Varnish

Varnish is a reverse caching proxy that acts as an HTTP accelerator, optimizing content-heavy dynamic websites and APIs.

Use HiTechCloud > Caching > Varnish to manage the Varnish service, enable or disable it per domain, and view service logs.

Status

Enable or disable the Varnish service globally.

The current service status is displayed.
Use the toggle to enable or disable Varnish as needed.

Varnish Cache

While the service is running, real-time cache performance and efficiency metrics are displayed, including Hit Ratio, Hits, Misses, Pass, Requests, Backend Requests, Backend Failures and an overall Efficiency Score.

Domains

Control Varnish caching on a per-domain basis.

Each domain has a toggle showing its current status.
Click the toggle to enable or disable Varnish caching for that specific domain.

Edge Side Includes (ESI)

A website whose pages are built from fragments can have Varnish assemble them: every <esi:include src="/fragment"> in the page is replaced with whatever that URL answers, so the shell of the page and each fragment are cached — and expire — on their own.

This is off for every website and is turned on by the server administrator, one hostname at a time:

hitechcloudcli varnish esi example.com on     # on for this site only
hitechcloudcli varnish esi example.com off    # back to off
hitechcloudcli varnish esi example.com        # what is it now?

It is not a self-serve switch, because it changes what visitors are sent rather than how fast they are sent it: with ESI on, Varnish parses the page and removes every <esi:include>, <esi:remove> and  it finds. A page that was not written for ESI can contain that markup for its own reasons — a tutorial, a quoted code block, a feed — and there the parse would delete what the author wrote. Ask your provider to turn it on for a site whose markup is ESI.

What it leaves alone:

Only text/html answers are parsed; stylesheets, scripts, JSON and downloads are passed on untouched.
Every other website on the same cache is unaffected, including the other sites of the same account.
A page that sets a cookie, or that the cache is not allowed to store, is still assembled — a logged-in visitor never sees the raw markup — and is still not stored.

Turning it on or off restarts the account's cache, so it starts empty. Fill it again with hitechcloudcli varnish warm example.com.

Container

While the service is running, real-time resource usage (CPU, memory, network and block I/O) is displayed. Click Edit limits to adjust the container's resource limits from the Docker/Containers page.