1. What is Docker?

What is a Container?

A standardized unit of software

Analogy

Explanation Part 1; Manual Tent

Explanation Part 2; Popup Tent

Close Enough

2. Let's talk about Docker

One more mention of tents

Let's Install Docker

For Windows / Mac Users;

For (most) Linux Users;

curl -sSL https://get.docker.com/ | sh

Even Docker isn't safe from "Hello, World!"

Once you have it installed;

docker run hello-world

should contain the following output;

                            Hello from Docker!
                            This message shows that your installation appears to be working correctly.
                        

2.5 More on Images

In the output of the last command I gave you, you might have seen something like this;

                            Unable to find image 'hello-world:latest' locally
                            latest: Pulling from library/hello-world
                        

This is Docker saying
"I don't have the 'hello-world' image on this machine, let me go get it"

Where does it get images?

If only there was some kind of website where people could upload Docker images for various widely used applications...

The Docker Hub!

2.8 Building our own images

Example: techtalks-flask

Step 1: Dockerfile

Step 1: Dockerfile

                            # Base image is the python 3.7 docker image
                            FROM python:3.7

                            # Set the working directory inside the image
                            WORKDIR /home/freyamade/public_html

                            # Copy from the build context to the image
                            COPY . .

                            # Install requirements
                            RUN pip install -r requirements.txt

                            # Load the latest submodules
                            RUN git submodule init
                            RUN git submodule update --remote

                            # Expose port 5000
                            EXPOSE 5000

                            # Set the entrypoint (CMD also works here)
                            ENTRYPOINT python3.7 app.py
                        

Step 2: Building the image

docker build -t techtalks-flask .

Step 3: Running the image

docker images

docker run -p 5000:5000 -d techtalks-flask

Step 4: Test

                                # show running containers
                                docker ps

                                # show all containers, dead or alive
                                docker ps -a
                            

0.2 Some other cool stuff

Before I spill some company secrets, I want to share a couple of other cool things with you

-v

docker run -p 5000:5000 -v $(pwd):/home/freyamade/public_html -d freyamade

-v + web development

                                # Run from inside project directory, then go to localhost:8080
                                docker run -v $(pwd):/usr/local/apache2/htdocs/ -p 8080:80 -d httpd
                            

Compose

techtalks-flask + Compose

Let's say I add some reason to use redis in the techtalks-flask project.

I could have the following compose file;

                            version: '3'
                            services:
                              web:
                                image: "techtalks-flask"
                                ports:
                                 - "5000:5000"
                              redis:
                                image: "redis:alpine"
                        

And then bring up both images using;

docker-compose up -d

Kubernetes

Kubernetes (k8s) is an open-source system for automating deployment, scaling, and management of containerized applications.

Docker DOOM

3. Let's spill some trade secrets

CIX Software

Why is the second one better?

Speed Increase

Speed Increase (cont'd)

Old Deployment System