Beautiful, useful, configurable MOTD generation with zero¹ runtime dependencies

I got stuck in dependency hell one too many times trying to update interpreted alternatives and decided to write my own MOTD generator in Rust. The goal of this project is to provide beautiful yet useful status screens which can quickly give an overview of your server or personal computer.

• Install rustup and cargo
• Install and configure the default toolchain with rustup install stable and rustup default stable
• Install the equivalent of the libssl-dev package using your package manager
• Clone this repository and enter it
• Run cargo build or cargo run

Note: To cross compile, you may need to install additional packages. For example, to cross compile for Alpine, it was necessary to install the musl-tools package on Ubuntu (specifically to compile the ring crate), after which an executable could be successfully cross-compiled with cargo build --target x86_64-unknown-linux-musl (assuming you've already added the musl toolchain via rustup target add x86_64-unknown-linux-musl). See more.

rust-motd is in the AUR under rust-motd-bin thanks to cargo-aur.

• You can install rust-motd-deb with pacstall.
• There is a .deb file available in the Releases tab.

rust-motd is available in the nix package manager under the name rust-motd. Unlike the other formats, this is not packaged by the authors of rust-motd.

rust-motd is configured using a KDL file. Support for the legacy TOML configuration is maintained for backwards compatibility, but it may be removed during a future major release. The rest of this section will assume the new KDL format. See the migration guide for details.

The most basic configuration is given below. global.version must be specified and the value must be 1.0. The components (described in the next sections) will be displayed in the order they appear inside of components {}. Each component can occur as many times as you'd like, with different parameters each time. An example configuration file example_config.kdl.

global {
  version "1.0"
}
components {
}

A configuration file can either be specified as the first argument to rust-motd via the command line or placed in one of two default locations. If a config file is not specified as an argument, rust-motd will check $XDG_CONFIG_HOME/rust-motd/config.kdl and $HOME/.config/rust-motd/config.kdl in that order.

The options for each component are listed below. Each section lists children, properties, and attributes. Components that take children show multiple pieces of information:

components {
  component-with-children {
    child
    child
  }
}

If a component (or a child of a component) takes properties, put the name of the property, an equals sign (=), and the value.

components {
  component property-name="value"
}

If a component (or a child of a component) takes arguments, do not put the argument name or equals sign, just place the value.

components {
  command "echo this is the command to run"
}

Display the output of a command (executed via sh).

Example:

command color="red" "hostname | figlet -f slant"

Arguments:

• Command: The command to run. Essentially the argument to sh -c.

Properties:

• color: The color of the banner text. Options are black, red, green, yellow, blue, magenta, cyan, white, and light variants of each. The default is white.

The weather component allows you to either specify a wttr.in URL, or a location and display style which will be used to build the URL.

Example:

weather loc="Toronto,Canada" style="oneline" timeout=10

Properties:

• url: a wttr.in query URL for the relevant location. E.g. https://wttr.in or https://wttr.in/New+York,New+York?0. For more detail about the options available via the request URL, see the wttr.in documentation. The response of an http request to the specified URL is output directly to the console, so in theory you could use a service other than wttr.in. If unspecified, the URL is automatically built from the following properties.
• loc: The location to retrieve the weather for, e.g. "New York,New York". If url is specified, this has no effect. If unspecified, wttr.in will try to determine your location automatically.
• style: One of either "oneline", "day", or "full". If url is specified, this has no effect. The default is "day".
• user-agent: User-Agent to use when connecting. The default is curl.
• proxy: The http proxy server which used to access internet.
• timeout: Timeout in seconds for the network request. The default is 5.

Displays the status of systemd services.

Example:

service-status {
  service display-name="Accounts" unit="accounts-daemon"
  service display-name="Cron" unit="cronie"
}

Children:

• service: Specify once for each service

Properties of service:

• unit: The name of the unit. Basically corresponds to the argument to systemctl commands.
• display-name: The display name. Can be anything. For example, unit is called accounts-daemon, you may want to display Accounts.

Displays the status of systemd services.

Example:

user-service-status {
  service display-name="gpg-agent" unit="gpg-agent"
}

Displays the status of docker containers.

