build: refactor JSON info files to `profiles.json`

JSON info files contain machine readable information of built profiles
and resulting images. These files were added in commit 881ed09ee6e2
("build: create JSON files containing image info").

They are useful for firmware wizards and script checking for
reproducibility.

Currently all JSON files are stored next to the built images, resulting
in up to 168 individual files for the ath79/generic target.

This patch refactors the JSON creation to store individual per image
(not per profile) files in $(BUILD_DIR)/json_info_files and create an
single overview file called `profiles.json` in the target directory.

Storing per image files and not per profile solves the problem of
parallel file writes. If a profiles sysupgrade and factory image are
finished at the same time both processes would write to the same JSON
file, resulting in randomly broken outputs.

Some target like x86/64 do not use the image code yet, resulting in
missing JSON files. If no JSON info files were created, no
`profiles.json` files is created as it would be empty anyway.

As before, this creation is enabled by default only if `BUILDBOT` is set.

Tested via buildroot & ImageBuilder on ath79/generic, imx6 and x86/64.

Signed-off-by: Paul Spooren <mail@aparcar.org>
[json_info_files dir handling in Make, if case refactoring]
Signed-off-by: Petr Štetiar <ynezz@true.cz>

6 files changed, 136 insertions, 66 deletions

diff --git a/Makefile b/Makefile
index fd705a37ad..32c050bb48 100644
--- a/Makefile
+++ b/Makefile
@@ -88,6 +88,14 @@ prereq: $(target/stamp-prereq) tmp/.prereq_packages
 		exit 1; \
 	fi
 
+$(BIN_DIR)/profiles.json: FORCE
+	$(if $(CONFIG_JSON_OVERVIEW_IMAGE_INFO), \
+		WORK_DIR=$(BUILD_DIR)/json_info_files \
+			$(SCRIPT_DIR)/json_overview_image_info.py $@ \
+	)
+
+json_overview_image_info: $(BIN_DIR)/profiles.json
+
 checksum: FORCE
 	$(call sha256sums,$(BIN_DIR),$(CONFIG_BUILDBOT))
 
@@ -109,6 +117,7 @@ prepare: .config $(tools/stamp-compile) $(toolchain/stamp-compile)
 
 world: prepare $(target/stamp-compile) $(package/stamp-compile) $(package/stamp-install) $(target/stamp-install) FORCE
 	$(_SINGLE)$(SUBMAKE) -r package/index
+	$(_SINGLE)$(SUBMAKE) -r json_overview_image_info
 	$(_SINGLE)$(SUBMAKE) -r checksum
 
 .PHONY: clean dirclean prereq prepare world package/symlinks package/symlinks-install package/symlinks-clean
diff --git a/config/Config-build.in b/config/Config-build.in
index 6a6fb2882c..61a9265ad7 100644
--- a/config/Config-build.in
+++ b/config/Config-build.in
@@ -7,12 +7,13 @@
 
 menu "Global build settings"
 
-	config JSON_ADD_IMAGE_INFO
-		bool "Create JSON info files per build image"
+	config JSON_OVERVIEW_IMAGE_INFO
+		bool "Create JSON info file overview per target"
 		default BUILDBOT
 		help
-		  The JSON info files contain information about the device and
-		  build images, stored next to the firmware images.
+		  Create a JSON info file called profiles.json in the target
+		  directory containing machine readable list of built profiles
+		  and resulting images.
 
 	config ALL_NONSHARED
 		bool "Select all target specific packages by default"
diff --git a/include/image.mk b/include/image.mk
index 6204e8ab61..441f55b741 100644
--- a/include/image.mk
+++ b/include/image.mk
@@ -545,8 +545,11 @@ endef
 
 define Device/Build/image
   GZ_SUFFIX := $(if $(filter %dtb %gz,$(2)),,$(if $(and $(findstring ext4,$(1)),$(CONFIG_TARGET_IMAGES_GZIP)),.gz))
-  $$(_TARGET): $(BIN_DIR)/$(call IMAGE_NAME,$(1),$(2))$$(GZ_SUFFIX)
+  $$(_TARGET): $(if $(CONFIG_JSON_OVERVIEW_IMAGE_INFO), \
+	  $(BUILD_DIR)/json_info_files/$(call IMAGE_NAME,$(1),$(2)).json, \
+	  $(BIN_DIR)/$(call IMAGE_NAME,$(1),$(2))$$(GZ_SUFFIX))
   $(eval $(call Device/Export,$(KDIR)/tmp/$(call IMAGE_NAME,$(1),$(2)),$(1)))
+
   ROOTFS/$(1)/$(3) := \
 	$(KDIR)/root.$(1)$$(strip \
 		$$(if $$(FS_OPTIONS/$(1)),+fs=$$(call param_mangle,$$(FS_OPTIONS/$(1)))) \
@@ -568,32 +571,33 @@ define Device/Build/image
 
