[process-reboot-cause]Address the issue: Incorrect reboot cause returned when warm reboot follows a hardware caused reboot (#3880)

* [process-reboot-cause]Address the issue: Incorrect reboot cause returned when warm reboot follows a hardware caused reboot
1. check whether /proc/cmdline indicates warm/fast reboot.
   if yes the software reboot cause file will be treated as the reboot cause.
   finish
2. check whether platform api returns a reboot cause.
   if yes it is treated as the reboot cause.
   finish.
3. check whether /hosts/reboot-cause contains a cause.
   if yes it is treated as the cause otherwise return unknown.

* [process-reboot-cause]Fix review comments

* [process-reboot-cause]address comments
1. use "with" statement
2. update fast/warm reboot BOOT_ARG

* [process-reboot-cause]address comments

* refactor the code flow

* Remove escape

* Remove extra ':'

files/image_config/process-reboot-cause/process-reboot-cause

@@ -11,6 +11,7 @@ try:
     import pwd
     import sys
     import syslog
+    import re
 except ImportError as err:
     raise ImportError("%s - required module not found" % str(err))
 
@@ -22,6 +23,16 @@ REBOOT_CAUSE_DIR = "/host/reboot-cause/"
 REBOOT_CAUSE_FILE = REBOOT_CAUSE_DIR + "reboot-cause.txt"
 PREVIOUS_REBOOT_CAUSE_FILE = REBOOT_CAUSE_DIR + "previous-reboot-cause.txt"
 FIRST_BOOT_PLATFORM_FILE = "/tmp/notify_firstboot_to_platform"
+REBOOT_TYPE_KEXEC_FILE = "/proc/cmdline"
+# The following SONIC_BOOT_TYPEs come from the warm/fast reboot script which is in sonic-utilities
+# Because the system can be rebooted from some old versions, we have to take all possible BOOT options into consideration.
+# On 201803, 201807 we have
+# BOOT_OPTIONS="$(echo $KERNEL_OPTIONS | sed -e 's/\s*linux\s*/BOOT_IMAGE=/') fast-reboot"
+# On 201811 and later we have
+# BOOT_OPTIONS="$(echo $KERNEL_OPTIONS | sed -e 's/\s*linux\s*/BOOT_IMAGE=/') SONIC_BOOT_TYPE=${BOOT_TYPE_ARG}" where BOOT_TYPE_ARG can be warm, fastfast or fast
+# To extract the commom part of them, we should have the following PATTERN
+REBOOT_TYPE_KEXEC_PATTERN_WARM = ".*SONIC_BOOT_TYPE=(warm|fastfast).*"
+REBOOT_TYPE_KEXEC_PATTERN_FAST = ".*SONIC_BOOT_TYPE=(fast|fast-reboot).*"
 
 UNKNOWN_REBOOT_CAUSE = "Unknown"
 
@@ -47,7 +58,32 @@ def log_error(msg):
 
 
 # ============================= Functions =============================
+def parse_warmfast_reboot_from_proc_cmdline():
+    if os.path.isfile(REBOOT_TYPE_KEXEC_FILE):
+        with open(REBOOT_TYPE_KEXEC_FILE, "r") as cause_file:
+            cause_file_kexec = cause_file.readline()
+        m = re.match(REBOOT_TYPE_KEXEC_PATTERN_WARM, cause_file_kexec)
+        if m and m.group(1):
+            return 'warm-reboot'
+        m = re.match(REBOOT_TYPE_KEXEC_PATTERN_FAST, cause_file_kexec)
+        if m and m.group(1):
+            return 'fast-reboot'
+    return None
 
+
+def find_software_reboot_cause():
+    software_reboot_cause = UNKNOWN_REBOOT_CAUSE
+
+    if os.path.isfile(REBOOT_CAUSE_FILE):
+        with open(REBOOT_CAUSE_FILE, "r") as cause_file:
+            software_reboot_cause = cause_file.readline().rstrip('\n')
+
+    if os.path.isfile(FIRST_BOOT_PLATFORM_FILE):
+        os.remove(FIRST_BOOT_PLATFORM_FILE)
+
+    return software_reboot_cause
+ 
+ 
 def main():
     log_info("Starting up...")
 
