[Feature]: Telegram alert feature

[congto]

Feature category

New notifier type

Problem / use case

Thank you for providing such a useful tool for Victorialogs. I think it would be even better if you could integrate the ability to send alerts directly to Telegram.

I see you already have a feature to send alerts to webhooks; it could also send to Telegram, but the setup would take more time for the user.

Please consider this. Thank you very much.

Proposed solution

notifiers:
  telegram:
    type: telegram
    chat_id: "-999999999999999,-888888888"              # Require: Multi chat ID
    bot_token: "xuyyyyyyyyyyyyyyyyyyyyyy"               # Require: display name
    icon_url: "https://example.com/icon.png"            # Optional: avatar

Alternatives considered

No response

[fxthiry]

Hi @congto, thanks for the feature request.

I've implemented the Telegram notifier. PR: #23 (should ship in v1.1.0 once merged and tagged).

What you can use today

notifiers:
  telegram-alerts:
    type: telegram
    bot_token: "${TELEGRAM_BOT_TOKEN}"   # supports env var substitution
    chat_ids:
      - "-100123456789"
      - "-100987654321"
    parse_mode: HTML                     # default
    disable_notification: false          # optional
    disable_web_page_preview: true       # optional
    body_template: |                     # optional (Jinja)
      <b>{{ title|e }}</b>
      {{ body|e }}

A few differences from your original proposal:

• chat_ids is a YAML list instead of a comma-separated string. More idiomatic, and each value is validated individually.
• icon_url is dropped. The Bot API doesn't support per-message avatar overrides, the bot's avatar is set via @BotFather.
• Added: parse_mode, disable_notification, disable_web_page_preview, body_template (all optional).

Safety & reliability

• bot_token is stored as a secret and never logged (reqwest errors are sanitized before tracing).
• One sequential sendMessage per chat_id. Telegram rate-limits 1 msg/sec/chat, so parallelism wouldn't help.
• Partial success: if at least one chat delivers, the alert is Ok.
• 429 Retry-After is honored, clamped to [1s, 60s].
• Messages over 4096 codepoints are truncated with … and counted in valerter_alerts_truncated_total.

Known caveat

If you use Telegram alongside another notifier with a shared template body: written in Markdown (e.g. **bold**, triple-backtick fences), Telegram in HTML parse_mode renders those markers literally. Workaround: override body_template on your Telegram notifier with HTML-friendly Jinja. A cleaner per-notifier render-pipeline is planned for 1.2.

Testing

Once v1.1.0 is tagged, you'll find the .deb and .tar.gz on the Releases page. I'd appreciate it if you could try it in your setup and report back. Does the formatting work for your use case? Any rough edges?

Docs: docs/notifiers.md#telegram.

[congto]

Hi @fxthiry

I will check and respond.

Thanks