Mattermost (via Shoutrrr) is using incorrect pot

[My-Random-Thoughts]

Describe the bug

Using the following in my docker-compose:

- WATCHTOWER_NOTIFICATION_URL=mattermost://watchtower@home.lan:8065/53hwxy8nqf8c98diqoo4rmekjw/watchtower-messages

I get the following error message upon startup:

Failed to send shoutrrr notification" error="Post \"https://home.lan/hooks/53hwxy8nqf8c98diqoo4rmekjw\": dial tcp 192.168.1.31:443: connect: connection refused" index=0 notify=no service=mattermost

As you can see, it's not using the correct port listed, and tries to use HTTPS whereas I am using HTTP only.

Steps to reproduce

1. Have self-hosted mattermost instance, not using any proxy and HTTP only
2. Create Incoming Webhook for Watchtower
3. Get URL fro webhook
4. Use in WATCHTOWER_NOTIFICATION_URL using correct format

Expected behavior

• Should use HTTP or have option for it
• Should use specified port

Screenshots

No response

Environment

• Platform: Debian
• Architecture: x64
• Docker Version: 28.0.1

Your logs

time="2025-03-16T00:31:38Z" level=debug msg="Sleeping for a second to ensure the docker api client has been properly initialized."
time="2025-03-16T00:31:39Z" level=debug msg="Making sure everything is sane before starting"
time="2025-03-16T00:31:39Z" level=debug msg="Retrieving running, stopped and exited containers"
time="2025-03-16T00:31:39Z" level=debug msg="There are no additional watchtower containers"
time="2025-03-16T00:31:39Z" level=info msg="Watchtower 1.7.1"
time="2025-03-16T00:31:39Z" level=info msg="Using notifications: mattermost"
time="2025-03-16T00:31:39Z" level=info msg="Checking all containers (except explicitly disabled with label)"
time="2025-03-16T00:31:39Z" level=info msg="Scheduling first run: 2025-03-16 17:00:00 +0000 GMT"
time="2025-03-16T00:31:39Z" level=info msg="Note that the first check will be performed in 16 hours, 28 minutes, 20 seconds"
time="2025-03-16T00:31:39Z" level=error msg="Failed to send shoutrrr notification" error="Post \"https://home.lan/hooks/53hwxy8nqf8c98diqoo4rmekjw\": dial tcp 192.168.1.31:443: connect: connection refused" index=0 notify=no service=mattermost

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! 🙏