@@ -73,51 +109,48 @@ def main():
     try:
         import sonic_platform
 
-        # Check if the previous reboot was caused by hardware
+        # 1. Check if the previous reboot was warm/fast reboot by testing whether there is "fast|fastfast|warm" in /proc/cmdline
-        platform = sonic_platform.platform.Platform()
+        #    If yes, the content of /hosts/reboot-cause/reboot-cause.txt will be treated as the reboot cause
-
+        proc_cmdline_reboot_cause = parse_warmfast_reboot_from_proc_cmdline()
-        chassis = platform.get_chassis()
+        if proc_cmdline_reboot_cause:
-
+            log_info("/proc/cmdline indicates reboot type: {}".format(proc_cmdline_reboot_cause))
-        hardware_reboot_cause, optional_details = chassis.get_reboot_cause()
-
-        if hardware_reboot_cause == chassis.REBOOT_CAUSE_NON_HARDWARE:
-            # The reboot was not caused by hardware. If there is a REBOOT_CAUSE_FILE, it will
-            # contain any software-related reboot info. We will use it as the previous cause.
             if os.path.isfile(REBOOT_CAUSE_FILE):
-                cause_file = open(REBOOT_CAUSE_FILE, "r")
+                with open(REBOOT_CAUSE_FILE, "r") as cause_file:
-                previous_reboot_cause = cause_file.readline().rstrip('\n')
+                    proc_cmdline_reboot_cause = cause_file.readline().rstrip('\n')
-                cause_file.close()
+            else:
-            # If it is FirstTime Boot and previous_reboot_cause is unknown
+                # /proc/cmdline says it's a warm/fast reboot but /host/reboot-cause.txt doesn't exist.
-            # and hardware_reboot cause is non_hardware then
+                # This could happen when upgrading from a version doesn't support reboot cause.
-            # Update the reboot cause as required
+                log_info("Reboot cause file {} doesn't exist".format(REBOOT_CAUSE_DIR))
-            if os.path.isfile(FIRST_BOOT_PLATFORM_FILE):
+
-                if (previous_reboot_cause == UNKNOWN_REBOOT_CAUSE):
+        if proc_cmdline_reboot_cause is not None:
-                     previous_reboot_cause = UNKNOWN_REBOOT_CAUSE
+            previous_reboot_cause = proc_cmdline_reboot_cause
-                os.remove(FIRST_BOOT_PLATFORM_FILE)
-        elif hardware_reboot_cause == chassis.REBOOT_CAUSE_HARDWARE_OTHER:
-            previous_reboot_cause = "{} ({})".format(hardware_reboot_cause, optional_details)
         else:
-            previous_reboot_cause = hardware_reboot_cause
+            # 2. Check if the previous reboot was caused by hardware
+            #    If yes, the hardware reboot cause will be treated as the reboot cause
+            platform = sonic_platform.platform.Platform()
+
+            chassis = platform.get_chassis()
+
+            hardware_reboot_cause, optional_details = chassis.get_reboot_cause()
+
+            if hardware_reboot_cause == chassis.REBOOT_CAUSE_NON_HARDWARE:
+                # The reboot was not caused by hardware. If there is a REBOOT_CAUSE_FILE, it will
+                # contain any software-related reboot info. We will use it as the previous cause.
+                previous_reboot_cause = find_software_reboot_cause()
+            elif hardware_reboot_cause == chassis.REBOOT_CAUSE_HARDWARE_OTHER:
+                previous_reboot_cause = "{} ({})".format(hardware_reboot_cause, optional_details)
+            else:
+                previous_reboot_cause = hardware_reboot_cause
     except ImportError as err:
         log_warning("sonic_platform package not installed. Unable to detect hardware reboot causes.")
 
         # If there is a REBOOT_CAUSE_FILE, it will contain any software-related
         # reboot info. We will use it as the previous cause.
-        if os.path.isfile(REBOOT_CAUSE_FILE):
+        previous_reboot_cause = find_software_reboot_cause()
-            cause_file = open(REBOOT_CAUSE_FILE, "r")
-            previous_reboot_cause = cause_file.readline().rstrip('\n')
-            cause_file.close()
 
-        # If it is FirstTime Boot and previous_reboot_cause is unknown
-        # Update the reboot cause as required
-        if os.path.isfile(FIRST_BOOT_PLATFORM_FILE):
-            if (previous_reboot_cause == UNKNOWN_REBOOT_CAUSE):
-                 previous_reboot_cause = UNKNOWN_REBOOT_CAUSE
-            os.remove(FIRST_BOOT_PLATFORM_FILE)
     # Write the previous reboot cause to PREVIOUS_REBOOT_CAUSE_FILE
-    prev_cause_file = open(PREVIOUS_REBOOT_CAUSE_FILE, "w")
+    with open(PREVIOUS_REBOOT_CAUSE_FILE, "w") as prev_cause_file:
-    prev_cause_file.write(previous_reboot_cause)
+        prev_cause_file.write(previous_reboot_cause)
-    prev_cause_file.close()
 
     # Also log the previous reboot cause to the syslog
     log_info("Previous reboot cause: {}".format(previous_reboot_cause))
@@ -127,9 +160,8 @@ def main():
         os.remove(REBOOT_CAUSE_FILE)
 
     # Write a new default reboot cause file for the next reboot
-    cause_file = open(REBOOT_CAUSE_FILE, "w")
+    with open(REBOOT_CAUSE_FILE, "w") as cause_file:
-    cause_file.write(UNKNOWN_REBOOT_CAUSE)
+        cause_file.write(UNKNOWN_REBOOT_CAUSE)
-    cause_file.close()
 
 
 if __name__ == "__main__":