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twin-gatus/alerting/alert/alert.go
TwiN f2c5f5911c
feat(alerting): Persist triggered alerts across application restart (#764)
* feat(alerting): Persist triggered alerts across application restart

Fixes #679

* test(alerting): Add numerous tests related to alerts
2024-05-15 21:29:45 -04:00

113 lines
4 KiB
Go

package alert
import (
"crypto/sha256"
"encoding/hex"
"errors"
"strconv"
"strings"
)
var (
// ErrAlertWithInvalidDescription is the error with which Gatus will panic if an alert has an invalid character
ErrAlertWithInvalidDescription = errors.New("alert description must not have \" or \\")
)
// Alert is a endpoint.Endpoint's alert configuration
type Alert struct {
// Type of alert (required)
Type Type `yaml:"type"`
// Enabled defines whether the alert is enabled
//
// Use Alert.IsEnabled() to retrieve the value of this field.
//
// This is a pointer, because it is populated by YAML and we need to know whether it was explicitly set to a value
// or not for provider.ParseWithDefaultAlert to work.
Enabled *bool `yaml:"enabled,omitempty"`
// FailureThreshold is the number of failures in a row needed before triggering the alert
FailureThreshold int `yaml:"failure-threshold"`
// SuccessThreshold defines how many successful executions must happen in a row before an ongoing incident is marked as resolved
SuccessThreshold int `yaml:"success-threshold"`
// Description of the alert. Will be included in the alert sent.
//
// This is a pointer, because it is populated by YAML and we need to know whether it was explicitly set to a value
// or not for provider.ParseWithDefaultAlert to work.
Description *string `yaml:"description"`
// SendOnResolved defines whether to send a second notification when the issue has been resolved
//
// This is a pointer, because it is populated by YAML and we need to know whether it was explicitly set to a value
// or not for provider.ParseWithDefaultAlert to work. Use Alert.IsSendingOnResolved() for a non-pointer
SendOnResolved *bool `yaml:"send-on-resolved"`
// ResolveKey is an optional field that is used by some providers (i.e. PagerDuty's dedup_key) to resolve
// ongoing/triggered incidents
ResolveKey string `yaml:"-"`
// Triggered is used to determine whether an alert has been triggered. When an alert is resolved, this value
// should be set back to false. It is used to prevent the same alert from going out twice.
//
// This value should only be modified if the provider.AlertProvider's Send function does not return an error for an
// alert that hasn't been triggered yet. This doubles as a lazy retry. The reason why this behavior isn't also
// applied for alerts that are already triggered and has become "healthy" again is to prevent a case where, for
// some reason, the alert provider always returns errors when trying to send the resolved notification
// (SendOnResolved).
Triggered bool `yaml:"-"`
}
// ValidateAndSetDefaults validates the alert's configuration and sets the default value of fields that have one
func (alert *Alert) ValidateAndSetDefaults() error {
if alert.FailureThreshold <= 0 {
alert.FailureThreshold = 3
}
if alert.SuccessThreshold <= 0 {
alert.SuccessThreshold = 2
}
if strings.ContainsAny(alert.GetDescription(), "\"\\") {
return ErrAlertWithInvalidDescription
}
return nil
}
// GetDescription retrieves the description of the alert
func (alert *Alert) GetDescription() string {
if alert.Description == nil {
return ""
}
return *alert.Description
}
// IsEnabled returns whether an alert is enabled or not
// Returns true if not set
func (alert *Alert) IsEnabled() bool {
if alert.Enabled == nil {
return true
}
return *alert.Enabled
}
// IsSendingOnResolved returns whether an alert is sending on resolve or not
func (alert *Alert) IsSendingOnResolved() bool {
if alert.SendOnResolved == nil {
return false
}
return *alert.SendOnResolved
}
// Checksum returns a checksum of the alert
// Used to determine which persisted triggered alert should be deleted on application start
func (alert *Alert) Checksum() string {
hash := sha256.New()
hash.Write([]byte(string(alert.Type) + "_" +
strconv.FormatBool(alert.IsEnabled()) + "_" +
strconv.FormatBool(alert.IsSendingOnResolved()) + "_" +
strconv.Itoa(alert.SuccessThreshold) + "_" +
strconv.Itoa(alert.FailureThreshold) + "_" +
alert.GetDescription()),
)
return hex.EncodeToString(hash.Sum(nil))
}