rust-motd

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.

Installation

Building from source

• 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.

Arch Linux

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

Debian and derivatives

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

NixOS

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.

Configuration

rust-motd uses a TOML configuration file to determine which components to run, and any parameters for those components. Components can be enabled or disabled by including or removing/commenting-out the relevant section of configuration. The enabled components will be printed in the order they appear in the configuration file. In other words, you can customize the printing order by rearranging the sections of the configuration file. An example configuration file is included in example_config.toml.

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.toml and $HOME/.config/rust-motd/config.toml in that order.

The options for each component are listed below:

Banner

• color: The color of the banner text. Options are black, red, green, yellow, blue, magenta, cyan, white, and light variants of each.
• command: A command executed via sh which generates the banner. For example, you could pipe the output of hostname to figlet to generate a block letter banner.

Weather

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.

Either:

• 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.

or:

• loc: The location to retrieve the weather for, e.g. "New York,New York".
• style: One of either "oneline", "day", or "full".

In the case both are specified, the url parameter is given priority.

User-Agent can also be specified when connecting to the url.

• user_agent: A string to be supplied. If not specified, it will be "curl".

If you need a proxy to access the internet, specify it in below item:

• proxy: The http proxy server which used to access internet.

You may also specify a timeout for the network request. The default is 5.

• timeout: Timeout, seconds

Service Status

• List of systemd services to display the status of. Keys are used as the service display name, while the value is the name of the service itself.

Docker Status

• List of containers to show the status of. Keys are used as the internal docker names (NAMES column of docker ps) (containers can have multiple names, and the container is selected if any of the names match). Values are the display name shown in the output. The key must start with a / for internal containers (please see here).

Uptime

• prefix: Text to print before the formatted uptime.

SSL Certificates

• 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.
• [ssl_certificates.certs]: A subsection that is a list pairs of of certificate display names (keys) and certificate paths (values). If using LetsEncrypt, this should be cert.pem, not privkey.pem.

Filesystems

• List of filesystems to print the information of, in the form of pairs of names (used for display) and mount points.

Memory

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

Fail2Ban

• jails: A list of Fail2Ban jails to print the ban amounts of.

Last Login

• List of users (keys) and number n (values) of that user's n most recent logins to display.

Last Run

• If present, prints the time that the rust-motd was run (useful if updating the motd only periodically e.g. via Cron).

Global Config

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

• 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"): time format string

Setup

Displaying MOTD on login (server setup)

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

Displaying MOTD on every new terminal (personal computer setup)

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

Alternatives

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!

Acknowledgements

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

Footnotes

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.