searxng/docs/dev/lxcdev.rst
Markus Heiser 5bea04869d [docs] move LXC blog article into developer documentation.
Move article 'Developing in Linux Containers' from blog section do developer
section.  Since there are no more articles in the blog section, remove the
section completely.

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
2021-06-04 15:05:58 +02:00

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.. _lxcdev:
==============================
Developing in Linux Containers
==============================
.. _LXC: https://linuxcontainers.org/lxc/introduction/
In this article we will show, how you can make use of Linux Containers (LXC_) in
*distributed and heterogeneous development cycles* (TL;DR; jump to the
:ref:`lxcdev summary`).
.. sidebar:: Audience
This blog post is written for experienced admins and developers. Readers
should have a serious meaning about the terms: *distributed*, *merge* and
*linux container*.
.. contents:: Contents
:depth: 2
:local:
:backlinks: entry
Motivation
==========
Usually in our development cycle, we edit the sources and run some test and/or
builds by using ``make`` :ref:`[ref] <makefile>` before we commit. This cycle
is simple and perfect but might fail in some aspects we should not overlook.
**The environment in which we run all our development processes matters!**
The :ref:`makefile` and the :ref:`make install` encapsulate a lot for us, but
they do not have access to all prerequisites. For example, there may have
dependencies on packages that are installed on the developer's desktop, but
usually are not preinstalled on a server or client system. Another example is;
settings have been made to the software on developer's desktop that would never
be set on a *production* system.
**Linux Containers are isolate environments and not to mix up all the
prerequisites from various projects on developer's desktop is always a good
choice.**
The scripts from :ref:`searx_utils` can divide in those to install and maintain
software:
- :ref:`searx.sh`
- :ref:`filtron.sh`
- :ref:`morty.sh`
and the script :ref:`lxc.sh`, with we can scale our installation, maintenance or
even development tasks over a stack of isolated containers / what we call the:
**searxNG LXC suite**
Gentlemen, start your engines!
==============================
.. _LXD: https://linuxcontainers.org/lxd/introduction/
.. _archlinux: https://www.archlinux.org/
Before you can start with containers, you need to install and initiate LXD_
once:
.. tabs::
.. group-tab:: desktop
.. code:: sh
$ snap install lxd
$ lxd init --auto
And you need to clone from origin or if you have your own fork, clone from your
fork:
.. tabs::
.. group-tab:: desktop
.. code:: sh
$ cd ~/Downloads
$ git clone https://github.com/searxng/searxng.git searx
$ cd searx
The :ref:`lxc-searx.env` consists of several images, see ``export
LXC_SUITE=(...`` near by :origin:`utils/lxc-searx.env#L19`. For this blog post
we exercise on a archlinux_ image. The container of this image is named
``searx-archlinux``. Lets build the container, but be sure that this container
does not already exists, so first lets remove possible old one:
.. tabs::
.. group-tab:: desktop
.. code:: sh
$ sudo -H ./utils/lxc.sh remove searx-archlinux
$ sudo -H ./utils/lxc.sh build searx-archlinux
.. sidebar:: The ``searx-archlinux`` container
is the base of all our exercises here.
In this container we install all services :ref:`including searx, morty & filtron
<lxc.sh install suite>` in once:
.. tabs::
.. group-tab:: desktop
.. code:: sh
$ sudo -H ./utils/lxc.sh install suite searx-archlinux
To proxy HTTP from filtron and morty in the container to the outside of the
container, install nginx into the container. Once for the bot blocker filtron:
.. tabs::
.. group-tab:: desktop
.. code:: sh
$ sudo -H ./utils/lxc.sh cmd searx-archlinux \
./utils/filtron.sh nginx install
...
INFO: got 429 from http://10.174.184.156/searx
and once for the content sanitizer (content proxy morty):
.. tabs::
.. group-tab:: desktop
.. code:: sh
$ sudo -H ./utils/lxc.sh cmd searx-archlinux \
./utils/morty.sh nginx install
...
