Task A11 - Deployment or installation of applications using Docker containers

SM1: Open-source operating systems

ASIX/DAW/DAM-1

Task A11: Deployment or installation of application using Docker containers

16-1-26

Task A11: Deployment or installation of applications using Docker containers

GENERAL CONDITIONS
Deadline ASIX1: 29-1-2026
Deadline ASIX1: 2-2-2026

DOCUMENTATION

1- How to deploy or install an application

Nowadays there 3 typical ways to deploy a web application or install a system application:

You can deploy or install your application in a physical computer. if you deploy or install an application in a physical computer, you have to install:

hardware
operating system
servers
Tools
libraries required to develop and run the application.
The application

You can deploy or install your application in a virtual computer. if you deploy or install an application in a virtual computer, you have to install:

hardware
physical operating system
virtual computer manager like Virtualbox
The virtual operating system
Servers on the virtual operating system
Tools
Libraries required to develop and run the application on the virtual operating system
The application itself in your virtuals computer.

You can deploy or install your application in a container. if you deploy or install an application in a virtual computer, you have to install:

hardware
physical operating system
A container engine to manage containerized application
A container with a minimal set of tools, servers, the application and libraries required to run the application. A kernel operating system is not required because they share the host operating system's kernel.

2- Disadavantages of deploying/installing applications on physical machines, virtual machines and container

a) The disadvantages of deploying/installing application on physical computer with regard virtual machines or containers are the following:

Resource utilization: Physical computers often underutilize resources. You do no take fully advantage of CPU time, disk space or RAM installed.
Scalability: Scaling physical computers involves purchasing and configuring additional hardware, which can be time-consuming and expensive.
Isolation and Security: Physical computers lack the isolation capabilities provided by virtual machines and containers. Running applications directly on physical hardware increases the risk of conflicts between applications and security vulnerabilities.
Flexibility and Portability: Applications deployed on physical computers are tightly coupled with the underlying hardware, making them less portable and flexible.

b) The disadvantages of deploying/installing application on virtual computers with regard containers are the following::

Resource utilitzation: Virtual machines consume more resources compared to containers because each virtual machine requires its own operating system instance. Part of the RAM memory, storage, and CPU resources are used to run the operating systen, leading to less efficient resource utilization compared to containers.
Slower Startup Times: Virtual machines typically have slower startup times compared to containers due to the time required to boot up the operating system for each virtual machine. Containers, on the other hand, can start almost instantly since they share the host operating system's kernel.
Complexity: Managing virtual machines involves dealing with full-fledged operating systems, which adds complexity to deployment, configuration, and maintenance. Containers offer a more lightweight and streamlined approach, reducing complexity and overhead.
Limited Scalability: While virtual machines offer scalability by adding or removing instances, they are less scalable than containers due to the higher resource overhead per instance. Containers can be more easily scaled up or down since they consume fewer resources and have faster startup times.

c) Generally speaking deployment/Installation via containers means that your application are faster, more portable, more efficient (cpu, ram, disk..) and hihghly scalable. The only problem is isolation. The best way to provide isolation among applications is working with virtual machines. But isolation provides by containers is betters than isolation provided by physical machines.

3- Container engines
a) A container engine, also known as a container runtime, is a software component responsible for creating, managing, and running containers on a host system.
b) One of the most popular container engines is Docker Engine. Docker Engine utilizes the Docker daemon dockerd to manage containers and images, along with the Docker CLI docker for interacting with the daemon.
c) Other container engines include Containerd, cri-o, LXD or Podman. These container runtimes offer similar functionalities to Docker Engine but may differ in implementation details and features.

