Dockers & Devops

• Installation of Nginx on Ubuntu
• Nginx with Let's Encrypt
• Flask Docker Image
• Reverse Proxy For Window Server
• Jenkins
• Jenkins-Adding Ubuntu Agent

Installation of Nginx on Ubuntu

Introduction

Nginx is one of the most popular web servers in the world and is responsible for hosting some of
the largest and highest-traffic sites on the internet. It is more resource-friendly than Apache in
most cases and can be used as a web server or reverse proxy.
In this guide, we’ll explain how to install Nginx on your Ubuntu 18.04 server and use that as a reverse proxy for microservices created in flask and other applications.

Prerequisites

Before you begin this guide, you should have the following:
An Ubuntu 18.04 server and a regular, non-root user with sudo privileges. Additionally, you
will need to enable a basic firewall to block non-essential ports. You can learn how to
configure a regular user account and set up a firewall by following our initial server setup
guide for Ubuntu 18.04.

https://www.digitalocean.com/community/tutorials/initial-server-setup-with-ubuntu-18-04

Step 1 – Installing Nginx

You can install it using the apt packaging system.

Update your local package index:

sudo apt update

sudo apt install nginx

Step 2 – Adjusting the Firewall

sudo ufw app list

Output
    Available applications:
    Nginx Full
    Nginx HTTP
    Nginx HTTPS
    OpenSSH

permitting traffic on port 80 :

sudo ufw allow 'Nginx HTTP'

Verify the change:

Output
Status: active
To 				Action 		From
-- 				------ 		----
OpenSSH 		ALLOW 		Anywhere
Nginx HTTP 		ALLOW 		Anywhere
OpenSSH (v6) 	ALLOW 		Anywhere (v6)
Nginx HTTP (v6) ALLOW 		Anywhere (v6)

Step 3 – Checking your Web Server

systemctl status nginx

Finally access your website using your localIP address.

http://your_server_ip

You should see the default Nginx landing page:

Conclusion

Now you have installed Ngix server on your Ubuntu. Now you can do the following steps.

1. Server Blocking which I will explain in other chapter.
2. Install Letsencrypt for Https Access.
3. Use this as reverse proxy for your existing webservice such as flask etc..
4. Host your website in Ngix.

Nginx with Let's Encrypt

Introduction

In this tutorial we will discuss about installing certbot on ubuntu to install Let's Encrypt SSL on to your ubuntu server.

Prerequisites

Before we start you need to make sure you have followings:

1. Your own domain for example ( www.example.com)
2. DNS management credentials.
3. Update A records in DNS, your A records should look like below.
   1.  A --- > www.example.com ---> 103.x.x.x (your public IP)
   2.  A --- > example.com ---> 103.x.x.x (your public IP)

Let's Encrypt can be installed for the subdomain to. I have personally tried that and it was working fine.

In case you want to do it for subdomain your A records should look like below.

1. 1. A ---> subdomain.example.com --- > 103.x.x.x (your public IP)

Step 1 — Installing Certbot

We will be using Certbot to install Let's Encrypt, Lets start by adding the repository.

First, add the repository:

sudo add-apt-repository ppa:certbot/certbot

Install Certbot’s Nginx package with apt:

sudo apt install python-certbot-nginx

Now Certbot is ready, before we proceed we need to do some configuration on Nginx server default file.

Open the Nginx default website file.

sudo nano /etc/nginx/sites-available/default

Flask Docker Image

Introduction

Please note use lowercase for all the folder names. In my case I have created a folder "DOCKER" on my folder where all my docker images will be created.

Go to /home/snk/dockers/

Create a directory with the application name for example allclaims

Place *.py , Dockerfile and Requirement.txt

Step 1 - Stop Docker Container (If Any)

docker container ps

Take the correct container id and stop it

docker container stop  Name_of_the_container

Remove the container 

docker container rm Name_of_the_container

Build the container using container build command

docker build -t name_of_the_image:latest .

