The author selected the Electronic Frontier Foundation to receive a donation as part of the Write for DOnations program.

Introduction

Code quality is an approximation of how useful and maintainable a specific piece of code is. Quality code will make the task of maintaining and expanding your application easier. It helps ensure that fewer bugs are introduced when you make required changes in the future.

SonarQube is an open-source tool that assists in code quality analysis and reporting. It scans your source code looking for potential bugs, vulnerabilities, and maintainability issues, and then presents the results in a report which will allow you to identify potential issues in your application.

The SonarQube tool consists of two sub-applications: an analysis engine, which is installed locally on the developer's machine, and a centralized server for record-keeping and reporting. A single SonarQube server instance can support multiple scanners, enabling you to centralize code quality reports from many developers in a single place.

In this guide, you will deploy a SonarQube server and scanner to analyze your code and create code quality reports. Then you'll perform a test on your machine by scanning it with the SonarQube tool.

Prerequisites

Before you begin this guide you'll need the following:

• One Ubuntu 16.04 server with 2GB or more memory set up by following this Ubuntu 16.04 initial server setup tutorial, including a sudo non-root user and a firewall.
• Oracle Java 8 installed on the server, configured by following the Oracle JDK section in this Oracle JDK installation tutorial.
• Nginx and MySQL, configured by following the Nginx and MySQL sections in this LEMP installation guide.
• Certbot (the Let's Encrypt client), configured by following How to Set Up Let's Encrypt with Nginx server blocks on Ubuntu 16.04.
• A fully-qualified domain name and an A record pointing to the server where you'll install SonarQube. If you're using DigitalOcean's DNS service, this DNS record setup guide will help you set that up. We'll use sonarqube.example.com in this tutorial.

Step 1 — Preparing for the Install

There are a few steps we'll need to do before we install SonarQube. As SonarQube is a Java application that will run as a service, and because running services as the root user is certainly not ideal, we'll create another system user specifically to run the SonarQube services. Then we'll create the installation directory and set its permissions, and then we'll create a MySQL database and user for SonarQube.

First, create a sonarqube user:

sudo adduser --system --no-create-home --group --disabled-login sonarqube

We'll only use this user to run the SonarQube service, so we create a system user that can't log in to the server directly.

Next, create the directory that will hold the SonarQube files:

sudo mkdir /opt/sonarqube

Once the directory is created, update the permissions so that the sonarqube user will be able to read and write files in this directory:

sudo chown -R sonarqube:sonarqube /opt/sonarqube

SonarQube releases are packaged in a zipped format, so install the unzip utility using your package manager so you can extract the distribution files:

sudo apt-get install unzip

Next, we need to create a database and credentials that SonarQube will use. Log in to the MySQL server as the root user:

mysql -u root -p

Then create the SonarQube database:

CREATE DATABASE sonarqube;
EXIT;

Now create the credentials that SonarQube will use to access the database.

CREATE USER sonarqube@'localhost' IDENTIFIED BY 'some_secure_password';
GRANT ALL ON sonarqube.* to sonarqube@'localhost';

Then grant permissions so that the newly-created user can make changes to the SonarQube database:

GRANT ALL ON sonarqube.* to sonarqube@'localhost';

Then apply the permission changes and exit the MySQL console:

FLUSH PRIVILEGES;
EXIT;

Now that we've got the user and directory in place, let's download and install SonarQube itself.

Step 2 - Downloading and Installing SonarQube

Start by changing the current working directory to the SonarQube installation directory:

cd /opt/sonarqube

Then, head over to the SonarQube downloads page and grab the download link for SonarQube 7.0. There are two versions of SonarQube available for download on the page, but in this specific tutorial we'll be using SonarQube 7.0.

After getting the link, download the file:

sudo wget https://sonarsource.bintray.com/Distribution/sonarqube/sonarqube-7.0.zip

Then unzip the file:

sudo unzip sonarqube-7.0.zip

Once the files extract, delete the downloaded zip file, as you no longer need it:

sudo rm sonarqube-7.0.zip

Now that all the files are in place, it's time to configure SonarQube.

Step 3 - Configuring the SonarQube Server

We'll need to edit a few things in the SonarQube configuration file. Namely:

• We need to specify the username and password that the SonarQube server will use for the database connection.
• We also need to tell SonarQube to use MySQL for our backend database.
• We'll tell SonarQube to run in server mode, which will yield improved performance.
• We'll also tell SonarQube to only listen on the local network address since we will be using a reverse proxy.

Start by opening the SonarQube configuration file:

sudo nano sonarqube-7.0/conf/sonar.properties

First, change the username and password that SonarQube will use to access the database to the username and password you created for MySQL:

    ...

    sonar.jdbc.username=sonarqube
    sonar.jdbc.password=some_secure_password

    ...

