wait-for-mysql

wait-for-mysql.sh is a small script for check when DB is ready for queries. The main goal write this script was a usage mysql docker as a microservice for several other containers. When we have a cold start of mysql - it requires some time to be ready to do queries, but some services could run earlier and we would obtain 50* errors on server. To prevent it wrote this script for check when DB really ready for queries.

The script will finished when connection to DB will establish.

Requirements

You shuld have installed mysql console client on your server/container.

Ubuntu/Debian

$ sudo apt-get install mysql-client

Usage

First of all you should know all about parameters for console mysql client. For more details see here:

$ man mysql

wait-for-mysql.sh [--host=localhost] [-u root] [--wait-timeout=10] [--no-wait-log] [--wait-show-err]
    --wait-timeout=10           Timeout in seconds for loop repeating establish connection
    --no-wait-log               Do now show every timeout time log about another repeating to establish connection
    --wait-show-err             Enable to show stderr of mysql command

Examples

$ ./wait-for-mysql.sh -u root --host=mysqlhost -e exit --wait-timeout=5 && npm start

On this example we see that the npm start command will execute after mysql connection success.