packer: Support overrides in provisioners for each build

packer/build.go

@@ -29,7 +29,7 @@ type coreBuild struct {
 // within the build.
 type coreBuildProvisioner struct {
 	provisioner Provisioner
-	config      interface{}
+	config      []interface{}
 }
 
 // Returns the name of the build.
@@ -51,7 +51,7 @@ func (b *coreBuild) Prepare(ui Ui) (err error) {
 
 	// Prepare the provisioners
 	for _, coreProv := range b.provisioners {
-		if err = coreProv.provisioner.Prepare(coreProv.config); err != nil {
+		if err = coreProv.provisioner.Prepare(coreProv.config...); err != nil {
 			return
 		}
 	}

packer/build_test.go

@@ -14,7 +14,7 @@ func testBuild() Build {
 			"foo": []Hook{&TestHook{}},
 		},
 		provisioners: []coreBuildProvisioner{
-			coreBuildProvisioner{&TestProvisioner{}, 42},
+			coreBuildProvisioner{&TestProvisioner{}, []interface{}{42}},
 		},
 	}
 }

packer/template.go

@@ -220,7 +220,16 @@ func (t *Template) Build(name string, components *ComponentFinder) (b Build, err
 			return
 		}
 
-		coreProv := coreBuildProvisioner{provisioner, rawProvisioner.rawConfig}
+		configs := make([]interface{}, 1, 2)
+		configs[0] = rawProvisioner.rawConfig
+
+		if rawProvisioner.Override != nil {
+			if override, ok := rawProvisioner.Override[name]; ok {
+				configs = append(configs, override)
+			}
+		}
+
+		coreProv := coreBuildProvisioner{provisioner, configs}
 		provisioners = append(provisioners, coreProv)
 	}
 

packer/template_test.go

@@ -448,3 +448,59 @@ func TestTemplate_Build(t *testing.T) {
 	assert.Equal(coreBuild.builderConfig, expectedConfig, "should have proper config")
 	assert.Equal(len(coreBuild.provisioners), 1, "should have one provisioner")
 }
+
+func TestTemplate_Build_ProvisionerOverride(t *testing.T) {
+	assert := asserts.NewTestingAsserts(t, true)
+
+	data := `
+	{
+		"name": "my-image",
+		"builders": [
+			{
+				"name": "test1",
+				"type": "test-builder"
+			}
+		],
+
+		"provisioners": [
+			{
+				"type": "test-prov",
+
+				"override": {
+					"test1": {}
+				}
+			}
+		]
+	}
+	`
+
+	template, err := ParseTemplate([]byte(data))
+	assert.Nil(err, "should not error")
+
+	builder := testBuilder()
+	builderMap := map[string]Builder{
+		"test-builder": builder,
+	}
+
+	provisioner := &TestProvisioner{}
+	provisionerMap := map[string]Provisioner{
+		"test-prov": provisioner,
+	}
+
+	builderFactory := func(n string) (Builder, error) { return builderMap[n], nil }
+	provFactory := func(n string) (Provisioner, error) { return provisionerMap[n], nil }
+	components := &ComponentFinder{
+		Builder:     builderFactory,
+		Provisioner: provFactory,
+	}
+
+	// Get the build, verifying we can get it without issue, but also
+	// that the proper builder was looked up and used for the build.
+	build, err := template.Build("test1", components)
+	assert.Nil(err, "should not error")
+
+	coreBuild, ok := build.(*coreBuild)
+	assert.True(ok, "should be a core build")
+	assert.Equal(len(coreBuild.provisioners), 1, "should have one provisioner")
+	assert.Equal(len(coreBuild.provisioners[0].config), 2, "should have two configs on the provisioner")
+}