How to install and configure Varnish cache on Ubuntu Linux 16.04 LTS

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Originally published at: https://www.cyberciti.biz/faq/how-to-install-and-configure-varnish-cache-on-ubuntu-linux-16-04-lts/

How do I install Varnish Cache server to improve the performance of my existing Apache web server especially caching dynamic content on Ubuntu Linux 16.04 LTS server?

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I am running a Cakephp based website on a Debian server. I am trying to configure varnish on my website, but getting 503 error. I tried to follow your tutorial (https://www.cyberciti.biz/faq/how-to-install-and-configure-varnish-cache-on-ubuntu-linux-16-04-lts/ ) and another tutorial (Use Varnish Cache to Boost Performance [Detailed Guide] ) as well, but in both cases I am getting 503 error. I cannot figure what is causing this issue. Maybe something else on my server or app is conflicting with varnish?

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This error means varnish failed to connect to the backend server running a Cakephp based app. Try:

  1. Can you see requests from Varnish in your backend webserver log file?
  2. From varnish server one can use nc/telenet to see if you can connect to backend. Say backend is running on 192.168.1.10:8080, run telnet and see if it connects:
    telnet 192.168.1.10 8080
  3. cd into /var/log/varnish/ and look for error logs. Another option is to run varnishlog command.