Varnish install and configuration on Ubuntu 9.x (notes)

Here are my notes on installing and configuring varnish proxy cache on ubuntu systems ::

# Install varnish on webserver via apt-get

# Uncomment the backend default setting in /etc/varnish/default.vcl

# Change the port numbers in /etc/default/varnish

# Change the port numbers in /etc/apache/ports.conf

# Restart Apache and Varnish

Function	Description	Possible keywords
vcl_recv	Called after receiving a request. Decides how to serve the request	error, pass, pipe
vcl_pipe	Called after entering pipe mode.Creates a direct connection between the client and the backend, bypassing Varnish all together.	error, pipe
vcl_pass	Called after entering pass mode. Unlike pipe mode, only the current request bypasses Varnish. Subsequent requests for the same connection are handled normally.	error, pass
vcl_hash	Called when computing the hash key for an object.	hash
vcl_hit	Called after a cache hit.	error, pass, deliver
vcl_miss	Called after a cache miss.	error, pass, fetch
vcl_fetch	Called after a successful retrieval from the backend. An â€˜insertâ€™ will add the retrieved object in the cache and then continue to vcl_deliver	error, pass, insert
vcl_deliver	Called before the cached object is delivered to the client.	error, deliver
vcl_timeout	Called by the reaper thread shortly before an object expires in the cache â€˜discardâ€™ will discard the object and â€˜fetchâ€™ will retrieve a fresh copy	discard, fetch
vcl_discard	Called by the reaper thread when a cached object is about to be discarded due to expiration or space is running low	discard, keep

Varnish tools

Varnish has a set of command line tools and utilities to monitor and administer Varnish. These are:

varnishncsa: Displays the varnishd shared memory logs in Apache / NCSA combined log format
varnishlog: Reads and presents varnishd shared memory logs.
varnishstat: Displays statistics from a running varnishd instance.
varnishadm: Sends a command to the running varnishd instance.
varnishhist: Reads varnishd shared memory logs and presents a continuously updated histogram showing the distribution of the last N requests by their processing.
varnishtop: Reads varnishd shared memory logs and presents a continuously updated list of the most commonly occurring log entries.
varnishreplay: Parses varnish logs and attempts to reproduce the traffic.