add BuilderDataCommonKeys var to see what common keys a builder can return

packer/provisioner.go

@@ -42,6 +42,24 @@ type ProvisionHook struct {
 	Provisioners []*HookedProvisioner
 }
 
+// BuilderDataCommonKeys is the list of common keys that all builder will
+// return
+var BuilderDataCommonKeys = []string{
+	"ID",
+	"Host",
+	"Port",
+	"User",
+	"Password",
+	"ConnType",
+	"PackerRunUUID",
+	"PackerHTTPPort",
+	"PackerHTTPIP",
+	"PackerHTTPAddr",
+	"SSHPublicKey",
+	"SSHPrivateKey",
+	"WinRMPassword",
+}
+
 // Provisioners interpolate most of their fields in the prepare stage; this
 // placeholder map helps keep fields that are only generated at build time from
 // accidentally being interpolated into empty strings at prepare time.
@@ -53,26 +71,9 @@ type ProvisionHook struct {
 // data.
 func BasicPlaceholderData() map[string]string {
 	placeholderData := map[string]string{}
-	msg := "Build_%s. " + common.PlaceholderMsg
+	for _, key := range BuilderDataCommonKeys {
-	placeholderData["ID"] = fmt.Sprintf(msg, "ID")
+		placeholderData[key] = fmt.Sprintf("Build_%s. "+common.PlaceholderMsg, key)
-	// The following correspond to communicator-agnostic functions that are
+	}
-	// part of the SSH and WinRM communicator implementations. These functions
-	// are not part of the communicator interface, but are stored on the
-	// Communicator Config and return the appropriate values rather than
-	// depending on the actual communicator config values. E.g "Password"
-	// reprosents either WinRMPassword or SSHPassword, which makes this more
-	// useful if a template contains multiple builds.
-	placeholderData["Host"] = fmt.Sprintf(msg, "Host")
-	placeholderData["Port"] = fmt.Sprintf(msg, "Port")
-	placeholderData["User"] = fmt.Sprintf(msg, "User")
-	placeholderData["Password"] = fmt.Sprintf(msg, "Password")
-	placeholderData["ConnType"] = fmt.Sprintf(msg, "Type")
-	placeholderData["PackerRunUUID"] = fmt.Sprintf(msg, "PackerRunUUID")
-	placeholderData["PackerHTTPPort"] = fmt.Sprintf(msg, "PackerHTTPPort")
-	placeholderData["PackerHTTPIP"] = fmt.Sprintf(msg, "PackerHTTPIP")
-	placeholderData["PackerHTTPAddr"] = fmt.Sprintf(msg, "PackerHTTPAddr")
-	placeholderData["SSHPublicKey"] = fmt.Sprintf(msg, "SSHPublicKey")
-	placeholderData["SSHPrivateKey"] = fmt.Sprintf(msg, "SSHPrivateKey")
 
 	// Backwards-compatability: WinRM Password can get through without forcing
 	// the generated func validation.