Documentation
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Overview ¶
Package alert defines threshold alerts on event metrics — "fire when <event> count over the last N hours is above/below a threshold". The Server evaluates them on a schedule and delivers via webhooks; this package is the persisted rules + their runtime state.
Index ¶
Constants ¶
const ( // KindCount is the original: events in a window against a fixed threshold. Default when a // stored alert has no kind, so every alert that already exists keeps behaving identically. KindCount = "count" // KindRelative compares the window against the SAME-LENGTH window before it. "Tell me if // signups fall 30%" needs no knowledge of what signups usually are. KindRelative = "relative" // KindAnomaly defers entirely to the anomaly detector: no event, no threshold, no direction. // "Tell me when something is unusual." KindAnomaly = "anomaly" // KindRatio watches one event over another — the share, not the count. KindRatio = "ratio" )
Alert shapes.
There was one: a raw event count against a number you typed in. That shape has a problem nobody names — it asks you to already know your own numbers. "Alert me if signups drop below 40" needs you to know that 40 is low, and to keep knowing it as the product grows, or the alert silently stops meaning anything. The fixed threshold is why most alerts are either never set up or muted within a month.
The other three ask nothing of you. A relative alert knows what normal was because it looks at the prior window. An anomaly alert uses the detector that has been sitting in internal/insight this whole time, wired to nothing — the dashboard could tell you "signups dropped 40% in the last 24h" and there was no way to be TOLD that without opening the page. And a ratio alert watches a derived metric, which is where most real health lives: not "how many errors" but "what share of sessions hit one".
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Alert ¶
type Alert struct {
ID string `json:"id"`
Name string `json:"name"`
Event string `json:"event"`
// KindName is the alert shape; empty means the original count alert, so every alert stored
// before kinds existed keeps watching exactly what it watched. Read it through Kind().
KindName string `json:"kind,omitempty"`
// Against is the denominator for a ratio alert ("$exception per $pageview"). Ignored by
// every other kind.
Against string `json:"against,omitempty"`
Op string `json:"op"` // "gt" | "lt"
Threshold float64 `json:"threshold"`
WindowHours int `json:"window_hours"`
Enabled bool `json:"enabled"`
Created time.Time `json:"created"`
LastChecked time.Time `json:"last_checked"`
LastValue float64 `json:"last_value"`
LastFired time.Time `json:"last_fired"`
}
Alert is one rule plus its last-evaluation state.
func (Alert) Describe ¶ added in v0.30.0
Describe renders the rule in words. Alerts are read months after they are written, usually by someone deciding whether a page at 3am was worth it, and "gt 40" is not a rule anyone can judge.
func (Alert) Kind ¶ added in v0.30.0
Kind returns the alert's shape, defaulting to the original.
A stored alert written before kinds existed has an empty string here, and it MUST mean count. Treating it as anything else would silently change what a live alert watches, which is the one thing an alert must never do.
Source Files