无法使用PHP从主机登录Docker MySQL

Question

I wish to run PHP code on the host machine which makes a connection to a MySQL (containerized using Docker) database. But I am getting the following error:

Connection failed: MySQL server has gone away

On the host machine(Ubuntu 18.04 LTS) I have the following software installed:

PHP 7.2.10 (Non-Docker)
MySQL 8.0.13 (Docker)
Apache 2.5.29 (Non-Docker)

I am using the following connection string in the program on the host machine:

<?php
 $connection=mysqli_connect('127.0.0.1','vernemq','xyzw','some_db');
 if (!$connection) {
 die("Connection failed: " . mysqli_connect_error());
}
?>

Note: The above program is written in a PHP file which is located in directory /var/www/html

For understanding let's say the host machine has the IP address 172.10.10.15.

When running this same program with a LAMPP server on a different machine (IP address: 172.10.10.16) on the same network as that of the host, I am able to connect to the MySQL server. I am running the following modified program on the different machine:

<?php
 $connection=mysqli_connect('172.10.10.15','vernemq','xyzw','some_db');
 if (!$connection) {
 die("Connection failed: " . mysqli_connect_error());
}
?>

I am even able to connect to the Dockerized MySQL server on the host machine by running the following command on the command prompt of the host machine:

$mysql -h 127.0.0.1 -u vernemq -p

Running the following command from the MySQL prompt returns the following:

mysql> SELECT user, host FROM mysql.user
    -> ;
+------------------+-----------+
| user             | host      |
+------------------+-----------+
| root             | %         |
| vernemq          | %         |
| mysql.infoschema | localhost |
| mysql.session    | localhost |
| mysql.sys        | localhost |
| root             | localhost |
| vernemq          | localhost |
+------------------+-----------+

Any pointer on what could be wrong?

Update 04/01/2019 I noted following things

When I ran the db connection file from the command line, I got the following error.

Getting following error when running the php file from the command prompt
PHP Warning:  mysqli_connect(): Unexpected server respose while doing caching_sha2 auth: 109 in /var/www/html/db.php on line 2
PHP Warning:  mysqli_connect(): MySQL server has gone away in /var/www/html/db.php on line 2
PHP Warning:  mysqli_connect(): (HY000/2006): MySQL server has gone away in /var/www/html/db.php on line 2
Connection failed: MySQL server has gone away

For this I changed the User authentication method from mysql_native to caching_sha2 with following command

ALTER USER 'vernemq' IDENTIFIED WITH caching_sha2_password BY 'vernemq';

And it started working.

But I don't want to use caching_sha2 authentication because it breaks another programs that were working with native_mysql authentication method. What is the way out?

Answer 1

Probably you're running on Mac OS and Docker for Mac doesn't provide the docker0 interface, so you need to create a network alias:

sudo sudo ifconfig lo0 alias 10.10.0.10/24

After that try to use the connection string 10.10.0.10:3306 , it should work.