mag37/dockcheck

• v0.8.3:
  • FIX: Using the full compose file path to determine if a container already got restarted.
  • FIX: Sourcing the dockcheck.config earlier so CLI always take precedence.
  • FIX: Only print update process messages when actually processing updates.
• v0.8.2:
  • FIX: Blocking any self-updates when containerized (both script and image).
  • FIX: Only print exclusion message when excluded container actually has an update.
• v0.8.1:
  • NEW: Added Docker Compose - possibility to run dockcheck fully containerized.
  • FIX: Clarified interactive output around -E (exclude from update).
• v0.8.0:
  • NEW: Added Home Assistant event integration.
  • NEW: Added option -E to exclude from updating, while still checking for updates.
  • NEW: Added option -C to temporarily fall back to default configs, ignoring dockcheck.config.
  • NEW: Added option -N to test notifications by simulating updates.
  • NEW: More URLs to urls.list.
  • FIX: Docker restart/pull handling rework to avoid restarting already restarted stacks and skip failed pulls.
  • FIX: Clarified Image backups restoration section in the readme.
  • FIX: Changed some array variable handling to be more compatible.
  • FIX: Script update notification consistency, didn't always trigger.
  • FIX: Function call to print current backups, some environments didn't source the function.

$ ./dockcheck.sh -h
Syntax:     dockcheck.sh [OPTION] [comma separated names to include]
Example:    dockcheck.sh -y -x 10 -d 10 -e nextcloud,heimdall

Options:
-a|y   Automatic updates, without interaction.
-b N   Enable image backups and sets number of days to keep from pruning. Ignores -p auto-prune.
-B     List currently backed up images, then exit.
-c D   Exports metrics as prom file for the prometheus node_exporter. Provide the collector textfile directory.
-C     Temporarily use default configs - override dockcheck.config file.
-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.
-E X   Exclude containers from applying updates but check available, 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 include containers with label 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.
-N     No updates or checks; simulating updates to test notifications unconditionally.
-o     Hides the \"No updates available\" message and only shows updateable images.
-p     Auto-Prune dangling images after update. Ignored when -b is used.
-r     Allow checking/updating images created by `docker run`, containers need to be recreated manually.
-R     Skip container recreation after pulling images.
-s     Include stopped containers, returns to stopped state after recreation.
-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.

$ ./dockcheck.sh
[##################################################] 5/5

Containers on latest version:
glances
homer

Containers with updates available:
01) adguardhome
02) syncthing
03) whoogle-search

Choose what containers to update:
Enter number(s) or range(s) separated by comma (e.g. 1-2,4-5,09), [a] for all - [q] to quit: 1-2

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.

• 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.

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.

Warning - Mounting the docker socket with full permissions.
Info - The dockcheck container is currently required to be manually updated, self-updates blocked.

Either use the compose-example-configfile.yml together with setting up a dockcheck.config with your notification settings and options. Or use the compose-example-envvars.yml and set everything as environment varialbes (use the default.config as reference).

Make sure the docker project volumes match 1:1 between the host and inside the container.

If you'd like to run it interactively (while having the container running), for example:

docker exec -it dockcheck ./dockcheck.sh -e container1 -x 10
## or create an alias:
alias dockcheck="docker exec -it dockcheck ./dockcheck.sh"

Or run it once, interactively with docker run (excluding config+crontab in this example):

docker run -it \
  -v /etc/localtime:/etc/localtime:ro \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -v /path/to/projects/docker/:/path/to/projects/docker/\
  mag37/dockcheck ./dockcheck.sh -x 10 -b 5

_{^{Thanks to vorezal.}}

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.

Triggered with the -i flag. Will send a list of containers with updates available and a notification when dockcheck.sh itself has an update. notify_templates/notify_v2.sh is the default notification wrapper, if notify.sh is present and configured, it will override.

Example of a cron scheduled job running non-interactive at 10'oclock excluding 1 container and sending notifications: 0 10 * * * /home/user123/.local/bin/dockcheck.sh -nix 10 -e excluded_container1

To test notifications after setting them up, use the -N flag.

Set up a directory structure as below. You only need the notify_templates/notify_v2.sh file and any notification templates you wish to enable, but there is no harm in having all of them present.

 .
├── notify_templates/
│   ├── notify_DSM.sh
│   ├── notify_apprise.sh
│   ├── notify_bark.sh
│   ├── notify_discord.sh
│   ├── notify_generic.sh
│   ├── notify_gotify.sh
│   ├── notify_HA.sh
│   ├── notify_matrix.sh
│   ├── notify_ntfy.sh
│   ├── notify_pushbullet.sh
│   ├── notify_pushover.sh
│   ├── notify_slack.sh
│   ├── notify_smtp.sh
│   ├── notify_telegram.sh
│   ├── notify_v2.sh
│   └── notify_xmpp.sh
├── dockcheck.config
├── dockcheck.sh
└── urls.list         # optional

• 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. Eg. GOTIFY_DOMAIN="" + GOTIFY_TOKEN="".

