135 lines
4.3 KiB
Python
135 lines
4.3 KiB
Python
#!/usr/bin/env python
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# coding=utf-8
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# (C) Copyright 2018 FUJITSU LIMITED
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Health check for MySQL returns 0 when all checks works properly.
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It's checking if requested database already exists.
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For using this script you need to set some environment variables:
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* `MYSQL_HOST` for connection string to MySQL.
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Example: `mysql`, `192.168.10.6`.
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Default: `mysql`.
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* `MYSQL_PORT` for connection string to MySQL port.
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Default: `3306`.
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* `MYSQL_USER` for user that is cappable to connect to MySQL.
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Default: `monapi`.
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* `MYSQL_PASSWORD` for user password.
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Default: `password`.
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* `MYSQL_DB` for database that you need to have before starting service.
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Default: `mon`.
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After making sure that this environment variables are set you can simply
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execute this script in the following way:
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`python3 mysql_check.py && ./start_service.sh`
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`python3 mysql_check.py || exit 1`
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Additional environment variables available are:
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* `LOG_LEVEL` - default to `INFO`
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* `MYSQL_WAIT_RETRIES` - number of retries, default to `24`
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* `MYSQL_WAIT_INTERVAL` - in seconds, default to `5`
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"""
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import logging
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import os
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import sys
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import time
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import pymysql
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# Run this script only with Python 3
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if sys.version_info.major != 3:
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sys.stdout.write("Sorry, requires Python 3.x\n")
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sys.exit(1)
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logLevelEnv = os.environ.get('LOG_LEVEL', 'INFO')
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LOG_LEVEL = logging.getLevelName(logLevelEnv.upper())
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logging.basicConfig(level=LOG_LEVEL)
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logger = logging.getLogger(__name__)
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MYSQL_HOST = os.environ.get('MYSQL_HOST', 'mysql')
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MYSQL_PORT = int(os.environ.get('MYSQL_PORT', 3306))
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MYSQL_USER = os.environ.get('MYSQL_USER', 'monapi')
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MYSQL_PASSWORD = os.environ.get('MYSQL_PASSWORD', 'password')
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MYSQL_DB = os.environ.get('MYSQL_DB', 'mon')
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MYSQL_WAIT_RETRIES = int(os.environ.get('MYSQL_WAIT_RETRIES', '24'))
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MYSQL_WAIT_INTERVAL = int(os.environ.get('MYSQL_WAIT_INTERVAL', '5'))
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def retry(retries=MYSQL_WAIT_RETRIES, delay=MYSQL_WAIT_INTERVAL,
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check_exceptions=()):
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"""Retry decorator."""
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def decorator(func):
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"""Decorator."""
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def f_retry(*args, **kwargs):
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"""Retry running function on exception after delay."""
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for i in range(1, retries + 1):
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try:
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return func(*args, **kwargs)
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# pylint: disable=W0703
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# We want to catch all exceptions here to retry.
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except check_exceptions + (Exception,) as exc:
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if i < retries:
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logger.info('Connection attempt %d of %d failed',
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i, retries)
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if isinstance(exc, check_exceptions):
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logger.debug('Caught known exception, retrying...',
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exc_info=True)
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else:
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logger.warn(
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'Caught unknown exception, retrying...',
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exc_info=True)
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else:
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logger.exception('Failed after %d attempts', retries)
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raise
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# No exception so wait before retrying
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time.sleep(delay)
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return f_retry
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return decorator
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@retry(check_exceptions=(pymysql.err.OperationalError,))
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def connect_mysql(host, port, user, password, database):
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"""Connect to MySQL with retries."""
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return pymysql.connect(
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host=host, port=port,
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user=user, passwd=password,
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db=database
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)
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def main():
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"""Start main part of the wait script."""
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logger.info('Waiting for database: `%s`', MYSQL_DB)
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connect_mysql(
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host=MYSQL_HOST, port=MYSQL_PORT,
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user=MYSQL_USER, password=MYSQL_PASSWORD,
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database=MYSQL_DB
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)
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logger.info('Database `%s` found', MYSQL_DB)
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if __name__ == '__main__':
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main()
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