django cannot connect mysql in docker-compose - mysql

Question

I'm very new for docker, now I am trying to run django with mariadb in docker through docker-compose, but I always get this error:
I use Docker version 17.09.1-ce, build 19e2cf6, docker-compose version 1.18.0, build 8dd22a9
django.db.utils.OperationalError: (2003, 'Can\'t connect to MySQL
server on \'mariadb55\' (111 "Connection refused")')
I can connect db correctly after run docker-compose up db in local or remote, and I even can run python manage.py runserver 0.0.0.0:6001 correctly in anaconda virtual environment to connect db service in docker by setting parameters of settings.py file like below:
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.mysql',
'NAME': 'test',
'USER': 'belter',
# 'HOST': 'mariadb55',
'HOST': '127.0.0.1',
'PORT': '3302',
'PASSWORD': 'belter_2017',
'default-character-set': 'utf8',
'OPTIONS': {
'sql_mode': 'traditional',
}
}
}
This is my docker-compose.yml file
version: '3'
services:
db:
image: mariadb:5.5
restart: always
environment:
- MYSQL_HOST=localhost
- MYSQL_PORT=3306
- MYSQL_ROOT_HOST=%
- MYSQL_DATABASE=test
- MYSQL_USER=belter
- MYSQL_PASSWORD=belter_2017
- MYSQL_ROOT_PASSWORD=123456_abc
volumes:
- /home/belter/mdbdata/mdb55:/var/lib/mysql
ports:
- "3302:3306"
web:
image: onlybelter/django_py35
command: python3 manage.py runserver 0.0.0.0:6001
volumes:
- /mnt/data/www/mysite:/djcode
ports:
- "6001:6001"
depends_on:
- db
links:
- db:mariadb55
I almost tried everything I can find, but still cannot figure it out, any help would be nice!
What I have tried:
Docker compose mysql connection failing
Linking django and mysql containers using docker-compose
Django connection to postgres by docker-compose

Answer 1

Finally, I figured it out!
The key point is, just as #SangminKim said, I need to use 3306 not 3302 in settings.py, and use db as HOST not 127.0.0.1.
So this is my docker-compose.yml file now:
version: '3'
services:
db:
image: mariadb:5.5
restart: always
environment:
- MYSQL_HOST=localhost
- MYSQL_PORT=3306 # cannot change this port to other number
- MYSQL_ROOT_HOST=%
- MYSQL_DATABASE=test
- MYSQL_USER=belter
- MYSQL_PASSWORD=belter_2017
- MYSQL_ROOT_PASSWORD=123456_abc
volumes:
- /home/belter/mdbdata/mdb55:/var/lib/mysql
ports:
- "3302:3306"
web:
image: onlybelter/django_py35
command: python3 manage.py runserver 0.0.0.0:6001
volumes:
- .:/djcode
ports:
- "6001:6001"
depends_on:
- db
So now we can connect this docker-mysql by mysql -h 127.0.0.1 -P 3302 -u root -p in shell directly, but we have to use db and 3306 in django settings.py file:
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.mysql',
'NAME': 'test',
'USER': 'belter',
# 'HOST': 'mariadb55',
'HOST': 'db', #<---
'PORT': '3306', #<---
'PASSWORD': 'belter_2017',
'default-character-set': 'utf8',
'OPTIONS': {
'sql_mode': 'traditional',
}
}
}
And we can still check if this port is open, by running extra command in docker-compose.yml file:
...
web:
image: onlybelter/django_py35
command: /bin/sh -c "python check_db.py --service-name mysql --ip db --port 3306"
volumes:
- .:/djcode
...
Here is check_db.py file:
# check_db.py
import socket
import time
import argparse
""" Check if port is open, avoid docker-compose race condition """
parser = argparse.ArgumentParser(description='Check if port is open, avoid\
docker-compose race condition')
parser.add_argument('--service-name', required=True)
parser.add_argument('--ip', required=True)
parser.add_argument('--port', required=True)
args = parser.parse_args()
# Get arguments
service_name = str(args.service_name)
port = int(args.port)
ip = str(args.ip)
# Infinite loop
while True:
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
result = sock.connect_ex((ip, port))
if result == 0:
print("{0} port is open! Bye!".format(service_name))
break
else:
print("{0} port is not open! I'll check it soon!".format(service_name))
time.sleep(3)
By the way, this is my Dockerfile for build django-py35:
FROM python:3.5-alpine
MAINTAINER Xin Xiong "xiongxin20008#126.com"
ENV PYTHONUNBUFFERED 1
RUN set -e; \
apk add --no-cache --virtual .build-deps \
gcc \
libc-dev \
linux-headers \
mariadb-dev \
python3-dev \
postgresql-dev \
freetype-dev \
libpng-dev \
g++ \
;
RUN mkdir /djcode
WORKDIR /djcode
ENV REFRESHED_AT 2017-12-25
ADD requirements.txt /djcode/
RUN pip install --no-cache-dir -r /djcode/requirements.txt
RUN pip install uwsgi
ADD . /djcode/ # copy . to /djcode/
EXPOSE 6001
See more details from here: https://github.com/OnlyBelter/django-compose

Answer 2

You should use the container name instead of localhost (or 127.0.0.1) in your settings.py file. Try providing a container name to the db service in the docker-compose.yml file using container_name attribute and replace the host name in the settings.py by the value of the container_name. (Make sure that they are in the same network that docker compose creates for you.)

Answer 3

Build container with this:
docker run --name mysql-latest \
-p 3306:3306 -p 33060:33060 \
-e MYSQL_ROOT_HOST='%' -e MYSQL_ROOT_PASSWORD='strongpassword' \
-d mysql/mysql-server:latest
Make sure MYSQL_ROOT_HOST='%', that means root can connect from any IP.