2023年11月30日木曜日

Gitlab の alertmanager でテンプレートファイルを使用する方法

Gitlab の alertmanager でテンプレートファイルを使用する方法

概要

前回メール本文のテンプレートをカスタマイズする方法を紹介しました
今回は直接テンプレートを docker-compose に記載せずテンプレートファイルを使ってカスタムしてみたいと思います

環境

  • Gitlab 16.3.6
  • Alertmanager 0.25.0

my_email_html.tmpl

まずは html メールのカスタマイズからしていきます
html テンプレートのベースはこれを使います
リンクの部分を削除するのとテンプレート名を「my.email.html」という名前に変更しています

  • vim my_email_html.tmpl
{{ define "email.default.subject" }}{{ template "__subject" . }}{{ end }}
{{ define "my.email.html" }}
<!--
Style and HTML derived from https://github.com/mailgun/transactional-email-templates


The MIT License (MIT)

Copyright (c) 2014 Mailgun

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
-->
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
<head>
<meta name="viewport" content="width=device-width">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>{{ template "__subject" . }}</title>
<style>
@media only screen and (max-width: 640px) {
  body {
    padding: 0 !important;
  }

  h1,
h2,
h3,
h4 {
    font-weight: 800 !important;
    margin: 20px 0 5px !important;
  }

  h1 {
    font-size: 22px !important;
  }

  h2 {
    font-size: 18px !important;
  }

  h3 {
    font-size: 16px !important;
  }

  .container {
    padding: 0 !important;
    width: 100% !important;
  }

  .content {
    padding: 0 !important;
  }

  .content-wrap {
    padding: 10px !important;
  }

  .invoice {
    width: 100% !important;
  }
}
</style>
</head>

<body itemscope itemtype="https://schema.org/EmailMessage" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; -webkit-font-smoothing: antialiased; -webkit-text-size-adjust: none; height: 100%; line-height: 1.6em; background-color: #f6f6f6; width: 100%;">

<table class="body-wrap" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; background-color: #f6f6f6; width: 100%;" width="100%" bgcolor="#f6f6f6">
  <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
    <td style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; vertical-align: top;" valign="top"></td>
    <td class="container" width="600" style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; vertical-align: top; display: block; max-width: 600px; margin: 0 auto; clear: both;" valign="top">
      <div class="content" style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; max-width: 600px; margin: 0 auto; display: block; padding: 20px;">
        <table class="main" width="100%" cellpadding="0" cellspacing="0" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; background-color: #fff; border: 1px solid #e9e9e9; border-radius: 3px;" bgcolor="#fff">
          <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
            {{ if gt (len .Alerts.Firing) 0 }}
            <td class="alert alert-warning" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; vertical-align: top; font-size: 16px; color: #fff; font-weight: 500; padding: 20px; text-align: center; border-radius: 3px 3px 0 0; background-color: #E6522C;" valign="top" align="center" bgcolor="#E6522C">
              {{ .Alerts | len }} alert{{ if gt (len .Alerts) 1 }}s{{ end }} for {{ range .GroupLabels.SortedPairs }}
                {{ .Name }}={{ .Value }}
              {{ end }}
            </td>
            {{ else }}
            <td class="alert alert-good" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; vertical-align: top; font-size: 16px; color: #fff; font-weight: 500; padding: 20px; text-align: center; border-radius: 3px 3px 0 0; background-color: #68B90F;" valign="top" align="center" bgcolor="#68B90F">
              {{ .Alerts | len }} alert{{ if gt (len .Alerts) 1 }}s{{ end }} for {{ range .GroupLabels.SortedPairs }}
                {{ .Name }}={{ .Value }} 
              {{ end }}
            </td>
            {{ end }}
          </tr>
          <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
            <td class="content-wrap" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; vertical-align: top; padding: 30px;" valign="top">
              <table width="100%" cellpadding="0" cellspacing="0" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                  <td class="content-block" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; vertical-align: top; padding: 0 0 20px;" valign="top">
                  </td>
                </tr>
                {{ if gt (len .Alerts.Firing) 0 }}
                <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                  <td class="content-block" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; vertical-align: top; padding: 0 0 20px;" valign="top">
                    <strong style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">[{{ .Alerts.Firing | len }}] Firing</strong>
                  </td>
                </tr>
                {{ end }}
                {{ range .Alerts.Firing }}
                <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                  <td class="content-block" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; vertical-align: top; padding: 0 0 20px;" valign="top">
                    <strong style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">Labels</strong><br style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                    {{ range .Labels.SortedPairs }}{{ .Name }} = {{ .Value }}<br style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">{{ end }}
                    {{ if gt (len .Annotations) 0 }}<strong style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">Annotations</strong><br style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">{{ end }}
                    {{ range .Annotations.SortedPairs }}{{ .Name }} = {{ .Value }}<br style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">{{ end }}
                  </td>
                </tr>
                {{ end }}

                {{ if gt (len .Alerts.Resolved) 0 }}
                  {{ if gt (len .Alerts.Firing) 0 }}
                <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                  <td class="content-block" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; vertical-align: top; padding: 0 0 20px;" valign="top">
                    <br style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                    <hr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                    <br style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                  </td>
                </tr>
                  {{ end }}
                <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                  <td class="content-block" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; vertical-align: top; padding: 0 0 20px;" valign="top">
                    <strong style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">[{{ .Alerts.Resolved | len }}] Resolved</strong>
                  </td>
                </tr>
                {{ end }}
                {{ range .Alerts.Resolved }}
                <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                  <td class="content-block" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; vertical-align: top; padding: 0 0 20px;" valign="top">
                    <strong style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">Labels</strong><br style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
                    {{ range .Labels.SortedPairs }}{{ .Name }} = {{ .Value }}<br style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">{{ end }}
                    {{ if gt (len .Annotations) 0 }}<strong style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">Annotations</strong><br style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">{{ end }}
                    {{ range .Annotations.SortedPairs }}{{ .Name }} = {{ .Value }}<br style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">{{ end }}
                  </td>
                </tr>
                {{ end }}
              </table>
            </td>
          </tr>
        </table>

