solve influxdb counter with grafana

随着6.0.0-beta1的发布,上一篇influxdb counter with grafana里的问题可以解决了

template variables query support $timeFilter

5.3.0-beta1已支持,参见Release Notes v5.3.x

InfluxDB: Support timeFilter in query templating for InfluxDB.#12598

可以定义一个template variables:$other_range_first_time

select first("copy_time") from request where type='other' and $timeFilter

表示time range内第一个请求发生的时间.这里对copy_time字段取第一个，而不是time字段是因为

select first("time") from request where type='other' and $timeFilter

不会有结果的,无语,只有额外定义一个字段，保存时间.
注意copy_time字段的类型是float，所以写入时copy_time不要加双引号

local copy_time=ngx.time()..'000'
local http = require "resty.http"
local httpc = http.new()
local res, err = httpc:request_uri("http://influxdb.default.svc.cluster.local:8086/write?db=blog_stat", {
  method = "POST",
  body = 'request url="'..path..'",type="'..request_type..'",ip="'..forwarded_for..'",copy_time='..copy_time,
})

否则，copy_time类型是string,不好比较

搞定copy_time后，之前的起始值$other_init_count

select count(*) from request where type='other' and time<now()-$range_start

变为

select count(*) from request where type='other' and copy_time<$other_range_first_time

这样就不用每次修改time range后，都要选择其他的$range_start

$from and $to built-in template variables

grafana现在支持新的内置变量$__from,$__to,表示time range的起始时间和结束时间。太感动了！这样就不用绕一圈了,上面的influxQL可以变为

select count(*) from request where type='other' and time<$__from

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不定期更新