provider/docker: add option to keep local image on destroy

builtin/providers/docker/resource_docker_image.go

@@ -26,6 +26,11 @@ func resourceDockerImage() *schema.Resource {
 				Type:     schema.TypeString,
 				Computed: true,
 			},
+
+			"keep_locally": &schema.Schema{
+				Type:     schema.TypeBool,
+				Optional: true,
+			},
 		},
 	}
 }

builtin/providers/docker/resource_docker_image_funcs.go

@@ -63,6 +63,11 @@ func searchLocalImages(data Data, imageName string) *dc.APIImages {
 
 func removeImage(d *schema.ResourceData, client *dc.Client) error {
 	var data Data
+
+	if keepLocally := d.Get("keep_locally").(bool); keepLocally {
+		return nil
+	}
+
 	if err := fetchLocalImages(&data, client); err != nil {
 		return err
 	}

builtin/providers/docker/resource_docker_image_test.go

@@ -44,9 +44,36 @@ func TestAccDockerImage_private(t *testing.T) {
 	})
 }
 
-func testAccDockerImageDestroy(s *terraform.State) error {
-	//client := testAccProvider.Meta().(*dc.Client)
+func TestAccDockerImage_destroy(t *testing.T) {
+	resource.Test(t, resource.TestCase{
+		PreCheck:  func() { testAccPreCheck(t) },
+		Providers: testAccProviders,
+		CheckDestroy: func(s *terraform.State) error {
+			for _, rs := range s.RootModule().Resources {
+				if rs.Type != "docker_image" {
+					continue
+				}
+
+				client := testAccProvider.Meta().(*dc.Client)
+				_, err := client.InspectImage(rs.Primary.Attributes["latest"])
+				if err != nil {
+					return err
+				}
+			}
+			return nil
+		},
+		Steps: []resource.TestStep{
+			resource.TestStep{
+				Config: testAccDockerImageKeepLocallyConfig,
+				Check: resource.ComposeTestCheckFunc(
+					resource.TestMatchResourceAttr("docker_image.foobarzoo", "latest", contentDigestRegexp),
+				),
+			},
+		},
+	})
+}
 
+func testAccDockerImageDestroy(s *terraform.State) error {
 	for _, rs := range s.RootModule().Resources {
 		if rs.Type != "docker_image" {
 			continue
@@ -76,3 +103,10 @@ resource "docker_image" "foobar" {
 	keep_updated = true
 }
 `
+
+const testAccDockerImageKeepLocallyConfig = `
+resource "docker_image" "foobarzoo" {
+	name = "crux:3.1"
+	keep_locally = true
+}
+`

website/source/docs/providers/docker/r/image.html.markdown

@@ -33,6 +33,9 @@ The following arguments are supported:
   always be updated on the host to the latest. If this is false, as long as an
   image is downloaded with the correct tag, it won't be redownloaded if
   there is a newer image.
+* `keep_locally` - (Optional, boolean) If true, then the Docker image won't be
+  deleted on destroy operation. If this is false, it will delete the image from
+  the docker local storage on destroy operation.
 
 ## Attributes Reference