How to Install Omeka Classic 2.4 CMS on a CentOS 7 LAMP VPS

How to Install Omeka Classic CMS on a CentOS 7? Omeka Classic 2.4 CMS is a free and open source digital publishing platform and Content Management System (CMS) for sharing digital collections and creating media-rich online exhibits.

Omeka Classic 2.4 CMS enables scholars, librarians, archivists, museum professionals and cultural enthusiasts to create complex narratives and share rich collections and content at low cost without sacrificing design and technical quality.

Omeka accepts and stores all types of files, including images, video, audio, multi-page documents, PDFs, Power Point presentations; and can handle large archives of metadata and files (with over 1 million items) with the only limitations being the power of your server.

In this tutorial we are going to install Omeka Classic CMS on a CentOS 7 LAMP VPS using Apache web server, PHP 7.1, and a MariaDB database.

Prerequisites

• A clean CentOS 7 server instance with SSH access

How to Install Omeka Classic CMS on a CentOS 7

Step 1: Add a Sudo User

We will start by adding a new sudo user.

First, log into your server as root:

ssh root@YOUR_VULTR_IP_ADDRESS

Add a new user called user1 (or your preferred username):

useradd user1

Next, set the password for the user1 user:

passwd user1

When prompted, enter a secure and memorable password.

Now check the /etc/sudoers file to make sure that the sudoers group is enabled:

visudo

Look for a section like this:

%wheel        ALL=(ALL)       ALL

This line tells us that users who are members of the wheel group can use the sudo command to gain root privileges. It will be uncommented by default so you can simply exit the file.

Next we need to add user1 to the wheel group:

usermod -aG wheel user1

We can verify the user1 group membership and check that the usermod command worked with the groups command:

groups user1

Now use the su command to switch to the new sudo user user1 account:

su - user1

The command prompt will update to indicate that you are now logged into the user1 account. You can verify this with the whoami command:

whoami

Now restart the sshd service so that you can login via ssh with the new non-root sudo user account you have just created:

sudo systemctl restart sshd

Exit the user1 account:

exit

Exit the root account (which will disconnect your ssh session):

exit

You can now ssh into the server instance from your local host using the new non-root sudo user user1 account:

ssh user1@YOUR_VULTR_IP_ADDRESS

If you want to execute sudo without having to type a password every time, then open the /etc/sudoers file again, using visudo:

sudo visudo

Edit the section for the wheel group so that it looks like this:

%wheel        ALL=(ALL)       NOPASSWD: ALL

Please note: Disabling the password requirement for the sudo user is not a recommended practice, but it is included here as it can make server configuration much more convenient and less frustrating, especially during longer systems administration sessions. If you are concerned about the security implications, you can always revert the configuration change to the original after you finish your administration tasks.

Whenever you want to log into the root user account from within the sudo user account, you can use one of the following commands:

sudo -i
sudo su -

You can exit the root account and return back to your sudo user account any time by simply typing the following:

exit

Step 2: Update CentOS 7 System

Before installing any packages on the CentOS server instance, we will first update the system.

Make sure you are logged in to the server using a non-root sudo user and run the following command:

sudo yum -y update

Step 3: Install Apache Web Server

Install the Apache web server:

sudo yum -y install httpd

Then use the systemctl command to start and enable Apache to execute automatically at boot time:

sudo systemctl enable httpd
sudo systemctl start httpd

Check your Apache configuration file to ensure that the DocumentRoot directive points to the correct directory:

sudo vi /etc/httpd/conf/httpd.conf 

The DocumentRoot configuration option will look like this:

DocumentRoot "/var/www/html"

Now, let’s make sure that the mod_rewrite Apache module is loaded. We can do this by searching the Apache base modules configuration file for the term “mod_rewrite“.

Open the file:

sudo vi /etc/httpd/conf.modules.d/00-base.conf

Search for the term mod_rewrite.

If the mod_rewrite Apache module is loaded, you will find a configuration line looking like this:

LoadModule rewrite_module modules/mod_rewrite.so

If the above line starts with a semi-colon, you will need to remove the semi-colon to uncomment the line and load the module. This, of course, applies to any other required Apache modules too.