        <div class="footer" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; width: 100%; clear: both; color: #999; padding: 20px;">
          <table width="100%" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
            <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px;">
            </tr>
          </table>
        </div></div>
    </td>
    <td style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 14px; vertical-align: top;" valign="top"></td>
  </tr>
</table>

</body>
</html>

{{ end }}

テンプレートファイルの配置

コンテナで動作する Gitlab が参照できるようにします
今回はホストマシンの一部のパスをマウントしてコンテナが参照できるようにしています

  • mkdir /path/to/opt/alertmanager/template
  • cp my_email_html.tmpl /path/to/opt/alertmanager/template

gitlab.rb

あとはテンプレートを参照するように alertmanager の設定を書き換えます

html の部分を定義した template を使うように変更します
また配置したテンプレートファイルを読み込むように alertmanager['templates'] を定義します

  • vim .gitlab.rb
alertmanager['listen_address'] = '0.0.0.0:9093'
alertmanager['receivers'] = [
  {
    name: 'email',
    email_configs: [
      to: 'your_to@mail',
      from: 'your_from@mail',
      smarthost: 'smtp.ess.nifcloud.com:465',
      auth_username: 'your_access_key',
      auth_password: 'your_secret_key',
      require_tls: false,
      headers: {
        subject: '[{{ .Status | toUpper }}{{ if eq .Status "firing" }}:{{ .Alerts.Firing | len }}{{ end }}] ({{ $$alerts := "" }}{{ $$instance_id := (index .Alerts 0).Labels.instance_id }}{{ range .Alerts }}{{ $$alerts = (printf "%v %v" $$alerts .Labels.alertname) }}{{ end }}{{ $$instance_id }} ->{{ $$alerts }})'
      },
      html: '{{ template "my.email.html" . }}',
      send_resolved: true
    ]
  }
]
alertmanager['routes'] = [
  {
    receiver: 'email',
    group_wait: '30s',
    group_interval: '5m',
    repeat_interval: '4h',
    matchers: [ 'instance_id = hoge' ]
  }
]
alertmanager['templates'] = ['/var/opt/gitlab/alertmanager/template/*.tmpl']
# alertmanager['default_receiver'] = 'email'

動作確認

あとは redis などを停止すればアラートがきます

  • docker-compose exec gitlab gitlab-ctl stop redis

こんな感じで alertmanager へのリンクが削除されているのが確認できると思います

テキストメールのテンプレート化

次にテキストメールでもテンプレート化してみます
テンプレート化する内容は前回の本文とタイトルの内容をテンプレート化してみます

今回は1つのテンプレートファイルに2つの define を使って本文とタイトル用のテンプレートを定義します

  • vim my_email_text.tmpl
{{ define "my.email.text.body" }}
{{ range .Alerts.Firing }}
{{ range .Annotations.SortedPairs }}
- {{ .Name }} = {{ .Value }}
{{ end }}
{{ end }}
{{ end }}

{{ define "my.email.text.subject" }}
{{ $alerts := "" }}
{{ $instance_id := (index .Alerts 0).Labels.instance_id }}
{{ range .Alerts }}
{{ $alerts = (printf "%v %v" $alerts .Labels.alertname) }}
{{ end }}
[{{ .Status | toUpper }}{{ if eq .Status "firing" }}:{{ .Alerts.Firing | len }}{{ end }}] ({{ $instance_id }} ->{{ $alerts }})
{{ end }}

コンテナが参照できるパスにコピーします

  • cp my_email_text.tmpl /path/to/opt/alertmanager/template

gitlab.rb でテキストメールの本文とタイトルにテンプレートを使うように変更します
html メールは無効化するのでブランクを設定します

  • vim gitlab.rb
alertmanager['listen_address'] = '0.0.0.0:9093'
alertmanager['receivers'] = [
  {
    name: 'email',
    email_configs: [
      to: 'your_to@mail',
      from: 'your_from@mail',
      smarthost: 'smtp.ess.nifcloud.com:465',
      auth_username: 'your_access_key',
      auth_password: 'your_secret_key',
      require_tls: false,
      headers: {
        subject: '{{ template "my.email.text.subject" . }}'
      html: '',
      text: '{{ template "my.email.text.body" . }}',
      send_resolved: true
    ]
  }
]
alertmanager['routes'] = [
  {
    receiver: 'email',
    group_wait: '30s',
    group_interval: '5m',
    repeat_interval: '4h',
    matchers: [ 'instance_id = hoge' ]
  }
]
alertmanager['templates'] = ['/var/opt/gitlab/alertmanager/template/*.tmpl']
# alertmanager['default_receiver'] = 'email'

あとは再起動して再度 redis を停止すればテンプレートファイル化された内容でテキストメールのアラートが届くことが確認できると思います

最後に

docker-compose に直接テンプレート構文を使うこともできますがテンプレートの内容が長くなり一行では管理しづらい場合などはテンプレートファイル化してあげるといいのかなと思います

参考サイト

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