VictoriaMetrics报'metric对象缺失'，求正确JSON上报请求体

问题现象 #

调用VictoriaMetrics的http://127.0.0.1:8428/api/v1/import接口上报监控数据，发送数组形式的JSON请求体后，收到"missing 'metric' object"错误。

错误细节 #

错误请求体 #

[
  {
    "metric": {
      "__name__": "test_counter",
      "instance": "test-01"
    },
    "value": [1690000000, 123]
  }
]

报错日志 #

level=error ts=2023-07-23T10:00:00.000Z caller=request_handler.go:123 msg="error processing request" url=/api/v1/import error="missing 'metric' object"

初始Go代码 #

package main

import (
	"bytes"
	"encoding/json"
	"net/http"
)

type Metric struct {
	Metric map[string]string `json:"metric"`
	Value  []interface{}     `json:"value"`
}

func main() {
	metrics := []Metric{
		{
			Metric: map[string]string{
				"__name__": "test_counter",
				"instance": "test-01",
			},
			Value: []interface{}{1690000000, 123},
		},
	}
	data, _ := json.Marshal(metrics)
	_, err := http.Post("http://127.0.0.1:8428/api/v1/import", "application/json", bytes.NewBuffer(data))
	if err != nil {
		panic(err)
	}
}

问题原因 #

VictoriaMetrics的/api/v1/import接口接收的是单个JSON对象，而非JSON数组。用数组包裹请求体后，接口无法解析出顶层的metric字段，因此抛出错误。

修正方案 #

正确的单指标请求体（非数组形式） #

{
  "metric": {
    "__name__": "test_counter",
    "instance": "test-01"
  },
  "value": [1690000000, 123]
}

修正后的单指标上报Go代码 #

package main

import (
	"bytes"
	"encoding/json"
	"net/http"
)

type Metric struct {
	Metric map[string]string `json:"metric"`
	Value  []interface{}     `json:"value"`
}

func main() {
	metric := Metric{
		Metric: map[string]string{
			"__name__": "test_counter",
			"instance": "test-01",
		},
		Value: []interface{}{1690000000, 123},
	}
	data, _ := json.Marshal(metric)
	_, err := http.Post("http://127.0.0.1:8428/api/v1/import", "application/json", bytes.NewBuffer(data))
	if err != nil {
		panic(err)
	}
}

批量上报多指标方案 #

如果需要批量上报多个指标，可使用接口支持的换行分隔JSON格式（每个指标占一行），示例请求体：

{"metric": {"__name__": "test_counter", "instance": "test-01"}, "value": [1690000000, 123]}
{"metric": {"__name__": "test_gauge", "instance": "test-01"}, "value": [1690000000, 45.6]}

对应的批量上报Go代码：

package main

import (
	"bytes"
	"encoding/json"
	"net/http"
)

type Metric struct {
	Metric map[string]string `json:"metric"`
	Value  []interface{}     `json:"value"`
}

func main() {
	metrics := []Metric{
		{
			Metric: map[string]string{
				"__name__": "test_counter",
				"instance": "test-01",
			},
			Value: []interface{}{1690000000, 123},
		},
		{
			Metric: map[string]string{
				"__name__": "test_gauge",
				"instance": "test-01",
			},
			Value: []interface{}{1690000000, 45.6},
		},
	}

	var buf bytes.Buffer
	for _, m := range metrics {
		data, _ := json.Marshal(m)
		buf.Write(data)
		buf.WriteByte('\n')
	}

	_, err := http.Post("http://127.0.0.1:8428/api/v1/import", "application/json", &buf)
	if err != nil {
		panic(err)
	}
}

内容的提问来源于stack exchange，提问作者27P