Configure your web server

Configure your web server to listen on a port other than the default port 80 because Varnish responds directly to incoming HTTP requests, not the web server.

The following sections use port 8080 as an example.

To change the Apache 2.4 listen port:

Modify the Varnish system configuration

To modify the Varnish system configuration:

Modify the default VCL

This section discusses how to provide minimal configuration so Varnish returns HTTP response headers. This enables you to verify that Varnish works before you configure the Commerce application to use Varnish.

To minimally configure Varnish:

If Varnish fails to start, try running it from the command line as follows:

varnishd -d -f /etc/varnish/default.vcl

This should display error messages.

Verify Varnish is working

The following sections discuss how you can verify that Varnish is working but without configuring Commerce to use it. You should try this before you configure Commerce.

Perform the tasks discussed in the following sections in the order shown:

Start Varnish

Enter: service varnish start

If Varnish fails to start as a service, start it from the command line as follows:

netstat

Log in to the Varnish server and enter the following command:

netstat -tulpn

Look for the following output in particular:

tcp        0      0 0.0.0.0:80                  0.0.0.0:*                   LISTEN      32614/varnishd
tcp        0      0 127.0.0.1:58484             0.0.0.0:*                   LISTEN      32604/varnishd
tcp        0      0 :::8080                     :::*                        LISTEN      26822/httpd
tcp        0      0 ::1:48509                   :::*                        LISTEN      32604/varnishd

The preceding shows Varnish running on port 80 and Apache running on port 8080.

If you do not see output for varnishd, make sure that Varnish is running.

See netstat options.

Install the Commerce software

Install the Commerce software if you have not already done so. When prompted for a Base URL, use the Varnish host and port 80 (for Varnish) because Varnish receives all incoming HTTP requests.

Possible error installing Commerce:

Error 503 Service Unavailable
Service Unavailable
XID: 303394517
Varnish cache server

If you experience this error, edit default.vcl and add a timeout to the backend stanza as follows:

backend default {
   .host = "127.0.0.1";
   .port = "8080";
   .first_byte_timeout = 600s;
}

Verify HTTP response headers

Now you can verify that Varnish is serving pages by looking at HTML response headers returned from any page.

Before you can look at headers, you must set Commerce for developer mode. There are several ways to do it, the simplest of which is to modify .htaccess in the Commerce application root. You can also use the magento deploy:mode:set command.

Set Commerce for developer mode

To set Commerce for developer mode, use the magento deploy:mode:set command.

Look at the Varnish log

Make sure that Varnish is running then enter the following command on the Varnish server:

varnishlog

In a web browser, go to any Commerce page.

A long list of response headers display in your command prompt window. Look for headers like the following:

-   BereqHeader    X-Varnish: 3
-   VCL_call       BACKEND_FETCH
-   VCL_return     fetch
-   BackendOpen    17 default(10.249.151.10,,8080) 10.249.151.10 60914
-   Backend        17 default(10.249.151.10,,8080)
-   Timestamp      Bereq: 1440449534.261791 0.000618 0.000618
-   ReqHeader      Host: 10.249.151.10
-   ReqHeader      Connection: keep-alive
-   ReqHeader      Content-Length: 86
-   ReqHeader      Cache-Control: max-age=0
-   ReqHeader      Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
-   ReqHeader      Origin: http://10.249.151.10

If headers like these do not display, stop Varnish, check your default.vcl, and try again.

Look at HTML response headers

There are several ways to look at response headers, including using a browser plug-in or a browser inspector.

The following example uses curl. You can enter this command from any machine that can access the Commerce server using HTTP.

curl -I -v --location-trusted '<your Commerce base URL>'

For example,

curl -I -v --location-trusted 'http://192.0.2.55/magento2'

Look for headers like the following:

Content-Type: text/html; charset=iso-8859-1
X-Varnish: 15
Age: 0
Via: 1.1 varnish-v6
X-Magento-Cache-Debug: HIT