plans/usecases-pnf-sw-upgrade/pnf-sw-upgrade/simulators/pnfsim/pnf-sw-upgrade/subscriber.py

   1 #!/usr/bin/env python3
   2
   3 # ============LICENSE_START=======================================================
   4 #  Copyright (C) 2020 Nordix Foundation.
   5 # ================================================================================
   6 # Licensed under the Apache License, Version 2.0 (the "License");
   7 # you may not use this file except in compliance with the License.
   8 # You may obtain a copy of the License at
   9 #
  10 #      http://www.apache.org/licenses/LICENSE-2.0
  11 #
  12 # Unless required by applicable law or agreed to in writing, software
  13 # distributed under the License is distributed on an "AS IS" BASIS,
  14 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15 # See the License for the specific language governing permissions and
  16 # limitations under the License.
  17 #
  18 # SPDX-License-Identifier: Apache-2.0
  19 # ============LICENSE_END=========================================================
  20
  21 __author__ = "Eliezio Oliveira <eliezio.oliveira@est.tech>"
  22 __copyright__ = "Copyright (C) 2020 Nordix Foundation"
  23 __license__ = "Apache 2.0"
  24
  25 import os
  26 import time
  27 from threading import Timer
  28
  29 import sysrepo as sr
  30 from loguru import logger
  31
  32 YANG_MODULE_NAME = 'pnf-sw-upgrade'
  33
  34 XPATH_CTX = sr.Xpath_Ctx()
  35 PAUSE_TO_LOCK = 0.5
  36
  37 #
  38 # ----- BEGIN Finite State Machine definitions -----
  39 #
  40
  41 # Actions
  42 ACT_PRE_CHECK = 'PRE_CHECK'
  43 ACT_DOWNLOAD_NE_SW = 'DOWNLOAD_NE_SW'
  44 ACT_ACTIVATE_NE_SW = 'ACTIVATE_NE_SW'
  45 ACT_CANCEL = 'CANCEL'
  46
  47 # States
  48 ST_CREATED = 'CREATED'
  49 ST_INITIALIZED = 'INITIALIZED'
  50 ST_DOWNLOAD_IN_PROGRESS = 'DOWNLOAD_IN_PROGRESS'
  51 ST_DOWNLOAD_COMPLETED = 'DOWNLOAD_COMPLETED'
  52 ST_ACTIVATION_IN_PROGRESS = 'ACTIVATION_IN_PROGRESS'
  53 ST_ACTIVATION_COMPLETED = 'ACTIVATION_COMPLETED'
  54
  55 # Timeouts used for timed transitions
  56 SWUG_TIMED_TRANSITION_TO = int(os.environ.get("SWUG_TIMED_TRANSITION_TO", "7"))
  57 TO_DOWNLOAD = SWUG_TIMED_TRANSITION_TO
  58 TO_ACTIVATION = SWUG_TIMED_TRANSITION_TO
  59
  60
  61 def timestamper(sess, key_id):
  62     xpath = xpath_of(key_id, 'state-change-time')
  63     now = time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime())
  64     state = sr.Val(now, sr.SR_STRING_T)
  65     sess.set_item(xpath, state)
  66
  67
  68 def xpath_of(key_id, leaf_id):
  69     selector = "[id='{0}']".format(key_id) if key_id else ''
  70     return "/%s:software-upgrade/upgrade-package%s/%s" % (YANG_MODULE_NAME, selector, leaf_id)
  71
  72
  73 """
  74 The finite state machine (FSM) is represented as a dictionary where the current state is the key, and its value is
  75 an object (also represented as a dictionary) with the following optional attributes:
  76
  77 - on_enter: a function called when FSM enters this state;
  78 - transitions: a dictionary mapping every acceptable action to the target state;
  79 - timed_transition: a pair for a timed transition that will automatically occur after a given interval.
