added data_tailscale_acl data source (#304)

fixes #180

docs/data-sources/acl.md

@@ -0,0 +1,21 @@
+---
+# generated by https://github.com/hashicorp/terraform-plugin-docs
+page_title: "tailscale_acl Data Source - terraform-provider-tailscale"
+subcategory: ""
+description: |-
+  The acl data source gets the Tailscale ACL for a tailnet
+---
+
+# tailscale_acl (Data Source)
+
+The acl data source gets the Tailscale ACL for a tailnet
+
+
+
+<!-- schema generated by tfplugindocs -->
+## Schema
+
+### Read-Only
+
+- `id` (String) The ID of this resource.
+- `json` (String) The contents of Tailscale ACL as JSON

tailscale/data_source_acl.go

@@ -0,0 +1,45 @@
+package tailscale
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
+
+	"github.com/tailscale/tailscale-client-go/tailscale"
+)
+
+func dataSourceACL() *schema.Resource {
+	return &schema.Resource{
+		Description: "The acl data source gets the Tailscale ACL for a tailnet",
+		ReadContext: dataSourceACLRead,
+		Schema: map[string]*schema.Schema{
+			"json": {
+				Computed:    true,
+				Type:        schema.TypeString,
+				Description: "The contents of Tailscale ACL as JSON",
+			},
+		},
+	}
+}
+
+func dataSourceACLRead(ctx context.Context, d *schema.ResourceData, m interface{}) diag.Diagnostics {
+	client := m.(*tailscale.Client)
+
+	acl, err := client.ACL(ctx)
+	if err != nil {
+		return diagnosticsError(err, "Failed to fetch ACL")
+	}
+
+	aclJson, err := json.Marshal(acl)
+	if err != nil {
+		return diag.FromErr(err)
+	}
+	if err := d.Set("json", string(aclJson)); err != nil {
+		return diag.Errorf("setting json: %s", err)
+	}
+
+	d.SetId(createUUID())
+	return nil
+}

tailscale/provider.go

@@ -80,6 +80,7 @@ func Provider(options ...ProviderOption) *schema.Provider {
 			"tailscale_device":  dataSourceDevice(),
 			"tailscale_devices": dataSourceDevices(),
 			"tailscale_4via6":   dataSource4Via6(),
+			"tailscale_acl":     dataSourceACL(),
 		},
 	}