It's recommended to only do configuration with variables within dockcheck.config and not modify notify_templates/notify_X.sh directly. If you wish to customize the notify templates yourself, you may copy them to your project root directory alongside the main dockcheck.sh (where they're also ignored by git).
Customizing notify_v2.sh is handled the same as customizing the templates, but it must be renamed to notify.sh within the dockcheck.sh root directory.

Configure to receive scheduled notifications only if they're new since the last notification - within a set time frame.

Example: Dockcheck is scheduled to run every hour. You will receive an update notification within an hour of availability.
Snooze enabled: You will not receive a repeated notification about an already notified update within the snooze duration.
Snooze disabled: You will receive additional (possibly repeated) notifications every hour.

To enable snooze uncomment the SNOOZE_SECONDS variable in your dockcheck.config and set it to the number of seconds you wish to prevent duplicate alerts.
Snooze is split into three categories; container updates, dockcheck.sh self updates and notification template updates.

If an update becomes available for an item that is not snoozed, notifications will be sent and include all available updates for that item's category, even snoozed items.

The actual snooze duration will be 60 seconds less than SNOOZE_SECONDS to account for minor scheduling or run time issues.

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

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

All required environment variables for each notification channel are provided in the default.config file as comments and must be uncommented and modified for your requirements.
For advanced users, additional functionality is available via custom configurations and environment variables.
Use cases - all configured in dockcheck.config:
(replace <CHANNEL> with the upper case name of the of the channel as listed in NOTIFY_CHANNELS variable, eg TELEGRAM_SKIPSNOOZE)

• To bypass the snooze feature, even when enabled, add the variable <CHANNEL>_SKIPSNOOZE and set it to true.
• To configure the channel to only send container update notifications, add the variable <CHANNEL>_CONTAINERSONLY and set it to true.
• To send notifications even when there are no updates available, add the variable <CHANNEL>_ALLOWEMPTY and set it to true.
• To use another notification output format, add the variable <CHANNEL>_OUTPUT and set it to csv, json, or text. If unset or set to an invalid value, defaults to text.
• To send multiple notifications using the same notification template:
  • Strings in the NOTIFY_CHANNELS list are now treated as unique names and do not necessarily refer to the notification template that will be called, though they do by default.
  • Add another notification channel to NOTIFY_CHANNELS in dockcheck.config. The name can contain upper and lower case letters, numbers and underscores, but can't start with a number.
  • Add the variable <CHANNEL>_TEMPLATE to dockcheck.config where <CHANNEL> is the name of the channel added above and set the value to an available notification template script (slack, apprise, gotify, etc.)
  • Add all other environment variables required for the chosen template to function with <CHANNEL> in upper case as the prefix rather than the template name.
    • For example, if <CHANNEL> is mynotification and the template configured is slack, you would need to set MYNOTIFICATION_CHANNEL_ID and MYNOTIFICATION_ACCESS_TOKEN.

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.

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.config. To disable the subprocess function set MaxAsync=0.

When the option BackupForDays is set dockcheck will store the image being updated as a backup, retagged with a different name and removed due to age configured (BackupForDays) in a future run.
Let's say we're updating b4bz/homer:latest - then before replacing the current image it will be retagged with the name dockcheck/homer:2025-10-26_1132_latest

1. dockcheck as repo name to not interfere with others.
2. homer is the image.
3. 2025-10-26_1132 is the time when running the script.
4. latest is the tag of the image.

If an update breaks, you could restore the previous image with these steps (using the naming above as examples):

• First take the container down, docker compose down or similar.
• Remove the new (faulty) image: docker rmi b4bz/homer:latest -f
• List backed up image names: dockcheck.sh -B | grep "homer"
• Create a new tag from backup (matching the real name): docker tag dockcheck/homer:2025-10-26_1132_latest b4bz/homer:latest
• Start the container again: docker compose up -d, now with the previous image faked as latest.
• The temporary image will be overwritten with the real latest/other tag next time you pull new images (with dockcheck or elsewhere).

The backed up images will be removed if they're older than BackupForDays value (passed as -b N or set in the dockcheck.config with BackupForDays=N) and then pruned.
If configured for eg. 7 days, force earlier cleaning by just passing a lower number of days, eg. -b 2 to clean everything older than 2 days.
Backed up images will not be cleaned up if neither -b flag nor BackupForDays config variable is set.

When backups are enabled, the -p auto-prune option is ignored to preserve backed up images.

Use the capital option -B to list currently backed up images. Or list all images with docker images.
To manually remove any backed up images, do docker rmi dockcheck/homer:2025-10-26_1132_latest.

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.

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.}}

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

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

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

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 check and update containers with this label set and skip the rest.
• 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).

Adding or modifying labels in compose-files requires a restart of the container to take effect.

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).

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.

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 "$@"
}

Wont auto-update the containers, only their images. (compose is recommended)
docker run doesn't 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!

• 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).

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.

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

🔸 avegy 🔸 eichhorn 🔸 stepdg 🔸 acer2220 🔸 shgew 🔸 jonas3456 🔸 4ndreasH 🔸 markoe01 🔸 mushrowan 🔸