CLI tool to automate docker image updates or notifying when updates are available.

selective updates, exclude containers, custom labels, notification plugins, prune when done etc.

🐳 Docker Hub pull limit 📉 not an issue for checks but for actual pulls - read more

For Podman - see the fork sudo-kraken/podcheck!

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🔔 Changelog

• v0.6.5: Refactored notification logic. See notify_templates/notify_v2.sh for upgrade steps.
  • Added helper functions to simplify sourcing files and executing functions if they exist.
  • Created notify_v2.sh wrapper script.
    • Simplified and consolidated notification logic within notify_v2.sh.
    • Added support for notification management via environment variables.
    • Moved notification secrets to dockcheck.config.
  • Added retries to wget/curl to not get empty responses when github is slow.
• v0.6.4: Restructured the update process - first pulls all updates, then recreates all containers.
  • Added logic to skip update check on non-compose containers (unless -r option).
  • Added option -F to revert to compose up -d <ContainerName> targeting specific container and not the stack.
    • Also added corresponding label and config-option.
  • Added markdown formatting to notify_ntfy-sh.sh template.
• v0.6.3: Some fixes and changes:
  • Stops when a container recreation (compose up -d) fails, also ups the whole stack now.
  • -M, Markdown format url-releasenotes in notification (requires template rework, look at gotify!)
  • Added addons/DSM/README.md for more info Synology DSM info.
  • Permission checks - graceful exit if no docker permissions + checking if root for pkg-manager.
• v0.6.2: Style and colour changes, prometheus hotfix, new options:
  • -u, Allow auto self update of dockcheck.sh
  • -I, Print container release URLs in the CLI "choose update" list. (please contribute to urls.list)
  • Extras: -m, Monochrome mode now hides the progress bar.

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🔎 dockcheck.sh

$ ./dockcheck.sh -h
Syntax:     dockcheck.sh [OPTION] [part of name to filter]
Example:    dockcheck.sh -y -x 10 -d 10 -e nextcloud,heimdall

Options:
-a|y   Automatic updates, without interaction.
-c D   Exports metrics as prom file for the prometheus node_exporter. Provide the collector textfile directory.
-d N   Only update to new images that are N+ days old. Lists too recent with +prefix and age. 2xSlower.
-e X   Exclude containers, separated by comma.
-f     Force stop+start stack after update. Caution: restarts once for every updated container within stack.
-F     Only compose up the specific container, not the whole compose stack (useful for master-compose structure).
-h     Print this Help.
-i     Inform - send a preconfigured notification.
-I     Prints custom releasenote urls alongside each container with updates in CLI output (requires urls.list).
-l     Only update if label is set. See readme.
-m     Monochrome mode, no printf colour codes and hides progress bar.
-M     Prints custom releasenote urls as markdown (requires template support).
-n     No updates, only checking availability.
-p     Auto-Prune dangling images after update.
-r     Allow updating images for docker run, wont update the container.
-s     Include stopped containers in the check. (Logic: docker ps -a).
-t N   Set a timeout (in seconds) per container for registry checkups, 10 is default.
-u     Allow automatic self updates - caution as this will pull new code and autorun it.
-v     Prints current version.
-x N   Set max asynchronous subprocesses, 1 default, 0 to disable, 32+ tested.

Basic example:

$ ./dockcheck.sh
. . .
Containers on latest version:
glances
homer

Containers with updates available:
1) adguardhome
2) syncthing
3) whoogle-search

Choose what containers to update:
Enter number(s) separated by comma, [a] for all - [q] to quit:

Then it proceeds to run pull and up -d on every container with updates.
After the updates are complete, you'll get prompted if you'd like to prune dangling images.

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🔩 Dependencies

• Running docker (duh) and compose, either standalone or plugin. (see Podman fork
• Bash shell or compatible shell of at least v4.3
  • POSIX xargs, usually default but can be installed with the findutils package - to enable async.
• jq
  • User will be prompted to install with package manager or download static binary.
• regclient/regctl (Licensed under Apache-2.0 License)
  • User will be prompted to download regctl if not in PATH or PWD.
  • regctl requires amd64/arm64 - see workaround if other architecture is used.