Example:

docker {
  container display-name="Nginx" docker-name="/nginx-nginx-1"
  container display-name="MariaDB" docker-name="/mariadb-mariadb-1"
}

Properties:

• socket: The socket to use. Allows connecting to the Podman daemon instead of Docker, for example, by setting socket="unix:///run/user/1000/podman/podman.sock". The default is the docker socket.
• title: Allows changing the title of the component. For example, you may want to change it to Podman if you use the Podman socket. The default is Docker.

Children:

• container: Specify once for each service.

Properties of container:

• display-name: The pretty name of the container.
• docker-name: The internal docker name (NAMES column of docker ps). Containers can have multiple names, and the container is selected if any of the names match. The key must start with a / for internal containers (please see here).

Displays the status of all docker containers in a compose stack.

Example:

docker-compose {
  stack display-name="Nginx" path="~/docker/nginx"
}

Properties:

• socket: The socket to use. Allows connecting to the Podman daemon instead of Docker, for example, by setting socket="unix:///run/user/1000/podman/podman.sock". The default is the docker socket.
• title: Allows changing the title of the component. For example, you may want to change it to Podman if you use the Podman socket. The default is Docker.
• style:
  • count: On one line, show only the number of containers in each state (default).
  • full: Show each container from each compose stack on its own line with its status.

Children:

• stack: Specify once for each stack.

Properties of stack:

• display-name: The pretty name of the stack.
• path: The path to the parent directory of the docker-compose.yml file. Supports ~ expansion.

Displays the uptime.

Example:

uptime prefix="Uptime"

• prefix: Text to print before the formatted uptime. The default is Up.

Shows the expiration of SSL certificates.

Example:

ssl-certs sort-method="alphabetical" {
  cert name="example.com"  path="./cert.pem"
}

Properties:

• sort-method: The order to sort the displayed SSL certificates. Options are "alphabetical", "expiration", or "manual", in which case the certs will be displayed in the same order that they appear in the config file.

Children:

• cert: Specify once for each certificate.

Properties of cert:

• name: The pretty name to display.
• path: Path to the certificate file. If using LetsEncrypt, this should be cert.pem, not privkey.pem.

Displays information about filesystems and a bar showing the used space.

Example:

filesystems {
  filesystem name="root" mount-point="/"
  filesystem name="home" mount-point="/home"
}

Children:

• filesystem: Specify once for each filesystem.

Properties of filesystem:

• name: Display name for the filesystem.
• mount-point: The directory where the filesystem is mounted, used to identify it.

Displays information about used memory.

Example:

memory swap-pos="beside"

Properties:

• swap-pos: Either beside, below or none to indicate the location to display the swap memory usage, if any.

Shows information about Fail2Ban jails.

Example:

fail2ban {
  jail "sshd"
}

Children:

• jail: Specify once for each jail.

Arguments of jail:

• name: The name of the jail.

Displays the last logins to the machine.

Example:

last-login {
  user username="marcel" num-logins=2
}

Children:

• user: Specify once for each user.

Properties of user:

• username: Username of the user.
• num-logins: The number of logins to display.

Displays the timestamp of the last time rust-motd was run. This is useful if updating the motd only periodically e.g. via Cron.

Example:

last-run

Displays information about the current system load.

Example:

load-avg format="Load (1, 5, 15 min.): {one:.02}, {five:.02}, {fifteen:.02}"

Properties:

• format: Format of the printed message. Can contain specifiers for parameters one, five and fifteen representing different load average values.
• warn-threshold: Optional threshold for printing load values in yellow. Defaults to the number of CPUs in the system.
• bad-threshold: Optional threshold for for printing load values in red. Defaults to four times the number of CPUs in the system.

Prints CPU usage by users and services since the last invocation. The numbers are based on statistics from systemd-managed cgroups.

Example:

cg-stats state-file="cg_stats.toml" threshold=0.01

Properties:

• state-file: File name where to store cgroup statistics for the next invocation.
• threshold: Number in range [0.0, 1.0]. Output lines are generated only for cgroups with CPU usage higher than this value.

The global configuration is used for settings that may span multiple components, e.g. the time format string, and progress bar style.

