How to Install Varnish Cache?

Introduction to Varnish Cache

Varnish Cache is an open-source web application accelerator designed to improve website performance by caching (storing) frequently accessed content in memory. This allows the server to quickly serve content to users without having to retrieve it from the database or other external sources every time. The benefits of Varnish Cache include reduced server load, quicker response times for users, and improved website scalability during high-traffic periods. It also helps improve website speed and overall performance, which can ultimately lead to a better user experience and higher search engine rankings.

Understanding Varnish Cache Requirements

Varnish Cache can be installed on a variety of operating systems, including Linux, FreeBSD, and macOS. The following are the system requirements for installing Varnish Cache on a server:

• Operating System: Varnish Cache supports various Linux distributions such as Ubuntu, CentOS, Debian, and Red Hat Enterprise Linux. Support for other operating systems includes FreeBSD and macOS.

• Web Server: Varnish Cache requires a functioning web server, such as Apache or NGINX, to be installed and configured. Varnish Cache can run on both Apache and NGINX web servers, but Apache is the recommended web server.

• Processor and Memory: Varnish Cache does not require a high-end server to run efficiently. It can run on a server with at least 256MB of RAM, but a minimum of 512MB is recommended for better performance. As for the processor, a single-core processor is enough to run Varnish Cache efficiently.

• Disk Space: Varnish Cache requires a minimum of 100MB of free disk space to install all its dependencies and run smoothly.

• Compiler: Varnish Cache requires a working compiler to install properly. For Linux systems, the GNU C Compiler (GCC) is the most commonly used compiler, while FreeBSD systems use the Clang compiler.

• Dependencies: The following software dependencies need to be installed on the server to run Varnish Cache successfully:

• PCRE (Perl Compatible Regular Expressions)

• Libtool

• D-Bus

• Make

• A gettext implementation (such as GNU gettext)

• readline library

• Python

7. Root Access: Root access is required to install Varnish Cache and all its dependencies on the server.

It is crucial to ensure that all required dependencies are installed and up to date before installing Varnish Cache to ensure smooth operation. It is also recommended to have a basic understanding of a Linux command line interface or terminal to install and configure Varnish Cache.

Pre-Installation Steps

Step 1: Check system compatibility

Before installing Varnish Cache, it is important to check if your server meets the minimum system requirements. These generally include a Linux-based operating system (such as CentOS or Ubuntu), a minimum of 1GB of RAM, and any prerequisites for Varnish Cache, such as the presence of the libjemalloc library.

Step 2: Ensure necessary permissions

Make sure that you have root access to the server or have a user account with sudo privileges. You will need these permissions to install and configure Varnish Cache.

Step 3: Update the server

It is always recommended to update your server’s software packages before installing any new software. Use the appropriate command for your operating system to update the packages.

For example, on Ubuntu, you can use the command: sudo apt-get update

Step 4: Check for existing web servers

If your server already has a web server such as Apache or Nginx installed, make sure it is not using the same port Varnish Cache will be using (usually port 80). If they are using the same port, you will need to change one of the ports before installing Varnish Cache.

Step 5: Install dependencies

Varnish Cache has a few dependencies that need to be installed before installation. These dependencies include the GNU Compiler Collection (gcc), the GNU Make utility, and the binary format description library (libbsd). Use the command appropriate for your operating system to install these dependencies.

For example, on CentOS, you can use the command: sudo yum install gcc make libbsd.

Step 6: Download and install Varnish Cache

You can download the latest stable version of Varnish Cache from their official website. Once downloaded, extract the files from the archived folder and follow the instructions in the INSTALL file.

Step 7: Configure Varnish Cache

After installation, you will need to configure Varnish Cache with your desired settings. This includes specifying the ports, the backend web server address, and any additional configurations you want to enable.

Step 8: Test Varnish Cache

After configuration, restart the Varnish Cache service and run some tests to ensure that it is working properly. You can use the command: varnishd -V to check the version of Varnish Cache running on your server.

Step 9: Setup Varnish Cache to start at boot

To ensure that Varnish Cache starts automatically when your server restarts, add it to the list of startup services. The command to do this varies depending on your operating system, but it is usually something like: sudo systemctl enable varnish

Step 10: Secure Varnish Cache

To ensure that your Varnish Cache installation is secure, it is recommended to enable some basic security measures such as setting a strong administrator password and limiting access to the Varnish management port.