  80 """
  81 STATE_MACHINE = {
  82     ST_CREATED: {
  83         'transitions': {ACT_PRE_CHECK: ST_INITIALIZED}
  84     },
  85     ST_INITIALIZED: {
  86         'on_enter': timestamper,
  87         'transitions': {ACT_DOWNLOAD_NE_SW: ST_DOWNLOAD_IN_PROGRESS}
  88     },
  89     ST_DOWNLOAD_IN_PROGRESS: {
  90         'on_enter': timestamper,
  91         'timed_transition': (TO_DOWNLOAD, ST_DOWNLOAD_COMPLETED),
  92         'transitions': {ACT_CANCEL: ST_INITIALIZED}
  93     },
  94     ST_DOWNLOAD_COMPLETED: {
  95         'on_enter': timestamper,
  96         'transitions': {ACT_ACTIVATE_NE_SW: ST_ACTIVATION_IN_PROGRESS}
  97     },
  98     ST_ACTIVATION_IN_PROGRESS: {
  99         'on_enter': timestamper,
 100         'timed_transition': (TO_ACTIVATION, ST_ACTIVATION_COMPLETED),
 101         'transitions': {ACT_CANCEL: ST_DOWNLOAD_COMPLETED}
 102     },
 103     ST_ACTIVATION_COMPLETED: {
 104         'on_enter': timestamper,
 105         'transitions': {ACT_ACTIVATE_NE_SW: ST_ACTIVATION_IN_PROGRESS}
 106     }
 107 }
 108
 109
 110 #
 111 # ----- END Finite State Machine definitions -----
 112 #
 113
 114
 115 def main():
 116     try:
 117         conn = sr.Connection(YANG_MODULE_NAME)
 118         sess = sr.Session(conn)
 119         subscribe = sr.Subscribe(sess)
 120
 121         subscribe.module_change_subscribe(YANG_MODULE_NAME, module_change_cb, conn)
 122
 123         try:
 124             print_current_config(sess, YANG_MODULE_NAME)
 125         except Exception as e:
 126             logger.error(e)
 127
 128         sr.global_loop()
 129
 130         logger.info("Application exit requested, exiting.")
 131     except Exception as e:
 132         logger.error(e)
 133
 134
 135 # Function to be called for subscribed client of given session whenever configuration changes.
 136 def module_change_cb(sess, module_name, event, private_ctx):
 137     if event == sr.SR_EV_APPLY:
 138         try:
 139             conn = private_ctx
 140             change_path = xpath_of(None, 'action')
 141             it = sess.get_changes_iter(change_path)
 142             while True:
 143                 change = sess.get_change_next(it)
 144                 if change is None:
 145                     break
 146                 op = change.oper()
 147                 if op in (sr.SR_OP_CREATED, sr.SR_OP_MODIFIED):
 148                     handle_trigger_action(conn, sess, change.new_val())
 149         except Exception as e:
 150             logger.error(e)
 151     return sr.SR_ERR_OK
 152
 153
 154 # Function to print current configuration state.
 155 # It does so by loading all the items of a session and printing them out.
 156 def print_current_config(session, module_name):
 157     select_xpath = f"/{module_name}:*//*"
 158     values = session.get_items(select_xpath)
 159     if values:
 160         logger.info("========== BEGIN CONFIG ==========")
 161         for i in range(values.val_cnt()):
 162             logger.info(values.val(i).to_string().strip())
 163         logger.info("=========== END CONFIG ===========")
 164
 165
 166 def handle_trigger_action(conn, sess, action_val):
 167     """
 168     Handle individual changes on the model.
 169     """
 170     logger.info("CREATED/MODIFIED: %s" % action_val.to_string())
 171     xpath = action_val.xpath()
 172     last_node = XPATH_CTX.last_node(xpath)
 173     # Warning: 'key_value' modifies 'xpath'!
 174     key_id = XPATH_CTX.key_value(xpath, 'upgrade-package', 'id')
 175     if key_id and last_node == 'action':
 176         action = action_val.data().get_enum()
 177         cur_state = sess.get_item(xpath_of(key_id, 'current-status')).data().get_enum()
 178         next_state_str = STATE_MACHINE[cur_state]['transitions'].get(action, None)
 179         if next_state_str:
 180             Timer(PAUSE_TO_LOCK, try_change_state, (conn, key_id, next_state_str)).start()
 181
 182
 183 def try_change_state(conn, key_id, state_str):
 184     sess = sr.Session(conn)
 185     try:
 186         try:
 187             sess.lock_module(YANG_MODULE_NAME)
 188         except RuntimeError:
 189             logger.warning(f"Retrying after {PAUSE_TO_LOCK}s")
 190             Timer(PAUSE_TO_LOCK, try_change_state, (conn, key_id, state_str)).start()
 191             return
 192         try:
 193             state = sr.Val(state_str, sr.SR_ENUM_T)
 194             sess.set_item(xpath_of(key_id, 'current-status'), state)
 195             on_enter = STATE_MACHINE[state_str].get('on_enter', None)
 196             if callable(on_enter):
 197                 on_enter(sess, key_id)
 198             sess.commit()
 199         finally:
 200             sess.unlock_module(YANG_MODULE_NAME)
 201         delay, next_state_str = STATE_MACHINE[state_str].get('timed_transition', [0, None])
 202         if delay:
 203             Timer(delay, try_change_state, (conn, key_id, next_state_str)).start()
 204     finally:
 205         sess.session_stop()
 206
 207
 208 if __name__ == '__main__':
 209     main()