⛺ Install Instructions

Download the script to a directory in PATH, I'd suggest using ~/.local/bin as that's usually in PATH.
For OSX/macOS preferably use /usr/local/bin.

# basic example with curl:
curl -L https://raw.githubusercontent.com/mag37/dockcheck/main/dockcheck.sh -o ~/.local/bin/dockcheck.sh
chmod +x ~/.local/bin/dockcheck.sh

# or oneliner with wget:
wget -O ~/.local/bin/dockcheck.sh "https://raw.githubusercontent.com/mag37/dockcheck/main/dockcheck.sh" && chmod +x ~/.local/bin/dockcheck.sh

# OSX or macOS version with curl:
 curl -L https://raw.githubusercontent.com/mag37/dockcheck/main/dockcheck.sh -o /usr/local/bin/dockcheck.sh && chmod +x /usr/local/bin/dockcheck.sh

Then call the script anywhere with just dockcheck.sh. Add preferred notify.sh-template to the same directory - this will not be touched by the scripts self-update function.

👜 Configuration

To modify settings and have them persist through updates - copy the default.config to dockcheck.config alongside the script or in ~/.config/.
Alternatively create an alias where specific flags and values are set.
Example alias dc=dockcheck.sh -p -x 10 -t 3.

📢 Notifications

Trigger with the -i flag. If notify.sh is present and configured, it will be used. Otherwise, notify_v2.sh will be enabled. Will send a list of containers with updates available and a notification when dockcheck.sh itself has an update. Run it scheduled with -ni to only get notified when there's updates available!

V2 installation and configuration (tag v0.6.5 or later): Remove or rename notify.sh if previously configured using the legacy method. Uncomment and set the NOTIFY_CHANNELS environment variable in dockcheck.config to a space separated string of your desired notification channels to enable. Uncomment and set the environment variables related to the enabled notification channels. It is recommended not to make changes directly to the notify_X.sh template files and to use only environment variables defined in dockcheck.config using this method.

Legacy installation and configuration: Use a previous version of a notify_X.sh template file (tag v0.6.4 or earlier) from the notify_templates directory, copy it to notify.sh alongside the script, modify it to your needs! (notify.sh is added to .gitignore)

Current templates:

• Synology DSM
• Email with mSMTP (or deprecated alternative sSMTP)
• Apprise (with it's multitude of notifications)
  • both native caronc/apprise and the standalone linuxserver/docker-apprise-api
  • Read the QuickStart
• ntfy.sh - HTTP-based pub-sub notifications.
• Gotify - a simple server for sending and receiving messages.
• Pushbullet - connecting different devices with cross-platform features.
• Telegram - Telegram chat API.
• Matrix-Synapse - Matrix, open, secure, decentralised communication.
• Pushover - Simple Notifications (to your phone, wearables, desktops)
• Discord - Discord webhooks.
• Slack - Slack curl api

Further additions are welcome - suggestions or PR!
_{^{Initiated and first contributed by yoyoma2.}}

📅 Release notes addon

There's a function to use a lookup-file to add release note URL's to the notification message.
Copy the notify_templates/urls.list file to the script directory, it will be used automatically if it's there.
Modify it as necessary, the names of interest in the left column needs to match your container names.
To also list the URL's in the CLI output (choose containers list) use the -I option or variable config.
For Markdown formatting also add the -M option. (this requires the template to be compatible - see gotify for example)

The output of the notification will look something like this:

Containers on hostname with updates available:
apprise-api  ->  https://github.com/linuxserver/docker-apprise-api/releases
homer  ->  https://github.com/bastienwirtz/homer/releases
nginx  ->  https://github.com/docker-library/official-images/blob/master/library/nginx
...

The urls.list file is just an example and I'd gladly see that people contribute back when they add their preferred URLs to their lists.

⏩ Asyncronous update checks with xargs; -x N option. (default=1)

Pass -x N where N is number of subprocesses allowed, experiment in your environment to find a suitable max!
Change the default value by editing the MaxAsync=N variable in dockcheck.sh. To disable the subprocess function set MaxAsync=0.

📈 Extra plugins and tools:

🔸 Using dockcheck.sh with the Synology DSM

If you run your container through the Container Manager GUI - only notifications are supported.
While if running manual (vanilla docker compose CLI) will allow you to use the update function too.
Some extra setup to tie together with Synology DSM - check out the addons/DSM/README.md.

