Gain insights into Docker fundamentals, delve into advanced concepts like database connectivity and Docker Compose, and discover how to monitor and scale services with Docker Swarm.

course_final_image.tar.gz

Flask App_new

docker-compose

Docker_build

flask_venv

Flask_demo_test

add db to container

Exercise

Exercise 2

exercise 3

exercise_4

Bonus Section - Flask

exercise 3-copy

docker-compose-copy

Docker_build-copy

add db to container-copy

Exercise 2-copy

exercise_4-copy

Bonus Section - Flask-copy

Docker_build-copy-copy

Whether you are a DevOps beginner or just a developer who wants to start working with containers, you’re in the right place. Docker is an in-demand technology that you will be exposed to frequently while on the job.

 

Docker is used for setting up, deploying, and running applications, at scale, by containerizing them. More on that later. Docker also provides developers with a consistent environment for product development, and along with Kubernetes, makes managing the development lifecycle a breeze.

 

In this course, you will learn the fundamentals of Docker such as containers, images, and commands. You’ll then progress to more advanced concepts like connecting to a database container and how to simplify workflows with Docker Compose. At the end, you’ll learn how to monitor clusters and scale Docker services with Swarm.

Working with Containers: Docker & Docker Compose

# Layers
In the last chapter, we saw that when we pulled the Docker hello-world image, it pulled a layer. The hello-world image is a very small-sized image. So, Docker pulled only one layer. If you pull a bigger image, say, Nginx we get something like this:
```
venkateshs-air:~ venkateshachintalwar$ docker pull nginx
Using the default tag: latest
latest: Pulling from library/nginx
b8f262c62ec6: Pull complete 
e9218e8f93b1: Pull complete 
7acba7289aa3: Pull complete 
Digest: sha256:aeded0f2a861747f43a01cf1018cf9efe2bdd02afd57d2b11fcc7fcadc16ccd1
```
Docker pulled three layers. If you think a little bit, you asked the Docker daemon to pull one image, which is Nginx. Why is it pulling three?

The reason is whenever the Docker pulls an image, it takes up a lot of space on the device. If you type
```
venkateshs-air:~ venkateshachintalwar$ docker image ls nginx
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
nginx               latest              f949e7d76d63        8 days ago          126MB
```

You can see above that the Nginx image took 126 MB of space.
If images were built as a standalone image with no component sharing, every image would have taken a .iso size memory, which is not efficient.

As every image is built on top of Linux kernel, it has some common dependencies that can be reused by other images. Docker bundles these dependencies in one stack and these stacks are called layers. 

>Only the instructions RUN, COPY, and ADD create layers. Other instructions create temporary intermediate images and do not increase the size of the build. We will see in the next section what these instructions are.

Docker caches these intermediate layers to speed up the image building process. We will see that in the upcoming lessons.

Before moving to the next lesson, try pulling a Python 3.5 image using `$ sudo docker pull python:3.5` and see how many layers Docker fetches.


# Layers
In the last chapter, we saw that when we pulled the Docker hello-world image, it pulled a layer. The hello-world image is a very small-sized image. So, Docker pulled only one layer. If you pull a bigger image, say, Nginx we get something like this:
```
venkateshs-air:~ venkateshachintalwar$ docker pull nginx
Using the default tag: latest
latest: Pulling from library/nginx
b8f262c62ec6: Pull complete 
e9218e8f93b1: Pull complete 
7acba7289aa3: Pull complete 
Digest: sha256:aeded0f2a861747f43a01cf1018cf9efe2bdd02afd57d2b11fcc7fcadc16ccd1
```
Docker pulled three layers. If you think a little bit, you asked the Docker daemon to pull one image, which is Nginx. Why is it pulling three?

The reason is whenever the Docker pulls an image, it takes up a lot of space on the device. If you type
```
venkateshs-air:~ venkateshachintalwar$ docker image ls nginx
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
nginx               latest              f949e7d76d63        8 days ago          126MB
```

You can see above that the Nginx image took 126 MB of space.
If images were built as a standalone image with no component sharing, every image would have taken a .iso size memory, which is not efficient.

As every image is built on top of Linux kernel, it has some common dependencies that can be reused by other images. Docker bundles these dependencies in one stack and these stacks are called layers. 

>Only the instructions RUN, COPY, and ADD create layers. Other instructions create temporary intermediate images and do not increase the size of the build. We will see in the next section what these instructions are.

Docker caches these intermediate layers to speed up the image building process. We will see that in the upcoming lessons.

Before moving to the next lesson, try pulling a Python 3.5 image using `＄ sudo docker pull python:3.5` and see how many layers Docker fetches.


Layers - speed up the build and pull process of an image by breaking down the components into minor pieces.

Layers - Building Blocks in Docker

Introduction to Course

Why Docker?

Getting Started With Docker

Docker Fundamentals

Automation using Dockerfile

Advance Docker

Introduction to Docker-Compose

Exposure to Docker Swarm

Bonus Section

Layers - Building Blocks in Docker

Layers