packer: overrides work

packer/core.go

@@ -144,8 +144,11 @@ func (c *Core) Build(n string) (Build, error) {
 		// Get the configuration
 		config := make([]interface{}, 1, 2)
 		config[0] = rawP.Config
-
+		if rawP.Override != nil {
-		// TODO override
+			if override, ok := rawP.Override[rawName]; ok {
+				config = append(config, override)
+			}
+		}
 
 		// If we're pausing, we wrap the provisioner in a special pauser.
 		if rawP.PauseBefore > 0 {

packer/core_test.go

@@ -222,6 +222,53 @@ func TestCoreBuild_provSkipInclude(t *testing.T) {
 	}
 }
 
+func TestCoreBuild_provOverride(t *testing.T) {
+	config := TestCoreConfig(t)
+	testCoreTemplate(t, config, fixtureDir("build-prov-override.json"))
+	b := TestBuilder(t, config, "test")
+	p := TestProvisioner(t, config, "test")
+	core := TestCore(t, config)
+
+	b.ArtifactId = "hello"
+
+	build, err := core.Build("test")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if _, err := build.Prepare(); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	artifact, err := build.Run(nil, nil)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if len(artifact) != 1 {
+		t.Fatalf("bad: %#v", artifact)
+	}
+
+	if artifact[0].Id() != b.ArtifactId {
+		t.Fatalf("bad: %s", artifact[0].Id())
+	}
+	if !p.ProvCalled {
+		t.Fatal("provisioner not called")
+	}
+
+	found := false
+	for _, raw := range p.PrepConfigs {
+		if m, ok := raw.(map[string]interface{}); ok {
+			if _, ok := m["foo"]; ok {
+				found = true
+				break
+			}
+		}
+	}
+	if !found {
+		t.Fatal("override not called")
+	}
+}
+
 func TestCoreBuild_postProcess(t *testing.T) {
 	config := TestCoreConfig(t)
 	testCoreTemplate(t, config, fixtureDir("build-pp.json"))

packer/test-fixtures/build-prov-override.json

@@ -0,0 +1,14 @@
+{
+    "builders": [{
+        "type": "test"
+    }],
+
+    "provisioners": [{
+        "type": "test",
+        "override": {
+            "test": {
+                "foo": "bar"
+            }
+        }
+    }]
+}