package main import ( "bytes" "fmt" "log" "os/exec" "strings" "text/template" "time" ) // Alert is a config driven mechanism for sending a notice type Alert struct { Name string Command CommandOrShell commandTemplate []*template.Template commandShellTemplate *template.Template } // AlertNotice captures the context for an alert to be sent type AlertNotice struct { MonitorName string AlertCount int16 FailureCount int16 LastCheckOutput string LastSuccess time.Time IsUp bool } // IsValid returns a boolean indicating if the Alert has been correctly // configured func (alert Alert) IsValid() bool { return !alert.Command.Empty() } // BuildTemplates compiles command templates for the Alert func (alert *Alert) BuildTemplates() error { // TODO: Remove legacy template support later after 1.0 legacy := strings.NewReplacer( "{alert_count}", "{{.AlertCount}}", "{alert_message}", "{{.MonitorName}} check has failed {{.FailureCount}} times", "{failure_count}", "{{.FailureCount}}", "{last_output}", "{{.LastCheckOutput}}", "{last_success}", "{{.LastSuccess}}", "{monitor_name}", "{{.MonitorName}}", ) if LogDebug { log.Printf("DEBUG: Building template for alert %s", alert.Name) } if alert.commandTemplate == nil && alert.Command.Command != nil { alert.commandTemplate = []*template.Template{} for i, cmdPart := range alert.Command.Command { cmdPart = legacy.Replace(cmdPart) alert.commandTemplate = append(alert.commandTemplate, template.Must( template.New(alert.Name+string(i)).Parse(cmdPart), )) } } else if alert.commandShellTemplate == nil && alert.Command.ShellCommand != "" { alert.commandShellTemplate = template.Must( template.New(alert.Name).Parse( legacy.Replace(alert.Command.ShellCommand), ), ) } else { return fmt.Errorf("No template provided for alert %s", alert.Name) } return nil } // Send will send an alert notice by executing the command template func (alert Alert) Send(notice AlertNotice) (outputStr string, err error) { log.Printf("INFO: Sending alert %s for %s", alert.Name, notice.MonitorName) var cmd *exec.Cmd if alert.commandTemplate != nil { command := []string{} for _, cmdTmp := range alert.commandTemplate { var commandBuffer bytes.Buffer err = cmdTmp.Execute(&commandBuffer, notice) if err != nil { return } command = append(command, commandBuffer.String()) } cmd = exec.Command(command[0], command[1:]...) } else if alert.commandShellTemplate != nil { var commandBuffer bytes.Buffer err = alert.commandShellTemplate.Execute(&commandBuffer, notice) if err != nil { return } shellCommand := commandBuffer.String() cmd = ShellCommand(shellCommand) } else { err = fmt.Errorf("No templates compiled for alert %v", alert.Name) return } // Exit if we're not ready to run the command if cmd == nil || err != nil { return } var output []byte output, err = cmd.CombinedOutput() outputStr = string(output) if LogDebug { log.Printf("DEBUG: Alert output for: %s\n---\n%s\n---", alert.Name, outputStr) } return outputStr, err } // NewLogAlert creates an alert that does basic logging using echo func NewLogAlert() *Alert { return &Alert{ Name: "log", Command: CommandOrShell{ Command: []string{ "echo", "{{.MonitorName}} check has failed {{.FailureCount}} times", }, }, } }