INFO: got 200 from http://10.174.184.156/morty/
.. sidebar:: Fully functional searXNG suite
From here on you have a fully functional searXNG suite running with bot
blocker (filtron) and WEB content sanitizer (content proxy morty), both are
needed for a *privacy protecting* search engine.
On your system, the IP of your ``searx-archlinux`` container differs from
http://10.174.184.156/searx, just open the URL reported in your installation
protocol in your WEB browser from the desktop to test the instance from outside
of the container.
In such a searXNG suite admins can maintain and access the debug log of the
different services quite easy.
.. _working in containers:
In containers, work as usual
============================
Usually you open a root-bash using ``sudo -H bash``. In case of LXC containers
open the root-bash in the container using ``./utils/lxc.sh cmd
searx-archlinux``:
.. tabs::
.. group-tab:: desktop
.. code:: sh
$ sudo -H ./utils/lxc.sh cmd searx-archlinux bash
INFO: [searx-archlinux] bash
[root@searx-archlinux searx]# pwd
/share/searx
The prompt ``[root@searx-archlinux ...]`` signals, that you are the root user in
the searx-container. To debug the running searXNG instance use:
.. tabs::
.. group-tab:: root@searx-archlinux
.. code:: sh
$ ./utils/searx.sh inspect service
...
use [CTRL-C] to stop monitoring the log
...
Back in the browser on your desktop open the service http://10.174.184.156/searx
and run your application tests while the debug log is shown in the terminal from
above. You can stop monitoring using ``CTRL-C``, this also disables the *"debug
option"* in searXNG's settings file and restarts the searXNG uwsgi application.
To debug services from filtron and morty analogous use:
.. tabs::
.. group-tab:: root@searx-archlinux
.. code:: sh
$ ./utils/filtron.sh inspect service
$ ./utils/morty.sh inspect service
Another point we have to notice is that each service (:ref:`searx <searx.sh>`,
:ref:`filtron <filtron.sh>` and :ref:`morty <morty.sh>`) runs under dedicated
system user account with the same name (compare :ref:`create searx user`). To
get a shell from theses accounts, simply call one of the scripts:
.. tabs::
.. group-tab:: root@searx-archlinux
.. code:: sh
$ ./utils/searx.sh shell
$ ./utils/filtron.sh shell
$ ./utils/morty.sh shell
To get in touch, open a shell from the service user (searx@searx-archlinux):
.. tabs::
.. group-tab:: desktop
.. code:: sh
$ sudo -H ./utils/lxc.sh cmd searx-archlinux \
./utils/searx.sh shell
// exit with [CTRL-D]
(searx-pyenv) [searx@searx-archlinux ~]$ ...
The prompt ``[searx@searx-archlinux]`` signals that you are logged in as system
user ``searx`` in the ``searx-archlinux`` container and the python *virtualenv*
``(searx-pyenv)`` environment is activated.
.. tabs::
.. group-tab:: searx@searx-archlinux
.. code:: sh
(searx-pyenv) [searx@searx-archlinux ~]$ pwd
/usr/local/searx
Wrap production into developer suite
====================================
In this section we will see how to change the *"Fully functional searXNG suite"*
from a LXC container (which is quite ready for production) into a developer
suite. For this, we have to keep an eye on the :ref:`installation basic`:
- searXNG setup in: ``/etc/searx/settings.yml``
- searXNG user's home: ``/usr/local/searx``
- virtualenv in: ``/usr/local/searx/searx-pyenv``
- searXNG software in: ``/usr/local/searx/searx-src``
The searXNG software is a clone of the ``git_url`` (see :ref:`settings global`)
and the working tree is checked out from the ``git_branch``. With the use of
the :ref:`searx.sh` the searx service was installed as :ref:`uWSGI application
<searx uwsgi>`. To maintain this service, we can use ``systemctl`` (compare
:ref:`service architectures on distributions <uwsgi configuration>`).
.. tabs::
.. group-tab:: desktop
.. code:: sh
$ sudo -H ./utils/lxc.sh cmd searx-archlinux \
systemctl stop uwsgi@searx
With the command above, we stopped the searx uWSGI-App in the archlinux
container.