   $(BIN_DIR)/$(call IMAGE_NAME,$(1),$(2)): $(KDIR)/tmp/$(call IMAGE_NAME,$(1),$(2))
 	cp $$^ $$@
-	$(if $(CONFIG_JSON_ADD_IMAGE_INFO), \
-		DEVICE_ID="$(DEVICE_NAME)" \
-		BIN_DIR="$(BIN_DIR)" \
-		IMAGE_NAME="$(IMAGE_NAME)" \
-		IMAGE_TYPE=$(word 1,$(subst ., ,$(2))) \
-		IMAGE_PREFIX="$(IMAGE_PREFIX)" \
-		DEVICE_VENDOR="$(DEVICE_VENDOR)" \
-		DEVICE_MODEL="$(DEVICE_MODEL)" \
-		DEVICE_VARIANT="$(DEVICE_VARIANT)" \
-		DEVICE_ALT0_VENDOR="$(DEVICE_ALT0_VENDOR)" \
-		DEVICE_ALT0_MODEL="$(DEVICE_ALT0_MODEL)" \
-		DEVICE_ALT0_VARIANT="$(DEVICE_ALT0_VARIANT)" \
-		DEVICE_ALT1_VENDOR="$(DEVICE_ALT1_VENDOR)" \
-		DEVICE_ALT1_MODEL="$(DEVICE_ALT1_MODEL)" \
-		DEVICE_ALT1_VARIANT="$(DEVICE_ALT1_VARIANT)" \
-		DEVICE_ALT2_VENDOR="$(DEVICE_ALT2_VENDOR)" \
-		DEVICE_ALT2_MODEL="$(DEVICE_ALT2_MODEL)" \
-		DEVICE_ALT2_VARIANT="$(DEVICE_ALT2_VARIANT)" \
-		DEVICE_TITLE="$(DEVICE_TITLE)" \
-		TARGET="$(BOARD)" \
-		SUBTARGET="$(if $(SUBTARGET),$(SUBTARGET),generic)" \
-		VERSION_NUMBER="$(VERSION_NUMBER)" \
-		VERSION_CODE="$(VERSION_CODE)" \
-		SUPPORTED_DEVICES="$(SUPPORTED_DEVICES)" \
-		$(TOPDIR)/scripts/json_add_image_info.py \
-	)
+
+  $(BUILD_DIR)/json_info_files/$(call IMAGE_NAME,$(1),$(2)).json: $(BIN_DIR)/$(call IMAGE_NAME,$(1),$(2))$$(GZ_SUFFIX)
+	@mkdir -p $$(shell dirname $$@)
+	DEVICE_ID="$(DEVICE_NAME)" \
+	BIN_DIR="$(BIN_DIR)" \
+	IMAGE_NAME="$(IMAGE_NAME)" \
+	IMAGE_TYPE=$(word 1,$(subst ., ,$(2))) \
+	IMAGE_PREFIX="$(IMAGE_PREFIX)" \
+	DEVICE_VENDOR="$(DEVICE_VENDOR)" \
+	DEVICE_MODEL="$(DEVICE_MODEL)" \
+	DEVICE_VARIANT="$(DEVICE_VARIANT)" \
+	DEVICE_ALT0_VENDOR="$(DEVICE_ALT0_VENDOR)" \
+	DEVICE_ALT0_MODEL="$(DEVICE_ALT0_MODEL)" \
+	DEVICE_ALT0_VARIANT="$(DEVICE_ALT0_VARIANT)" \
+	DEVICE_ALT1_VENDOR="$(DEVICE_ALT1_VENDOR)" \
+	DEVICE_ALT1_MODEL="$(DEVICE_ALT1_MODEL)" \
+	DEVICE_ALT1_VARIANT="$(DEVICE_ALT1_VARIANT)" \
+	DEVICE_ALT2_VENDOR="$(DEVICE_ALT2_VENDOR)" \
+	DEVICE_ALT2_MODEL="$(DEVICE_ALT2_MODEL)" \
+	DEVICE_ALT2_VARIANT="$(DEVICE_ALT2_VARIANT)" \
+	DEVICE_TITLE="$(DEVICE_TITLE)" \
+	TARGET="$(BOARD)" \
+	SUBTARGET="$(if $(SUBTARGET),$(SUBTARGET),generic)" \
+	VERSION_NUMBER="$(VERSION_NUMBER)" \
+	VERSION_CODE="$(VERSION_CODE)" \
+	SUPPORTED_DEVICES="$(SUPPORTED_DEVICES)" \
+	$(TOPDIR)/scripts/json_add_image_info.py $$@
 