4- Basic ideas about Docker containers
a) List of basic ideas you should know and remember: Docker, Container, Image, Build, Run, Dockerfile, DockerHub
b) What is Docker? --> https://www.youtube.com/watch?v=YFl2mCHdv24 From 0:00 to 0:44
c) Virtual Machine vs Docker --> https://www.youtube.com/watch?v=YFl2mCHdv24   From 0:45 to 1:56
d) Container, instance, image, build and run --> https://www.youtube.com/watch?v=YFl2mCHdv24   From 1:57 to 2:16
e) Dockerfile and image --> https://www.youtube.com/watch?v=YFl2mCHdv24   From 2:17 to 2:41
f) DockerHub --> https://www.youtube.com/watch?v=YFl2mCHdv24   From 3:53 to 4:16
g) Virtual Machine and Container in a nutshell --> https://deshanigeethika.medium.com/docker-tutorial-a6aa5b41e3ff

5- Docker Compose

Docker Compose is a tool for defining and running multi-container Docker applications. It allows you to use a simple YAML file to configure the services, networks, and volumes required for your application, and then spin up all the containers with a single command. Here's how Docker Compose works:

Define Your Application Services: In a docker-compose.yml file, you specify the services that make up your application. Each service typically corresponds to a container, and you define various settings such as the Docker image to use, environment variables, ports to expose, volumes to mount, and dependencies between services.
Environment Variables and Overrides: Docker Compose allows you to use environment variables and override settings in the docker-compose.yml file using a separate .env file or environment variables passed directly to the docker-compose command. This flexibility enables you to customize your application's configuration for different environments (e.g., development, testing, production).
Start Your Application: Once you have defined your docker-compose.yml file, you can use the docker-compose up command to start all the containers defined in the file. Docker Compose will create the necessary networks and volumes, pull Docker images (if not already available locally), and start the containers in the correct order based on dependencies.
Manage Your Application: Docker Compose provides commands for managing your multi-container application.

Docker Compose simplifies the process of running multi-container applications locally or in development and testing environments. It's especially useful for applications that consist of multiple interconnected services, such as web servers, databases, caches, and message brokers, by providing a convenient way to define, configure, and manage the entire application stack with a single tool.

6- Installing and enabling Docker Engine on Debian Linux

a) Run the following commands:

sudo apt-get -y update

sudo apt-get -y install apt-transport-https ca-certificates curl gnupg2 gpg lsb-release

curl -fsSL https://download.docker.com/linux/debian/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker.gpg
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker.gpg] https://download.docker.com/linux/debian trixie stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get -y update

sudo apt-get -y install docker-ce docker-ce-cli containerd.io docker-compose-plugin

b) Check that a new group called docker has been added to the system.

c) Display status of a new service installed on your machine called docker

sudo systemctl status docker

and check that the service is started and enabled.

d) Add your default users to the docker group: sudo gpasswd -a $USER docker

e) Log out and log in and check that your user is now member of 984 (docker).

f) Check that a management utility called docker has been installed on your machine and check its version. Run: docker --version

7- Basic commands

a) Pulling an image

Command --> docker pull <image_name:version>

Example 1: --> docker pull photon:3.0

This command downloads the official image, version 3.0, of Photon OS, which is an open source minimal Linux.

Example 2 --> docker pull httpd:latest

This command downloads the latest version of an official image, which is called httpd in the DockerHub repository, with the software required to start an Apache web server when a new docker container is created using this image.

Important: Docker images are stored in the hard drive of your host machine, in a folder (/var/lib/docker/overlay2), and it means that they are using part of your hard drive space. Some heavy images could required up to1GiB or more hard drive space. Typical sizes of most downloaded images are around 100-200MiB.

b) Showing a list of downloaded images

Command --> docker images

In this example, you can see that two images called photon and httpd have been downloaded to your system.

c) Creating and starting a docker container: Basic options

Command --> docker run --name <container_name> -i -t -d -p <port_host:port_container> <image_name> where:

--name <container_name>=> Assign a name to the container
-i -t => Interactive session -i with a terminal attached -t. Required if we want to run a container command interpreter (usually /bin/bash).
-d => Run the docker container in the bakcground.
-p => Expose (or publish) a container's port, or range of ports, to the host machine.
<image_name> => Image used to create the docker container
Only <image_name> is mandatory and required..

