Proxy cache path configuration in Nginx - Step-by-Step Execution

Process Flow - Proxy cache path configuration

Define cache path with 'proxy_cache_path'

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Set cache zone name and size

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Configure cache keys and inactive time

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Use 'proxy_cache' in server/location block

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Cache stores responses in defined path

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Serve cached content on repeated requests

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Cache expires or is purged based on rules

This flow shows how nginx sets up a cache directory, assigns a cache zone, and then uses it to store and serve cached responses.

Execution Sample

Nginx

proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=mycache:10m max_size=1g inactive=60m;

server {
  location / {
    proxy_cache mycache;
    proxy_pass http://backend;
  }
}

This config sets a cache directory and zone, then enables caching for requests to the backend server.

Process Table

Step	Directive	Action	Result
1	proxy_cache_path	Define cache path '/var/cache/nginx' with zone 'mycache'	Cache zone 'mycache' created with 10MB memory, max size 1GB
2	levels=1:2	Set cache directory structure	Cache files stored in 2-level subdirectories for efficiency
3	inactive=60m	Set inactive timeout	Cache entries expire if not accessed for 60 minutes
4	proxy_cache mycache	Enable caching in location block	Requests will use 'mycache' zone for caching
5	proxy_pass http://backend	Forward request to backend	Response received and stored in cache
6	Repeat request	Serve cached response if valid	Faster response served from cache
7	Cache expires or purged	Old cache entries removed	Cache space freed for new entries

💡 Cache path and zone configured; caching enabled and serving cached content until cache expires or is purged

Status Tracker

Variable	Start	After Step 1	After Step 4	After Step 6	Final
cache_path	undefined	/var/cache/nginx	/var/cache/nginx	/var/cache/nginx	/var/cache/nginx
cache_zone	undefined	mycache (10m)	mycache (10m)	mycache (10m)	mycache (10m)
cache_files	empty	empty	empty	contains cached responses	contains cached responses or expired entries removed

Key Moments - 3 Insights

Why do we specify 'levels=1:2' in proxy_cache_path?

This creates a two-level directory structure inside the cache path to store cached files efficiently and avoid too many files in one folder, as shown in step 2 of the execution_table.

What happens if a cached response is not accessed for 60 minutes?

It expires and is removed from the cache, as set by 'inactive=60m' in step 3, freeing space for new cache entries.

How does nginx know to use the cache for requests?

By using 'proxy_cache mycache;' inside the location block (step 4), nginx enables caching for requests matching that location.

Visual Quiz - 3 Questions

Look at the execution_table, what is the cache zone size defined at step 1?

A 1 gigabyte

B 60 minutes

C 10 megabytes

D 2 levels

💡 Hint

Check the 'Result' column in step 1 for cache zone memory size.

At which step does nginx start serving cached responses?

A Step 3

B Step 6

C Step 5

D Step 7

💡 Hint

Look for when cached responses are served in the 'Action' column.

If we remove 'inactive=60m', what changes in the cache behavior?

A Cache entries expire after the default 10 minutes of inactivity

B Cache directory structure changes

C Cache zone size increases

D Caching is disabled

💡 Hint

Refer to step 3 about inactive timeout and its effect on cache expiration.

Concept Snapshot

proxy_cache_path sets cache directory and zone with size and structure
Use 'proxy_cache zone_name;' in location to enable caching
Cache stores responses on disk in subfolders
'inactive' sets how long unused cache stays
Cached responses speed up repeated requests
Expired cache entries are removed automatically

Full Transcript

This visual execution shows how nginx configures proxy cache path using 'proxy_cache_path' directive. First, it defines the cache directory and zone name with memory size and max disk size. Then it sets directory levels for storing cache files efficiently. The 'inactive' parameter sets how long cached items stay if not accessed. In the server block, 'proxy_cache' enables caching for requests. When a request is proxied, the response is stored in the cache path. Subsequent requests serve the cached response for faster delivery. Cache entries expire or are purged based on the inactive timeout or other rules. Variables like cache_path and cache_zone track the configuration state. Key moments include understanding directory levels, cache expiration, and enabling cache in location. The quiz tests knowledge of cache size, serving cached content, and effect of inactive timeout.