Installation Methods

Method 1: Using a Package Manager

A package manager is a tool that automates the process of installing, upgrading, configuring, and removing software packages on your operating system. This method is the easiest and recommended option for most users.

Step 1: Check Requirements

Before we start, make sure you have the following requirements in place:

• A supported Unix-like operating system such as Ubuntu, CentOS, Debian, etc.

• A user account with sudo privileges

• A properly configured web server (typically Apache or Nginx)

• A package manager installed (e.g., apt, yum, dnf, etc.)

Step 2: Add the Varnish Cache Repository (Optional)

Some operating systems may not have the latest version of Varnish Cache in their default repositories. In that case, you can add the official Varnish Cache repository to your system by running the following commands:

For Ubuntu/Debian:

$ curl -L https://packagecloud.io/varnishcache/varnish5/gpgkey | sudo apt-key add -
$ echo "deb https://packagecloud.io/varnishcache/varnish5/ubuntu/ xenial main" | sudo tee -a /etc/apt/sources.list.d/varnish5.list

For CentOS/RedHat:

$ sudo wget -O /etc/yum.repos.d/varnish5.repo https://packagecloud.io/install/repositories/varnishcache/varnish5/config_file.repo?os=el&dist=7&source=script

Note: Replace “xenial” and “dist=7” with the correct version of your operating system.

Step 3: Install Varnish Cache

Once you have added the repository, you can install Varnish Cache by running the following commands:

For Ubuntu/Debian:

$ sudo apt-get update
$ sudo apt-get install varnish

For CentOS/RedHat:

$ sudo yum install varnish

Method 2: Installing from Source Code

For experienced users who want more control over the installation process, installing Varnish Cache from source code is a great option. This method involves downloading the source code, compiling it, and then installing it on your system.

Step 1: Check Requirements

Before we start, make sure you have the following requirements in place:

• A supported Unix-like operating system such as Ubuntu, CentOS, Debian, etc.

• A user account with sudo privileges

• A properly configured web server (typically Apache or Nginx)

• Development packages and tools such as gcc, make, etc.

Step 2: Download the Source Code

You can download the latest stable version of Varnish Cache from the official website (https://varnish-cache.org/releases/). Alternatively, you can use the following commands to download the source code and extract it:

$ wget https://varnish-cache.org/_downloads/varnish-6.1.1.tgz
$ tar -xzvf varnish-6.1.1.tgz

Note: Replace “6.1.1” with the current version of Varnish Cache.

Step 3: Compile and Install Varnish Cache

Navigate to the extracted source directory and run the following commands to compile and install Varnish Cache:

$ cd varnish-6.1.1
$ ./configure
$ make
$ sudo make install

Step 4: Configure Varnish Cache

Once Varnish has been installed successfully, you will need to configure it for your specific setup. This typically involves setting up your caching rules, configuring backend servers, and specifying which ports Varnish will use. For detailed configuration instructions, refer to the official Varnish Cache documentation (https://varnish-cache.org/docs/6.1/users-guide/index.html).

Configuring Varnish Cache

• Storage options: Varnish Cache supports various storage options for caching content, including memory, file, and persistent storage. These options can be configured in the VCL file using the “storage” keyword.

Example:

1. Set the storage type to be memory:
`storage memory { }`

2. Set the storage type to be file with a maximum size of 1GB:
`storage file {`
` .malloc=1g;`
`}`

3. Caching policies: Varnish Cache allows for flexible and granular caching policies to be defined in the VCL file. These policies can be based on HTTP headers, cookies, URLs, or other request attributes.

Example:
`sub vcl_recv {`
` if (req.url ~ "category/bikes/") {`
` # Cache content for 1 hour`
` set req.ttl = 1h;`
` return (hash);`
` }`
`}`

In the above example, any requests for URLs that contain “category/bikes/” will be cached for 1 hour before being revalidated with the origin server.

4. Handling of user requests: Varnish Cache provides options for handling different types of user requests, such as purging cached content, redirecting requests, or serving cached content immediately without contacting the origin server.