Example 1:

The command creates a new container with the official image of Photon OS version 3. The new container will be called photon03. No particular application is asked to be run when the docker container is started. The docker container is running always in the background and will be stopped using docker stop (section 2.e). The docker container is ready to run any application installed using docker exec(section 2.g). The full Container ID is shown by the host machine operating system. Options -i and -t are added in case we wanted to run a container shell.

Example 2:

The command creates a container with the latest version of the Apache HTTP Server official image. The new container will be called apache2. Port 80 of container is exposed and published to port 8080 in the host machine. Container runs always in the background. No particular application is asked to be run when the docker container is started. Options -i and -t are added in case we want to run a container's shell (command interpreter).

d) Showing a list of containers, their status, container ID and additional information

Command --> docker ps -a

Example:

Container ID --> Container IDentifier. A unique number that identifies the docker container.
Name --> A unique name that identifies the docker container
Status --> Up means that the docker container is running on your system. Exited means that the docker container has been stopped.
Ports --> What internal port/ports of your docker container is/are exposed to port/ports of your host machine.
Image --> Image used to create the docker container

e) Stopping a docker container

Command --> docker stop <container_name> or docker stop <container_ID>

Example 1:

In this example, you can see how to stop a docker container using its Container ID.

Example 2:

In this example, you can see how to stop a docker container using its Name.

Important: Any container is a process on your system and therefore needs a PID, PPID, owner, %CPU time, nice value, RAM memory and an entry in the system process table. If you do not need to work with a docker container, it should be stopped in order to free system resources.

f) Starting a docker container

Command --> docker start <container_name> or docker start <container_ID>

Example :

In this example, you can see how to start a docker container using its Name or Container ID.

Important: Any started container is a new process on your system and therefore needs a PID, PPID, owner, %CPU time, nice value, RAM memory and an entry in the system process table. Data of a started container is stored in a special folder (/var/lib/docker/containers) located in the host machine hard drive.

g) Gaining access to a docker container.

Command --> docker exec <options> <container name or ID> bash

Example 1 - Gaining access to the bash of a docker container: docker exec -it <container_name> bash or docker exec -it <container_ID> bash

In this example, you can see how to gain access to the docker container executing the program bash installed in the container. Option -it is required because we want an interactive session and we want to work with a terminal and command interpreter. Also, we want to remain in the command interpreter and run some commands until the command exit is run.

h) Running commands or applications in a docker container.

Command --> docker exec <options> <container name or ID> <command or application name>

Example 1 - Running a command in a container: docker exec <container_name> command or docker exec -it <container_ID> command

We have run a command (cat /usr/local/apache2/htdocs/index.html) in the docker container usign the Container ID. This command shows the contents of index.html in the container. We do not remain, we just run a single command in the container.

Example 2 - Running another command in a container:

We have run a command (ls -ls /usr) in the docker container photon03. This command shows the contents of /usr in the container. We do not remain, we just run a single command in the container.

i) Removing a docker container

Important: Whenever you want to remove a docker container, first of all, you have to stop the docker container if it is currently running on your host system.

Commands:

1st Step [optional] ) Stopping the container (if the container is runnig) ==> docker stop <container_name> or docker stop <container_ID>
2nd Step) Removing the container ==> docker rm <container_name> or docker rm <container_ID>

Difference between stop and remove:

A stopped container can be started again because any data required by the container is stored on your host system.
A stopped container is shown by the command docker ps -a because the container exists.
Data of a stopped container is stored in a special folder (/var/lib/docker/containers) located in the host machine hard drive.
A removed container can not be started again because data required by the container are destroyed and permanently lost.
A removed container is not shown by the command docker ps -a because it does not exist any longer.
Data of a removed container is removed from the host machine hard drive.

Example:

In this example:

a) Docker container photon03 is stopped using its Container Name
b) Docker container apache2 is stopped using its Container ID
c) Docker container photon3 is already stopped so, running docker stop is not required.
d) Docker containers photon03 and photon3 are removed using their Container Names
e) Docker container apache2 is removed using its Container ID

j) Removing a docker image

Before removing an image:

Any containers created with the image we want to remove have to be stopped.
Any containers created with the image we want to remove have to be removed.

