47 lines
1.8 KiB
Markdown
47 lines
1.8 KiB
Markdown
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---
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date: "2019-02-12:00:00+02:00"
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title: "Metrics"
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draft: false
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type: "doc"
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menu:
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sidebar:
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parent: "practical instructions"
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---
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# Metrics
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Metrics work by exposing a `/metrics` endpoint which can then be accessed by prometheus.
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To keep the load on the database minimal, metrics are stored and updated in redis.
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The `metrics` package provides several functions to create and update metrics.
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## New metrics
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First, define a `const` with the metric key in redis. This is done in `pkg/metrics/metrics.go`.
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To expose a new metric, you need to register it in the `init` function inside of the `metrics` package like so:
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{{< highlight golang >}}
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// Register total user count metric
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promauto.NewGaugeFunc(prometheus.GaugeOpts{
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Name: "vikunja_team_count", // The key of the metric. Must be unique.
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Help: "The total number of teams on this instance", // A description about the metric itself.
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}, func() float64 {
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count, _ := GetCount(TeamCountKey) // TeamCountKey is the const we defined earlier.
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return float64(count)
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})
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{{< /highlight >}}
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Then you'll need to set the metrics initial value on every startup of vikunja.
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This is done in `pkg/routes/routes.go` to avoid cyclic imports.
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If metrics are enabled, it checks if a redis connection is available and then sets the initial values.
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A convenience function is available if the metric is based on a database struct.
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Because metrics are stored in redis, you are responsible to increase or decrease these based on criteria you define.
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To do this, use `metrics.UpdateCount(value, key)` where `value` is the amount you want to cange it (you can pass
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negative values to decrease it) and `key` it the redis key used to define the metric.
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# Using it
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A Prometheus config with a Grafana template is available at [our git repo](https://git.kolaente.de/vikunja/monitoring).
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