savsgio/kratgo 基於fasthttp 開發的web cache 服務，包含以下特性

支援的特性

• cache proxy
• lb （順序，然後輪轉模式，沒有權重）
• 配置cache 規則
• 配置http 請求頭
• 管理api 支援，基於管理api 我們可以進行cache 清理

參考使用

• docker-compose 檔案

version: "3"

services:

 proxy: 

  image: savsgio/kratgo

  command: -config /etc/config.yaml

  ports:

  - "6081:6081"

  volumes: 
 

   - "./config.yaml:/etc/config.yaml"

• 配置

###########################

#  KRATGO CONFIGURATION

###########################

​

# IMPORTANT: Be careful with the tabulation indentation

​

# --- Variables ---

​

# $(method) : request method

# $(host) : request host

# $(path) : request path
 

# $(contentType) : response backend's content type

# $(statusCode) : response backend's status code

# $(req.header::<NAME>) : request header name

# $(resp.header::<NAME>) : response header name

# $(cookie::<NAME>) : request cookie name

​

# --- Operators ---

​

# Modifiers: + - / * & | ^ ** % >> <<
 

# Comparators: > >= < <= == != =~ !~

# Logical ops: || &&

# Numeric constants, as 64-bit floating point (12345.678)

# String constants (single quotes: 'foobar')

# Date constants (single quotes, using any permutation of RFC3339, ISO8601, ruby date, or unix date; date parsing is automatically tried with any string constant)

# Boolean constants: true false

# Parenthesis to control order of evaluation ( )

# Arrays (anything separated by , within parenthesis: (1, 2, 'foo'))

# Prefixes: ! - ~

# Ternary conditional: ? :

# Null coalescence: ??

​

# --- Log ---

# Log level: fatal | error | warning | info | debug

# Log output:

#  - console: Write output in standard error

#  - <file path>: Write output in log file

​

logLevel: debug

logOutput: ./kratgo.log

​

# --- Cache ---

# ttl: Cache expiration in minutes

# cleanFrequency: Interval in minutes between removing expired entries (clean up)

# maxEntries: Max number of entries in cache. Used only to calculate initial size for cache

# maxEntrySize: Max size of entry in bytes

# hardMaxCacheSize: Limit for cache size in MB (Default value is 0 which means unlimited size)

​

cache:

 ttl: 10

 cleanFrequency: 1

 maxEntries: 600000

 maxEntrySize: 500

 hardMaxCacheSize: 0

​

# --- Invalidator ---

# maxWorkers: Maximum workers to execute invalidations

​

invalidator:

 maxWorkers: 5

​

# --- Proxy ---

# addr: IP and Port of Kratgo

# backendAddrs: Array with "addr:port" of the backends

# response: Configuration to manipulate reponse (Optional)

#  headers:

#   set: Configuration to SET headers from response (Optional)

#    - name: Header name

#     value: Value of header

#     if: Condition to set this header (Optional)

#

#   unset: Configuration to UNSET headers from response (Optional)

#    - name: Header name

#     if: Condition to unset this header (Optional)

#

# nocache: Conditions to not save in cache the backend response (Optional)

​

proxy:

 addr: 0.0.0.0:6081

 backendAddrs:

   [

    <address>

   ]

 response:

  headers:

   set:

    - name: X-Kratgo

     value: true

​

   unset:

    - name: Set-Cookie

     if: $(req.header::X-Requested-With) != 'XMLHttpRequest'

​

 nocache:

  - $(req.header::X-Requested-With) == 'XMLHttpRequest'

​

# --- Admin ---

# addr: IP and Port of admin api

​

admin:

 addr: 0.0.0.0:6082

• 效果

同時，如果斷開網路連結，你會發現網站依然還能訪問（因為cache了）

基於fasthttp 開發一個自己proxy 的簡單程式碼

package main

​

import (

 "flag"

 "fmt"

 "log"

​

 "github.com/valyala/fasthttp"

)

​

var (

 add = flag.String("add", "localhost", "proxy address")

)

​

type myLog struct {

 add string

}

​

func (l myLog) Printf(format string, args ...interface{}) {

 log.Printf(format, args...)

}

​

func (l myLog) myhandler(ctx *fasthttp.RequestCtx) {

 backend := fasthttp.HostClient{

  Addr: l.add,

  }

 backend.Do(&ctx.Request, &ctx.Response)

}

​

func main() {

 flag.Parse()

 fmt.Println(*add)

 log := myLog{

  add: *add,

  }

 s := fasthttp.Server{

  Handler:   log.myhandler,

  LogAllErrors: true,

  Logger:    log,

  }

 s.ListenAndServe(":8000")

}

原始碼簡單說明

savsgio/kratgo 的原始碼並不難，對於cache proxy 基於fasthttp 的Server提供，對於cache 部分基於bigcache
Server handler 使用了fasthttp 的fasthttp.HostClient,配置解析部分基於yaml，指定語法解析（配置自定義引數）
使用Knetic/govaluate，同時為了效能作者很多地方使用了sync.Pool ,lb 部分實現很簡單，就是資料索引的移動
當超過資料最大值得時候，重置索引為0，同時對於cache 管理，作者基於channel 實現了一個校驗任務，實際可以
看看原始碼，實際上以後也分享過gregjones/httpcache的開源實現，也是一個不錯的選擇

參考資料

https://github.com/savsgio/kratgo
https://github.com/Knetic/govaluate
https://github.com/valyala/fasthttp
https://github.com/allegro/bigcache
https://github.com/gregjones/httpcache