Technical assessment for the position of full-stack software developer at PackIOT.

• 1. Preliminaries
  • 1.1. Installing pip and virtualenv
  • 1.2. Virtual environment
• 2. Building and running
  • 2.1. PostgreSQL server
    • 2.1.1 For building
    • 2.1.2 For running
  • 2.2. pgAdmin 4
• 3. Where to now?

In order to build the project, you must have already installed and configured in your workspace:

• Docker
• Docker Compose
• Python (3.8)
• pip
• virtualenv (or any other suitable virtual environment manager for Python)

With the correct Python distribution, at the terminal, execute the following commands:

$ sudo apt install python3-pip python3-virtualenv

After you cloned this project, you must install its Python dependencies. So, at the project's root, execute in the terminal:

$ virtualenv --python=python3 venv                  # Creates the virtual env
$ source venv/bin/activate                          # Make it active inside the project
$ pip install --upgrade pip --no-cache-dir          # Upgrade the package manager
$ pip install -r requirements.txt --no-cache-dir    # Install dependencies listed in the .txt file

To construct the containers which encapsulate the PostgreSQL database server and the pgAdmin 4 web application, a suite of scripts was implemented in Python, in order to automate the users' interaction with the Docker and Compose actions. The documentation about these scripts can be found here.

The aforementioned containers and its associated images are built with Docker Compose, where the corresponding services are all declared in the YAML file, at the project's root. These services are:

• pgsqlserver: Runs the container that encapsulates a proper PostgreSQL server. The image for this container (Dockerfile) was implemented locally, for reasons of database automation;
• pgadmin: The web interface that consumes the PostgreSQL database, and for that it can not run without the previous service been built. It uses an officially distributed image, downloaded from Docker Hub.

We use here the automation script to perform building and runnning. At the project's root, execute in the terminal:

$ ./scripts/devenv.py build pgsqlserver 

$ ./scripts/devenv.py startwlogs pgsqlserver # Starts the container in detached mode and shows the logs

Note: The database for this challenge (packiotfscdb) is created when the container is started (you can see in the logs). More information on how to interact with it can be found here.

Similarly, we use the automation script to build and run this service, with the difference that the building part is not done separatedly, because the image for this container is obtained externally, i.e., there is no Dockerfile. So, you just need to run in the terminal:

$ ./scripts/devenv.py startwlogs pgadmin

With the container up and running, you can now access the pgAdmin's UI via browser. The credentials for signing in are defined in the container's .env file.

To access the database and its respective schema, you'll have to add a server and set up the connection to it. To do that, you can check out the official pgAdmin 4 documentation. It's pretty straightforward. The necessary database credentials are defined in the pgsqlserver container's .env file.

Note: When specifying the hostname in the connection dialog, you must enter the name of the service listed in the Docker Compose YAML file, i.e., (pgsqlserver).

• Database
• Scripts
• Table of contents