The uWSGI-App for the archlinux dsitros is configured in
:origin:`utils/templates/etc/uwsgi/apps-archlinux/searx.ini`, from where at
least you should attend the settings of ``uid``, ``chdir``, ``env`` and
``http``::
env = SEARX_SETTINGS_PATH=/etc/searx/settings.yml
http = 127.0.0.1:8888
chdir = /usr/local/searx/searx-src/searx
virtualenv = /usr/local/searx/searx-pyenv
pythonpath = /usr/local/searx/searx-src
If you have read the :ref:`"Good to know section" <lxc.sh>` you remember, that
each container shares the root folder of the repository and the command
``utils/lxc.sh cmd`` handles relative path names **transparent**. To wrap the
searXNG installation into a developer one, we simple have to create a smylink to
the **transparent** reposetory from the desktop. Now lets replace the
repository at ``searx-src`` in the container with the working tree from outside
of the container:
.. tabs::
.. group-tab:: container becomes a developer suite
.. code:: sh
$ sudo -H ./utils/lxc.sh cmd searx-archlinux \
mv /usr/local/searx/searx-src /usr/local/searx/searx-src.old
$ sudo -H ./utils/lxc.sh cmd searx-archlinux \
ln -s /share/searx/ /usr/local/searx/searx-src
Now we can develop as usual in the working tree of our desktop system. Every
time the software was changed, you have to restart the searx service (in the
conatiner):
.. tabs::
.. group-tab:: desktop
.. code:: sh
$ sudo -H ./utils/lxc.sh cmd searx-archlinux \
systemctl restart uwsgi@searx
Remember: :ref:`working in containers` .. here are just some examples from my
daily usage:
.. tabs::
.. group-tab:: desktop
To *inspect* the searXNG instance (already described above):
.. code:: sh
$ sudo -H ./utils/lxc.sh cmd searx-archlinux \
./utils/searx.sh inspect service
Run :ref:`makefile`, e.g. to test inside the container:
.. code:: sh
$ sudo -H ./utils/lxc.sh cmd searx-archlinux \
make test
To install all prerequisites needed for a :ref:`buildhosts`:
.. code:: sh
$ sudo -H ./utils/lxc.sh cmd searx-archlinux \
./utils/searx.sh install buildhost
To build the docs on a buildhost :ref:`buildhosts`:
.. code:: sh
$ sudo -H ./utils/lxc.sh cmd searx-archlinux \
make docs.html
.. _lxcdev summary:
Summary
=======
We build up a fully functional searXNG suite in a archlinux container:
.. code:: sh
$ sudo -H ./utils/lxc.sh install suite searx-archlinux
To access HTTP from the desktop we installed nginx for the services inside the
conatiner:
.. tabs::
.. group-tab:: [root@searx-archlinux]
.. code:: sh
$ ./utils/filtron.sh nginx install
$ ./utils/morty.sh nginx install
To wrap the suite into a developer one, we created a symbolic link to the
repository which is shared **transparent** from the desktop's file system into
the container :
.. tabs::
.. group-tab:: [root@searx-archlinux]
.. code:: sh
$ mv /usr/local/searx/searx-src /usr/local/searx/searx-src.old
$ ln -s /share/searx/ /usr/local/searx/searx-src
$ systemctl restart uwsgi@searx
To get information about the searxNG suite in the archlinux container we can
use:
.. tabs::
.. group-tab:: desktop
.. code:: sh
$ sudo -H ./utils/lxc.sh show suite searx-archlinux
...
[searx-archlinux] INFO: (eth0) filtron: http://10.174.184.156:4004/ http://10.174.184.156/searx
[searx-archlinux] INFO: (eth0) morty: http://10.174.184.156:3000/
[searx-archlinux] INFO: (eth0) docs.live: http://10.174.184.156:8080/
[searx-archlinux] INFO: (eth0) IPv6: http://[fd42:573b:e0b3:e97e:216:3eff:fea5:9b65]
...