Tom DeBerardine Tomanow

Clearing Nginx's HTTP Cache

I recently implemented Nginx HTTP content caching on our WordPress web servers to improve page load speeds and eliminate redundant, unneeded server-side page rendering. Caching the pages was relatively straightforward, but clearing the cache required a custom workaround.

Nginx comes in two versions: free and “Nginx Plus” at $2,500/year. The free version of Nginx does not offer the needed cache-clearing features of Nginx Plus, and I wasn’t comfortable paying $20,000 for 8 instances without trying to build my own solution.

Our Nginx servers run as an HTTP proxy for multiple PHP/MySQL-backed WordPress sites. The goal was to cache the dynamic PHP HTML responses in Nginx and serve the HTML pages from Nginx to avoid redundant, CPU-intensive PHP renders.

Site Cache Configuration

The example below shows how PHP response caching is configured for a site (other nginx configuration details are excluded for brevity). A cache named cachedemo-prod is defined to store cached HTML f

Introduction

When applications are running in production, they become black boxes that need to be traced and monitored. One of the simplest, yet main, ways to do so is logging. Logging allows us - at the time we develop our software - to instruct the program to emit information while the system is running that will be useful for us and our sysadmins.

	SEP = ", "
	QUOTE = "\'"
	NEWLINE = System.getProperty("line.separator")

	begin = true

	def record(columns, dataRow) {

	if (begin) {
	OUT.append("INSERT INTO ")


	FILE SPACING:

	# double space a file
	sed G

	# double space a file which already has blank lines in it. Output file
	# should contain no more than one blank line between lines of text.
	sed '/^$/d;G'