disk-usage-monitor-waybar

A storage monitoring Waybar module. Displays a summary of disk usage for each mounted fs.

Reads currently mounted filesystems from /proc/mounts, and outputs a summary in a Waybar-compatible JSON format. Updates every 20sec.

Demo:

Build

Requires Zig 0.15.1 (writergate).

Depends on libc for sys/statvfs.h.

zig build -Doptimize=ReleaseFast

I prefer ReleaseFast since it's running as part of my desktop, though you can use whatever safety mode you prefer.

Build for development/testing

I've added a no-bin option in build.zig to enable incremental build/filesystem watching without emitting a binary, to catch compiler errors immediately upon file save:

zig build -Dno-bin -fincremental --watch --debounce 100

Build for valgrind/massif:

zig build -Doptimize=ReleaseFast -Dcpu=baseline

Then run under i.e. massif:

valgrind --tool=massif ./zig-out/bin/disk-usage-monitor-waybar

Note: You must use the std.heap.c_allocator (or heap.raw_c_allocator) to profile a Zig executable under valgrind/massif, otherwise massif will report zero heap usage/incorrect leak results.

Executable comes out to ~380KiB depending on target. Peak heap usage around 13KiB with ~10 mounted filesystems.

Usage

After compiling, place the executable somewhere that's in Waybar's PATH, I prefer to create a bin directory at either ~/bin/ or ~/.config/bin/ - wherever you put your dotfile-related executables is fine.

Config

First, add it to your waybar config and configure however you want it. An example is included in example-configs/waybarloop.conf.

"modules-right": [
    "custom/disk-usage",
],

// Can name it whatever you want, as long as you use the same name everywhere (including CSS)
"custom/disk-usage": {
        "exec": "/path/to/bin/disk-usage-monitor-waybar", 
        "return-type": "json",
        "format": "{icon} {text} {percentage}%",
        // Update every 30 seconds:
        "restart-interval": 30,
        // This optional `format-icons` config will display warning icon if `percentage` is >75%, otherwise the HDD icon:
        "format-icons": {
            "default": [
                "🖴",
                "🖴",
                "🖴",
                "⚠️"
            ],
        }
    },

Styling

Module output includes some CSS class modifiers that Waybar will pull, so you can optionally style the widget with i.e. different colors based on level of disk usage - .low, .medium, .high, and .critical.

Example stylesheet applying various colors mapped to usage level:

/* Default color */
#custom-disk-usage {
    color: @darkForeground1;
}
#custom-disk-usage.low {
    color: @darkForeground1;
}
#custom-disk-usage.medium {
    color: @darkStrongYellow;
}
#custom-disk-usage.high {
    color: @darkStrongOrange;
}
#custom-disk-usage.critical, #custom-disk-usage.err {
    color: @darkStrongRed;
}