Azure: Where is default user/pass for Wordpress database using MySQL in-app(preview)?

The connection string can be seen in D:\home\data\mysql\MYSQLCONNSTR_localdb.txt. You can locate this file through Kudu Debug Console which could be accessed via https://<yourwebsitename>.scm.azurewebsites.net/DebugConsole.

The file content looks something like:

Database=localdb;Data Source=127.0.0.1:54306;User Id=azure;Password=6#vWHD_$

Following is a sample code snippet using PDO to connect MySQL in-app.

$dsn = 'mysql:dbname=localdb;host=127.0.0.1:54306;charset=utf8';
$user = 'azure';
$password = '6#vWHD_$';

try {
    $dbh = new PDO($dsn, $user, $password);
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
    exit;
}

echo "Success: A proper connection to MySQL was made!";

Important update:

From https://social.msdn.microsoft.com/Forums/azure/en-US/4c582216-bc1b-48b0-b80b-87ae540c3d05/php-azure-mysql-inapp-changed-ports-randomly

A VM can host multiple WebApps; hence multiple in-app MySQL processes. When we start MySql process, we attempt to use the same port as before. However, it may be taken by other service or other in-app MySQL. As a result, the port may change. In addition, web app can be moved from one VM to another and the set of available ports will be different.

In order to write the stable client app, do make sure you read the connection info from env variable. See this for more details.

So we should get the connection string from env variable in PHP like below:

$connectstr_dbhost = '';
$connectstr_dbname = '';
$connectstr_dbusername = '';
$connectstr_dbpassword = '';

foreach ($_SERVER as $key => $value) {
    if (strpos($key, "MYSQLCONNSTR_localdb") !== 0) {
        continue;
    }
    
    $connectstr_dbhost = preg_replace("/^.*Data Source=(.+?);.*$/", "\\1", $value);
    $connectstr_dbname = preg_replace("/^.*Database=(.+?);.*$/", "\\1", $value);
    $connectstr_dbusername = preg_replace("/^.*User Id=(.+?);.*$/", "\\1", $value);
    $connectstr_dbpassword = preg_replace("/^.*Password=(.+?)$/", "\\1", $value);
}