Add prerequisities and prepare the env sections

docs/tutorials/asyncio.rst

@@ -6,6 +6,12 @@ Asyncio daemon tutorial
 This tutorials shows how to build an ``asyncio`` daemon following the dependency injection
 principle.
 
+We will use next tools:
+
+- Python 3.8
+- Docker
+- Docker-compose
+
 Start from the scratch or jump to the section:
 
 .. contents::
@@ -21,7 +27,7 @@ What are we going to build?
 We will build a monitoring daemon that monitors web services availability.
 
 The daemon will send the requests to the `example.com <http://example.com>`_ and
-`httpbin.org <https://httpbin.org>`_ every couple of seconds. For each successfully completed
+`httpbin.org <https://httpbin.org>`_ every minute. For each successfully completed
 response it will log:
 
 - The response code
@@ -30,14 +36,160 @@ response it will log:
 
 .. image::  asyncio_images/diagram.png
 
-Prepare the environment
+Prerequisites
------------------------
+-------------
+
+We will use `Docker <https://www.docker.com/>`_ and
+`docker-compose <https://docs.docker.com/compose/>`_ in this tutorial. Let's check the versions:
+
+.. code-block:: bash
+
+   docker --version
+   docker-compose --version
+
+The output should look something like:
+
+.. code-block:: bash
+
+   Docker version 19.03.12, build 48a66213fe
+   docker-compose version 1.26.2, build eefe0d31
+
+.. note::
+
+   If you don't have ``Docker`` or ``docker-compose`` you need to install them before proceeding.
+   Follow these installation guides:
+
+   - `Install Docker <https://docs.docker.com/get-docker/>`_
+   - `Install docker-compose <https://docs.docker.com/compose/install/>`_
+
+The prerequisites are satisfied. Let's get started with the project layout.
 
 Project layout
 --------------
 
-Install the requirements
+Project layout starts with the project folder. It is also called the project root.
-------------------------
+
+Create the project root folder and set it as a working directory:
+
+.. code-block:: bash
+
+   mkdir monitoring-daemon-tutorial
+   cd monitoring-daemon-tutorial
+
+Now we need to create the project structure. Create the files and folders following next layout.
+All files should be empty for now. We will fill them in later.
+
+Initial project layout:
+
+.. code-block:: bash
+
+   ./
+   ├── monitoringdaemon/
+   │   ├── __init__.py
+   │   ├── __main__.py
+   │   ├── containers.py
+   │   └── dispatcher.py
+   ├── docker-compose.yml
+   ├── Dockerfile
+   └── requirements.txt
+
+The project layout is ready. Let's prepare the environment.
+
+Prepare the environment
+-----------------------
+
+In this section we are going to prepare the environment.
+
+First, we need to specify the project requirements. We will use next packages:
+
+- ``dependency-injector`` - the dependency injection framework
+- ``aiohttp`` - the web framework (we need only http client)
+- ``pyyaml`` - the YAML files parsing library, used for the reading of the configuration files
+- ``pytest`` - the testing framework
+- ``pytest-asyncio`` - the helper library for the testing of the ``asyncio`` application
+- ``pytest-cov`` - the helper library for measuring the test coverage
+
+Put next lines into the ``requirements.txt`` file:
+
+.. code-block:: bash
+
+   dependency-injector
+   aiohttp
+   pyyaml
+   pytest
+   pytest-asyncio
+   pytest-cov
+
+Second, we need to create the ``Dockerfile``. It will describe the daemon's build process and
+specify how to run it. We will use ``python:3.8-buster`` as a base image.
+
+Put next lines into the ``Dockerfile`` file:
+
+.. code-block:: bash
+
+   FROM python:3.8-buster
+
+   ENV PYTHONUNBUFFERED=1
+
+   WORKDIR /code
+   COPY . /code/
+
+   RUN apt-get install openssl \
+    && pip install --upgrade pip \
+    && pip install -r requirements.txt \
+    && rm -rf ~/.cache
+
+   CMD ["python", "-m", "monitoringdaemon"]
+
+Third, we need to define the container in the docker-compose configuration.
+
+Put next lines into the ``docker-compose.yml`` file:
+
+.. code-block:: yaml
+
+   version: "3.7"
+
+   services:
+
+     monitor:
+       build: ./
+       image: monitoring-daemon
+       volumes:
+         - "./:/code"
+
+All is ready. Let's check that the environment is setup properly.
+
+Run in the terminal:
+
+.. code-block:: bash
+
+   docker-compose build
+
+The build process may take a couple of minutes. You should see something like this in the end:
+
+.. code-block:: bash
+
+   Successfully built 5b4ee5e76e35
+   Successfully tagged monitoring-daemon:latest
+
+After the build is done run the container:
+
+.. code-block:: bash
+
+   docker-compose up
+
+The output should look like:
+
+.. code-block:: bash
+
+   Creating network "monitoring-daemon-tutorial_default" with the default driver
+   Creating monitoring-daemon-tutorial_monitor_1 ... done
+   Attaching to monitoring-daemon-tutorial_monitor_1
+   monitoring-daemon-tutorial_monitor_1 exited with code 0
+
+The environment is ready. The application does not do any work and just exits with a code 0.
+
+In the next section we will create the minimal application.
 
 Minimal application
 -------------------