Created
July 6, 2023 06:35
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| #!/usr/bin/env python | |
| """ | |
| Script to handle keepalived notifications. | |
| This script will be called by keepalived with three arguments: | |
| - "GROUP" or "INSTANCE" | |
| - name of the group or instance | |
| - target state of the transition: "MASTER", "BACKUP", "FAULT" | |
| The script should return 1 if the number of parameters is not 3, if the | |
| target state is not "MASTER", "BACKUP" or "FAULT", or if the first parameter | |
| is not "GROUP" or "INSTANCE". Otherwise it should return 0. | |
| It should log its actions to syslog. | |
| If the transition is to "MASTER", the script should start the service "zabbix-proxy". | |
| It should also call a GCP cloud function to change the route to point to the new master. | |
| This call will done to the URL defined in the variable FUNCTION_URL. | |
| It should be called with a parameter "target" passing the hostname of the new master. | |
| Is should also pass an Authorization header with a token. | |
| To generate the token, the script should call the GCP metadata server. | |
| If the transition is to "BACKUP" or "FAULT", the script should stop the service "zabbix-proxy". | |
| """ | |
| import logging | |
| import os | |
| import subprocess | |
| import sys | |
| import urllib.request | |
| import urllib.error | |
| from systemd.journal import JournalHandler | |
| # URL of the cloud function to call | |
| # We use the "zone" and "project" hostvars to get the region and project of the cloud function. | |
| FUNCTION_URL = "https://{{ (zone | split('-'))[:-1] | join('-') }}-{{ project }}.cloudfunctions.net/switch-route" | |
| def main(): | |
| """Main function""" | |
| logging.basicConfig(level=logging.INFO, format='%(asctime)s %(levelname)s %(message)s') | |
| logger = logging.getLogger(__name__) | |
| logger.addHandler(JournalHandler()) | |
| logger.info("Starting keepalived notification script") | |
| logger.debug("Arguments: %s", sys.argv) | |
| # https://github.com/acassen/keepalived/blob/ab91d7fe9430918371993dc6234be077915c879d/keepalived/vrrp/vrrp_notify.c#L166 | |
| # script {GROUP|INSTANCE} NAME {MASTER|BACKUP|FAULT|STOP|DELETED} PRIO | |
| if len(sys.argv) != 5: | |
| logger.error("Wrong number of arguments") | |
| return 1 | |
| if sys.argv[1] not in ["GROUP", "INSTANCE"]: | |
| logger.error("First argument must be GROUP or INSTANCE") | |
| return 1 | |
| # https://github.com/acassen/keepalived/blob/ab91d7fe9430918371993dc6234be077915c879d/keepalived/vrrp/vrrp_notify.c#L174 | |
| if sys.argv[3] not in ["MASTER", "BACKUP", "FAULT", "STOP", "DELETED"]: | |
| logger.error("Third argument must be MASTER, BACKUP, FAULT, STOP or DELETED") | |
| return 1 | |
| if sys.argv[3] == "MASTER": | |
| logger.info("Starting zabbix-proxy") | |
| r = subprocess.run(["/usr/bin/sudo", "systemctl", "start", "zabbix-proxy"]) | |
| if r.returncode != 0: | |
| logger.error("Error starting zabbix-proxy") | |
| logger.info("Calling cloud function") | |
| # Get the token. The request should add the header "Metadata-Flavor: Google". | |
| # The token should be passed as a bearer token in the Authorization header. | |
| # The audience should be the URL of the cloud function. | |
| req = urllib.request.Request("http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/identity?audience=" + FUNCTION_URL) | |
| req.add_header("Metadata-Flavor", "Google") | |
| # Capture if the request fails and return, logging the error and returning 1 | |
| try: | |
| token = urllib.request.urlopen(req).read().decode("utf-8") | |
| except urllib.error.HTTPError as err: | |
| logger.error("Error getting token: %s", err) | |
| return 1 | |
| logger.debug("Token: %s", token) | |
| # Set the target variable with the hostname of the current server | |
| target = os.uname()[1] | |
| req = urllib.request.Request(FUNCTION_URL + "?target=" + target) | |
| req.add_header("Authorization", "bearer " + token) | |
| try: | |
| urllib.request.urlopen(req) | |
| except urllib.error.HTTPError as err: | |
| logger.error("Error calling cloud function: %s", err) | |
| return 1 | |
| else: | |
| logger.info("Stopping zabbix-proxy") | |
| r = subprocess.run(["/usr/bin/sudo", "systemctl", "stop", "zabbix-proxy"]) | |
| if r.returncode != 0: | |
| logger.error("Error stopping zabbix-proxy") | |
| return 0 | |
| if __name__ == "__main__": | |
| sys.exit(main()) |
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