Error while executing mysql commands inside docker-compose - mysql

Question

When I execute the xdcomp_my_sql_client command it pings the ip but then when it tries to reach the mysql server it fails. If I do the exact same command once the container is running it works. It seems that the mysql server is not running at the moment the command is executed. But I have used the "depends_on" command, so what I'm doing wrong?
Thank you.
version: '2'
services:
xdcomp_my_sql_server:
image: mysql/mysql-server:latest
environment:
MYSQL_ROOT_PASSWORD: diego
MYSQL_USER: otro
MYSQL_PASSWORD: otro
MYSQL_ROOT_HOST: 172.28.0.101
networks:
SQLNetwork:
ipv4_address: 172.28.0.102
xdcomp_my_sql_client:
build: .
command: sh -c 'ping -c 5 172.28.0.102 && mysql -h 172.28.0.102 -u root -pdiego sys < /lafayette/forensic.sql && tail -f /etc/hostname'
ports:
- 83:80
networks:
SQLNetwork:
ipv4_address: 172.28.0.101
depends_on:
- xdcomp_my_sql_server
networks:
SQLNetwork:
driver: "bridge"
ipam:
config:
- subnet: 172.28.0.0/24
gateway: 172.28.0.201
Client Dockerfile
FROM ubuntu:16.04
RUN apt-get update
RUN apt-get install -y mysql-client
RUN apt-get install -y git
RUN git clone https://github.com/linkedin/lafayette
RUN apt-get update
RUN apt-get install -y python-dnspython
RUN apt-get install -y python-pip
RUN pip install Flask
RUN pip install python-dateutil
RUN apt-get install -y python-mysqldb
RUN pip install requests
RUN pip install multiprocessing
RUN pip install multiprocess
RUN apt-get install -y vim
RUN apt-get -y install iputils-ping

Answer 1

Working with docker includes 2 steps:
building a image
creating container based on image and running this container
The point is you mysql client can connect to server only on second step.
Dockerfile "executes" while you build image. In this time you don't have any containers, therefore you can`t connect to them.
You need move command
RUN cd lafayette && mysql –h 172.25.0.102 –u root –ppass sys < forensic.sql
from Dockerfile to entrypoint.sh
Can you show me your Dockerfile? I will try to fix the issue

Answer 2

The problem was the following: the mysql server was not running at the time the client command was executed. Even when the key "depends_on" was present (see:https://docs.docker.com/compose/startup-order/) For that reason the solution was to wait for the mysql server. This was done with the following command:
command: sh -c 'until nc -z -v -w20 172.28.0.102 3306; do sleep 1;
echo "Waiting for mysqlserver to come up..."; done && ping -c 5 172.28.0.102 &&
mysql -h 172.28.0.102 -u root -pdiego sys < /lafayette/forensic.sql &&
tail -f /etc/hostname'
The wait for was made by the following line:
until nc -z -v -w20 172.28.0.102 3306; do sleep 1;
echo "Waiting for mysqlserver to come up..."; done
nc= netcat command, it check the connection to a given ip and port