[warm-reboot] Add new preboot health check: verify database integrity (…

…sonic-net#1785)

What I did
Verify database integrity before proceeding with warm reboot or fast reboot.
This integrity check uses a JSON schema to validate DBs. To start with, only counters_db's table COUNTERS_PORT_NAME_MAP presence is verified. But, this list can advance in future.
The test logic is designed to be generic; any more databases or tables within them can be just added to schema list, and the verification logic needs no change.
How I did it
Added a JSON schema, and generic schema validation logic.

scripts/check_db_integrity.py

@@ -0,0 +1,84 @@
+#!/usr/bin/env python3
+
+"""
+This is to verify if Database has critical tables present before warmboot can proceed.
+If warmboot is allowed with missing critical tables, it can lead to issues in going
+down path or during the recovery path. This test detects such issues before proceeding.
+The verification procedure here uses JSON schemas to verify the DB entities.
+
+In future, to verify new tables or their content, just the schema modification is needed.
+No modification may be needed to the integrity check logic.
+"""
+
+import os, sys
+import json, jsonschema
+import syslog
+import subprocess
+import traceback
+
+DB_SCHEMA = {
+    "COUNTERS_DB":
+    {
+        "$schema": "http://json-schema.org/draft-06/schema",
+        "type": "object",
+        "title": "Schema for COUNTERS DB's entities",
+        "required": ["COUNTERS_PORT_NAME_MAP"],
+        "properties": {
+            "COUNTERS_PORT_NAME_MAP": {"$id": "#/properties/COUNTERS_PORT_NAME_MAP", "type": "object"}
+        }
+    }
+}
+
+
+def main():
+    if not DB_SCHEMA:
+        return 0
+
+    for db_name, schema in DB_SCHEMA.items():
+        db_dump_file = "/tmp/{}.json".format(db_name)
+        dump_db_cmd = "sonic-db-dump -n 'COUNTERS_DB' -y > {}".format(db_dump_file)
+        p = subprocess.Popen(dump_db_cmd, shell=True, text=True,
+            stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        (_, err) = p.communicate()
+        rc = p.wait()
+        if rc != 0:
+            print("Failed to dump db {}. Return code: {} with err: {}".format(db_name, rc, err))
+
+        try:
+            with open(db_dump_file) as fp:
+                db_dump_data = json.load(fp)
+        except ValueError as err:
+            syslog.syslog(syslog.LOG_DEBUG, "DB json file is not a valid json file. " +\
+                "Error: {}".format(str(err)))
+            return 1
+
+        # What: Validate if critical tables and entries are present in DB.
+        # Why: This is needed to avoid warmbooting with a bad DB; which can
+        #   potentially trigger failures in the reboot recovery path.
+        # How: Validate DB against a schema which defines required tables.
+        try:
+            jsonschema.validate(instance=db_dump_data, schema=schema)
+        except jsonschema.exceptions.ValidationError as err:
+            syslog.syslog(syslog.LOG_ERR, "Database is missing tables/entries needed for reboot procedure. " +\
+                "DB integrity check failed with:\n{}".format(str(err.message)))
+            return 1
+    syslog.syslog(syslog.LOG_DEBUG, "Database integrity checks passed.")
+    return 0
+
+
+if __name__ == '__main__':
+    res = 0
+    try:
+        res = main()
+    except KeyboardInterrupt:
+        syslog.syslog(syslog.LOG_NOTICE, "SIGINT received. Quitting")
+        res = 1
+    except Exception as e:
+        syslog.syslog(syslog.LOG_ERR, "Got an exception %s: Traceback: %s" % (str(e), traceback.format_exc()))
+        res = 2
+    finally:
+        syslog.closelog()
+    try:
+        sys.exit(res)
+    except SystemExit:
+        os._exit(res)

scripts/fast-reboot

@@ -12,6 +12,7 @@ SHUTDOWN_ORDER_FILE="/etc/sonic/${REBOOT_TYPE}_order"
 VERBOSE=no
 FORCE=no
 IGNORE_ASIC=no
+IGNORE_DB_CHECK=no
 STRICT=no
 REBOOT_METHOD="/sbin/kexec -e"
 ASSISTANT_IP_LIST=""
@@ -38,6 +39,7 @@ EXIT_SYNCD_SHUTDOWN=11
 EXIT_FAST_REBOOT_DUMP_FAILURE=12
 EXIT_FILTER_FDB_ENTRIES_FAILURE=13
 EXIT_COUNTERPOLL_DELAY_FAILURE=14
+EXIT_DB_INTEGRITY_FAILURE=15
 EXIT_NO_CONTROL_PLANE_ASSISTANT=20
 EXIT_SONIC_INSTALLER_VERIFY_REBOOT=21
 
@@ -59,8 +61,9 @@ function showHelpAndExit()
     echo "Usage: ${REBOOT_SCRIPT_NAME} [options]"
     echo "    -h,-? : get this help"
     echo "    -v    : turn on verbose"
-    echo "    -f    : force execution"
-    echo "    -i    : ignore MD5-checksum-verification of ASIC configuration files"
+    echo "    -f    : force execution - ignore Orchagent RESTARTCHECK failure"
+    echo "    -i    : force execution - ignore ASIC MD5-checksum-verification"
+    echo "    -d    : force execution - ignore database integrity check"
     echo "    -r    : reboot with /sbin/reboot"
     echo "    -k    : reboot with /sbin/kexec -e [default]"
     echo "    -x    : execute script with -x flag"
@@ -74,7 +77,7 @@ function showHelpAndExit()
 
 function parseOptions()
 {
-    while getopts "vfih?rkxc:s" opt; do
+    while getopts "vfidh?rkxc:s" opt; do
         case ${opt} in
             h|\? )
                 showHelpAndExit
@@ -88,6 +91,9 @@ function parseOptions()
             i )
                 IGNORE_ASIC=yes
                 ;;
+            d )
+                IGNORE_DB_CHECK=yes
+                ;;
             r )
                 REBOOT_METHOD="/sbin/reboot"
                 ;;
@@ -327,6 +333,23 @@ function check_docker_exec()
     done
 }
 
+function check_db_integrity()
+{
+    if [[ "$REBOOT_TYPE" = "warm-reboot" || "$REBOOT_TYPE" = "fastfast-reboot" ]]; then
+        CHECK_DB_INTEGRITY=0
+        /usr/local/bin/check_db_integrity.py || CHECK_DB_INTEGRITY=$?
+        if [[ CHECK_DB_INTEGRITY -ne 0 ]]; then
+            if [[ x"${IGNORE_DB_CHECK}" == x"yes" ]]; then
+                debug "Ignoring Database integrity checks..."
+            else
+                error "Failed to validate DB's integrity. Exit code: ${CHECK_DB_INTEGRITY}. \
+                    Use '-d' option to force ignore this check."
+                exit ${EXIT_DB_INTEGRITY_FAILURE}
+            fi
+        fi
+    fi
+}
+
 function reboot_pre_check()
 {
     check_docker_exec
@@ -337,6 +360,8 @@ function reboot_pre_check()
     fi
     rm ${filename}
 
+    check_db_integrity
+
     # Make sure /host has enough space for warm reboot temp files
     avail=$(df -k /host | tail -1 | awk '{ print $4 }')
     if [[ ${avail} -lt ${MIN_HD_SPACE_NEEDED} ]]; then