Make two containers interact using Docker Compose.
In our last lab, we created a database container that our website could use.
Let’s modify our website to query the database. Edit index.html as below. If
you don’t completely understand all the code, don’t worry! We’re focusing on
Docker here, not PHP. The important thing to understand is that PHP code running
in our web container (PHP/Apache) is going to run a query against the SQL
database running in our db container by connecting to it at the hostname db.
index.php
<html>
<h1>My Website</h1>
<p>This web site is being served from inside a Docker container!</p>
<?php
$today = date("D M j G:i:s T Y");
print "<p>The current date is $today.</p>";
?>
<hr />
<h2>Students</h2>
<?php
$dbHost = 'db';
$dbUser = 'my_user';
$dbPass = 'password';
$dbName = 'SCHOOL';
$pdo = new PDO("mysql:host=$dbHost;dbname=$dbName", $dbUser, $dbPass);
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$results = $pdo->query('SELECT name, nickname FROM STUDENTS WHERE id < 4');
$row = $results->fetch(PDO::FETCH_ASSOC);
while($row !== false) {
print "<p>{$row['name']} goes by {$row['nickname']}.</p>\n";
$row = $results->fetch(PDO::FETCH_ASSOC);
}
?>
</html>
Cool! Our website is going to query a database, and it’s all happening in Docker!
Wait a minute… If you try to visit the website at
http://localhost, you’ll see an error message. Fatal error:
Uncaught PDOException: could not find driver in /var/www/html/index.php:13.
That’s not good. As it turns out, we’re missing the pdo_mysql PHP module in
our PHP container. In the next lab, we’ll learn how to fix that.