doc/packaging_apps.md

App packaging

There are few things you need to know if you want to package an application for YunoHost.

Content

A YunoHost package is composed of:

• A JSON file manifest.json
• A scripts directory, which contains the install, remove and upgrade scripts
• Optional other directories, like sources or conf if you need them

An example package is available here: https://github.com/opi/example_ynh, feel free to use it as a framework.

Manifest

The manifest.json file defines the app's constants, a bunch of values that YunoHost needs to identify the app and install it correctly. It looks like this :

{
    "name": "Roundcube",
    "id": "roundcube",
    "description": {
        "en": "Open Source Webmail software",
        "fr": "Webmail Open Source"
    },
    "license": "GPL-3",
    "developer": {
        "name": "kload",
        "email": "kload@kload.fr",
        "url": "http://kload.fr"
    },
    "multi_instance": "true",
    "arguments": {
        "install" : [
            {
                "name": "domain",
                "ask": {
                    "en": "Choose a domain for Roundcube"
                },
                "example": "domain.org"
            },
            {
                "name": "path",
                "ask": {
                    "en": "Choose a path for Roundcube"
                },
                "example": "/webmail",
                "default": "/webmail"
            }
        ]
    }
}

• name: The name of the app. It does not have to be unique, but it should be, since it is the name shown to all the YunoHost administrators in the app list.

• id: The unique ID of the app. You have to ensure that this ID is unique before submit an app integration request.

• description: The complete description of the app. You can make it as detailed as you feel it should be. Only en is required right now, but you can translate the description by prepending the locale prefix.

• license: The license under which the app is distributed. Please use the short name of the license, e.g. GPL-3 for the GNU General Public License v3. You can find a list of standard abbreviations here: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/#license-short-name

• developer: Some information about the app maintainer (you!).

• multi_instance: This defines your app's ability to be installed multiple times. When YunoHost tries to install a second instance of your app, it will replace the id in your scripts by an id__2. It means that, if you want to be multi_instance, you have to put all the identifiers in the scripts.
  
  E.g. In my roundcube script, I have to call my database roundcube, my install directory roundcube and my nginx configuration roundcube. This way, the second instance of roundcube will not conflict, and will be installed in the roundcube__2 database, in the roundcube__2directory, and with the roundcube__2 nginx configuration.

• arguments: The settings for the YunoHost's administrator to enter at installation. You have to set a name (for argument identification), and a question in ask (at least in en) that you can translate like the description above. You can also set a default value and an example to help administrator to fill the input.

Scripts

For now, a YunoHost package must contain 3 bash scripts: install, remove, and upgrade. These scripts will be executed as admin on the YunoHost instances.

Here is an example:

# Retrieve arguments
domain=$1
path=$2

# Check domain/path availability
sudo yunohost app checkurl $domain$path -a roundcube
if [[ ! $? -eq 0 ]]; then
    exit 1
fi

# Generate random DES key & password
deskey=$(dd if=/dev/urandom bs=1 count=200 2> /dev/null | tr -c -d '[A-Za-z0-9]' | sed -n 's/\(.\{24\}\).*/\1/p')
db_pwd=$(dd if=/dev/urandom bs=1 count=200 2> /dev/null | tr -c -d '[A-Za-z0-9]' | sed -n 's/\(.\{24\}\).*/\1/p')

# Use 'roundcube' as database name and user
db_user=roundcube

# Initialize database and store mysql password for upgrade
sudo yunohost app initdb $db_user -p $db_pwd -s $(readlink -e ../sources/SQL/mysql.initial.sql)
sudo yunohost app setting roundcube mysqlpwd -v $db_pwd

# Copy files to the right place
final_path=/var/www/roundcube
sudo mkdir -p $final_path
sudo cp -a ../sources/* $final_path
sudo cp ../conf/main.inc.php $final_path/config/
sudo cp ../conf/db.inc.php $final_path/config/
sudo mv $final_path/plugins/managesieve/config.inc.php.dist $final_path/plugins/managesieve/config.inc.php

# Change variables in Roundcube configuration
sudo sed -i "s/rcmail-ynhDESkeyTOchange/$deskey/g" $final_path/config/main.inc.php
sudo sed -i "s/yunouser/$db_user/g" $final_path/config/db.inc.php
sudo sed -i "s/yunopass/$db_pwd/g" $final_path/config/db.inc.php
sudo sed -i "s/yunobase/$db_user/g" $final_path/config/db.inc.php

# Set permissions to roundcube directory
sudo chown -R www-data: $final_path

# Modify Nginx configuration file and copy it to Nginx conf directory
sed -i "s@PATHTOCHANGE@$path@g" ../conf/nginx.conf
sed -i "s@ALIASTOCHANGE@$final_path/@g" ../conf/nginx.conf
sudo cp ../conf/nginx.conf /etc/nginx/conf.d/$domain.d/roundcube.conf

# Reload nginx and regenerate SSOwat conf
sudo service nginx reload
sudo yunohost app ssowatconf

Usage

You have to put everything in the script in order for the app to install without issue. It means that you have to install dependencies, create required repositories, initialize potential databases, copy sources and configure everything in the single install script (and of course do the reverse process in the remove script).

Be careful: For security reasons, the script is executed as the admin user in YunoHost. Be sure to test it as admin and prepend sudo to commands that require it.

Architecture and arguments

Since YunoHost has a unified architecture, you will be able to guess most of the settings you need. But if you need variable ones, like the domain or web path, you will have to ask the administrator at installation (see arguments section in the manifest above).

Note: The arguments will be passed in the order that they appear in the manifest. For example for roundcube, the domain argument will be referenced as $1 in the script, and path as $2.

Hooks

YunoHost provides a hook system, which is accessible via the packager's script callbacks in moulinette (CLI). The scripts have to be placed in the hooks repository at the root of the YunoHost package, and must be named priority-hook_name, for example: hooks/50-post_user_create will be executed after each user creation.

Note: priority is optional, default is 50.

Take a look at the ownCloud package for a working example.

Helpers

The CLI moulinette provides a few tools to make the packager's work easier:

sudo yunohost app checkport <port>

This helper checks the port and returns an error if the port is already in use.

sudo yunohost app setting <id> <key> [ -v <value> ]

This is the most important helper of YunoHost. It allows you to store some settings for a specific app, in order to be either reused afterward or used for YunoHost configuration (**e.g.** for the SSO).

It sets the value if you append ```-v ```, and gets it otherwise.

sudo yunohost app checkurl <domain><path> -a <id>

This helper is useful for web apps and allows you to be sure that the web path is not taken by another app. If not, it "reserves" the path.

**Note**: Do not prepend `http://` or `https://` to the ``.

sudo yunohost app initdb <db_user> [ -p <db_pwd> ] [ -s <SQL_file> ]

This helper creates a MySQL database. If you do not append a password, it generates one and returns it. If you append a SQL file, it initializes your database with the SQL statements inside.

sudo yunohost app ssowatconf

This helper reloads the SSO configuration. You have to call it at the end of the script when you are packaging a web app.

Test it!

In order to test your package, you can execute your script standalone as admin (do not forget to append required arguments):

su - admin -c "/bin/bash /path/to/my/script my_arg1 my_arg2"

Or you can use moulinette:

yunohost app install /path/to/my/app/package

Note that it also works with a Git URL:

yunohost app install https://github.com/author/my_app_package.git