• version: Must be specified and must be 1.0.
• progress-full-character (Default "="): The character to use for the line segment of the progress bar indicating the "active" portion of the quantity represented
• progress-empty-character (Default "="): The character to use for the line segment of the progress bar indicating the "inactive" portion of the quantity represented
• progress-prefix (Default "["): The character to used to cap the left side of the progress bar
• progress-suffix (Default "]"): The character to used to cap the right side of the progress bar
• progress-width (Default 80): The default width of the progress bar, used only if no other "size hint" is available. More specifically, the filesystem component will automatically determine its width. If the filesystem component is present, then the memory component will use the width of the filesystem as its size hint. Otherwise it will use the configured value.
• time-format (Default "%Y-%m-%d %H:%M:%S %Z"): time format string

This is the recommended setup for the fastest performance opening a new shell.

The canonical MOTD is a message printed on login. To achieve this, the file /etc/motd must be kept up to date with the output of rust-motd. One of the simplest ways to do this is with a cron job. The line below will update /etc/motd every 5 minutes. This must be run as root (sudo crontab -e) in order to write to the protected file /etc/motd.

*/5 * * * * rust-motd > /etc/motd

It can also be nice to show the MOTD locally every time you launch a new terminal emulator (or on every new pane if you use tmux). Indeed, some components make more sense on a server (ssl, fail2ban, last_login) whereas others make more sense on a local machine (weather, user services).

The setup for this is slightly different. First of all, you will probably want to run rust-motd as your normal user, not as root. This is especially true if you are using the user services component. This also means that you won't have permission to write to /etc/motd. I chose ~/.local/etc/motd. Finally, I had to set the environment variable DBUS_SESSION_BUS_ADDRESS in my crontab in order to see the status of my user systemd services. Without it, the underlying call to systemctl would return nothing and nothing would be shown in rust-motd.

*/5 * * * *  export DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus; rust-motd > ~/.local/etc/motd

Finally, with ~/.local/etc/motd populated, the last step is to print the contents of this file every time a new terminal emulator is launched. Open your shell's configuration file (.bashrc, .zshrc, etc.) and add the following line at the very bottom (if you aliased cat to bat as I did replace cat below with command cat):

cat $HOME/.local/etc/motd

This setup prioritizes up-to-date data above shell performance. It should only be used if rust-motd is very fast with your configuration. Some components can take considerable time (weather has to hit the internet). You will experience this delay on every new shell.

The simplest way to show rust-motd with fresh data on every new shell is simply to add the command rust-motd to your shell configuration file (~/.bashrc, ~/.zshrc, ...).

update-motd is Ubuntu's standard method for dynamically updating a MOTD (see update-motd(5)).

You can create a script like this (/etc/update-motd.d/99-rust-motd) :

#!/usr/bin/env bash
rust-motd /etc/rust-motd.kdl

Don't forget to make the script executable.

This is the most "Linux standard" solution.

Place the execution of an optional script (not affecting authentication in case of failure) before the execution of the pam module pam_motd.so.

session optional pam_exec.so /usr/local/bin/update-motd

And in the script /usr/local/bin/update-motd, put:

#!/usr/bin/env bash
rust-motd /etc/rust-motd.kdl > /etc/motd

rust-motd took a lot of inspiration from panda-motd.

• panda-motd: "a utility for generating a more useful MOTD", Ruby
• motd-on-acid: "This MOTD has so many colors!", Shell
• fancy-motd: "Fancy, colorful MOTD written in bash. Server status at a glance.", Shell
• HermannBjorgvin/MOTD: "Mini MOTD, a customizable, configurable, standardized MOTD for your homelab server or laptop", Shell

Search "MOTD" on r/unixporn for more!

A huge thank you to the kind folks at Jupiter Broadcasting for featuring rust-motd on Linux Unplugged 428!

rust-motd is made possible by the following packages:

• wttr.in ":partly_sunny: The right way to check the weather"
• systemstat: "Rust library for getting system information", used for filesystem usage
• termion: Rust library used to print fancy colours in the terminal
• termtosvg: "Record terminal sessions as SVG animations", used to generate the preview in the README
• bytesize: Rust library used for binary size representations
• humantime: "Human-friendly time parser and formatter", used for uptime component

¹: Certain components do have dependencies: fail2ban (fail2ban), service_status (systemd), last_login (last). However, it would not make sense to request the status of a package that is not installed. Furthermore, there are some caveats when compiling for minimal distributions like Alpine Linux.