Dependencies manager

Implementation of a program to automate the process of adding and removing software packages

Free software: MIT license
Documentation:

Features

Maintain a record of installed packages and their dependencies.
Support explicitly installing a package in response to a command (unless it is already installed).
Support implicitly installing a package if it is needed to install another package.
Support explicitly removing a package in response to a command (if it is not needed to support other packages).
Support implicitly removing a package if it is no longer needed to support another component and was not explicitly installed.

Quick start

You can build an image tagged deps from this Dockerfile by running:

docker build -t deps .

Then, run a container named deps based in the built image by executing:

docker run --name deps -t -d deps

To check the container is properly running, execute this:

docker ps

You will see an output like this:

CONTAINER ID   IMAGE     COMMAND     CREATED         STATUS         PORTS     NAMES
e5014d217bd7   deps      "python3"   3 seconds ago   Up 2 seconds             deps

To open a bash shell in the container:

docker exec -it deps /bin/bash

How to execute

To execute the dependencies manager using the sample input file included in this repo just run:

docker run --rm deps python /usr/dependency_manager/app/deps_manager.py /usr/dependency_manager/data/sample_input.txt

You will see an output like this (TODO)

DEPEND TELNET TCPIP NETCARD
DEPEND TCPIP NETCARD
DEPEND DNS TCPIP NETCARD
DEPEND BROWSER TCPIP HTML
INSTALL NETCARD
    NETCARD successfully installed
INSTALL TELNET
    TCPIP successfully installed
    TELNET successfully installed
INSTALL foo
    foo successfully installed
REMOVE NETCARD
    NETCARD is still needed
INSTALL BROWSER
    HTML successfully installed
    BROWSER successfully installed
INSTALL DNS
    DNS successfully installed
LIST
    HTML
    BROWSER
    DNS
    NETCARD
    foo
    TCPIP
    TELNET
REMOVE TELNET
    TELNET successfully removed
REMOVE NETCARD
    NETCARD is still needed
REMOVE DNS
    DNS successfully removed
REMOVE NETCARD
    NETCARD is still needed
INSTALL NETCARD
    NETCARD is already installed
REMOVE TCPIP
    TCPIP is still needed
REMOVE BROWSER
    BROWSER successfully removed
    HTML is no longer needed
    HTML successfully removed
    TCPIP is no longer needed
    TCPIP successfully removed
REMOVE TCPIP
    TCPIP is not installed
LIST
    NETCARD
    foo
END

How to run tests

To run the included tests execute:

docker run --rm deps pytest /usr/dependency_manager/tests

How to run linter

To run flake8 linter, execute:

docker run --rm deps flake8 /usr/dependency_manager/app

Design

Main ideas:

Separate file reading / writing from command execution
Build and iterator to read the file, to work with just one command in each step
Build the registry of installed packages as a dependency tree using the DEPEND commands as guide

Options to model the registry:

A dict in which each key is the package name and its associated value is a set with the names of the dep.packages
An actual tree, with nodes and edges

First approach is way simpler and enough for this problem: for each package we just need to know the name of its dependencies.

Credits

Created by Jorge Arévalo <jorgeas80@gmail.com>