clean up a few final issues with info sharing

helper/common/shared_state.go

@@ -10,7 +10,7 @@ import (
 // This is used in the BasicPlaceholderData() func in the packer/provisioner.go
 // To force users to access generated data via the "generated" func.
 const PlaceholderMsg = "To set this dynamically in the Packer template, " +
-	"you must use the `generated` function"
+	"you must use the `build` function"
 
 // Used to set variables which we need to access later in the build, where
 // state bag and config information won't work

helper/config/decode.go

@@ -163,7 +163,7 @@ func DetectContextData(raws ...interface{}) (map[interface{}]interface{}, []inte
 	placeholderData := raws[len(raws)-1]
 	if pd, ok := placeholderData.(map[string]string); ok {
 		if uuid, ok := pd["PackerRunUUID"]; ok {
-			if strings.Contains(uuid, "Generated_PackerRunUUID.") {
+			if strings.Contains(uuid, "Build_PackerRunUUID.") {
 				cast := make(map[interface{}]interface{})
 				for k, v := range pd {
 					cast[k] = v
@@ -178,12 +178,13 @@ func DetectContextData(raws ...interface{}) (map[interface{}]interface{}, []inte
 	// map[interface]interface, not a map[string]string
 	if pd, ok := placeholderData.(map[interface{}]interface{}); ok {
 		if uuid, ok := pd["PackerRunUUID"]; ok {
-			if strings.Contains(uuid.(string), "Generated_PackerRunUUID.") {
+			if strings.Contains(uuid.(string), "Build_PackerRunUUID.") {
 				raws = raws[:len(raws)-1]
 				return pd, raws
 			}
 		}
 	}
+
 	return nil, raws
 }
 

packer/provisioner.go

@@ -53,7 +53,7 @@ type ProvisionHook struct {
 // data.
 func BasicPlaceholderData() map[string]string {
 	placeholderData := map[string]string{}
-	msg := "Generated_%s. " + common.PlaceholderMsg
+	msg := "Build_%s. " + common.PlaceholderMsg
 	placeholderData["ID"] = fmt.Sprintf(msg, "ID")
 	// The following correspond to communicator-agnostic functions that are
 	// part of the SSH and WinRM communicator implementations. These functions

template/interpolate/funcs.go

@@ -166,6 +166,19 @@ func funcGenTemplateDir(ctx *Context) interface{} {
 
 func funcGenBuild(ctx *Context) interface{} {
 	return func(s string) (string, error) {
+		if data, ok := ctx.Data.(map[string]string); ok {
+			if heldPlace, ok := data[s]; ok {
+				// If we're in the first interpolation pass, the goal is to
+				// make sure that we pass the value through.
+				// TODO match against an actual string constant
+				if strings.Contains(heldPlace, common.PlaceholderMsg) {
+					return fmt.Sprintf("{{.%s}}", s), nil
+				} else {
+					return heldPlace, nil
+				}
+			}
+			return "", fmt.Errorf("loaded data, but couldnt find %s in it.", s)
+		}
 		if data, ok := ctx.Data.(map[interface{}]interface{}); ok {
 			// PlaceholderData has been passed into generator, so if the given
 			// key already exists in data, then we know it's an "allowed" key