We now need to edit Apache’s default configuration file so that mod_rewrite will work correctly with Omeka Classic CMS.

Open the file:

sudo vi /etc/httpd/conf/httpd.conf

Then find the section that starts with <Directory "/var/www/html"> and change AllowOverride none to AllowOverride All. The end result (with all comments removed) will look something like this:

<Directory "/var/www/html">
    Options Indexes FollowSymLinks
    AllowOverride All
    Require all granted
</Directory>

Now save and close the Apache configuration file.

We will restart Apache at the end of this tutorial, but restarting Apache regularly during installation and configuration is certainly a good habit, so let’s do it now:

sudo systemctl restart httpd

Step 4: Open Web Firewall Ports

We now need to open the default HTTP and HTTPS ports as they will be blocked by firewalld by default.

Open the firewall ports:

sudo firewall-cmd --permanent --add-port=80/tcp
sudo firewall-cmd --permanent --add-port=443/tcp

Reload the firewall to apply the changes:

sudo firewall-cmd --reload

You will see the word success displayed in your terminal after each successful firewall configuration command.

We can quickly verify that the Apache HTTP port is open by visiting the IP address or domain of the server instance in a browser:

http://YOUR_VULTR_IP_ADDRESS/

You will see the default Apache web page in your browser.

Step 5: Disable SELinux (if enabled)

SELinux stands for “Security Enhanced Linux”. It is a security enhancement to Linux which allows users and administrators more control over access control. It is disabled by default on Vultr CentOS 7 instances, but we will cover the steps to disable it, just in case you are not starting from a clean install and it was previously enabled.

To avoid file permission problems with Omeka Classic CMS we need to ensure that SELinux is disabled.

First, let’s check whether SELinux is enabled or disabled with the sestatus command:

sudo sestatus

If you see something like: SELinux status: disabled then it is definitely disabled and you can skip straight to Step 6. If you see any other message, then you will need to complete this section.

Open the SELinux configuration file with your favourite terminal editor:

sudo vi /etc/selinux/config

Change SELINUX=enforcing to SELINUX=disabled and then save the file.

To apply the configuration change, SELinux requires a server reboot, so you can either restart the server using the Vultr control panel or you can simply use the shutdown command:

sudo shutdown -r now

When the server reboots, your SSH session will get disconnected and you may see a message informing you about a 'broken pipe' or 'Connection closed by remote host'. This is nothing to worry about, simply wait for 20 seconds or so and then SSH back in again (with your own username and domain):

ssh user1@YOUR_DOMAIN

Or (with your own username and IP address):

ssh user1@YOUR_VULTR_IP_ADDRESS

Once you have logged back in, you should check the status of SELinux again with the sestatus command to make sure it is properly disabled:

sudo sestatus

You should see a message saying SELinux status: disabled. If you see a message saying SELinux status: enabled (or something similar) you will need to repeat the above steps and ensure that you properly restart your server.

Step 6: Install PHP 7.1

CentOS 7 requires us to add an external repo in order to install PHP 7.1, so run the following command:

sudo rpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm

We can now install PHP 7.1 along with all of the necessary PHP modules required by Omeka Classic CMS:

sudo yum -y install php71w php71w-gd php71w-mbstring php71w-mysql php71w-xml php71w-common php71w-pdo php71w-mysqlnd

Step 7: Install MariaDB (MySQL) Server

CentOS 7 defaults to using MariaDB database server, which is an enhanced, fully open source, community developed, drop-in replacement for MySQL server.

Install MariaDB database server:

sudo yum -y install mariadb-server

Start and enable MariaDB server to execute automatically at boot time:

sudo systemctl enable mariadb
sudo systemctl start mariadb    

Secure your MariaDB server installation:

sudo mysql_secure_installation

The root password will be blank, so simply hit enter when prompted for the root password.

When prompted to create a MariaDB/MySQL root user, select “Y” (for yes) and then enter a secure root password. Simply answer “Y” to all of the other yes/no questions as the default suggestions are the most secure options.