🔸 Prometheus and node_exporter

Dockcheck can be used together with Prometheus and node_exporter to export metrics via the file collector, scheduled with cron or likely. This is done with the -c option, like this:

dockcheck.sh -c /path/to/exporter/directory

See the README.md for more detailed information on how to set it up!
_{^{Contributed by tdralle.}}

🔸 Zabbix config to monitor docker image updates

If you already use Zabbix - this config will Shows number of available docker image updates on host.
Example: 2 Docker Image updates on host-xyz
See project: thetorminal/zabbix-docker-image-updates

🔸 Serve REST API to list all available updates

A custom python script to serve a REST API to get pulled into other monitoring tools like homepage.
See discussion here.

🔸 Wrapper Script for Unraid's User Scripts

A custom bash wrapper script to allow the usage of dockcheck as a Unraid User Script plugin.
See discussion here.

🔖 Labels

Optionally add labels to compose-files. Currently these are the usable labels:

    labels:
      mag37.dockcheck.update: true
      mag37.dockcheck.only-specific-container: true
      mag37.dockcheck.restart-stack: true

• mag37.dockcheck.update: true will when used with the -l option only update containers with this label and skip the rest. Will still list updates as usual.
• mag37.dockcheck.only-specific-container: true works instead of the -F option, specifying the updated container when doing compose up, like docker compose up -d homer.
• mag37.dockcheck.restart-stack: true works instead of the -f option, forcing stop+restart on the whole compose-stack (Caution: Will restart on every updated container within stack).

🎢 Workaround for non amd64 / arm64

regctl provides binaries for amd64/arm64, to use on other architecture you could try this workaround. Run regctl in a container wrapped in a shell script. Copied from regclient/docs/install.md:

cat >regctl <<EOF
#!/bin/sh
opts=""
case "\$*" in
  "registry login"*) opts="-t";;
esac
docker container run \$opts -i --rm --net host \\
  -u "\$(id -u):\$(id -g)" -e HOME -v \$HOME:\$HOME \\
  -v /etc/docker/certs.d:/etc/docker/certs.d:ro \\
  ghcr.io/regclient/regctl:latest "\$@"
EOF
chmod 755 regctl

Test it with ./regctl --help and then either add the file to the same path as dockcheck.sh or in your path (eg. ~/.local/bin/regctl).

🐳 Docker Hub pull limit 📉 not an issue for checks but for actual pulls

Due to recent changes in Docker Hub usage and limits

Unauthenticated users: 10 pulls/hour
Authenticated users with a free account: 100 pulls/hour

This is not an issue for registry checks. But if you have a large stack and pull more than 10 updates at once consider updating more often or to create a free account. You could use/modify the login-wrapper function in the example below to automate the login prior to running dockcheck.sh.

💂‍♂️ Function to auth with docker hub before running

Example - Change names, paths, and remove cat+password flag if you rather get prompted:

function dchk {
  cat ~/pwd.txt | docker login --username YourUser --password-stdin
  ~/dockcheck.sh "$@"
}

⚠️ -r flag disclaimer and warning

Wont auto-update the containers, only their images. (compose is recommended)
docker run dont support using new images just by restarting a container.
Containers need to be manually stopped, removed and created again to run on the new image.
Using the -r option together with eg. -i and -n to just check for updates and send notifications and not update is safe though!

🔨 Known issues

• No detailed error feedback (just skip + list what's skipped).
• Not respecting --profile options when re-creating the container.
• Not working well with containers created by Portainer.
• Watchtower might cause issues due to retagging images when checking for updates (and thereby pulling new images).

🔧 Debugging

If you hit issues, you could check the output of the extras/errorCheck.sh script for clues. Another option is to run the main script with debugging in a subshell bash -x dockcheck.sh - if there's a particular container/image that's causing issues you can filter for just that through bash -x dockcheck.sh nginx.

📜 License

dockcheck is created and released under the GNU GPL v3.0 license.

💗 Sponsorlist

• avegy
• eichhorn
• stepdg

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💾 The story behind it. 1 year in retrospect.