connecting to a docker-compose mysql container denies access but docker running same image does not
<p>I am having some issues connecting to the mysql docker container that I have launched with docker-compose. This is a long post (sorry!).</p>

<p>Here is my docker-compose.yml file:</p>

<pre><code>db:
  image: mysql:5.7
  ports:
    - "3306:3306" # I have tried both ports and expose "3306". Still doesn't work 
  environment:
    - MYSQL_ROOT_PASSWORD="secret"
    - MYSQL_USER="django"
    - MYSQL_PASSWORD="secret"
    - MYSQL_DATABASE="myAppDB"
</code></pre>

<p>Then:</p>

<pre><code>$&gt; docker-compose build
db uses an image, skipping #expected!
$&gt; docker-compose up
&lt;&lt;LOTS OF OUTPUT&gt;&gt;
</code></pre>

<p>OK, so now I have an up and running docker container runner mysql:5.7. Great! Or is it?
When testing in my django app, I get Operational errors saying that the user isn't allowed to connect the database. Ok, so maybe it's my django then?</p>

<pre><code>$&gt; docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
c7216f99ca0f        mysql:5.7           "docker-entrypoint.sh"   3 minutes ago       Up 3 minutes        0.0.0.0:3306-&gt;3306/tcp   sharpfin_db_1

$&gt; docker-machine ip dev
192.168.99.100
$&gt; mysql -h 192.168.99.100 -P 3306 -u django -p
Enter password: 
ERROR 1045 (28000): Access denied for user 'django'@'192.168.99.1' (using password: YES)
</code></pre>

<p>ok so maybe It's something to do with connecting to the docker-compose container?
What if I try connecting from inside the docker container?</p>

<pre><code>$&gt; docker exec -it c7216f99ca0f /bin/bash
root@c7216f99ca0f:/#
root@c7216f99ca0f:/# mysql -u django -p                                                                                                                                                           
Enter password: 
ERROR 1045 (28000): Access denied for user 'django'@'localhost' (using password: YES)
</code></pre>

<p>ok, so docker mysql won't let me connect, don't know why. Let's see what happens when I try do this without docker-compose:</p>

<pre><code>$&gt; docker run --name run-mysql -e MYSQL_ROOT_PASSWORD="secret" -e MYSQL_USER="django" -e MYSQL_PASSWORD="secret" -e MYSQL_DATABASE="myAppDB" -p "3306:3306" mysql:5.7
&lt;&lt;LOTS OF OUTPUT SAME AS BEFORE&gt;&gt;
</code></pre>

<p>Ok, so now we have a container running the same image as before with the same settings. (I think this assertion is probably not true - docker-compose is doing something different to docker run).</p>

<pre><code>$&gt; docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
73071b929e82        mysql:5.7           "docker-entrypoint.sh"   3 minutes ago       Up 3 minutes        0.0.0.0:3306-&gt;3306/tcp   run-mysql
</code></pre>

<p>There's my container (called run-mysql). Let's connect!</p>

<pre><code>$&gt; mysql -h 192.168.99.100 -P 3306 -u django -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.12 MySQL Community Server (GPL)

Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql&gt; SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| myAppDB            |
+--------------------+
2 rows in set (0.01 sec)

mysql&gt;
</code></pre>

<p>Alright. Can log in. That's weird... What about from inside the container?</p>

<pre><code>$&gt; docker exec -it 73071b929e82 /bin/bash
root@73071b929e82:/# mysql -u django -p                                                                                                                                                           
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.12 MySQL Community Server (GPL)

Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql&gt; SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| myAppDB            |
+--------------------+
2 rows in set (0.00 sec)

mysql&gt; 
</code></pre>

<p>Ok, I can log in from outside and inside the container when I launch with docker run, but not with docker-compose. What's going on? There must be something either docker-compose is doing behind the scenes that changes how the database is initialized.</p>

<p>All the above is the exact same if I try with the root user as well. So it's not a permissions issue with the django user.</p>

<p>Any ideas how to resolve this?</p>