200_rewrite-shorten-url.lua

function main()
        local uri = ngx.var.request_uri
        local chk = string.sub(uri,1,10)
        if chk == "/endpoint?" then
                local url = ngx.req.get_uri_args().url
                local res = ngx.location.capture("/encode?url="..url)
                ngx.print(res.body)
        else
                local nonce = string.sub(uri,2)
                local res = ngx.location.capture("/decode?nonce="..nonce)
                ngx.print(res.body)
        end
end

main()

201_encode-shorten-url.lua

function generate(wordlist,len)
        math.randomseed(os.time())
        local nonce = ""
        for i = 1, len do
                local r = math.random(1,#wordlist)
                nonce = nonce..wordlist[r]
        end
        return nonce
end

function register(url,nonce)
        local redis = require "resty.redis"
        local client = redis:new()
        client:connect("127.0.0.1",6379)
        client:hset(nonce,"Nginx::200_shorten-url.conf",url)
        return true
end

function main(wordlist,len)
        local raw = ngx.req.get_uri_args().url
        local nonce = generate(wordlist,len)
        while not register(raw,nonce) do
                local nonce = generate(wordlist,len)
        end
        local url = "http://10.0.10.101:90/"..nonce
        local html = "<a href=\""..url.."\">"..url.."</a>"
        ngx.print(html)
end

WORDLIST = {
        "a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z",
        "A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z",
        "0","1","2","3","4","5","6","7","8","9"
}
LENGTH=6
main(WORDLIST,LENGTH)

202_decode-shorten-url.lua

function lookup(nonce)
        local redis = require "resty.redis"
        local client = redis:new()
        client:connect("127.0.0.1",6379)
        url,err = client:hget(nonce,"Nginx::200_shorten-url.conf")
        return url
end

function main()
        local nonce = ngx.req.get_uri_args().nonce
        local url = lookup(nonce)
        local html = "<a href=\""..url.."\">"..url.."</a>"
        ngx.print(html)
end

main()