Waiting for MySQL to come up before talking to it

[bentcoder]

Hi,

This line prevents my custom /docker-entrypoint-initdb.d/init.sh from being run after container built. I need a way to run this script without removing the content of the data dir. What's the workaround for this issue? I don't want to send any request from other containers to MySQL container if it is not ready.

Thanks

Dockerfile

FROM mysql:5.7.24

COPY init.sh /docker-entrypoint-initdb.d/init.sh
RUN chmod +x /docker-entrypoint-initdb.d/init.sh

/docker-entrypoint-initdb.d/init.sh

#!/bin/sh
set -e

echo "Check DB!"
while ! MYSQL_PWD=custom_password mysqladmin -u custom_user ping -h localhost; do
    echo "Wait ..."
    sleep 1
done
echo "DB ready!"

[wglambert]

Well the file runs fine, and then exits. Are you wanting this to replicate healthcheck behavior?

Your init.sh is run at the end of the entrypoint script

mysql/5.7/docker-entrypoint.sh

Lines 195 to 197 in bb7ea52

	for f in /docker-entrypoint-initdb.d/*; do
	process_init_file "$f" "${mysql[@]}"
	done

$ docker run -d --rm --name mysql -e MYSQL_ROOT_PASSWORD="custom_password" -e MYSQL_USER="custom_user" -e MYSQL_PASSWORD="custom_password" mysql:test
5084a5828e759c757ef583cb70418bb8e2498843c0918539e46ebe0bec972d04

$ docker logs -f mysql 2>/dev/null
Initializing database
Database initialized
Initializing certificates
Certificates initialized
MySQL init process in progress...

/usr/local/bin/docker-entrypoint.sh: running /docker-entrypoint-initdb.d/init.sh
Check DB!
mysqld is alive
DB ready!


MySQL init process done. Ready for start up.

Filtering stderr will show your script's output above, you can also docker exec it at will

$ docker exec mysql /docker-entrypoint-initdb.d/init.sh
Check DB!
mysqld is alive
DB ready!

[bentcoder]

You are right. I actually had to remove all containers and rebuild them which outputs:

mysql_1  | Check DB!
mysql_1  | mysqladmin: [Warning] Using a password on the command line interface can be insecure.
mysql_1  | mysqld is alive
mysql_1  | DB ready!

Last question, how do I manually force it to delay so that the output is, e.g.:

mysql_1  | Check DB!
mysql_1  | Wait ...
mysql_1  | Wait ...
mysql_1  | DB ready!

Thanks?

This is the updated content:

echo "Check DB!"
while ! mysqladmin ping -h localhost -u ${MYSQL_USER} -p${MYSQL_PASSWORD}; do
    echo "Wait ..."
    sleep 1
done
echo "DB ready!"

[tianon]

Not sure why you'd want to force MySQL to wait longer before it starts listening externally for connections, but you should be able to just add a sleep 1 or sleep 2 in your script there if that's what you're looking for.

In the future, these sorts of questions/requests would be more appropriately posted to the Docker Community Forums, the Docker Community Slack, or Stack Overflow.

[vaibhavpandeyvpz]

Since I could not install mysqladmin on the remote machine, I used below:

while ! docker-compose logs mysql | grep "ready for connections"; do
  echo "Waiting for initdb to complete..."
  sleep 1
done