# | Introduction to docker (2) |


[TOC]

## II. Linking containers

### 1)





## III. Setting up a development stack



### 1) Choosing images



We will setup a simple web dev stack with :

- nginx (_i.e. nginx:latest_)
- mariadb (_i.e. mariadb:latest_)
- php-fpm (_i.e. php:7-fpm_)



### 2) Volume & network sharing policy



#### 1. Volume sharing



###### 	a) Configuration files

The **apache** and **php** configuration will be on the host machine (for easy modification) and only mounted on the containers to override the default configuration files. A [virtual](./virtual) folder will hold these configurations with the same path for consistency:
- the nginx configuration file is located at [virtual/etc/nginx/nginx.conf](./virtual/etc/nginx/nginx.conf).
- the php-fpm configuration file is located at [virtual/usr/local/etc/php-fpm.d/www.conf](./virtual/usr/local/etc/php-fpm.d/www.conf).



###### 	b) Storage files

MariaDB will have its whole data folder (_i.e. `/var/lib/mysql`_) on the host in the _virtual_ folder to have the data remaining throughout containers. This property makes the database consistent and persistent among container creation/deletion.

> In a real-world environment, we would not store the whole data folder (in fact it would be in the _.gitignore_), but we would add a script to dump a SQL file into the database when using the environment for the first time :
>
> ```bash
> cat backup.sql | docker exec -i mariadb mysql -uroot -p<password>
> ```
>
> Then, the volumes would be shared and persistent on the host.



###### 	c) Log files

Also logs will be mounted the same way in order for developers to easily check these out when needed (_e.g. `virtual/var/log/apache2/access.log`_). Also, note that even if the container is removed, the logs will remain.



######  d) Development folder

The development folder (_i.e. the actual code to test_) is located in the folder [virtual/vhost](./virtual/vhost). In a real-world use of this configuration, I would clone a git repository into it in order for my docker configuration and my actual code not to mix together ; we could then use _git submodules_ for version stability among the 2 repositories.



#### 2. Network sharing



###### a) Ports and network

The whole system will only expose its port `8080` ;

> We do not use the default HTTP port not to break a possible web server on the host.

Containers between them will be connected through the `privnet` network which is also reachable from the host ; except for the port 8080.



###### b) DNS

The `nginx` container is configured to only accept the host `somedomain.io`, it corresponds to the DNS record chosen for the production server. This domain must be added into the `/etc/hosts` file of each developer in order for them to access the web server at `somedomain.io:8080`.



###### c) Production deployment

If the project is pushed into a production server, if you have no other program occupying the port `80`, you can just replace the port binding `8080:80` in `docker-compose.yml`. If it is already taken by apache/nginx, you will have to create an entry in your web server to forward your requests from your address (_i.e. domain.com_) to the specific port 8080 (_c.f. [reverse proxy](https://en.wikipedia.org/wiki/Reverse_proxy)_).