Docker Container Connecting To Host MySQL - php

Question

I was following along a docker tutorial that used a container for MySQL. That worked, but I am trying to connect to my host's MySQL from a php/apache container.
I created a database called 'weather', a user 'admin'#'%' and granted the user all privileges to the weather database. I also created the necessary table/columns.
However, I keep getting the following message:
Warning: mysqli::__construct(): (HY000/2002): Connection refused in /var/www/html/index.php on line 15
Failed to connect to MySQL: Connection refused
Here's where the php app inside the container fails the connection:
<?php require 'vendor/autoload.php';
// Create a new Container
$container = new \Slim\Container([
// Add Guzzle as 'http'
'http' => function () {
return new GuzzleHttp\Client();
},
// Add mysqli as 'mysql'
'mysql' => function () {
$mysqli = new mysqli(
getenv('DATABASE_HOST'),
getenv('DATABASE_USER'),
getenv('DATABASE_PASSWORD'),
getenv('DATABASE_NAME')
);
if ($mysqli->connect_errno) {
echo "Failed to connect to MySQL: " . $mysqli->connect_error;
exit;
} else {
return $mysqli;
}
},
]);
I installed all the dependencies with composer and bound my host's ip address (172.17.0.1) in my.cnf. Here's the docker command I'm running:
docker run -d --rm --name=weather-app -p 38000:80 -v \
$(pwd):/var/www/html \
-e DATABASE_HOST='172.17.0.1' \
-e DATABASE_USER='admin' \
-e DATABASE_PASSWORD='password' \
-e DATABASE_NAME='weather' \
shiphp/weather-app
Here's the git repo if more info is needed: https://github.com/shiphp/weather-app.
Thanks in advance.
EDIT:
I figured out what's going on. I forgot to add the [mysqld] header in my.cnf when I bound the address. It works now.