[build]: allow to customize USERNAME and PASSWORD in command line (#492)

* [build]: allow to customize USERNAME and PASSWORD in command line

* use default password and username if not specified in the command line

Makefile

@@ -39,6 +39,8 @@ DOCKER_BUILD = docker build --no-cache \
 	    PLATFORM=$(PLATFORM) \
 	    BUILD_NUMBER=$(BUILD_NUMBER) \
 	    ENABLE_DHCP_GRAPH_SERVICE=$(ENABLE_DHCP_GRAPH_SERVICE) \
+	    PASSWORD=$(PASSWORD) \
+	    USERNAME=$(USERNAME) \
 	    $@
 
 sonic-slave-build :

rules/config

@@ -26,11 +26,11 @@ SONIC_CONFIG_LOG_TO_FILES = y
 # Comment next line to disable:
 # SONIC_CONFIG_ENABLE_COLORS = y
 
-# USERNAME - username for installer build
-USERNAME = admin
+# DEFAULT_USERNAME - default username for installer build
+DEFAULT_USERNAME = admin
 
-# PASSWORD - password for installer build
-PASSWORD = YourPaSsWoRd
+# DEFAULT_PASSWORD - default password for installer build
+DEFAULT_PASSWORD = YourPaSsWoRd
 
 # ENABLE_DHCP_GRAPH_SERVICE - specify the source of minigraph to generate configuration file.
 # If set to y SONiC will get the minigraph from graph service. Graph service URL need to be 

slave.mk

@@ -59,6 +59,14 @@ ifneq ($(CONFIGURED_PLATFORM), undefined)
 include $(PLATFORM_PATH)/rules.mk
 endif
 
+ifeq ($(USERNAME),)
+override USERNAME := $(DEFAULT_USERNAME)
+endif
+
+ifeq ($(PASSWORD),)
+override PASSWORD := $(DEFAULT_PASSWORD)
+endif
+
 MAKEFLAGS += -j $(SONIC_CONFIG_BUILD_JOBS)
 
 ###############################################################################