Chained Loggers Shoutrrr + STDOUT/STDERR

[AliSot2000]

Describe the bug

Hello there

There's either an issue with the documentation or with the way loggers / shoutrrr are set inside the watchtower:latest container.

I'm using smpt in conjunction with gmail - app passwords.

Emails don't get sent, if the log level of WATCHTOWER_LOG_LEVEL is too high.

Steps to reproduce

The observation is the following:

services:
  watchtower:
    container_name: watchtower
    image: containrrr/watchtower:latest
    hostname: watchtower.home.lan
    restart: always
    environment:
      - WATCHTOWER_MONITOR_ONLY=true
      - WATCHTOWER_CLEANUP=false
      - WATCHTOWER_POLL_INTERVAL=3600
      - WATCHTOWER_NOTIFICATIONS_LEVEL=info
      - WATCHTOWER_LOG_LEVEL=info
      - WATCHTOWER_NOTIFICATION_URL=smtp://source-email@gmail.com:email-password@smtp.gmail.com:587/?fromAddress=source-email@gmail.com&toAddresses=target-email
    volumes:
      - "/etc/localtime:/etc/localtime:ro"
      - "/var/run/docker.sock:/var/run/docker.sock"

Will send me an email with this content:

Watchtower 1.7.1
Using notifications: smtp
Checking all containers (except explicitly disabled with label)
Scheduling first run: 2025-10-20 15:17:18 +0000 UTC

However, changing it to:

services:
  watchtower:
    container_name: watchtower
    image: containrrr/watchtower:latest
    hostname: watchtower.home.lan
    restart: always
    environment:
      - WATCHTOWER_MONITOR_ONLY=true
      - WATCHTOWER_CLEANUP=false
      - WATCHTOWER_POLL_INTERVAL=3600
      - WATCHTOWER_NOTIFICATIONS_LEVEL=info
      - WATCHTOWER_LOG_LEVEL=warn
      - WATCHTOWER_NOTIFICATION_URL=smtp://source-email@gmail.com:email-password@smtp.gmail.com:587/?fromAddress=source-email@gmail.com&toAddresses=target-email
    volumes:
      - "/etc/localtime:/etc/localtime:ro"
      - "/var/run/docker.sock:/var/run/docker.sock"

Does not give me said email.

Expected behavior

I'm assuming that the logger that connects to shoutrrr and then sends the email is chained to the logger that emits info to stdout / stderr. This would mean, if the logger for stdout / stderr rejects a log-message, it won't reach the shoutrrr logger after.

It would be helpful if:

• The documentation reflected that i.e. the WATCHTOWER_NOTIFICATIONS_LEVEL only has an efffect if it's >= WATCHTOWER_LOG_LEVEL or
• The two loggers, the one that emits to stdout / stderr and the one that emits messages via shoutrrr are no longer chained.

Screenshots

No response

Environment

• Ubuntu 24.04.3 LTS
• Docker version 28.5.1, build e180ab
• watchtower:latest

Your logs

Log with `WATCHTOWER_LOG_LEVEL=info`

time="2025-10-20T14:17:18Z" level=info msg="Watchtower 1.7.1"
time="2025-10-20T14:17:18Z" level=info msg="Using notifications: smtp"
time="2025-10-20T14:17:18Z" level=info msg="Checking all containers (except explicitly disabled with label)"
time="2025-10-20T14:17:18Z" level=info msg="Scheduling first run: 2025-10-20 15:17:18 +0000 UTC"
time="2025-10-20T14:17:18Z" level=info msg="Note that the first check will be performed in 59 minutes, 59 seconds"


Log with `WATCHTOWER_LOG_LEVEL=warn`

<placeholder for empty logs>

Additional context

No response

[github-actions]

Hi there! 👋🏼 As you're new to this repo, we'd like to suggest that you read our code of conduct as well as our contribution guidelines. Thanks a bunch for opening your first issue! 🙏