Commands:

1st Step [optional] ) Stopping the container ==> docker stop <container_name> or docker stop <container_ID>
2nd Step [optional] ) Removing the container ==> docker rm <container_name> or docker rm <container_ID>
3rd Step) Removing the image ==> docker rmi <image_name:version>

Example:

In this example:

a) Docker image photon:3.0 is removed
b) Docker image httpd:latest is removed
c) We can see the list of images installed on the host machine before and after running the commands to remove images.
d) We can see the disk space usage of the host machine before and after running the commands to remove images. Check changes in the Used and Available space.

Important: Any image requires hard drive space and they are stored in a folder called /var/lib/docker/overlay2 in the host machine. If you do not need to work with a docker image any longer, it should be removed in order to free hard drive space.

k) Configure Docker to start on boot

The Docker daemon dockerd manages Docker objects such as images, containers, networks, and volumes. A daemon can also communicate with other daemons to manage Docker services.
Debian Linux uses systemctl to manage dockerd:

To automatically start dockerd on boot, run => sudo systemctl enable docker.service
To avoid starting dockerd on boot, run => sudo systemctl enable docker.service
To start dockerd => sudo systemctl start docker.service
To stop dockerd => sudo systemctl stop docker.service
To show status of dockerd => systemctl status docker.service

8- How to containerize, deploy and gain access to a single-container web application

a) In order to containerize, deploy and run an application you should complete the following steps:

1st Step: Create a folder called ppv.
2nd Step: Create a folder called app in the ppv folder. Store the html, php,... files of your web application in app.
3rd Step: Create a Dockerfile in the project folder with the information (commands to run, files to copy, startup commnand,.....) required to create a container image.
4th Step: Create a container image running in the folder project:
5th Step: Run the image to create a container.
6th Step: Gaining access to your containerized application through a web browser, terminal, etc...

b) Example: Contanairezing a web application:

1st Step: Create a folder called ppv on your home directory. Change to ppv.

2nd Step:

Create a folder called app in ppv.
Change to app.
Download a file called index.html, available from thee following URL: https://www.collados.org/asix1/sm1/tasks/sm1act11/ppv/index.html, to the app directory of your virtual machine.
Download a file called ppv.php, available from thee following URL: https://www.collados.org/asix1/sm1/tasks/sm1act11/ppv/ppv.php, to the app directory of your virtual machine.

3rd Step:

Change to the folder ppv again.
Create a text file called Dockerfile. Add the following contents to the file:

or alternatively, if you experience any problem downloading php:8.4-apache:

4th Step:

Run the following command to create a container image of your web application: docker build -t img_ppv:1.0 .
The command:

Creates an docker container image called img_ppv version 1.0 using as a base image another one called php:8.4-apache (with an apache web server and php) downloaded from the DockerHub (or AWS) repository server.
The default work directory on the new image will be /var/www/html.
The contents of app in your virtual machine will be are copied to the default work directory of your the new image container image.
Exposes port 80 of any container created with the new image.

Run docker images and check that a new image called ippv:1.0 has been created.

5th Step:

Create a new container running your web application. Run: docker run --name cont_ppv -i -t -d -p 8000:80 img_ppv:1.0
The command:

Create and start a container called cont_ppv form image img_ppv:1.0
Container runs in the background (option -d)
Container publish the internal exposed port 80 of your container to the port 8000 in the virtual machine (option -p). So, a new port 8000 is open in the virtual machine. Any request to port 8000 in virtual machine is redirect to port 80 in the container.
Container can be accessed with the help of its internal bash (option -i -t).

Run docker ps -a and check that a new container called cont_ppv has been created and that its status is Up.

6 Step:

Run docker exec -it cont_ppv bash to gain access to the container. Check that index.html and ppv.php were copied on /var/www/html.
Run exit to quit.
Check the ip address of your virtual machine.

