devilbox/docs/Technical.md

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Technical

1. Networking
2. Ports and forwarding
3. PHP Container
4. Docker Host
5. Works the same on Host and PHP Container

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1. Networking

It is best to use the hostnames and not to rely on the ip addresses as they might change. In most cases however you can use 127.0.0.1 for all connections. Read up to find out why.

E.g.: When you want to setup a MySQL database connection use mysql or 127.0.0.1 as the hostname.

Container	Container name	Hostname	IP Address
DNS	bind	bind	172.16.238.100
PHP / HHVM	php	php	172.16.238.10
Apache / Nginx	http	http	172.16.238.11
MySQL / MariaDB	mysql	mysql	172.16.238.12
PostgreSQL	pgsql	pgsql	172.16.238.13
Redis	redis	redis	172.16.238.14
Memcached	memcd	memcd	172.16.238.15
MongoDB	mongo	mongo	172.16.238.16

2. Ports and forwarding

2.1 PHP Container

The php container is the center of all container. Everything happens in there. This is also the reason it does some more magic than actually required.

Remote ports and remote sockets are made available to the php container.

The PHP container is using socat to

1. forward the remote mysql port 3306 (on the mysql container) to its own 127.0.0.1:3306
2. forward the remote pgsql port 5432 (on the pgsql container) to its own 127.0.0.1:5432
3. forward the remote redis port 6379 (on the redis container) to its own 127.0.0.1:6379
4. forward the remote memcached port 11211 (on the memcd container) to its own 127.0.0.1:11211
5. forward the remote mongodb port 27017 (on the mongo container) to its own 127.0.0.1:27017

The following container can be reached from within the PHP container via the following methods:

Container	Hostname	IP Address	IP Address	Port
DNS	bind	172.16.238.100	-	53
PHP / HHVM	php	172.16.238.10	-	9000
Apache / Nginx	http	172.16.238.11	-	80
MySQL / MariaDB	mysql	172.16.238.12	127.0.0.1	3306
PostgreSQL	pgsql	172.16.238.13	127.0.0.1	5432
Redis	redis	172.16.238.14	127.0.0.1	6379
Memcached	memcd	172.16.238.15	127.0.0.1	11211
MongoDB	mongo	172.16.238.16	127.0.0.1	27017

2.2 Docker Host

The docker host (your computer) does exactly the same as the php container.

1. container mysql port 3306 is exposed to the host on port 127.0.0.1:3306
2. container pgsql port 5432 is exposed to the host on port 127.0.0.1:5432
3. container redis port 6379 is exposed to the host on port 127.0.0.1:6379
4. container memcd port 11211 is exposed to the host on port 127.0.0.1:11211
5. container mongo port 27017 is exposed to the host on port 127.0.0.1:27017

The following container can be reached from the Docker host via the following methods:

Container	IP Address	Port
DNS	127.0.0.1	53
PHP / HHVM	-	9000
Apache / Nginx	127.0.0.1	80
MySQL / MariaDB	127.0.0.1	3306
PostgreSQL	127.0.0.1	5432
Redis	127.0.0.1	6379
Memcached	127.0.0.1	11211
MongoDB	127.0.0.1	27017

3. Works the same on Host and PHP Container

As you might have noticed, the ports and addresses will be exactly the same inside the PHP container and on the docker host (when using 127.0.0.1) for most container. That way it is possible to write your php application like this:

<?php
mysql_connect('127.0.0.1', 'user', 'pass');