Configure WSGI HTTP server for Python
=====================================

.. warning:: This section depends on how you set up previous instructions with
   installing flsk app from external repository.

Step 1 - Create custom recipe
-----------------------------

This WSGI HTTP server for python will be the base functionality of system so it
will be placed inside ``recipes-base`` folder.

.. code-block::

   mkdir -p ../meta-golemos/recipes-base/python3-gunicorn/files
   touch ../meta-golemos/recipes-base/python3-gunicorn/python3-gunicorn_%.bbappend


Inside created custom recipe place this instructions.

.. code-block::

   inherit allarch systemd

   FILESEXTRAPATHS_prepend := "${THISDIR}/files:"

   SRC_URI += " \
       file://datalogger_setup_page.service \
       file://datalogger_setup_page.socket \
   "

   SYSTEMD_AUTO_ENABLE = "enable"
   SYSTEMD_SERVICE__append = " datalogger_setup_page.service datalogger_setup_page.socket "

   FILES_${PN} += "${systemd_system_unitdir}"
   FILES_${PN} += "${systemd_system_unitdir}/datalogger_setup_page.service"
   FILES_${PN} += "${systemd_system_unitdir}/datalogger_setup_page.socket"

   do_install_append () {
       install -d ${D}/${systemd_system_unitdir}
       install -m 0644 ${WORKDIR}/datalogger_setup_page.s* ${D}/${systemd_system_unitdir}

       install -d ${D}${sysconfdir}/systemd/system/multi-user.target.wants/
       install -d ${D}${sysconfdir}/systemd/system/sockets.target.wants/

       ln -s ${systemd_system_unitdir}/datalogger_setup_page.socket ${D}${sysconfdir}/systemd/system/sockets.target.wants/datalogger_setup_page.socket
       ln -s ${systemd_system_unitdir}/datalogger_setup_page.service ${D}${sysconfdir}/systemd/system/multi-user.target.wants/datalogger_setup_page.service
   }


.. note:: This recipe depends on ``python3-gunicorn`` which is contained inside
   `meta-python`_ layer from `OpenEmbedded`_. Clone this layer and add to
   ``bblayers.conf`` in order to satisfy dependencies.

.. _meta-python: https://layers.openembedded.org/layerindex/branch/master/layer/meta-python/
.. _OpenEmbedded: https://www.openembedded.org/

Step 2 - Create service file
----------------------------

Previously created ``files`` folder are meant to store service file. It will
also store socket file, but about this in the next step.

Create service file

.. code-block::

   touch ../meta-golemos/recipes-base/python3-gunicorn/files/datalogger_setup_page.service

and place in it this content.

.. code-block::

   [Unit]
   Description=gunicorn daemon for datalogger_setup_page
   Requires=datalogger_setup_page.socket
   After=network.target

   [Service]
   Type=notify
   RuntimeDirectory=gunicorn
   WorkingDirectory=/var/www/datalogger-setup.local/
   ExecStart=/usr/bin/gunicorn wsgi
   ExecReload=/bin/kill -s HUP $MAINPID
   KillMode=mixed
   TimeoutStopSec=5
   PrivateTmp=true

   [Install]
   WantedBy=multi-user.target


.. warning:: This service file depends on where you place your python app, in
   this situation it is ``/var/www/datalogger-setup.local/``. It also requires
   that inside root folder there is wsgi file called ``wsgi.py``.

.. note:: This service file requires socket file, which will be created in the
   next step.

Step 3 - Create socket file
---------------------------

This gunicorn server will be listening on unix socket. To enable this, you have
to create file called ``datalogger_setup_page.socket``.

.. code-block::

   touch ../meta-golemos/recipes-base/python3-gunicorn/files/datalogger_setup_page.socket


Inside this file place such a configuration.

.. code-block::

   [Unit]
   Description=gunicorn socket for datalogger_setup_page

   [Socket]
   ListenStream=/run/datalogger_setup_page.sock
   SocketUser=www

   [Install]
   WantedBy=sockets.target


.. warning:: In next section you will find how to configure nginx web server.
   You have to find out which user nginx is using and if needed change them
   here.

Step 4 - Add packages
---------------------

To ensure that this recipe will take place add ``python3-gunicorn`` to your
python packages inside base package group.

Summary
-------

After all this steps your app should be exposed on 

.. code-block::

   http://unix:/run/datalogger_setup_page.sock


In next section you can find steps how to connect this to ``nginx`` web server
and expose this application to outside.

At the end your layer structure should look like this.

.. code-block::

   ../meta-golemos
   ├── COPYING.MIT
   ├── README
   ├── conf
   │   ├── bblayers.conf.sample
   │   ├── conf-notes.txt
   │   ├── distro
   │   │   └── golemos.conf
   │   ├── layer.conf
   │   └── local.conf.sample
   ├── recipes-base
   │   ├── datalogger-setup-page
   │   │   └── datalogger-setup-page.bb
   │   └── python3-gunicorn
   │       ├── files
   │       │   ├── datalogger_setup_page.service
   │       │   └── datalogger_setup_page.socket
   │       └── python3-gunicorn_%.bbappend
   ├── recipes-connectivity
   │   ├── hostapd
   │   │   ├── files
   │   │   │   ├── hostapd@.service
   │   │   │   └── wlan0.conf
   │   │   └── hostapd_%.bbappend
   │   ├── kea
   │   │   ├── files
   │   │   │   ├── kea-dhcp4.conf
   │   │   │   └── kea-dhcp4.service
   │   │   └── kea_%.bbappend
   │   └── wpa-supplicant
   │       ├── files
   │       │   └── wpa_supplicant-nl80211-wlan0.conf
   │       └── wpa-supplicant_%.bbappend
   ├── recipes-core
   │   ├── images
   │   │   ├── datalogger-dev-image.bb
   │   │   ├── datalogger-extended-image.bb
   │   │   └── datalogger-image.bb
   │   ├── packagegroups
   │   │   ├── datalogger-base-packagegroup.bb
   │   │   ├── datalogger-core-packagegroup.bb
   │   │   ├── datalogger-dev-packagegroup.bb
   │   │   └── datalogger-extended-packagegroup.bb
   │   ├── systemd
   │   │   └── systemd_%.bbappend
   │   └── systemd-conf
   │       ├── files
   │       │   └── wlan.network
   │       └── systemd-conf_%.bbappend
   └── recipes-example
       └── example
           └── example_0.1.bb