Gain access to the web application from your host machine using the following URL: http://ip_address_of_your_virtual_machine:8000

d) Additional information: https://docs.docker.com/get-started/02_our_app/

8- How to share data between a host machine and a docker container using volumes

a) Command --> docker run --name <container_name> -i -t -d -p <port_host:port_container> -v <folder_host_machine:folder_docker_container> <image_name> where:

--name <container_name>=> Assign a name to the container
-i -t => Interactive session -i with a terminal attached -t. Required if we want to run a container command interpreter (usually /bin/bash).
-d => Run the docker container in the bakcground.
-p => Expose (or publish) a container's port, or range of ports, to the host machine.
-v => Share data in older_host_machine with folder_docker_container
<image_name> => Image used to create the docker container
Only <image_name> is mandatory and required.

b) Example:

The command creates a container with the latest version of the Apache HTTP Server official image. The new container will be called apache2. Port 80 of container is exposed and published to port 8080 in the host machine. Container runs always in the background. No particular application is asked to be run when the docker container is started. Options -i and -t are added in case we want to run a container's shell (command interpreter). Folder ./webapp of the host machine shares date with folder /var/www/html of the container.

c) If you want to check the list of available volumes on your system run the following command: docker volume ls

9- How to containerize, deploy and gain access to a multi-container web application. Working with Docker compose

a) Docker Compose is a tool for running multi-container applications on Docker defined using the Compose file format. A Compose file is used to define how one or more containers that make up your application are configured. Once you have a Compose file, you can create easily create, start, stop, modify or remover your application with a single command.

b) In order to containerize, deploy and run an application using multiple containers, you should complete the following steps:

1st Step: Create a folder for your project.
2nd Step: Create a folder called app in your project folder. Store the html, php,css... files of your web application in app.
3rd Step (optional): Create a Dockerfile in the projecte folder in order to create customized images
4th Step: Create a Compose file in the folder project. The expected name for Compose files is docker-compose.yml (or .yaml).
5th Step: Start your application
6th Step: Gaining access to your containerized application through a web browser, terminal, etc...

c) Example: Creating and starting a multi-container a web application:

Create a folder called projects on your home directory. Change to projects.
Download sm1act11q3.tar.gz available through the following address: https://www.collados.org/asix1/sm1/tasks/sm1act11/sm1act11q3.tar.gz
Uncompress and unpack sm1act11q3.tar.gz running: tar xfz sm1act11q3.tar.gz.
Remove sm1act11q3.tar.gz
Check that a folder called sm1act11q3 has been created with the following files and directories:

app -> css, html and php file of a web application that can gain access to a database.
Dockerfile -> Required to create a customized image required by a container
docker-compose.yml -> Compose file required to create and start the multiple containers required by the application
sql -> SQL scripts required to create databases, tables and registers.
data -> Directory where the application database will be stored

Run the following command in the directory where the .yml file is stored: docker compose up -d --build
Run docker compose ps -a and check that 2 new container were created and started and that their status are Up
Run docker images and check that a new image was created and two images were downloaded from DockerHub.
Find the password for root user of the MySQL server in the docker-compose.yml file.
Gain access to the container running mysql and add databases, tables and registers required by the application. Run the following commands:

docker exec -it msyql_sm1act11q3 bash -> Gaining access to the docker container
mysql -u root -p --> Gaining access to the MySQL running in the docker container
source /sql/bd.sql --> Creating database, table and registers required by the application
use bd_sm1act11q3; --> Select database bd_sm1act11q3.
select * from users_sm1act11q3; -> Show all registers of table users_sm1act11q3 which is located in database bd_sm1act11q3.
quit --> Exit MySQL and go back to the docker container
exit --> Exit the docker container and fo back to the operating system.

