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UrlWatch UrlWatch

Container

Tools

A tool for monitoring webpages for updates

Image details

Pulls: 3k
Architecture: amd64
Image size: 180 MB
User: mediadepot
Created: Nov 13, 2018
Updated: 7 years ago
Status: active

Configuration

Type
Container
Image
mediadepot/urlwatch:master
Ports
8081/tcp
Volumes
/srv/urlwatch/config : /opt/mediadepot/apps/urlwatch/etc/localtime : /etc/localtime
Labels
traefik.enable=truetraefik.http.services.urlwatch.loadbalancer.server.port=8081traefik.http.routers.urlwatch.entrypoints=websecuretraefik.http.routers.urlwatch.tls.certresolver=mydnschallenge

Template by mediadepot

Standalone Install

Select an install method, to see config/commands for deploying UrlWatch

Installation method

Install on Portainer

Import all app templates into your Portainer instance, for easy 1-click deploys

  1. Ensure both Docker and Portainer are installed, and up-to-date
  2. Log into your Portainer web UI
  3. Under Settings → App Templates, paste the below URL
  4. Head to Home → App Templates, and the list of apps will show up
  5. Select UrlWatch, fill in any config options, and hit Deploy

Template Import URL

https://raw.githubusercontent.com/Lissy93/portainer-templates/main/templates.json
Show Me demo

More install options in our documentation.

References

  • https://github.com/thp/urlwatch
  • https://github.com/thp/urlwatch/issues/283
  • https://github.com/theia-ide/theia
  • https://github.com/edgi-govdata-archiving/awesome-website-change-monitoring

Serve UrlWatch on your own domain behind Caddy, Nginx or Traefik. Fill in your domain and copy the result. It's a starting point, some apps need their own base URL or extra headers set too.

Proxying urlwatch.example.com to http://urlwatch:8081

Add this to your Caddyfile

urlwatch.example.com {
	reverse_proxy http://urlwatch:8081
}

Check the logs first

Nine times out of ten the logs tell you exactly what went wrong.

  • In Portainer, go to Containers, click the container, then Logs. Or run docker logs urlwatch
  • Exit codes help too: 137 means killed, usually out of memory. 126 or 127 means the command inside the image is broken.

Published on a random port

This template exposes 8081/tcp without setting a host port, so Docker picks a random free one on every deploy.

  • Find it in the Ports column of Portainer's container list, or with docker port urlwatch

Permission denied on volumes

If the logs show "permission denied", the app can't write to its data folder on the host.

  • Fix the ownership: sudo chown -R 1000:1000 /opt/mediadepot/apps/urlwatch
  • Seeing "read-only file system"? /etc/localtime is mounted read-only on purpose, the app isn't meant to write there.

Image won't pull

Test the pull directly on the host: docker pull mediadepot/urlwatch:master

  • "manifest unknown" means the tag no longer exists.
  • "toomanyrequests" is the Docker Hub rate limit. Log in with docker login to raise it.
  • "no space left on device" means a full disk. Reclaim space with docker system prune

"exec format error"

This means the image was built for a different CPU architecture than your server.

  • This image supports: amd64
  • Check yours with uname -m: x86_64 is amd64, aarch64 is arm64. Raspberry Pi and other ARM boards are the usual culprits.

Raise an issue

Found something which isn't working as it should? Here's how to report it.

A single container

UrlWatch runs as one container, the simplest kind of app here. Just the one image to pull and nothing else wired up alongside it.

The app image

An image is the app packed up ready to go, everything UrlWatch needs bundled into one download. This template pulls mediadepot/urlwatch:master, which Docker fetches once (about 180 MB) and then starts your own copy from.

Where the image comes from

Docker pulls its images from registries, public libraries of ready-built apps. UrlWatch's comes from Docker Hub, published by mediadepot.

Version tags

The bit after the colon in the image name is the version tag. This one pins master, so every redeploy gives you that exact build until you bump it yourself.

Which machines it runs on

Every image is built for particular CPU types. This one ships for amd64, so it runs on regular x86 PCs and servers, though not ARM boards like a Raspberry Pi.

Ports

A port is the door the app answers on. Here the app exposes a port but leaves the host side blank, so Docker picks a free one for you. It opens:

  • 8081, published on a random host port

Volumes

A volume is where UrlWatch keeps its files so they survive an update or a restart. Without one, anything it saves would sit inside the container and vanish the moment it's recreated. This template mounts:

  • /srv/urlwatch/config from /opt/mediadepot/apps/urlwatch on the host
  • /etc/localtime from /etc/localtime on the host, read-only

Networking

Nothing custom is set, so UrlWatch sits on Docker's default bridge network: its own private space that reaches the outside world only through the ports it publishes.

Container name

Once it's deployed, Portainer names the container urlwatch. That's what you'll spot in the containers list and use in commands like docker logs urlwatch.

Labels

Labels are small notes pinned to the container. They don't change how UrlWatch behaves, but other tools read them, most often a reverse proxy like Traefik working out which apps to route where. This template sets:

  • traefik.enable=true
  • traefik.http.services.urlwatch.loadbalancer.server.port=8081
  • traefik.http.routers.urlwatch.entrypoints=websecure
  • traefik.http.routers.urlwatch.tls.certresolver=mydnschallenge

Portainer app templates

Zooming out, this whole page comes from a Portainer app template: a short recipe telling Portainer how to set UrlWatch up. Add the template list to Portainer once, then deploying UrlWatch is a click rather than a wall of config.