无法在 GCP 监控上获取指标比率：错误 400：分子是增量指标但分母不是增量指标

Question

我正在尝试根据 PubSub 订阅中失败消息的比率创建警报策略。我喜欢使用 pubsub.googleapis.com/subscription/dead_letter_message_count 作为分子，使用 pubsub.googleapis.com/subscription/pull_ack_request_count 作为分母。 Alignment Periods 匹配，我使用 Cross Series Reducer 通过消除所有标签来消除分母中的附加标签。我打算创建的警报策略如下所示：

monitoring/alertPolicy:AlertPolicy:
        combiner   : "AND"
        conditions : [
            [0]: {
                conditionThreshold: {
                    aggregations           : [
                        [0]: {
                            alignmentPeriod   : "600s"
                            crossSeriesReducer: "REDUCE_SUM"
                            perSeriesAligner  : "ALIGN_SUM"
                        }
                    ]
                    comparison             : "COMPARISON_GT"
                    denominatorAggregations: [
                        [0]: {
                            alignmentPeriod   : "600s"
                            crossSeriesReducer: "REDUCE_SUM"
                            perSeriesAligner  : "ALIGN_SUM"
                        }
                    ]
                    denominatorFilter      : "resource.type = \"pubsub_subscription\" AND resource.labels.subscription_id = \"subscription\" AND metric.type = \"pubsub.googleapis.com/subscription/pull_ack_request_count\""
                    duration               : "1800s"
                    filter                 : "resource.type = \"pubsub_subscription\" AND resource.labels.subscription_id = \"subscription\" AND metric.type = \"pubsub.googleapis.com/subscription/dead_letter_message_count\""
                    thresholdValue         : 0.5
                }
            }
        ]

但是我得到了错误：

Error creating AlertPolicy: googleapi: Error 400: 分子是一个 增量指标但分母不是增量指标。

这看起来很混乱，因为这两个指标都是 Delta。我使用 API 资源管理器来检索时间序列。对于分子，我得到：

{
  "timeSeries": [
    {
      "metric": {
        "type": "pubsub.googleapis.com/subscription/dead_letter_message_count"
      },
      "resource": {
        "type": "pubsub_subscription",
        "labels": {
          "project_id": "redacted"
        }
      },
      "metricKind": "DELTA",
      "valueType": "INT64",
      "points": [
        {
          "interval": {
            "startTime": "2023-03-13T10:10:00Z",
            "endTime": "2023-03-13T10:20:00Z"
          },
          "value": {
            "int64Value": "0"
          }
        },
        ....,
        {
          "interval": {
            "startTime": "2023-03-13T09:10:00Z",
            "endTime": "2023-03-13T09:20:00Z"
          },
          "value": {
            "int64Value": "93"
          }
        },
        {
          "interval": {
            "startTime": "2023-03-13T09:00:00Z",
            "endTime": "2023-03-13T09:10:00Z"
          },
          "value": {
            "int64Value": "9"
          }
        },
        {
          "interval": {
            "startTime": "2023-03-13T08:50:00Z",
            "endTime": "2023-03-13T09:00:00Z"
          },
          "value": {
            "int64Value": "34"
          }
        }
      ]
    }
  ],
  "unit": "1"
}

对于分母：

{
  "timeSeries": [
    {
      "metric": {
        "type": "pubsub.googleapis.com/subscription/pull_ack_request_count"
      },
      "resource": {
        "type": "pubsub_subscription",
        "labels": {
          "project_id": "redacted"
        }
      },
      "metricKind": "DELTA",
      "valueType": "INT64",
      "points": [
        {
          "interval": {
            "startTime": "2023-03-13T09:50:00Z",
            "endTime": "2023-03-13T10:00:00Z"
          },
          "value": {
            "int64Value": "6"
          }
        },
        ....,
        {
          "interval": {
            "startTime": "2023-03-13T08:20:00Z",
            "endTime": "2023-03-13T08:30:00Z"
          },
          "value": {
            "int64Value": "104"
          }
        },
        {
          "interval": {
            "startTime": "2023-03-13T08:10:00Z",
            "endTime": "2023-03-13T08:20:00Z"
          },
          "value": {
            "int64Value": "93"
          }
        },
        {
          "interval": {
            "startTime": "2023-03-13T08:00:00Z",
            "endTime": "2023-03-13T08:10:00Z"
          },
          "value": {
            "int64Value": "111"
          }
        }
      ]
    }
  ],
  "unit": "1"
}

Answer 1

由于某些实现细节，无法在基于 JSON 的警报中定义此基于比率的警报。 来自谷歌：

我们从产品团队那里得到了一个更新，指出这个问题是由于 到增量字段中的不一致。显然是这个的原因 是 pull_ack_request_count 有一个增量窗口操作 其定义中的显式窗口。这个明确的窗口阻止 被标记为增量的预计算。

比率是 Google 内部的查询功能。我们缺乏信心 实施并且不能保证不会出现错误。建议 一般都是用MQL代替分母过滤器。