Chapter 4 - clean up code, switch to f-strings, remove tokens, and unwanted fluff (#20)

* change to python 3 syntax

* clean up for ch 04

Author: SathyaBhat

.gitignore

@@ -1,3 +1,3 @@
 **/*.pyc
-**/venv/*
+**/*venv/*
 **/.idea/*

source-code/chapter-4/exercise-1/docker-hello-world/Dockerfile

@@ -1,9 +1,8 @@
 FROM python:3-alpine
 
-LABEL author="sathyabhat"
 LABEL description="Dockerfile for Python script which prints Hello, Name"
 
 COPY hello-world.py /app/
-ENV NAME=Sathya
+ENV NAME=Readers
 CMD python3 /app/hello-world.py
 

source-code/chapter-4/exercise-1/docker-hello-world/hello-world.py

@@ -1,10 +1,8 @@
 #!/usr/bin/env python3
-
 from os import getenv
 
 if getenv('NAME') is None:
     name = 'World'
 else:
     name = getenv('NAME')
-
-print("Hello, {}!".format(name))
+print(f"Hello, {name}!")

source-code/chapter-4/exercise-2/README.md

@@ -1,3 +1,6 @@
 ### README
 
-This exercise contains the source code for the second exercise of chapter 4. In this exercise, you will build two Docker images, the first one using a standard build process using python:3 as the base image.
+This exercise contains the source code for the second exercise of chapter 4. In this exercise, you will build two Docker images
+
+ - Using the standard build process using python:3 as the base image (present in [docker-multi-stage/standard-build](docker-multi-stage/standard-build) directory. 
+ - Using Multi-Stage builds (present [docker-multi-stage/multistage-build](docker-multi-stage/multistage-build) directory. 

source-code/chapter-4/exercise-2/docker-multi-stage/multistage-build/requirements.txt

@@ -1 +1 @@
-praw
+praw==3.6.0

source-code/chapter-4/exercise-2/docker-multi-stage/standard-build/Dockerfile

@@ -1,4 +1,3 @@
 FROM python:3
 COPY requirements.txt .
 RUN pip install -r requirements.txt
-

source-code/chapter-4/exercise-2/docker-multi-stage/standard-build/requirements.txt

@@ -1 +1 @@
-praw
+praw==3.6.0

source-code/chapter-4/exercise-3/README.md

@@ -1,3 +1,20 @@
 ### README
 
-This exercise contains the source code for the third exercise of chapter 4. In this exercise, we’ll try writing the Dockerfile for the project.
+This exercise contains the source code for the third exercise of chapter 4. In this exercise, we compose a Dockerfile for Newsbot and then use the Dockerfile to build a Docker image and run the container.
+
+
+### Building the Docker image
+
+Build the image using the below command
+
+```
+docker build -t sathyabhat/newsbot
+```
+
+Run the container using 
+
+```
+docker run -e NBT_ACCESS_TOKEN=<token> sathyabhat/newsbot
+```
+
+Replace `<token>` with the Telegram API Token that was generated.