provider/null: null_data_source data source

A companion to the null_resource resource, this is here primarily to
enable manual quick testing of data sources workflows without depending
on any external services.

The "inputs" map gets copied to the computed "outputs" map on read,
"rand" gives a random number to exercise cases with constantly-changing
values (an anti-pattern!), and "has_computed_default" is settable in
config but computed if not set.

builtin/providers/null/data_source.go

@@ -0,0 +1,54 @@
+package null
+
+import (
+	"fmt"
+	"math/rand"
+	"time"
+
+	"github.com/hashicorp/terraform/helper/schema"
+)
+
+func init() {
+	rand.Seed(time.Now().Unix())
+}
+
+func dataSource() *schema.Resource {
+	return &schema.Resource{
+		Read: dataSourceRead,
+
+		Schema: map[string]*schema.Schema{
+			"inputs": &schema.Schema{
+				Type:     schema.TypeMap,
+				Optional: true,
+			},
+			"outputs": &schema.Schema{
+				Type:     schema.TypeMap,
+				Computed: true,
+			},
+			"random": &schema.Schema{
+				Type:     schema.TypeString,
+				Computed: true,
+			},
+			"has_computed_default": &schema.Schema{
+				Type:     schema.TypeString,
+				Optional: true,
+				Computed: true,
+			},
+		},
+	}
+}
+
+func dataSourceRead(d *schema.ResourceData, meta interface{}) error {
+
+	inputs := d.Get("inputs")
+	d.Set("outputs", inputs)
+
+	d.Set("random", fmt.Sprintf("%d", rand.Int()))
+	if d.Get("has_computed_default") == "" {
+		d.Set("has_computed_default", "default")
+	}
+
+	d.SetId("static")
+
+	return nil
+}

builtin/providers/null/provider.go

@@ -13,5 +13,9 @@ func Provider() terraform.ResourceProvider {
 		ResourcesMap: map[string]*schema.Resource{
 			"null_resource": resource(),
 		},
+
+		DataSourcesMap: map[string]*schema.Resource{
+			"null_data_source": dataSource(),
+		},
 	}
 }