wait-mysql

#!/usr/bin/env bash
# wait-mysql
#
# @author Jon Pugh
#
# Uses the wait-for command to pause execution until an SQL connection is active.
#
# Use Environment variables for options:
#
# DATABASE_HOST: The host to connect to. Passed to --host
# MYSQL_ROOT_USER: The user to connect with. Passed to --user Default: root
# COMMAND: The command to use instead of the default.
#
# See ./bin/wait-for for more environment variables to use.
#

# Document usage
usage() {
  cat <<<EOF
Usage:
  wait-mysql

    Continously check for access to database server return once connected.

EOF
}

# Set Environment
set -e
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
PATH="$DIR:$PATH"

# Prepare arguments and options.
MYSQL_ROOT_USER=${MYSQL_ROOT_USER:-root}

# Returns true once mysql can connect.
# Thanks to http://askubuntu.com/questions/697798/shell-script-how-to-run-script-after-mysql-is-ready
# Set SILENT=1 to tell `wait-for` script not to print the command.
COMMAND=${COMMAND:-"mysqladmin ping --host=$DATABASE_HOST --user=$MYSQL_ROOT_USER --password=$MYSQL_ROOT_PASSWORD"}

# Check for required variables
if [ -z "${DATABASE_HOST}" ]; then
  echo "No DATABASE_HOST variable found. Unable to check for database."
  exit 1
fi
if [ -z "${MYSQL_ROOT_PASSWORD}" ]; then
  echo "No MYSQL_ROOT_PASSWORD variable found. Unable to check for database."
  exit 1
fi

echo "Waiting for access to database server $MYSQL_ROOT_USER@$DATABASE_HOST ..."

# Set SILENT=1 to tell `wait-for` script not to print the command.
# DO NOT CHANGE unless you want to expose MYSQL_ROOT_PASSWORD in your echos.
export SILENT=1
wait-for $COMMAND && \
  echo "Database connected and accessible!" || \
  exit 1