Next, tell SonarQube to use MySQL as the database driver:

    ...

    sonar.jdbc.url=jdbc:mysql://localhost:3306/sonarqube?useUnicode=true&characterEncoding=utf8&rewriteBatchedStatements=true&useConfigs=maxPerformance&useSSL=false

    ...

Finally, tell SonarQube to run in server mode and only listen to the local address:

    ...

    sonar.web.host=127.0.0.1
    sonar.web.javaAdditionalOpts=-server

Once those fields have been updated, save and close the file.

Next, we'll configure the SonarQube server to run as a service so that it starts automatically when the server reboots.

Create the service file:

sudo nano /etc/systemd/system/sonarqube.service

Add the following content to the file which specifies how the SonarQube service should start and stop:

[Unit]
Description=SonarQube service
After=syslog.target network.target

[Service]
Type=forking

ExecStart=/opt/sonarqube/sonarqube-7.0/bin/linux-x86-64/sonar.sh start
ExecStop=/opt/sonarqube/sonarqube-7.0/bin/linux-x86-64/sonar.sh stop

User=sonarqube
Group=sonarqube
Restart=always

[Install]
WantedBy=multi-user.target

You can learn more about systemd unit files in Understanding Systemd Units and Unit Files.

Close and save the file, then start the SonarQube service:

sudo service sonarqube start

Check the status of the SonarQube service to ensure that it has started and is running as expected:

service sonarqube status

If the service has successfully started, you'll see a line that says "Active" similar to this:

● sonarqube.service - SonarQube service
   Loaded: loaded (/etc/systemd/system/sonarqube.service; enabled; vendor preset
   Active: active (running) since Sun 2018-03-04 01:29:44 UTC; 1 months 14 days

Next, configure the SonarQube service to start automatically on boot:

sudo systemctl enable sonarqube

As with most other Java applications, SonarQube will take some time to initialize. Once the initialization process is complete, you can move on to the next step.

Step 4 - Configuring the Reverse Proxy

Now that we've got the SonarQube server running, it's time to configure Nginx, which will be the reverse proxy and HTTPS terminator for our SonarQube instance.

Start by creating a new Nginx configuration file for the site:

sudo nano /etc/nginx/sites-enabled/sonarqube

Add this configuration so that Nginx will be able to route incoming traffic to SonarQube:

server {
    listen 80;
    server_name sonarqube.example.com;

    location / {
        proxy_pass http://127.0.0.1:9000;
    }
}

Save and close the file.

Next, make sure your configuration file has no syntax errors:

sudo nginx -t

If you see errors, fix them and run sudo nginx -t again. Once there are no errors, restart Nginx:

sudo service nginx restart

For a quick test, you can now visit http://sonarqube.example.com in your web browser. You'll be greeted with the SonarQube web interface.

Now we'll use Let's Encrypt to create HTTPS certificates for our installation so that data will be securely transferred between the server and your local machine. Use certbot to create the certificate for Nginx:

sudo certbot --nginx -d sonarqube.example.com

If this is your first time requesting a Let's Encrypt certificate, Certbot will prompt for your email address and EULA agreement. Enter your email and accept the EULA.

Certbot will then ask how you'd like to configure your security settings. Select the option to redirect all requests to HTTPS, ensuring that any requests sent to your server will be encrypted.

Now that we're done setting up the reverse proxy, we can move on to securing our SonarQube server.

Step 5 - Securing SonarQube

SonarQube ships with a default administrator username and password of admin. This default password is not secure, so we'll want to update it to something more secure as a good security practice.

Start by visiting the URL of your installation, and log in using the default credentials.

Once logged in, click the Administration tab, select Security from the dropdown list, and then select Users:

From here, click on the small cog on the right of the "administrator" account row, then click on "Change password". Be sure to change the password to something that's easy to remember but hard to guess.

Now create a normal user that you can use to create projects and submit analysis results to your server from the same page. Click on the Create User button on the top-right of the page:

Then create a token for a specific user by clicking on the button in the "Tokens" column and giving this token a name. You'll need this token later when you invoke the code scanner, so be sure to write it down in a safe place.

Finally, you may notice that the SonarQube instance is wide-open to the world, and anyone could view analysis results and your source code.
This setting is highly insecure, so we'll configure SonarQube to only allow logged-in users access to the dashboard. From the same administration tab, click on Configuration, then Security on the left pane. Flip the switch on this page to require user authentication.

Now that we're done setting up our server, let's set up the scanner.

