NGINX Cache

NGINX Cache 동작 - Process관점

Cache Manager
- Cache 관리 등등 활용
- Cache Delete 등등도 활용
Cache Loader
- 디스크의 캐시 파일을 반복하여 캐싱 메타데이터를 메모리에 로드 수행
Image

NGINX Cache 동작 - caching Data 관점

DATA 영역에서의 관점
- Content 저장 Disk
- Hash Cached 저장 : RAM

Working Flow

Client -> NGINX Server Access (First Access)
 -> No Cached Data  
       Client         -> NGINX Server -> Backend Server Access 
Client Received Data  <- NGINX Server <- Data Send 

Client -> NGINX Server Access (Second Access / Same Request ) 
 -> NGINX Generator Hash (Shared Memory)
 -> Hash Key
 -> Cached Data -> Client Received

Image

NGINX Cache 기본 설정

HTTP Context : proxy_cache_path 에 Cache 설정
HTTP / Server / Location : proxy_cache 설정 ( Cache Enable )

NGINX Cache Options

NGINX Cache Options - Proxy_cache_path

Sample : proxy_cache_path /path/to/cache levels=1:2 keys_zone=my_cache:10m max_size=10g inactive=60m use_temp_path=off;
Options
- /path/to/cache → Cache 저장할 위치 ( NGINX User R/W 가능하여야 함 )
- levels=1:2 → Disk 에서 Cache 파일구조 정의 ( 디렉토리갯수 : 계층(Depth) )
- keys_zone=mycache:10m → Cache Memory 이름 및 용량 설정 (Shared Memory)
- max_size=10g → 디스크의 최대 캐시 크기 정의
- inactive=60m → 해당 시간 이후, Cache Data 자동 삭제 ( Default :10m)
- use_temp_path=off → 임시 디렉토리에 먼저 저장 설정하는 기능 ( Default : Off )
  off : 임시 파일을 캐시 디렉터리에 직접 저장 / On : 지정된 위치에 proxy_temp_path 에 의해 설정된 디렉토리 사용
- cache Loader : SharedMemory 에 저장된 기존 메터데이터 불러옴
  - loader_threshold → 요청에 대한 최대 대기 시간을 지정(ms)
  - loader_files → 한번의 호출에 불러오는 파일 갯수 지정
  - loader_sleeps → 호출 간격 (ms)
- Cache Manager : 최대 가용한 사이즈(max_size)에 도달 시 기존 캐시 컨텐츠의 삭제 관리
  - manager_files → 한번 수행 시 항목의 제거 ( Default : 100 EA )
  - manager_threshold → 한번 수행 시 지속시간을 설정
  - manager_sleep → 반복 실행 간의 Sleep 시간 설정
- Cache Purger : 캐시된 컨텐츠 기반의 API 삭제 수행
  - purger → 정의된 Key 와 일치하는 Cache항목이 디스크에서 제거되는지 여부를 확인
  - purger_files → 한번 실행 시, 검색하는 항목 수 설정
  - purger_threshold → 한번 실행 시, 지속 시간 설정
  - purger_sleep → 반복 실행 간의 Sleep 시간 설정

NGINX Cache Options - proxy_cache_key

Caching 을 위한 Key 를 정의함
Default : proxy_cache_key $scheme$proxy_host$request_uri;

NGINX Cache Status Check - CURL & Header

CURL -I
- HIT / Miss 확인

Header 추가로 확인 가능 #Trouble Shoot 에 유용함

add_header X-Cache-Status $upstream_cache_status;

$upstream_cache_status 값

MISS – The response was not found in the cache and so was fetched from an origin server. The response might then have been cached.

BYPASS – The response was fetched from the origin server instead of served from the cache because the request matched a proxy_cache_bypass directive (see Can I Punch a Hole Through My Cache? below.) The response might then have been cached.

EXPIRED – The entry in the cache has expired. The response contains fresh content from the origin server.

STALE – The content is stale because the origin server is not responding correctly, and proxy_cache_use_stale was configured.

UPDATING – The content is stale because the entry is currently being updated in response to a previous request, and proxy_cache_use_stale updating is configured.

REVALIDATED – The proxy_cache_revalidate directive was enabled and NGINX verified that the current cached content was still valid (If-Modified-Since or If-None-Match).

HIT – The response contains valid, fresh content direct from the cache.

(Plus) DashBoard 확인 가능
- CAP

NGINX Sample Config

Case1 - Default NGINX Cache Config

Default NGINX Cache Config

Config

log_format  caching  '$remote_addr - $remote_user [$time_local] "$request" '
                         '$status $body_bytes_sent "$http_referer" '
                        '"$http_user_agent" "$http_x_forwarded_for" "$upstream_cache_status"';

proxy_cache_path /etc/nginx/cache keys_zone=nginx_cache:100m;

upstream upstream_test_pool {
        zone upstream_test_pool 128k;
        server 10.250.11.101:80;
        server 10.250.11.102:80;
        server 10.250.11.201:80;
        server 10.250.11.202:80;
}

server {
    listen       80 default_server;
    server_name  localhost;
    proxy_cache nginx_cache;
    access_log  /var/log/nginx/host.access.log  main;
    location / {
        proxy_pass http://upstream_test_pool;
        health_check;
    }
}

