fix(engines): add docker build triggers

Author: tjholm

engines/terraform/modules/image/main.tf

@@ -1,3 +1,10 @@
+locals {
+  context_path     = "${path.root}/../../../${var.build_context != "." ? var.build_context : ""}"
+  original_command = join(" ", compact([data.external.inspect_base_image.result.entrypoint, data.external.inspect_base_image.result.cmd]))
+  image_id         = var.image_id == null ? docker_image.base_service.image_id : var.image_id
+  build_trigger    = var.image_id == null ? sha1(join("", [for f in fileset(local.context_path, "**") : filesha1("${local.context_path}/${f}")])) : var.image_id
+}
+
 resource "docker_image" "base_service" {
   name = var.image_id == null ? "${var.tag}_base_service" : var.image_id
 
@@ -7,12 +14,16 @@ resource "docker_image" "base_service" {
       builder  = "default"
       platform = var.platform
       # NOTE: This assumes the terraform output is three dirs down from the root of the project
-      context    = "${path.root}/../../../${var.build_context != "." ? var.build_context : ""}"
-      dockerfile = "${path.root}/../../../${var.dockerfile}"
+      context    = local.context_path
+      dockerfile = "${local.context_path}/${var.dockerfile}"
       tag        = ["${var.tag}:base"]
       build_args = var.args
     }
   }
+  
+  triggers = {
+    build_trigger = local.build_trigger
+  }
 }
 
 # Extract entrypoint and command using Docker CLI via external data source
@@ -21,11 +32,6 @@ data "external" "inspect_base_image" {
   program    = ["docker", "inspect", docker_image.base_service.image_id, "--format", "{\"entrypoint\":\"{{join .Config.Entrypoint \" \"}}\",\"cmd\":\"{{join .Config.Cmd \" \"}}\"}"]
 }
 
-locals {
-  original_command = join(" ", compact([data.external.inspect_base_image.result.entrypoint, data.external.inspect_base_image.result.cmd]))
-  image_id         = var.image_id == null ? docker_image.base_service.name : var.image_id
-}
-
 # Next we want to wrap this image withing a suga service
 resource "docker_image" "service" {
   name = var.tag
@@ -42,4 +48,8 @@ resource "docker_image" "service" {
     }, var.args)
     tag = ["${var.tag}:latest"]
   }
+
+  triggers = {
+    base_image_id = local.image_id 
+  }
 }