问题

I have a service to collect projects' test coverage data from their pull-requests, it was put into different pods internally by the collector. So the data will be like:

example input data:

test_coverage{project="a", pod="pod-a"} 80@1684921872
82@1684921882
test_coverage{project="a", pod="pod-b"} 90@1684982920

How can I get the last coverage value across different pods, so that I can get the value 90.

I tried last_over_time(test_coverage{project="a"}[1w]) but get 2 results with

test_coverage{project="a", pod="pod-a"} 82
test_coverage{project="a", pod="pod-b"} 90

My expectation is only the 90 be returned.

test_coverage{project="a", pod="pod-a"} 80@1684921872
                                        82@1684921882
test_coverage{project="a", pod="pod-b"} 90@1684982920

test_coverage{project="a", pod="pod-a"} 82
test_coverage{project="a", pod="pod-b"} 90

答案1

得分: 1

1. 移除 pod 标签。可以使用聚合函数进行移除，可以选择使用或不使用。对于您的示例，我会使用以下查询：max by (project) (test_coverage{project="a"})

2. 获取聚合结果的最后一个值，可以使用 last_over_time。请注意，由于参数不是即时选择器，您需要使用subquery语法。

最终的查询如下所示：

last_over_time((max by (project) (test_coverage{project="a"}))[1w:])

<details>
<summary>英文:</summary>

You need to do it in two steps:
1. Remove `pod` label. It can be done with aggregation by/without. For your example I&#39;d use `max by (project) (test_coverage{project=&quot;a&quot;})`
2. Take last value of aggregation with `last_over_time`. Notice that since argument is not a instant selector you need ti use [subquery][1] syntax.

Resulting query would look like this:

last_over_time((max by (project) (test_coverage{project="a"}))[1w:])

  [1]: https://prometheus.io/docs/prometheus/latest/querying/basics/#subquery

</details>