Ledge stats

gistfile1.lua

location /stats {
    default_type application/json;
    content_by_lua '
        local redis = require "resty.redis"
        local red = redis:new()
        local ledge = require "ledge.ledge"

        local ok, err = red:connect("127.0.0.1", 6379)
        if not ok then
            ngx.exit(500)
            return
        end

        local total_hits_hot = red:get("ledge:counter:HOT")
        if total_hits_hot == ngx.null then total_hits_hot = 0 end
        local total_hits_warm = red:get("ledge:counter:WARM")
        if total_hits_warm == ngx.null then total_hits_warm = 0 end
        local total_hits_subzero = red:get("ledge:counter:SUBZERO")
        if total_hits_subzero == ngx.null then total_hits_subzero = 0 end
        local known_url_count = red:zcount("ledge:uris_by_expiry", "-inf", "+inf")
        local fresh_url_count = #red:keys("ledge:cache_obj:*") or 0
        local dbsize = red:dbsize()

        function total_hits()
            return total_hits_hot + total_hits_warm + total_hits_subzero
        end

        function round(val, decimal)
            if (decimal) then
                return math.floor( (val * 10^decimal) + 0.5) / (10^decimal)
            else
                return math.floor(val+0.5)
            end
        end

        function parse_info(response)
            local info = {}
            local current = info

            response:gsub("([^\\r\\n]*)\\r\\n", function(kv)
                if kv == "" then return end

                local section = kv:match("^# (%w+)$")
                if section then
                    current = {}
                    info[section:lower()] = current
                    return
                end

                local k,v = kv:match(("([^:]*):([^:]*)"):rep(1))
                if k:match("db%d+") then
                    current[k] = {}
                    v:gsub(",", function(dbkv)
                        local dbk,dbv = kv:match("([^:]*)=([^:]*)")
                        current[k][dbk] = dbv
                    end)
                else
                    if tonumber(v) then
                         v = tonumber(v)
                    end
                    current[k] = v
                end
            end)

            return info
        end

        local stats = {
            ledge_version = ledge._VERSION,
            ["requests"] = {
                counters = {
                    HOT = tonumber(total_hits_hot),
                    WARM = tonumber(total_hits_warm),
                    SUBZERO = tonumber(total_hits_subzero),
                },
                total = total_hits(),
                hit_rate = tostring(round(total_hits_hot / total_hits() * 100)).."%",
            },
            uris = {
                known = known_url_count,
                fresh = fresh_url_count
            },
            health  = {
                total_items = dbsize,
            },
            redis = {
                dbsize = dbsize,
                info = parse_info(red:info()),
            }
        }

        local cjson = require "cjson"
        ngx.say(cjson.encode(stats))
        red:close()
    ';
}


-- In main ledge config, to increment the counters..
ledge.bind("response_ready", function(req, res)
     local state = res.header["X-Cache-State"]
     if state then
         ngx.ctx.redis:incr("ledge:counter:"..state)
     end
 end)