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[config reload]: On dual ToR systems, cache ARP and FDB tables (#1465)
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Use the fast-reboot-dump and filter_fdb_entries scripts to cache the current ARP and FDB tables in /host/config-reload. Also create a file in the same directory to indicate to SWSS that it should restore from the cache.

Signed-off-by: Lawrence Lee <lawlee@microsoft.com>
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theasianpianist authored Mar 4, 2021
1 parent 10a359a commit 10de91d
Showing 1 changed file with 41 additions and 1 deletion.
42 changes: 41 additions & 1 deletion config/main.py
Original file line number Diff line number Diff line change
Expand Up @@ -793,6 +793,38 @@ def update_sonic_environment():
display_cmd=True
)

def cache_arp_entries():
success = True
cache_dir = '/host/config-reload'
click.echo('Caching ARP table to {}'.format(cache_dir))

if not os.path.exists(cache_dir):
os.mkdir(cache_dir)

arp_cache_cmd = '/usr/local/bin/fast-reboot-dump.py -t {}'.format(cache_dir)
cache_proc = subprocess.Popen(arp_cache_cmd, shell=True, text=True, stdout=subprocess.PIPE)
_, cache_err = cache_proc.communicate()
if cache_err:
click.echo("Could not cache ARP and FDB info prior to reloading")
success = False

if not cache_err:
fdb_cache_file = os.path.join(cache_dir, 'fdb.json')
arp_cache_file = os.path.join(cache_dir, 'arp.json')
fdb_filter_cmd = '/usr/local/bin/filter_fdb_entries -f {} -a {} -c /etc/sonic/configdb.json'.format(fdb_cache_file, arp_cache_file)
filter_proc = subprocess.Popen(fdb_filter_cmd, shell=True, text=True, stdout=subprocess.PIPE)
_, filter_err = filter_proc.communicate()
if filter_err:
click.echo("Could not filter FDB entries prior to reloading")
success = False

# If we are able to successfully cache ARP table info, signal SWSS to restore from our cache
# by creating /host/config-reload/needs-restore
if success:
restore_flag_file = os.path.join(cache_dir, 'needs-restore')
open(restore_flag_file, 'w').close()
return success

# This is our main entrypoint - the main 'config' command
@click.group(cls=clicommon.AbbreviationGroup, context_settings=CONTEXT_SETTINGS)
@click.pass_context
Expand Down Expand Up @@ -953,9 +985,10 @@ def load(filename, yes):
@click.option('-y', '--yes', is_flag=True)
@click.option('-l', '--load-sysinfo', is_flag=True, help='load system default information (mac, portmap etc) first.')
@click.option('-n', '--no_service_restart', default=False, is_flag=True, help='Do not restart docker services')
@click.option('-d', '--disable_arp_cache', default=False, is_flag=True, help='Do not cache ARP table before reloading (applies to dual ToR systems only)')
@click.argument('filename', required=False)
@clicommon.pass_db
def reload(db, filename, yes, load_sysinfo, no_service_restart):
def reload(db, filename, yes, load_sysinfo, no_service_restart, disable_arp_cache):
"""Clear current configuration and import a previous saved config DB dump file.
<filename> : Names of configuration file(s) to load, separated by comma with no spaces in between
"""
Expand Down Expand Up @@ -994,6 +1027,13 @@ def reload(db, filename, yes, load_sysinfo, no_service_restart):
else:
cfg_hwsku = cfg_hwsku.strip()

# For dual ToR devices, cache ARP and FDB info
localhost_metadata = db.cfgdb.get_table('DEVICE_METADATA')['localhost']
cache_arp_table = not disable_arp_cache and 'subtype' in localhost_metadata and localhost_metadata['subtype'].lower() == 'dualtor'

if cache_arp_table:
cache_arp_entries()

#Stop services before config push
if not no_service_restart:
log.log_info("'reload' stopping services...")
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