 endef
 
@@ -612,8 +616,6 @@ define Device/Build/artifact
 endef
 
 define Device/Build
-  $(shell rm -f $(BIN_DIR)/$(IMG_PREFIX)-$(1).json)
-
   $(if $(CONFIG_TARGET_ROOTFS_INITRAMFS),$(call Device/Build/initramfs,$(1)))
   $(call Device/Build/kernel,$(1))
 
@@ -699,6 +701,7 @@ define BuildImage
 
     image_prepare: compile
 		mkdir -p $(BIN_DIR) $(KDIR)/tmp
+		rm -rf $(BUILD_DIR)/json_info_files
 		$(call Image/Prepare)
 
     legacy-images-prepare-make: image_prepare
diff --git a/scripts/json_add_image_info.py b/scripts/json_add_image_info.py
index 44b4031f85..b6628113ac 100755
--- a/scripts/json_add_image_info.py
+++ b/scripts/json_add_image_info.py
@@ -1,18 +1,22 @@
 #!/usr/bin/env python3
 
-import json
-import os
+from os import getenv
+from pathlib import Path
+from sys import argv
 import hashlib
+import json
 
+if len(argv) != 2:
+    print("ERROR: JSON info script requires output arg")
+    exit(1)
 
-def e(variable, default=None):
-    return os.environ.get(variable, default)
-
-
-json_path = "{}{}{}.json".format(e("BIN_DIR"), os.sep, e("IMAGE_PREFIX"))
+json_path = Path(argv[1])
+bin_dir = Path(getenv("BIN_DIR"))
+image_file = bin_dir / getenv("IMAGE_NAME")
 
-with open(os.path.join(e("BIN_DIR"), e("IMAGE_NAME")), "rb") as image_file:
-    image_hash = hashlib.sha256(image_file.read()).hexdigest()
+if not image_file.is_file():
+    print("Skip JSON creation for non existing image ", image_file)
+    exit(0)
 
 
 def get_titles():
@@ -20,36 +24,40 @@ def get_titles():
     for prefix in ["", "ALT0_", "ALT1_", "ALT2_"]:
         title = {}
         for var in ["vendor", "model", "variant"]:
-            if e("DEVICE_{}{}".format(prefix, var.upper())):
-                title[var] = e("DEVICE_{}{}".format(prefix, var.upper()))
+            if getenv("DEVICE_{}{}".format(prefix, var.upper())):
+                title[var] = getenv("DEVICE_{}{}".format(prefix, var.upper()))
 
         if title:
             titles.append(title)
 
     if not titles:
-        titles.append({"title": e("DEVICE_TITLE")})
+        titles.append({"title": getenv("DEVICE_TITLE")})
 
