Add DEVICE_TYPE

Allow for device type names and machine to differ. Until know, the
device type contract had to be named `$MACHINE.json`, and then the
slug in it could be something else.

The DEVICE_TYPE variable that defaults to MACHINE for backwards
compatibility allows for the same MACHINE to build several device types
by passing a different DEVICE_TYPE to the build.

Change-type: patch
Signed-off-by: Alex Gonzalez <alexg@balena.io>

meta-balena-common/classes/image-balena.bbclass

@@ -321,11 +321,12 @@ def get_rel_path(layers, rel, d):
 def get_slug(d):
     import json
     slug = "unknown"
+    device_type = d.getVar("DEVICE_TYPE", True)
     machine = d.getVar("MACHINE", True)
     resinboardpath = get_rel_path(['meta-resin-common','meta-balena-common'], '../../../', d)
     if not resinboardpath:
         return slug
-    jsonfile = os.path.normpath(os.path.join(resinboardpath, machine + ".json"))
+    jsonfile = os.path.normpath(os.path.join(resinboardpath, device_type + ".json"))
     try:
         with open(jsonfile, 'r') as fd:
             machinejson = json.load(fd)

meta-balena-common/conf/distro/include/balena-os.inc

@@ -154,3 +154,6 @@ BALENA_USE_LUKS ?= "1"
 # This is the docker API version for v20.10
 # balena version --format '{{.Server.APIVersion}}'
 BALENA_API_VERSION ?= "1.41"
+
+# Override if the device-type.json file is not named as the machine
+DEVICE_TYPE ?= "${MACHINE}"

meta-balena-common/recipes-core/images/balena-image-flasher.bb

@@ -55,7 +55,7 @@ BALENA_BOOT_PARTITION_FILES:append = "${@bb.utils.contains('MACHINE_FEATURES','e
 BALENA_BOOT_PARTITION_FILES:append = " balena-logo.png:/splash/balena-logo.png"
 
 # add the generated <machine-name>.json to the flash-boot partition, renamed as device-type.json
-BALENA_BOOT_PARTITION_FILES:append = " ${BALENA_COREBASE}/../../../${MACHINE}.json:/device-type.json"
+BALENA_BOOT_PARTITION_FILES:append = " ${BALENA_COREBASE}/../../../${DEVICE_TYPE}.json:/device-type.json"
 
 # Put balena-image in the flasher rootfs
 add_resin_image_to_flasher_rootfs() {

meta-balena-common/recipes-core/images/balena-image.bb

@@ -75,7 +75,7 @@ BALENA_BOOT_PARTITION_FILES:append = "${@oe.utils.conditional('SIGN_API','','','
 BALENA_BOOT_PARTITION_FILES:append = "${@bb.utils.contains('MACHINE_FEATURES','efi',' grub.cfg_internal_luks:/EFI/BOOT/grub-luks.cfg','',d)}"
 
 # add the generated <machine-name>.json to the resin-boot partition, renamed as device-type.json
-BALENA_BOOT_PARTITION_FILES:append = " ${BALENA_COREBASE}/../../../${MACHINE}.json:/device-type.json"
+BALENA_BOOT_PARTITION_FILES:append = " ${BALENA_COREBASE}/../../../${DEVICE_TYPE}.json:/device-type.json"
 
 # example NetworkManager config file
 BALENA_BOOT_PARTITION_FILES:append = " \