Varnish Administration Certification Class – Milan, Italy

Partecipa al primo training italiano di ‪‎Varnish‬ Software in collaborazione con ‪FullTechnology‬ ed ottieni la certificazione!

Il corso si terrà a Milano il 2-3-4 Febbraio e prevede teoria, esercitazioni ed esame finalizzato al conseguimento della certificazione ed indirizzato a sysAdmin/devOps.

Partecipa all’evento di Milano

Varnish Administration Certification Class - Milan, Italy
Varnish Administration Certification Class – Milan, Italy

HTTPie: a CLI, cURL-like tool for humans

HTTPie is available on Linux, Mac OS X and Windows. On a Debian or Ubuntu system HTTPie can be installed with apt-get install httpie. For other platforms, see http://httpie.org.

Testing httpie is simple:

http -p Hh http://www.atomictag.com
GET / HTTP/1.1
Accept: */*
Accept-Encoding: gzip, deflate
Connection: keep-alive
Host: www.atomictag.com
User-Agent: HTTPie/0.9.2
   
HTTP/1.1 200 OK
CF-RAY: 250beb7295742666-FRA
Cache-Control: max-age=0, public
Content-Encoding: gzip
Content-Type: text/html; charset=UTF-8
Date: Sun, 06 Dec 2015 23:55:06 GMT
ETag: W/"7524-526422bb3df6c"
Expires: Sun, 06 Dec 2015 23:55:06 GMT
Last-Modified: Sun, 06 Dec 2015 22:22:06 GMT
Pragma: public
Server: cloudflare-nginx
Set-Cookie: __cfduid=dad70ed346cbd17091806e91a67d56c1f1449446106; expires=Mon, 05-Dec-16 23:55:06 GMT; path=/; domain=.atomictag.com; HttpOnly
Transfer-Encoding: chunked
Vary: Accept-Encoding,Cookie

The -p option to http can be used to control output. Specifically:

-p H will print request headers.
-p h will print response headers.
-p B will print request body.
-p b will print response body.

 

Enable VCL variables logging

Varnish Cache offers several ways to log and most of the documentation is related to varnishlog which includes several information related to request, response and backend response. Now what’s happen if we need to log our own variables or message to a file?

The key function is std.syslog enabled via std (standard) Varnish module, which is the only built-in “vmod” and is thus natively available and doesn’t have to be compiled.

 import std; 

then you can easily add into your VCL the following line:


std.syslog(180, "log description");

The first parameter, 180, is the priority value. If you want to add some variables to your log message:


std.syslog(180, "log description" + beresp.ttl);

This will logo the message to general system log, which is often, in a Linux system, is located in /var/log/messages.

Monitoring heart beat in Varnish Cache

In order to know Varnish Cache if is running and able to handle HTTP requests properly, without having the backends as part the equation please add the following VCL snippet makes sure that the URL /heart-beat always returns 200:

Varnish 4 equivalent:


sub vcl_recv {
if (req.method == "GET" && req.url == “/heart-beat") {
   return(synth(200, "OK"));
   }
}

Varnish 3 equivalent:


sub vcl_recv {
if (req.request == "GET" && req.url == "/heart-beat") {
    error 200 "OK";
   }
}

You may want to protect the URL by using ACLs if you don’t want to expose /heart-beat to the public.

Please see original page: https://www.varnish-software.com/blog/blog-sysadmin-monitoring-health-varnish-cache

vclFiddle for Varnish Cache

vclFiddle, is a free online tool for experimenting with the Varnish Cache HTTP reverse-proxy in a sandboxed environment where you can reproduce a website caching scenario for testing, collaborative debugging, or just trying new ideas, with the least friction possible.

You can use it now at http://www.vclfiddle.net and it is open-sourced on GitHub too.

vcl-fiddle
vcl-fiddle

Easy reloading of Varnish VCL


#!/bin/bash
# Reload a varnish config

FILE="/opt/varnish/etc/config/default.vcl"

# Hostname and management port
# (defined in /etc/default/varnish or on startup)
HOSTPORT="localhost:2000"
NOW=`date +'%d/%m/%Y_%H:%M:%S:%N'`

error() {
   echo 1>&2 "Failed to reload $FILE."
   exit 1
}

varnishadm -T $HOSTPORT -S /opt/varnish/etc/secret vcl.load reload_$NOW $FILE || error
varnishadm -T $HOSTPORT -S /opt/varnish/etc/secret vcl.use reload_$NOW || error
echo Current configs:
varnishadm -T $HOSTPORT -S /opt/varnish/etc/secret vcl.list