Step 6 - Setting up the Code Scanner

SonarQube's code scanner is a separate package that you can install on a different machine than the one running the SonarQube server, such as your local development workstation or a continuous delivery server. There are packages available for Windows, MacOS, and Linux which you can find at the SonarQube web site

In this tutorial, we'll install the code scanner on the same server that hosts our SonarQube server.

Start by creating a directory for the scanner and changing into the new directory:

sudo mkdir /opt/sonarscanner
cd /opt/sonarscanner

Then download the SonarQube scanner for Linux using wget:

sudo wget https://sonarsource.bintray.com/Distribution/sonar-scanner-cli/sonar-scanner-cli-3.0.3.778-linux.zip

Extract the scanner, then delete the zip archive file:

sudo unzip sonar-scanner-cli-3.0.3.778-linux.zip
sudo rm sonar-scanner-cli-3.0.3.778-linux.zip

After that, we'll need to modify a few settings to get the scanner working with our server install. Open the configuration file for editing:

sudo nano sonar-scanner-3.0.3.778-linux/conf/sonar-scanner.properties

First, tell the scanner where it should submit the code analysis results. Uncomment the line starting with sonar.host.url and set it to the URL of your SonarQube server:

    sonar.host.url=https://sonarqube.example.com

Save and close the file. Now make the scanner binary executable:

sudo chmod +x sonar-scanner-3.0.3.778-linux/bin/sonar-scanner

Then create a symbolic link so that you can call the scanner without specifying the path:

sudo ln -s /opt/sonarscanner/sonar-scanner-3.0.3.778-linux/bin/sonar-scanner /usr/local/bin/sonar-scanner

Now that the scanner is set up, we're ready to run our first code scan.

Step 7 - Running a Test Scan

If you'd like to just poke around with SonarQube to see what it can do, you might consider running a test scan on the SonarQube example projects. These are example projects created by the SonarQube team that contains many issues that SonarQube will then detect and report.

Creating a new working directory in your home directory, then change to the directory:

cd ~
mkdir sonar-test && cd sonar-test

Download the example project:

wget https://github.com/SonarSource/sonar-scanning-examples/archive/master.zip

Unzip the project and delete the archive file:

unzip master.zip
rm master.zip

Next, switch to the example project directory:

cd sonar-scanning-examples-master/sonarqube-scanner

Run the scanner, passing it the token you created earlier:

sonar-scanner -D sonar.login=your_token_here

Once the scan is complete, you'll see something like this on the console:

INFO: Task total time: 9.834 s
INFO: ------------------------------------------------------------------------
INFO: EXECUTION SUCCESS
INFO: ------------------------------------------------------------------------
INFO: Total time: 14.076s
INFO: Final Memory: 47M/112M
INFO: ------------------------------------------------------------------------

The example project's report will now be on the SonarQube dashboard like so:

Now that you've confirmed that both the SonarQube server and scanner works as expected, you can put SonarQube to work analyzing your own code.

Transfer your project to the server, or follow the steps in Step 6 to install and configure the SonarQube scanner on your workstation and configure it to point to your SonarQube server.

Then, in your project's root directory, create a SonarQube configuration file:

nano sonar-project.properties

You'll use this file to tell SonarQube a few things about your project:

First, define a project key, which is a unique ID for the project. You can use anything you'd like, but this ID must be unique for your SonarQube instance:

    # Unique ID for this project
    sonar.projectKey=foobar:hello-world

    ...

Then, specify the project name and version so that SonarQube will be able to display this information in the dashboard:

    ...

    sonar.projectName=Hello World Project
    sonar.projectVersion=1.0

    ...

Finally, tell SonarQube where to look for the code files itself. Note that this is relative to the directory that the configuration file resides. Set it to the current directory:

    # Path is relative to the sonar-project.properties file. Replace "\" by "/" on Windows.
    sonar.sources=.

Close and save the file.

You're ready to run a code quality analysis on your own code. Run sonar-scanner again, passing it your token:

sonar-scanner -D sonar.login=your_token_here

Once the scan is complete, you'll see a summary screen similar to this:

INFO: Task total time: 5.417 s
INFO: ------------------------------------------------------------------------
INFO: EXECUTION SUCCESS
INFO: ------------------------------------------------------------------------
INFO: Total time: 9.659s
INFO: Final Memory: 39M/112M
INFO: ------------------------------------------------------------------------

And the project's code quality report will now be on the SonarQube dashboard.

Conclusion

In this tutorial, you've set up a SonarQube server and scanner for code quality analysis. Now you could make sure that your code is easy to maintain and easily maintainable by simply running a scan - SonarQube will tell you where the potential problems might be!

From here, you might want to read the SonarQube Scanner documentation to learn how to run analysis on your local development machine or as part of your build process.