Step 8: Create Database for Omeka Classic CMS

Log into the MariaDB shell as the MariaDB root user by running the following command:

sudo mysql -u root -p

To access the MariaDB command prompt, simply enter the MariaDB root password when prompted.

Run the following queries to create a MariaDB database and database user for Omeka Classic CMS:

CREATE DATABASE omeka_db CHARACTER SET utf8 COLLATE utf8_general_ci;
CREATE USER 'omeka_user'@'localhost' IDENTIFIED BY 'UltraSecurePassword';
GRANT ALL PRIVILEGES ON omeka_db.* TO 'omeka_user'@'localhost';
FLUSH PRIVILEGES;
EXIT;

You can replace the database name omeka_db and username omeka_user with something more to your liking, if you prefer. (Please note that the default maximum length for usernames in MariaDB on CentOS 7 is 16 characters). Also, make sure that you replace “UltraSecurePassword” with an actually secure password.

Step 9: Install Omeka Classic CMS Files

Change your current working directory to the default web directory:

cd /var/www/html/

If you get an error message saying something like 'No such file or directory' then try the following command:

cd /var/www/ ; sudo mkdir html ; cd html

Your current working directory will now be: /var/www/html/. You can check this with the pwd (print working directory) command:

pwd

Now use wget to download the Omeka Classic CMS installation package:

sudo wget https://github.com/omeka/Omeka/releases/download/v2.5.1/omeka-2.5.1.zip

Please note: You should definitely check for the most recent version by visiting the Omeka Classic CMS download page.

List the current directory to check that you have successfully downloaded the file:

ls -la

Let’s quickly install unzip so we can unzip the file:

sudo yum -y install unzip

Now uncompress the zip archive:

sudo unzip omeka-2.5.1.zip

Move all of the installation files to the web root directory:

sudo mv omeka-2.5.1/* /var/www/html

Change ownership of the web files to avoid any permissions problems:

sudo chown -R apache:apache * ./

Restart Apache again:

sudo systemctl restart httpd

Now we’re ready to move on to the final step.

Step 10: Install ImageMagick

Omeka Classic CMS requires ImageMagick to process images so let’s make sure that it is installed:

sudo yum -y install ImageMagick

Step 11: Complete Omeka Classic CMS Installation

1. To complete the Omeka Classic CMS installation, we first need to edit the Omeka Classic CMS database configuration file, so first make sure you are in the webroot and then open the db.ini file:

   sudo vi ./db.ini
   

   Replace the XXXXXXX values with your database configuration details, as follows:

   [database]
   host     = "localhost"
   username = "omeka_user"
   password = "UltraSecurePassword"
   dbname   = "omeka_db"
   prefix   = "omeka_"
   charset  = "utf8"
   ;port     = ""
   

   Once you have added the appropriate configuration values you can save and exit the configuration file.

2. Now visit the IP address of your server instance in your browser, or if you’ve already configured your Vultr DNS settings (and given it enough time to propagate) you can simply visit your domain instead.

   To access the Omeka Classic CMS installation page, enter your Vultr instance IP address into your browser address bar, followed by /install/:

       http://YOUR_VULTR_IP_ADDRESS/install/
   

3. On the Omeka Configure Your Site page, enter the following Default Superuser Account:

   Username:               <superuser username>
   Password:               <a secure password>
   Email:                  <superuser email address>
   

4. Next, enter the following Site Settings:

   Administrator Email:    <administrator email>
   Site Title:             <the title off the site>
   

   You can leave the rest of the Site Settings at their default values or you can edit them to suit your personal requirements.

5. When you are satisfied with the above site configuration details, click Install to finalize the installation.

You will be redirected to a Success page.

To access the admin section simply click on the Admin Dashboard button and enter your username and password. If you aren’t redirected to the admin login page, you can enter the admin address manually:

http://YOUR_VULTR_IP_ADDRESS/admin/

You are now ready to start adding your content and configuring your materials and collections. Make sure you check out the excellent Omeka Classic CMS documentation for more information about how to build and configure your site.