From 5baf0b9235a126f5721e827c75c93517d41e016c Mon Sep 17 00:00:00 2001
From: Andy Repton <Seth-Karlo@users.noreply.github.com>
Date: Mon, 31 Jan 2022 23:13:08 +0100
Subject: [PATCH] Add new datasource `consul_datacenters` (#293)

Closes https://github.com/hashicorp/terraform-provider-consul/issues/290
---
 consul/data_source_consul_datacenters.go      | 34 ++++++++++++
 consul/data_source_consul_datacenters_test.go | 27 ++++++++++
 consul/resource_provider.go                   |  1 +
 website/docs/d/datacenters.html.markdown      | 52 +++++++++++++++++++
 4 files changed, 114 insertions(+)
 create mode 100644 consul/data_source_consul_datacenters.go
 create mode 100644 consul/data_source_consul_datacenters_test.go
 create mode 100644 website/docs/d/datacenters.html.markdown

diff --git a/consul/data_source_consul_datacenters.go b/consul/data_source_consul_datacenters.go
new file mode 100644
index 00000000..b33234ca
--- /dev/null
+++ b/consul/data_source_consul_datacenters.go
@@ -0,0 +1,34 @@
+package consul
+
+import (
+	"github.com/hashicorp/terraform-plugin-sdk/helper/schema"
+)
+
+func dataSourceConsulDatacenters() *schema.Resource {
+	return &schema.Resource{
+		Read: dataSourceConsulDatacentersRead,
+		Schema: map[string]*schema.Schema{
+			// Out parameters
+			"datacenters": {
+				Computed: true,
+				Type:     schema.TypeList,
+				Elem:     &schema.Schema{Type: schema.TypeString},
+			},
+		},
+	}
+}
+
+func dataSourceConsulDatacentersRead(d *schema.ResourceData, meta interface{}) error {
+	client, _, _ := getClient(d, meta)
+
+	datacenters, err := client.Catalog().Datacenters()
+	if err != nil {
+		return err
+	}
+
+	d.SetId("-")
+	sw := newStateWriter(d)
+	sw.set("datacenters", datacenters)
+
+	return sw.error()
+}
diff --git a/consul/data_source_consul_datacenters_test.go b/consul/data_source_consul_datacenters_test.go
new file mode 100644
index 00000000..b543c8e2
--- /dev/null
+++ b/consul/data_source_consul_datacenters_test.go
@@ -0,0 +1,27 @@
+package consul
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-sdk/helper/resource"
+)
+
+func TestAccDataConsulDatacenters_basic(t *testing.T) {
+	resource.Test(t, resource.TestCase{
+		PreCheck:  func() { testAccPreCheck(t) },
+		Providers: testAccProviders,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccDataConsulDatacentersConfig,
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckDataSourceValue("data.consul_datacenters.read", "datacenters.#", "1"),
+					testAccCheckDataSourceValue("data.consul_datacenters.read", "datacenters.0", "dc1"),
+				),
+			},
+		},
+	})
+}
+
+const testAccDataConsulDatacentersConfig = `
+data "consul_datacenters" "read" {}
+`
diff --git a/consul/resource_provider.go b/consul/resource_provider.go
index b0de1016..61c2ce52 100644
--- a/consul/resource_provider.go
+++ b/consul/resource_provider.go
@@ -150,6 +150,7 @@ func Provider() terraform.ResourceProvider {
 			"consul_acl_token_secret_id":  dataSourceConsulACLTokenSecretID(),
 			"consul_network_segments":     dataSourceConsulNetworkSegments(),
 			"consul_network_area_members": dataSourceConsulNetworkAreaMembers(),
+			"consul_datacenters":          dataSourceConsulDatacenters(),
 
 			// Aliases to limit the impact of rename of catalog
 			// datasources
diff --git a/website/docs/d/datacenters.html.markdown b/website/docs/d/datacenters.html.markdown
new file mode 100644
index 00000000..c974db9c
--- /dev/null
+++ b/website/docs/d/datacenters.html.markdown
@@ -0,0 +1,52 @@
+---
+layout: "consul"
+page_title: "Consul: consul_datacenters"
+sidebar_current: "docs-consul-data-source-datacenters"
+description: |-
+  Provides the list of all known datacenters.
+---
+
+# consul_datacenters
+
+The `consul_datacenters` data source returns the list of all knwown Consul
+datacenters.
+
+## Example Usage
+
+```hcl
+data "consul_datacenters" "all" {}
+
+# Register a prepared query in each of the datacenters
+resource "consul_prepared_query" "myapp-query" {
+  for_each = toset(data.consul_datacenters.all.datacenters)
+
+  name         = "myquery"
+  datacenter   = each.key
+  only_passing = true
+  near         = "_agent"
+
+  service = "myapp"
+  tags    = ["active", "!standby"]
+
+  failover {
+    nearest_n   = 3
+    datacenters = ["us-west1", "us-east-2", "asia-east1"]
+  }
+
+  dns {
+    ttl = "30s"
+  }
+}
+```
+
+## Argument Reference
+
+This data source has no arguments.
+
+## Attributes Reference
+
+The following attributes are exported:
+
+* `datacenters` - The list of datacenters known. The datacenters will be sorted
+  in ascending order based on the estimated median round trip time from the server
+  to the servers in that datacenter.