Docuum performs least recently used (LRU) eviction of Docker images to keep the disk usage below a given threshold.
Docker's built-in docker image prune --all --filter until=… command serves a similar purpose. However, the built-in solution isn't ideal since it uses the image creation time, rather than the last usage time, to determine which images to remove. That means it can delete frequently used images, which may be expensive to rebuild.
Docuum is ideal for use cases such as continuous integration (CI) workers, developer workstations, or any other environment in which Docker images accumulate on disk over time. Docuum works well with tools like Toast and Docker Compose.
Docuum is used by Airbnb on its fleet of 1.5k+ CI workers.
Docker doesn't record when an image was last used. To work around this, Docuum listens for notifications via docker events to learn when images are used. It maintains a small piece of state in a local data directory (see this for details about where this directory is on various platforms). That persisted state allows you to freely restart Docuum (or the whole machine) without losing the image usage timestamp data.
When Docuum first starts and subsequently whenever a new Docker event comes in, LRU eviction is performed until the total disk usage due to Docker images is below the given threshold. This design has a few advantages over evicting images based on a fixed time to live (TTL), which is what various other tools in the Docker ecosystem do:
Docuum also respects the parent-child relationships between images. In particular, it will delete children of a parent before deleting the parent (even if the children were used more recently than the parent), because Docker doesn't allow images with children to be deleted.
Once Docuum is installed, you can run it manually from the command line as follows:
sh
$ docuum --threshold '10 GB'
Docuum will then start listening for Docker events. You can use Ctrl+C to stop it.
You probably want to run Docuum as a daemon, e.g., with launchd, systemd, etc. See the Configuring your operating system to run the binary as a daemon section below for instructions.
Here are the supported command-line options:
``` USAGE: docuum
OPTIONS: -h, --help Prints help information
-k, --keep <REGEX>...
Prevents deletion of images for which repository:tag matches <REGEX>
-t, --threshold <THRESHOLD>
Sets the maximum amount of space to be used for Docker images (default: 10 GB)
-v, --version
Prints version information
```
The --threshold flag accepts multiple representations, like 10 GB, 10 GiB, or 10GB.
Installation consists of two steps:
If you're running macOS or Linux on an x86-64 CPU, you can install Docuum with this command:
sh
curl https://raw.githubusercontent.com/stepchowfun/docuum/main/install.sh -LSfs | sh
The same command can be used again to update to the latest version.
The installation script supports the following optional environment variables:
VERSION=x.y.z (defaults to the latest version)PREFIX=/path/to/install (defaults to /usr/local/bin)For example, the following will install Docuum into the working directory:
sh
curl https://raw.githubusercontent.com/stepchowfun/docuum/main/install.sh -LSfs | PREFIX=. sh
If you prefer not to use this installation method, you can download the binary from the releases page, make it executable (e.g., with chmod), and place it in some directory in your PATH (e.g., /usr/local/bin).
If you're running Windows on an x86-64 CPU, download the latest binary from the releases page and rename it to docuum (or docuum.exe if you have file extensions visible). Create a directory called Docuum in your %PROGRAMFILES% directory (e.g., C:\Program Files\Docuum), and place the renamed binary in there. Then, in the "Advanced" tab of the "System Properties" section of Control Panel, click on "Environment Variables..." and add the full path to the new Docuum directory to the PATH variable under "System variables". Note that the Program Files directory might have a different name if Windows is configured for language other than English.
To update to an existing installation, simply replace the existing binary.
If you have Homebrew, you can install Docuum as follows:
sh
brew install docuum
You can update an existing installation with brew upgrade docuum.
If you have Cargo, you can install Docuum as follows:
sh
cargo install docuum
You can run that command with --force to update an existing installation.
If you prefer not to install Docuum on your system and you're running macOS or Linux on an x86-64 CPU, you can run it in a container:
sh
docker run \
--init \
--rm \
--tty \
--name docuum \
--volume /var/run/docker.sock:/var/run/docker.sock \
--volume docuum:/root \
stephanmisc/docuum --threshold '10 GB'
The instructions below for configuring your operating system to run Docuum as a daemon assume it's installed as an executable binary. If you prefer to run it as a Docker container, change the relevant service definition to run a Docker command like the one above.
On macOS, launchd can be used to run Docuum as a daemon. Create a file (owned by root) called /Library/LaunchDaemons/local.docuum.plist with the following contents, adjusting the arguments as needed:
xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "https://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Label</key>
<string>local.docuum</string>
<key>Program</key>
<string>/usr/local/bin/docuum</string>
<key>ProgramArguments</key>
<array>
<string>/usr/local/bin/docuum</string>
<string>--threshold</string>
<string>10 GB</string>
</array>
<key>StandardOutPath</key>
<string>/var/log/docuum.log</string>
<key>StandardErrorPath</key>
<string>/var/log/docuum.log</string>
<key>EnvironmentVariables</key>
<dict>
<key>PATH</key>
<string>/bin:/usr/bin:/usr/local/bin</string>
</dict>
<key>KeepAlive</key>
<true/>
</dict>
</plist>
Run sudo launchctl load /Library/LaunchDaemons/local.docuum.plist to start the service. You can view the logs with tail -F /var/log/docuum.log.
On most Linux distributions, systemd can be used to run Docuum as a daemon. Create a file (owned by root) called /etc/systemd/system/docuum.service with the following contents, adjusting the arguments as needed:
```ini [Unit] Description=Docuum After=docker.service Wants=docker.service
[Service] Environment='THRESHOLD=10 GB' ExecStart=/usr/local/bin/docuum --threshold ${THRESHOLD} Restart=on-failure
[Install] WantedBy=multi-user.target ```
Run sudo systemctl enable docuum --now to enable and start the service. You can view the logs with sudo journalctl --follow --unit docuum.
On Windows, NSSM, the "Non-Sucking Service Manager", can be used to run Docuum as a daemon. Install NSSM by downloading the binary and adding it to your PATH (see the Installation on Windows (x86-64) section for instructions on how to configure this environment variable), then run Windows Terminal as Administrator and enter the following command:
powershell
nssm install Docuum
NSSM will then open a configuration window. Configure the following:
Application tab, select the path to the Docuum binary. You can optionally add arguments like --threshold "10 GB".I/O tab, choose where you want the logs to be written.Then click the Install service button. Back in Windows Terminal, run the following to start the service:
powershell
nssm start Docuum
If you configured a path for the log file in the I/O tab of the installation window, you can view those logs with Get-Content -Wait docuum.log (adjusting the file path as needed).
docker builder prune --all --force --keep-storage '10 GB'). If you are not using BuildKit mode, Docker's caching mechanism uses intermediate images, and Docuum will happily vacuum such images as usual.