Example:
`sub vcl_hit {`
` # Serve cached content immediately without revalidating`
` if (req.method == "GET") {`
` unset req.http.cookie;`
` }`
`}`

In the above example, any GET requests for cached content will be served immediately without contacting the origin server. This can significantly improve performance for frequently accessed content.

5. Timeouts: Varnish Cache allows for configuration of various timeouts, such as backend timeouts, request timeouts, and idle timeouts. These can be set in the VCL file using the “backend” and “return” keywords.

Example:
`backend default {`
` # Set backend timeout to 10 seconds`
` .connect_timeout = 10s;`
`}`

`sub vcl_backend_response {`
` # Set request timeout to 5 seconds`
` if (bereq.url ~ "api/") {`
` set bereq.connect_timeout = 5s;`
` }`
`}`

In the above example, the backend timeout for all requests will be 10 seconds, but for requests to the “api/” endpoint, the request timeout will be reduced to 5 seconds.

Integration with Web Servers

Integration with Apache:

• Install the Varnish Cache module for Apache. The first step is to install the Varnish Cache module for Apache. This module allows Apache to communicate with Varnish Cache and pass requests through it. Depending on your operating system, you can use package managers like yum or apt-get to install the module.

• Configure Apache to listen on a non-standard port. By default, Apache listens on port 80 for HTTP requests. However, Varnish Cache also needs to listen on the same port. To avoid conflicts, you can configure Apache to listen on a non-standard port, such as 8080, and leave port 80 for Varnish. This can be configured in the ‘Listen’ directive in your Apache configuration file.

• Configure Varnish Cache to listen on port 80 and pass requests to Apache. Next, you need to configure Varnish Cache to listen on port 80 and pass requests to Apache. This can be done by specifying Apache’s IP address and port in the ‘backend default’ section of your Varnish configuration file. For example:

backend default {
.host = "127.0.0.1";
.port = "8080";
}

4. Configure Apache to pass requests back to Varnish Cache. To complete the communication loop, you also need to configure Apache to pass requests back to Varnish Cache. This can be done by adding the following lines to your Apache configuration file, within the appropriate VirtualHost or Directory block: ProxyPass / http://<varnish_ip>:<varnish_port>/</varnish_port></varnish_ip> ProxyPassReverse / http://<varnish_ip>:<varnish_port>/</varnish_port></varnish_ip>

Make sure to replace <varnish_ip> and <varnish_port> with the IP address and port of your Varnish Cache server.

5. Restart both Apache and Varnish Cache. After making these configuration changes, restart both Apache and Varnish Cache for the changes to take effect. You can use command like ‘service httpd restart’ and ‘service varnish restart’ on CentOS, or ‘systemctl restart apache2’ and ‘systemctl restart varnish’ on Ubuntu.

Integration with Nginx:

• Install Nginx and Varnish Cache. The first step is to install Nginx and Varnish Cache on your server. Depending on your operating system, you can use package managers like yum or apt-get to install them.

• Configure Nginx to listen on a non-standard port. Similar to Apache, Nginx also listens on port 80 by default. To avoid conflicts, you can configure Nginx to listen on a non-standard port, such as 8080. This can be done by changing the ‘listen’ directive in your Nginx configuration file.

• Configure Varnish Cache to listen on port 80 and pass requests to Nginx. In your Varnish configuration file, specify Nginx’s IP address and port in the ‘backend default’ section, just like we did for Apache.

• Configure Nginx to pass requests back to Varnish Cache. To complete the communication loop, you need to configure Nginx to pass requests back to Varnish Cache. This can be done by adding the following lines to your Nginx configuration file, within the appropriate server block:

location / {
proxy_pass http://<varnish_ip>:<varnish_port>;</varnish_port></varnish_ip>
proxy_set_header Host $host;
}

Make sure to replace <varnish_ip> and <varnish_port> with the IP address and port of your Varnish Cache server.

5. Restart both Nginx and Varnish Cache. After making these configuration changes, restart both Nginx and Varnish Cache for the changes to take effect. You can use command like ‘service nginx restart’ and ‘service varnish restart’ on CentOS, or ‘systemctl restart nginx’ and ‘systemctl restart varnish’ on Ubuntu.

With these steps, you should now have Varnish Cache integrated with your web server, either Apache or Nginx. Requests will first pass through Varnish Cache, which will then forward them to the web server for processing.