Check the ip address of your virtual machine.
Finally, gain access to the web application from your host machine using the following URL: http://<ip_address_of_your_virtual_machine>:8080
Check that the web application works properly.

e) In order to stop the multi-container a web application created and started in the previous example:

Gain access to projects -> sm1act11q3.
Run the following command: docker compose stop
Run docker compose ps -a and check that containers were stopped.
Check that the application is not available.

f) In order to start again the multi-container a web application previously stopped:

Gain access to projects -> sm1act11q3.
Run the following command: docker compose start
Run docker compose ps -a and check that containers were created and started again.
Check that the application is available again.

g) In order to stop and remove the multi-container web application:

Gain access to projects -> sm1act11q3.
Run the following command: docker compose down
Run docker compose ps -a and check that containers were removed.
Check that the application is not available any longer.

PRACTICAL EXERCISE

PART 1

1.- Install docker on your system and add your default user to the group docker. Show clearly that:

Your default user is member of group docker.
Service docker is active, running and enabled.
Version of the management utility docker.

2.- Create and run a containerized web application:

Create a folder called sm1act11q1.
Create a folder called app in sm1act11q1. Gain access to app and download index.php and CostFabLlaBeg.php available in the following addresses:

wget https://github.com/globproj2/CostFabLlauBeg/raw/main/index.php
wget https://github.com/globproj2/CostFabLlauBeg/raw/main/CostFabLlauBeg.php

Change to folder sm1act11q1 again. Create and edit a Dockerfile with the following features:

The base image for your new image will be: php:8.4-apache
The default work directory on the new image will be /var/www/html.
The contents of app in your virtual machine will be are copied to the default work directory of your the new image container image.
Exposes port 80 of any container created with the new image.

Create a container image of your web application called img_sm1act11q1 version 1.0.
Create a new container to run your web application.

The container name cont_sm1act11q1.
The container runs in the background
The container publishes internal exposed port 80 to port 18000 in your virtual machine
The container can be accessed with the help of its internal bash

Check that a new container has been created on your system.
Gain access to the container and check index.html and CostFabLlauBeg.php were copied to /var/www/html.
Check the ip address of your virtual machine.
Gain access to the web application from your host machine.

3- Checking PART 1:

Display image img_sm1act11
Display container cont_sm1act11q1. If it works and it is running then, its status is Up.
Stop container cont_sm1act11q1. Check that the container was stopped.
Start container cont_sm1act11q1. Check that the container is running.
Gain access to the container and check index.html and CostFabLlauBeg.php were copied to /var/www/html.
Check the ip address of your virtual machine and gain access to the web application.
Check that the web application works properly.
Stop the container cont_sm1act11q1. Afterwards, remove the container. Check that the container does not exists any longer.
Remove the image img_sm1act11q1. Check that the image does not exists any longer.

PART 2

1.- Create a folder called sm1act11p2. Change to sm1act11q2 and create a folder called nr_data.

2.- Download an image of an application called node-red from a repository called nodered/node-red using docker pull.

3.- Create a docker container with the following characteristics:
a) Name: nr
b)
c) Container runs in the background
d) Container exposes and publish internal port 1880 to por 1880 in the virtual machine.
e) Folder ./nr_data of the host machine shares date with folder /data of the docker container.
f) Container is created from image nodered/node-red.

4.- Check the list of available volumes on your system running: docker inspect nr | grep nr_data

5- Check the IP address of your virtual machine.

6- Access node-red using a web browser from your physical computer. In the address bar type: http://<ip_address_of_your_virtual_machine>:1880 where <ip_address_of_your_virtual_machine> is the IP address found in point 4.

7- Checking PART 2:

Display container nr. If it works and it is running then, its status is Up.
Check the list of available volumes on your system,
Access node-red.
Stop container nr. Check that the node-red is not working.
Start container nr. Check that the node-red is working again

PART 3

1.- Follow steps in section DOCUMENTATION - Point 9: How to containerize, deploy and gain access to a multi-container web application. Working with Docker compose and deploy the application sm1act11q3.

2- Checking PART 3:

Access the application and check that it works.
Stop the application and check that is not working.
Start the application again and check that it works again.
Stop and remove the applications and check:

that it is not working any longer
the containers were removed