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#!/usr/bin/env python3
# ============LICENSE_START=======================================================
# Copyright (C) 2020 Nordix Foundation.
# ================================================================================
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# SPDX-License-Identifier: Apache-2.0
# ============LICENSE_END=========================================================
__author__ = "Eliezio Oliveira <eliezio.oliveira@est.tech>"
__copyright__ = "Copyright (C) 2020 Nordix Foundation"
__license__ = "Apache 2.0"
import os
import time
from threading import Timer
import sysrepo as sr
from loguru import logger
YANG_MODULE_NAME = 'pnf-sw-upgrade'
XPATH_CTX = sr.Xpath_Ctx()
PAUSE_TO_LOCK = 0.5
#
# ----- BEGIN Finite State Machine definitions -----
#
# Actions
ACT_PRE_CHECK = 'PRE_CHECK'
ACT_DOWNLOAD_NE_SW = 'DOWNLOAD_NE_SW'
ACT_ACTIVATE_NE_SW = 'ACTIVATE_NE_SW'
ACT_CANCEL = 'CANCEL'
# States
ST_CREATED = 'CREATED'
ST_INITIALIZED = 'INITIALIZED'
ST_DOWNLOAD_IN_PROGRESS = 'DOWNLOAD_IN_PROGRESS'
ST_DOWNLOAD_COMPLETED = 'DOWNLOAD_COMPLETED'
ST_ACTIVATION_IN_PROGRESS = 'ACTIVATION_IN_PROGRESS'
ST_ACTIVATION_COMPLETED = 'ACTIVATION_COMPLETED'
# Timeouts used for timed transitions
SWUG_TIMED_TRANSITION_TO = int(os.environ.get("SWUG_TIMED_TRANSITION_TO", "7"))
TO_DOWNLOAD = SWUG_TIMED_TRANSITION_TO
TO_ACTIVATION = SWUG_TIMED_TRANSITION_TO
def timestamper(sess, key_id):
xpath = xpath_of(key_id, 'state-change-time')
now = time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime())
state = sr.Val(now, sr.SR_STRING_T)
sess.set_item(xpath, state)
def xpath_of(key_id, leaf_id):
selector = "[id='{0}']".format(key_id) if key_id else ''
return "/%s:software-upgrade/upgrade-package%s/%s" % (YANG_MODULE_NAME, selector, leaf_id)
"""
The finite state machine (FSM) is represented as a dictionary where the current state is the key, and its value is
an object (also represented as a dictionary) with the following optional attributes:
- on_enter: a function called when FSM enters this state;
- transitions: a dictionary mapping every acceptable action to the target state;
- timed_transition: a pair for a timed transition that will automatically occur after a given interval.
"""
STATE_MACHINE = {
ST_CREATED: {
'transitions': {ACT_PRE_CHECK: ST_INITIALIZED}
},
ST_INITIALIZED: {
'on_enter': timestamper,
'transitions': {ACT_DOWNLOAD_NE_SW: ST_DOWNLOAD_IN_PROGRESS}
},
ST_DOWNLOAD_IN_PROGRESS: {
'on_enter': timestamper,
'timed_transition': (TO_DOWNLOAD, ST_DOWNLOAD_COMPLETED),
'transitions': {ACT_CANCEL: ST_INITIALIZED}
},
ST_DOWNLOAD_COMPLETED: {
'on_enter': timestamper,
'transitions': {ACT_ACTIVATE_NE_SW: ST_ACTIVATION_IN_PROGRESS}
},
ST_ACTIVATION_IN_PROGRESS: {
'on_enter': timestamper,
'timed_transition': (TO_ACTIVATION, ST_ACTIVATION_COMPLETED),
'transitions': {ACT_CANCEL: ST_DOWNLOAD_COMPLETED}
},
ST_ACTIVATION_COMPLETED: {
'on_enter': timestamper,
'transitions': {ACT_ACTIVATE_NE_SW: ST_ACTIVATION_IN_PROGRESS}
}
}
#
# ----- END Finite State Machine definitions -----
#
def main():
try:
conn = sr.Connection(YANG_MODULE_NAME)
sess = sr.Session(conn)
subscribe = sr.Subscribe(sess)
subscribe.module_change_subscribe(YANG_MODULE_NAME, module_change_cb, conn)
try:
print_current_config(sess, YANG_MODULE_NAME)
except Exception as e:
logger.error(e)
sr.global_loop()
logger.info("Application exit requested, exiting.")
except Exception as e:
logger.error(e)
# Function to be called for subscribed client of given session whenever configuration changes.
def module_change_cb(sess, module_name, event, private_ctx):
if event == sr.SR_EV_APPLY:
try:
conn = private_ctx
change_path = xpath_of(None, 'action')
it = sess.get_changes_iter(change_path)
while True:
change = sess.get_change_next(it)
if change is None:
break
op = change.oper()
if op in (sr.SR_OP_CREATED, sr.SR_OP_MODIFIED):
handle_trigger_action(conn, sess, change.new_val())
except Exception as e:
logger.error(e)
return sr.SR_ERR_OK
# Function to print current configuration state.
# It does so by loading all the items of a session and printing them out.
def print_current_config(session, module_name):
select_xpath = f"/{module_name}:*//*"
values = session.get_items(select_xpath)
if values:
logger.info("========== BEGIN CONFIG ==========")
for i in range(values.val_cnt()):
logger.info(values.val(i).to_string().strip())
logger.info("=========== END CONFIG ===========")
def handle_trigger_action(conn, sess, action_val):
"""
Handle individual changes on the model.
"""
logger.info("CREATED/MODIFIED: %s" % action_val.to_string())
xpath = action_val.xpath()
last_node = XPATH_CTX.last_node(xpath)
# Warning: 'key_value' modifies 'xpath'!
key_id = XPATH_CTX.key_value(xpath, 'upgrade-package', 'id')
if key_id and last_node == 'action':
action = action_val.data().get_enum()
cur_state = sess.get_item(xpath_of(key_id, 'current-status')).data().get_enum()
next_state_str = STATE_MACHINE[cur_state]['transitions'].get(action, None)
if next_state_str:
Timer(PAUSE_TO_LOCK, try_change_state, (conn, key_id, next_state_str)).start()
def try_change_state(conn, key_id, state_str):
sess = sr.Session(conn)
try:
try:
sess.lock_module(YANG_MODULE_NAME)
except RuntimeError:
logger.warning(f"Retrying after {PAUSE_TO_LOCK}s")
Timer(PAUSE_TO_LOCK, try_change_state, (conn, key_id, state_str)).start()
return
try:
state = sr.Val(state_str, sr.SR_ENUM_T)
sess.set_item(xpath_of(key_id, 'current-status'), state)
on_enter = STATE_MACHINE[state_str].get('on_enter', None)
if callable(on_enter):
on_enter(sess, key_id)
sess.commit()
finally:
sess.unlock_module(YANG_MODULE_NAME)
delay, next_state_str = STATE_MACHINE[state_str].get('timed_transition', [0, None])
if delay:
Timer(delay, try_change_state, (conn, key_id, next_state_str)).start()
finally:
sess.session_stop()
if __name__ == '__main__':
main()
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