Apache Traffic Server vs Varnish

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Apache Traffic Server

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Apache Traffic Server vs Varnish: What are the differences?


Apache Traffic Server and Varnish are both popular open-source web caching solutions used to improve the performance and scalability of websites. While they serve the same purpose, there are several key differences between the two.

  1. Architecture and Configuration:

    • Apache Traffic Server (ATS) follows a proxy-based architecture where it acts as an intermediary between clients and servers. It requires custom configuration for features like caching, SSL termination, and load balancing.
    • Varnish, on the other hand, is designed as a reverse proxy cache. It operates by sitting in front of web servers and caches content based on a set of predefined rules. Its configuration language, VCL (Varnish Configuration Language), allows fine-grained control over cache handling and response modification.
  2. HTTP/2 Support:

    • Apache Traffic Server supports HTTP/2, the latest HTTP protocol version. It can handle both HTTP/1.x and HTTP/2 traffic efficiently.
    • Varnish, as of now, only supports HTTP/1.x. It doesn't have built-in support for HTTP/2, which may limit its performance in websites utilizing this newer protocol.
  3. Plugins and Modules:

    • Apache Traffic Server offers a wide range of plugins and modules for additional functionality. It has a flexible plugin architecture that allows customization and integration with third-party tools and services.
    • Varnish also provides various modules to extend its capabilities, but the available options are relatively limited compared to ATS. However, Varnish excels in its ability to customize cache handling through VCL.
  4. Ecosystem and Community Support:

    • Apache Traffic Server has an extensive community with active development and regular updates. It is supported by the Apache Software Foundation and has a mature ecosystem with comprehensive documentation.
    • Varnish also benefits from a strong community but is not backed by a large organization like Apache. However, it has gained popularity and support from organizations that use it extensively in their infrastructure.
  5. Hardware Requirements:

    • Apache Traffic Server is known to require more resources, both in terms of CPU and memory, compared to Varnish. Large-scale deployments of ATS may require more powerful hardware to handle the traffic efficiently.
    • Varnish is designed to be lightweight and highly efficient in terms of resource consumption. It can handle significant traffic loads with minimal hardware requirements, making it a suitable choice for smaller or resource-constrained environments.
  6. TLS Termination and SSL Support:

    • Apache Traffic Server provides built-in support for TLS termination, allowing it to handle SSL encryption and decryption. It simplifies the setup process and offloads the SSL processing from backend servers.
    • Varnish, by default, does not have native support for SSL termination. It requires additional tools or setups (like HAProxy) before SSL traffic can be handled. This adds an extra layer of complexity in the configuration and deployment process.

In summary, Apache Traffic Server and Varnish differ in their architecture, HTTP/2 support, plugin/modules availability, community support, hardware requirements, and SSL handling capabilities. Choosing between the two depends on specific requirements, scalability needs, and the desired level of customization.

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Pros of Apache Traffic Server
Pros of Varnish
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    • 104
    • 67
      Very Fast
    • 57
      Very Stable
    • 44
      Very Robust
    • 37
      HTTP reverse proxy
    • 21
      Open Source
    • 18
      Web application accelerator
    • 11
      Easy to config
    • 5
      Widely Used
    • 4
      Great community
    • 2
      Essential software for HTTP

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    What is Apache Traffic Server?

    It is a fast, scalable and extensible HTTP/1.1 and HTTP/2.0 compliant caching proxy server.Improve your response time, while reducing server load and bandwidth needs by caching and reusing frequently-requested web pages, images, and web ser

    What is Varnish?

    Varnish Cache is a web application accelerator also known as a caching HTTP reverse proxy. You install it in front of any server that speaks HTTP and configure it to cache the contents. Varnish Cache is really, really fast. It typically speeds up delivery with a factor of 300 - 1000x, depending on your architecture.

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    Blog Posts

    May 6 2020 at 6:34AM


    What are some alternatives to Apache Traffic Server and Varnish?
    HAProxy (High Availability Proxy) is a free, very fast and reliable solution offering high availability, load balancing, and proxying for TCP and HTTP-based applications.
    Squid reduces bandwidth and improves response times by caching and reusing frequently-requested web pages. Squid has extensive access controls and makes a great server accelerator. It runs on most available operating systems, including Windows and is licensed under the GNU GPL.
    nginx [engine x] is an HTTP and reverse proxy server, as well as a mail proxy server, written by Igor Sysoev. According to Netcraft nginx served or proxied 30.46% of the top million busiest sites in Jan 2018.
    Apache HTTP Server
    The Apache HTTP Server is a powerful and flexible HTTP/1.1 compliant web server. Originally designed as a replacement for the NCSA HTTP Server, it has grown to be the most popular web server on the Internet.
    JavaScript is most known as the scripting language for Web pages, but used in many non-browser environments as well such as node.js or Apache CouchDB. It is a prototype-based, multi-paradigm scripting language that is dynamic,and supports object-oriented, imperative, and functional programming styles.
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