Run the container & expose port to use it in the Nginx reverse proxy.

docker run -it -d -p 5000:5000 name_of_the_image

Step 2 - Proxy pass in Nginx server

Use the default site file, in case if you don't use the server blocking, else use the respective server file in Nginx server.

sudo nano /etc/nginx/sites-available/default

Add the location with application name and its corresponding dockers port and path as shown bellow.

        location /allclaims/ {
                proxy_pass   http://103.4.6.220:5000/;
        }

Restart the Nginx server to changes to reflect.

sudo systemctl reload nginx

Information 

Most of the time when you run docker images inside the proxy you might end up with improper CSS or site load, in that case always use  environment variable of APP_URL, check each application for more information on the same

 Example while running the docker use the following command along with run statement. 

" -e APP_URL=https://docker2.auto-boxe.com/book "

Reverse Proxy For Window Server

To do reserve proxy for window server we need to do the following steps.

Create a website, in our case it is STAGE, with in the stage we created Application called Jaya-stage.

Please note that this application name is very important we need to create reverse proxy with the same name in Nginx server in ubuntu.

Next step to create a reverse proxy configuration on Nginx server as shown below. 

## ALLCLAIMS STAGElocation /jaya-stage/ {
	proxy_pass "http://192.168.204.18:9000/jaya-stage/";
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
    add_header X-Frame-Options SAMEORIGIN;
    add_header X-Content-Type-Options nosniff;
    add_header X-XSS-Protection "1; mode=block";c
    lient_max_body_size 2m;client_body_timeout 120s; # Default is 60, May need to be increased for very large uploads
 }

https://docker2.auto-boxe.com/jaya-stage/

Jenkins

Introduction

On this method we have created a Node on the stage or production server where we need our code to get deployed (Windows). This is basically to avoid using FTP or SFTP for code deployment as it might take more time and also we need credentials and FTP servers for the deployment

Step 1 - Create a Freestyle project ( Please refer Jenkins for creating different project type )

Step 2 - SVN or GIT connection as per your requirement.

You got to install Visual Studio Build on the respective Node Server for us to create the Build Step. Use Visual Studio community version.

Step 3 - Build.

Step 4 - ROBOCOPY or Deploy the code to the IIS.

set SOURCE=D:\jenkins\workspace\COLS365_Web_Application\Branch\DskyWebPortal\
set DESTINATION=C:\Hostingdata\DEVL\ColsWebPortal
set EXCLUDEFOLDER="D:\jenkins\workspace\COLS365_Web_Application\Branch\DskyWebPortal\fileupload"


robocopy /XO /E /Z /ZB /R:5 /W:5 /TBD /NP /MT:64 %SOURCE% %DESTINATION% /XD %EXCLUDEFOLDER% *. /XA:SH /XF *.CONFIG *.config *.svn-base
@echo robocopy exit code: %ERRORLEVEL%
@if %ERRORLEVEL% GTR 3 ( echo robocopy ERROR )
@if %ERRORLEVEL% GTR 3 ( exit %ERRORLEVEL% )
@set ERRORLEVEL=0

Jenkins-Adding Ubuntu Agent

sudo mkdir -p /usr/local/jenkin-service

sudo chown admin /usr/local/jenkin-service

cd /usr/local/jenkin-service

Execute the curl command from the Jenkins  -- below is the example only

curl -sO https://jenkins.issentialsolutions.com/jnlpJars/agent.jar

nano start-agent.sh

#1/bin/bash
cd /usr/local/jenkin-service
curl -sO https://jenkins.issentialsolutions.com/jnlpJars/agent.jar
java -jar agent.jar -url https://jenkins.issentialsolutions.com/ -secret 23569a2d25d3cf47de3950ea382db7f448d3f15e417cbf10562a1abf91f72453 -name "IS-IVH1-Ubuntu" -webSocket -workDir "/home/jenkins"
exit 0

chmod +x start-agent.sh

Create an another file jenkin-agent.service

nano /etc/systemd/system/jenkin-agent.service

[unit]
Description=Jenkin Agent

[Service]
User=admin
WorkingDirectory=/home/jenkins
ExecStart=/bin/bash /usr/local/jenkin-service/start-agent.sh
Restart=alwalys

[Install]
WantedBy=multi-user.target

sudo systemctl enable jenkin-agent.service

Before Enabling the agent, Install the Java

sudo apt install software-properties-common apt-transport-https -y
sudo add-apt-repository ppa:openjdk-r/ppa -y

sudo apt install openjdk-22-jdk -y