Set up Varnish reverse HTTP proxy

1 Install Varnish

1.1 Add GPG key

In order to install a deb repo, first you need to install the GPG key that used to sign repository metadata. To do this, execute the following command:

curl -L https://packagecloud.io/varnishcache/varnish60lts/gpgkey | sudo apt-key add -

1.2 Add repository configuration

Create a file named /etc/apt/sources.list.d/varnishcache_varnish60lts.list with:

sudo vi /etc/apt/sources.list.d/varnishcache_varnish60lts.list

and paste the following in it:

deb https://packagecloud.io/varnishcache/varnish60lts/ubuntu/ bionic main
deb-src https://packagecloud.io/varnishcache/varnish60lts/ubuntu/ bionic main

1.3 Lower default varnish package priority

Ubuntu 20.xx comes with Varnish 6.2 by default. This means that, even though we manually installed 6.0, doing apt upgrade will run over our 6.0 with the default 6.2. In order to prevent this, we need to lower the priority of the default 6.2 package.

To do that, create the following file:

sudo vi /etc/apt/preferences.d/varnish

and paste this inside:

Package: varnish
Pin: release o=Ubuntu
Pin-Priority: 100

And then create the following file:

sudo vi /etc/apt/preferences.d/varnish-dev

and paste this inside

Package: varnish-dev
Pin: release o=Ubuntu
Pin-Priority: 100

1.4 Install missing library `libjemalloc1_3.6.0`

If you try to install Varnish with apt install at this point, you will receive the following error:

The following packages have unmet dependencies:
 varnish : Depends: libjemalloc1 (>= 2.1.1) but it is not installable
E: Unable to correct problems, you have held broken packages.

This library libjemalloc1 doesn’t exist in Ubuntu 20.xx (although it exists in older versions, up to 18.xx) so we need to install it manually. To do this, execute the following commands:

cd ~
wget http://archive.ubuntu.com/ubuntu/pool/universe/j/jemalloc/libjemalloc1_3.6.0-11_amd64.deb
sudo dpkg -i libjemalloc1_3.6.0-11_amd64.deb

1.5 Install Varnish from repositories

Now you can install Varnish (and varnish-dev) simply with

sudo apt update
sudo apt install varnish varnish-dev

2 Install Varnish modules

Aside from standard Varnish installation, you’ll need xkey module as well.

2.1 Install needed tools for compiling

In order to be able to compile the modules, we need to install the following tools:

sudo apt install libtool automake docutils-common

2.2 Clone repository

Clone the Varnish modules in your home directory and checkout tag 0.15.0:

cd ~
git clone https://github.com/varnish/varnish-modules.git
cd varnish-modules
git checkout 0.15.0

2.3 Compile and install Varnish modules

Execute the following to compile and install module binaries:

./bootstrap
./configure
make
sudo make install

3 Start

On Ubuntu, Varnish is installed as a service so you can use the following commands:

sudo systemctl start varnish
sudo systemctl stop varnish
sudo systemctl status varnish
sudo systemctl restart varnish

To make sure that Varnish is running, you can use the following command:

ps aux | grep varnish

There you can see all the options which Varnish service uses to start Varnish.

If you want to enable or disable Varnish on startup (after reboot), use the following commands:

sudo systemctl enable varnish
sudo systemctl disable varnish
sudo systemctl is-enabled varnish

4 Configure VCL

Varnish service uses the /etc/varnish/default.vcl VCL file for configuration. In order to use a different file, we would have to modify the Varnish service file so it’s easier to keep using the default one.

You have to replace the /etc/varnish/default.vcl with desired VCL file and restart the Varnish service. For media site installations, you can find instructions for configuration here: https://github.com/netgen/media-site/blob/master/doc/varnish/varnish.md