minitor-go/alert.go

98 lines
2.8 KiB
Go

package main
import (
"bytes"
"log"
"os/exec"
"text/template"
"time"
)
// Alert is a config driven mechanism for sending a notice
type Alert struct {
Name string
Command []string
CommandShell string `yaml:"command_shell"`
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 {
atLeastOneCommand := (alert.CommandShell != "" || alert.Command != nil)
atMostOneCommand := (alert.CommandShell == "" || alert.Command == nil)
return atLeastOneCommand && atMostOneCommand
}
// BuildTemplates compiles command templates for the Alert
func (alert *Alert) BuildTemplates() {
if alert.commandTemplate == nil && alert.Command != nil {
// build template
log.Println("Building template for command...")
alert.commandTemplate = []*template.Template{}
for i, cmdPart := range alert.Command {
alert.commandTemplate = append(alert.commandTemplate, template.Must(
template.New(alert.Name+string(i)).Parse(cmdPart),
))
}
log.Printf("Template built: %v", alert.commandTemplate)
} else if alert.commandShellTemplate == nil && alert.CommandShell != "" {
log.Println("Building template for shell command...")
alert.commandShellTemplate = template.Must(
template.New(alert.Name).Parse(alert.CommandShell),
)
log.Printf("Template built: %v", alert.commandShellTemplate)
} else {
log.Fatalf("No template provided for alert %s", alert.Name)
}
}
// Send will send an alert notice by executing the command template
func (alert Alert) Send(notice AlertNotice) {
var cmd *exec.Cmd
if alert.commandTemplate != nil {
// build template
log.Println("Send command thing...")
command := []string{}
for _, cmdTmp := range alert.commandTemplate {
var commandBuffer bytes.Buffer
err := cmdTmp.Execute(&commandBuffer, notice)
if err != nil {
panic(err)
}
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 {
panic(err)
}
shellCommand := commandBuffer.String()
log.Printf("About to run alert command: %s", shellCommand)
cmd = ShellCommand(shellCommand)
} else {
panic("No template compiled?")
}
output, err := cmd.CombinedOutput()
log.Printf("Check %s\n---\n%s\n---", alert.Name, string(output))
if err != nil {
panic(err)
}
}