Varnish is a reverse proxy web accelerator  Written in C designed to improve HTTP performance by using server side caching.

In this video I’m going to go through how Varnish works, we will spin up a Varnish docker container and finally talk about the pros and cons of this tech.

Agenda

Classic HTTP Architecture

How Varnish Works?

HTTP Setup - Varnish

HTTPS Setup - Varnish with Caddy as TLS Terminator.

Varnish Pros & Cons

Summary

Pros

Cache & prefetching documents

Resolve DNS hostnames in documents

Rewrite scripts to optimize code

Load Balancing

Backend Connection Pooling

Varnish Modules (VMODS, e.g. rewrite headers)

Edge side includes (personalized dynamic page)

Cons

Cache Invalidation

Only works on unencrypted HTTP

For HTTPS frontend, terminate TLS

For HTTPS backend, no solution in Varnish open source

Can’t cache POST requests (e.g. GraphQL queries)

HTTP/2 backends won’t benefit

docker commands

docker run --name varnish -p 8080:80 varnish

docker cp default.vcl varnish:/etc/varnish

default.vcl

vcl 4.0;

backend default {

.host = "husseinmac";

.port = "2015";

}

timecodes

Classic HTTP Architecture : 1:53

How Varnish Works 3:50

Demo HTTP 7:50

Demo HTTPS 18:23

Varnish Pros 28:43

Varnish Cons 39:26

Cards:

Connection Pooling 2:15 https://www.youtube.com/watch?v=GTeCtIoV2Tw

Layer 4 vs Layer 7 Load balancing 6:25 https://www.youtube.com/watch?v=aKMLgFVxZYk

GET vs POST 6:48 https://www.youtube.com/watch?v=K8HJ6DN23zI

Postgres NodeJS Chrome 8:23 https://www.youtube.com/watch?v=0JNq46eFuOM

Redis 46:13 https://www.youtube.com/watch?v=sVCZo5B8ghE

TLS Termination 49:35 https://www.youtube.com/watch?v=H0bkLsUe3no

tags:

varnish http accelerator, varnish pros and cons, varnish with https, varnish disadvantages

Resources

edge side includes

https://www.fastly.com/blog/using-esi-part-1-simple-edge-side-include

Cache invalidation varnish

https://www.smashingmagazine.com/2014/04/cache-invalidation-strategies-with-varnish-cache/

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