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type Country = String
type Code = String
type Year = Int
type Value = Double
data Entry = Entry { country  :: !Country
                   , code     :: !Code
                   , year     :: !Year
                   , value    :: !Value
                   } deriving (Show)
type Trend = [Entry]

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{-|
Module      :   FastDegrade
Description :   Creates an image with multiple squares of different colors.
Copyright   :   (c) Fabio Thomaz MOlinar, 2021
Maintainer  :   fabiomolinar@gmail.com
Stability   :   experimental

Second attempt at trying to make a module that create an image with multiple
squares of different colors on it. The first attempt, the module 'Degrade'
had a __terrible__ performance.

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{-|
Module      :   Degrade
Description :   Creates an image with multiple squares of different colors.
Copyright   :   (c) Fabio Thomaz MOlinar, 2021
Maintainer  :   fabiomolinar@gmail.com
Stability   :   experimental

This was my first attempt at creating a module that would be able to create an
image with multiple squares of different colors. Although it works, the efficiency
is __TERRIBLE__.

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Environment:


Request Method: POST
Request URL: http://localhost:8000/en/cms_wizard/create/

Django Version: 1.11.16
Python Version: 2.7.15
Installed Applications:
('djangocms_admin_style',

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React Tip

Sources

• React Docs

Writing code

• It's a good practice to wrap components definitions with parenthesis.

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Linux permissions

In Linux, each and every file is owned by a single user and a single group, and has its own access permissions.

Users

To list all users on a Linux machine:

cat /etc/passwd

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Docker tips

Source:

• Learning Docker (Book)
• Authors: Jeeva S. Chelladhurai, Vinod Singh, Pethuru Raj

Networking

Useful commands include: docker network connect, docker network create, docker network disconnect, docker network inspect, docker network ls, and docker network rm.

Default networks include:

• bridge

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https://docs.docker.com/develop/develop-images/dockerfile_best-practices/

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Dockerfile cheat sheet

Source:

• Learning Docker (Chapter 3)
• Author: Jeeva S. Chelladhurai, Vinod Singh, Pethuru Raj

As we discussed in the previous chapter, we can craft an image manually by launching a container from a base image, install all the required applications, make the necessary configuration file changes, and then commit the container as an image. As a better alternative, we can resort to the automated approach of crafting the images using Dockerfile, which is a text-based build script that contains special instructions in a sequence for building the correct and relevant images from the base images. The sequential instructions inside Dockerfile can include selecting the base image, installing the required application, adding the configuration and the data files, and automatically running the services as well as exposing those services to the external world. Thus, the Dockerfile-based automated build system has simplified the image-building process remarkably. It also offers a great deal of

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List of useful Docker commands

Source:

• Learning Docker (Book)
• Authors: Jeeva S. Chelladhurai, Vinod Singh, Pethuru Raj

docker run

The docker run subcommand takes an image as an input and launches it as a container. You have to pass the -t and -i flags to the docker run subcommand in order to make the container interactive. The -i flag is the key driver, which makes the container interactive by grabbing the standard input (STDIN) of the container. The -t flag allocates a pseudo-TTY or a pseudo Terminal (Terminal emulator) and then assigns that to the container. In the following example, we are going to launch an interactive container using the ubuntu:16.04 image and /bin/bash as the command:

$ sudo docker run -i -t ubuntu:16.04 /bin/bash