     return titles
 
 
-if not os.path.exists(json_path):
-    device_info = {
-        "id": e("DEVICE_ID"),
-        "image_prefix": e("IMAGE_PREFIX"),
-        "images": [],
-        "metadata_version": 1,
-        "supported_devices": e("SUPPORTED_DEVICES").split(),
-        "target": "{}/{}".format(e("TARGET"), e("SUBTARGET", "generic")),
-        "titles": get_titles(),
-        "version_commit": e("VERSION_CODE"),
-        "version_number": e("VERSION_NUMBER"),
-    }
-else:
-    with open(json_path, "r") as json_file:
-        device_info = json.load(json_file)
-
-image_info = {"type": e("IMAGE_TYPE"), "name": e("IMAGE_NAME"), "sha256": image_hash}
-device_info["images"].append(image_info)
-
-with open(json_path, "w") as json_file:
-    json.dump(device_info, json_file, sort_keys=True, indent="  ")
+device_id = getenv("DEVICE_ID")
+image_hash = hashlib.sha256(image_file.read_bytes()).hexdigest()
+
+image_info = {
+    "metadata_version": 1,
+    "target": "{}/{}".format(getenv("TARGET"), getenv("SUBTARGET")),
+    "version_code": getenv("VERSION_CODE"),
+    "version_number": getenv("VERSION_NUMBER"),
+    "profiles": {
+        device_id: {
+            "image_prefix": getenv("IMAGE_PREFIX"),
+            "images": [
+                {
+                    "type": getenv("IMAGE_TYPE"),
+                    "name": getenv("IMAGE_NAME"),
+                    "sha256": image_hash,
+                }
+            ],
+            "supported_devices": getenv("SUPPORTED_DEVICES").split(),
+            "titles": get_titles(),
+        }
+    },
+}
+
+json_path.write_text(json.dumps(image_info, separators=(",", ":")))
diff --git a/scripts/json_overview_image_info.py b/scripts/json_overview_image_info.py
new file mode 100755
index 0000000000..5ed829249b
--- /dev/null
+++ b/scripts/json_overview_image_info.py
@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+
+import json
+from pathlib import Path
+from os import getenv
+from sys import argv
+
+if len(argv) != 2:
+    print("JSON info files script requires ouput file as argument")
+    exit(1)
+
+output_path = Path(argv[1])
+
+assert getenv("WORK_DIR"), "$WORK_DIR required"
+
+work_dir = Path(getenv("WORK_DIR"))
+
+assert work_dir.is_dir(), "$WORK_DIR not a directory"
+
+output = {}
+
+for json_file in work_dir.glob("*.json"):
+    image_info = json.loads(json_file.read_text())
+    if not output:
+        output.update(image_info)
+    else:
+        # get first (and only) profile in json file
+        device_id = next(iter(image_info["profiles"].keys()))
+        if device_id not in output["profiles"]:
+            output["profiles"].update(image_info["profiles"])
+        else:
+            output["profiles"][device_id]["images"].append(
+                image_info["profiles"][device_id]["images"][0]
+            )
+
+if output:
+    output_path.write_text(json.dumps(output, sort_keys=True, separators=(",", ":")))
+else:
+    print("JSON info file script could not find any JSON files for target")
diff --git a/target/imagebuilder/files/Makefile b/target/imagebuilder/files/Makefile
index 15b3d5c35c..835dd98ca5 100644
--- a/target/imagebuilder/files/Makefile
+++ b/target/imagebuilder/files/Makefile
@@ -118,6 +118,7 @@ _call_image: staging_dir/host/.prereq-build
 	$(MAKE) package_install
 	$(MAKE) -s prepare_rootfs
 	$(MAKE) -s build_image
+	$(MAKE) -s json_overview_image_info
 	$(MAKE) -s checksum
 
 _call_manifest: FORCE
@@ -163,12 +164,21 @@ prepare_rootfs: FORCE
 	$(CP) $(TARGET_DIR) $(TARGET_DIR_ORIG)
 	$(call prepare_rootfs,$(TARGET_DIR),$(USER_FILES),$(DISABLED_SERVICES))
 
+
 build_image: FORCE
 	@echo
 	@echo Building images...
 	$(NO_TRACE_MAKE) -C target/linux/$(BOARD)/image install TARGET_BUILD=1 IB=1 EXTRA_IMAGE_NAME="$(EXTRA_IMAGE_NAME)" \
 		$(if $(USER_PROFILE),PROFILE="$(USER_PROFILE)")
 
+$(BIN_DIR)/profiles.json: FORCE
+	$(if $(CONFIG_JSON_OVERVIEW_IMAGE_INFO), \
+		WORK_DIR=$(BUILD_DIR)/json_info_files \
+			$(SCRIPT_DIR)/json_overview_image_info.py $@ \
+	)
+
+json_overview_image_info: $(BIN_DIR)/profiles.json
+
 checksum: FORCE
 	@echo
 	@echo Calculating checksums...