go-etag-cache

Go package for caching HTTP response based on etag.

Concept

Store gob encoded response header etag into etag and response body into cache gob files.
Add If-None-Match header for all GET request.
Update etag and cache for required request url, when none 304 http status is received i.e if response is modified.
Return cache data for non-modified response.

Sample GET request header with If-None-Match:

map[Authorization:[token api_key:access_token]
If-None-Match:[W/"sBBM4eIM4NDlAf4R"]
User-Agent:[gokiteconnect/4.0.2]
X-Kite-Version:[3]]

Installation

go get -u github.com/ranjanrak/go-etag-cache

Usage

package main

import (
	"fmt"
	"net/http"

	etagcache "github.com/ranjanrak/go-etag-cache"
)

func main() {
    // Create new cache instance
    cacheClient := etagcache.New(etagcache.ClientParam{DirPath: ""})
    url := "https://api.kite.trade/orders"

    req, _ := http.NewRequest("GET", url, nil)

    // HTTP request params
    reqParam := etagcache.RequestParam{
        ReqClient: req,
        Headers: map[string]string{
            "User-Agent":     "gokiteconnect/4.0.2",
            "x-kite-version": "3",
            "authorization":  "token api_key:access_token",
        },
    }
    // Store and fetch response/cache data
    response, err := cacheClient.HandleEtagCache(reqParam, url)
    if err != nil {
        fmt.Printf("Error: %v", err)
    }
    fmt.Println(response)
}

Response

&{Status:304 Not Modified StatusCode:304 Proto:HTTP/2.0 ProtoMajor:2 ProtoMinor:0
Header:map[Cf-Cache-Status:[DYNAMIC] Cf-Ray:[6d179aa4dcf131d5-BOM] Content-Type:[application/json]
Date:[Sat, 22 Jan 2022 09:02:33 GMT] Expect-Ct:[max-age=604800,
report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"] Server:
[cloudflare] Strict-Transport-Security:[max-age=15552000; includeSubDomains]]
Body:{Reader:0xc00009aa80} ContentLength:0 TransferEncoding:[]
Close:false Uncompressed:false Trailer:map[] Request:0xc000108000 TLS:0xc00030e9a0}

{"status":"success","data":[{"order_id":"XXXXXX","exchange_order_id":null,"parent_order_id":null,
"status":"CANCELLED AMO","status_message":null,"status_message_raw":null,"order_timestamp":"2022-01-22
07:18:35","exchange_update_timestamp":null,"exchange_timestamp":null,"variety":"amo","exchange":"NSE",
"tradingsymbol":"BHEL","instrument_token":112129,"order_type":"MARKET","transaction_type":"BUY",
"validity":"DAY","product":"CNC","quantity":1,"disclosed_quantity":0,...}

Run unit tests

go test -v