolated references to variables or
+   attributes of other resources.
+

website/source/layouts/docs.erb

@@ -217,6 +217,10 @@
 					<li<%= sidebar_current("docs-provisioners-remote") %>>
 					<a href="/docs/provisioners/remote-exec.html">remote-exec</a>
 					</li>
+
+					<li<%= sidebar_current("docs-provisioners-null-resource") %>>
+					<a href="/docs/provisioners/null_resource.html">null_resource</a>
+					</li>
 				</ul>
 				</li>