Case2 - Logging Cache & Advanced Config

Cache Config 수정

Config

log_format  caching  '$remote_addr - $remote_user [$time_local] "$request" '
                  '$status $body_bytes_sent "$http_referer" '
                  '"$http_user_agent" "$http_x_forwarded_for" "$upstream_cache_status"';

proxy_cache_path /etc/nginx/cache levels=1:2 keys_zone=nginx_cache:100m inactive=10m max_size=200m;

upstream upstream_test_pool {
    zone upstream_test_pool 128k;
    server 10.250.11.101:80;
    server 10.250.11.102:80;
    server 10.250.11.201:80;
    server 10.250.11.202:80;
}

server {
    listen       80 default_server;
    server_name  localhost;
    location / {
        access_log  /var/log/nginx/host.access.log  caching;
        proxy_cache nginx_cache;
            proxy_cache_valid 5m;
            add_header X-Cache-Status $upstream_cache_status;
            
            proxy_pass http://upstream_test_pool;
            health_check;
    }
}

NGINX Cache Monitoring

NGINX Plus - API Cache Status Check

API 를 통한 Cache 상태 확인

Code

curl 127.0.0.1:8080/api/8/http/caches | jq
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   458  100   458    0     0   804k      0 --:--:-- --:--:-- --:--:--  447k
{
  "nginx_cache": {
    "size": 0,
    "max_size": 209715200,
    "cold": false,
    "hit": {
      "responses": 5411,
      "bytes": 3684891
    },
    "stale": {
      "responses": 0,
      "bytes": 0
    },
    "updating": {
      "responses": 0,
      "bytes": 0
    },
    "revalidated": {
      "responses": 0,
      "bytes": 0
    },
    "miss": {
      "responses": 1270,
      "bytes": 30434706,
      "responses_written": 3,
      "bytes_written": 9841859
    },
    "expired": {
      "responses": 2,
      "bytes": 1362,
      "responses_written": 2,
      "bytes_written": 1362
    },
    "bypass": {
      "responses": 0,
      "bytes": 0,
      "responses_written": 0,
      "bytes_written": 0
    }
  }
}
[root@

NGINX Plus - Cache Purge

Cached 된 DATA 에 대해 Purge 기능 수행

NGINX Config

log_format  caching  '$remote_addr - $remote_user [$time_local] "$request" '
                  '$status $body_bytes_sent "$http_referer" '
                  '"$http_user_agent" "$http_x_forwarded_for" "$upstream_cache_status"';

proxy_cache_path /etc/nginx/cache levels=1:2 keys_zone=nginx_cache:100m inactive=5m max_size=200m;

upstream upstream_test_pool {
    zone upstream_test_pool 128k;
    server 10.250.11.101:80;
    server 10.250.11.102:80;
    server 10.250.11.201:80;
    server 10.250.11.202:80;
}
    map $request_method $purge_method {
        PURGE 1;
        default 0;
    }
server {
    listen       80 default_server;
    server_name  localhost;
    location / {
        access_log  /var/log/nginx/host.access.log  caching;
            proxy_pass http://upstream_test_pool;
            health_check;
        ## Cache Options 
            proxy_cache nginx_cache;
            proxy_cache_valid 60m; ## 200,301,302 Code - 5Min 
        add_header X-Cache-Status $upstream_cache_status; ##  $upstream_cache_status : Cache Status Check 가능 
            proxy_cache_purge $purge_method;

    }
}

NGINX Cache Data Check

# tree
.
└── 1
    └── c6
        └── 9f64efd2a14c3bc10425bdba56f21c61

2 directories, 1 file

# cd 1/c6
[root@sglee c6]# ll
total 4
-rw------- 1 nginx nginx 1283 Apr  7 09:47 9f64efd2a14c3bc10425bdba56f21c61
[root@sglee c6]#

NGINX Cache Purge
```
curl -X PURGE 10.250.11.97
```

NGINX Cache Data Remove Check

# tree
.
└── 1
    └── c6

2 directories, 0 files
# date
Fri Apr  7 09:48:27 KST 2023

NGINX Cache Data Remove Check Logging (Access LOG)

127.0.0.1 - - [07/Apr/2023:09:47:17 +0900] "GET / HTTP/1.1" 200 681 "-" "curl/7.29.0" "-" "HIT"
10.250.11.97 - - [07/Apr/2023:09:48:11 +0900] "PURGE / HTTP/1.1" 204 0 "-" "curl/7.29.0" "-" "-"
127.0.0.1 - - [07/Apr/2023:09:49:09 +0900] "GET / HTTP/1.1" 200 681 "-" "curl/7.29.0" "-" "MISS"
127.0.0.1 - - [07/Apr/2023:09:49:10 +0900] "GET / HTTP/1.1" 200 681 "-" "curl/7.29.0" "-" "HIT"

Technical Service Center

NGINX Plus - Cache 인쇄

NGINX Cache

NGINX Cache 동작 - Process관점

NGINX Cache 동작 - caching Data 관점

NGINX Cache 기본 설정

NGINX Cache Options

NGINX Cache Options - Proxy_cache_path

NGINX Cache Options - proxy_cache_key

NGINX Cache Status Check - CURL & Header

NGINX Sample Config

Case1 - Default NGINX Cache Config

Case2 - Logging Cache & Advanced Config

NGINX Cache Monitoring

NGINX Plus - API Cache Status Check

NGINX Plus - Cache Purge

NGINX Plus - Cache 인쇄

NGINX Cache

NGINX Cache 동작 - Process관점

NGINX Cache 동작 - caching Data 관점

NGINX Cache 기본 설정

NGINX Cache Options

NGINX Cache Options - Proxy_cache_path

NGINX Cache Options - proxy_cache_key

NGINX Cache Status Check - CURL & Header

NGINX Sample Config

Case1 - Default NGINX Cache Config

Case2 - Logging Cache & Advanced Config

NGINX Cache Monitoring

NGINX Plus - API Cache Status Check

NGINX Plus - Cache Purge

관련 아티클