Redshift

Redshift is an open-source software application designed to adjust the color temperature of computer displays based on the time of day.

Redshift modifies the color temperature to reduce eye strain and improve sleep patterns. The application aims to provide a more comfortable viewing experience by dynamically changing the display's color temperature to match the user's surrounding light conditions.

It does this by gradually shifting the color temperature of the display from cooler (bluer) tones during the day to warmer (redder) tones at night.

Users have the flexibility to customize various settings in Redshift. They can specify custom values for day and night color temperatures, adjust the speed of color transitions, and temporarily disable or manually adjust the color temperature.

Redshift is currently unmaintained, however Gammastep is a modern fork of Redshift that supports Wayland. There is also wlsunset which is a lightweight modern alternative.

Installation

Using nix-shell

$ nix-shell -p redshift

Using Global Configuration

❄︎ /etc/nixos/configuration.nix

environment.systemPackages = [
  pkgs.redshift
];

After modifying your configuration, apply the changes by running:

$ sudo nixos-rebuild switch

Using Home Configuration

❄︎ /etc/nixos/home.nix

home.packages = [ 
  pkgs.redshift 
];

After updating your configuration, apply the changes by running:

$ home-manager switch

Configuration

Basic

❄︎ /etc/nixos/configuration.nix

services.redshift = {
  enable = true;
  temperature = {
    day = 5500;
    night = 3700;
  };
};

services.geoclue2.enable = true;
location.provider = "geoclue2";

Advanced (Home Manager)

❄︎ /etc/nixos/home.nix

services.redshift = {
  enable = true;
  
  # Display temperature settings
  temperature = {
    day = 5700;
    night = 3500;
  };
  
  # Location settings (replace with your coordinates)
  latitude = "27.9880614";
  longitude = "86.92521";
  
  # Schedule settings
  dawnTime = "6:00-7:45";
  duskTime = "18:35-20:15";
  
  # General settings
  brightness = {
    day = "1";
    night = "0.8";
  };
  
  extraOptions = [
    "-v"
    "-m randr"
  ];

  tray = false;

};

# Setting the location works either by using a provider
services.geoclue2.enable = true;
location.provider = "geoclue2";

# Or like this, which can also be set in services.redshift
location.latitude = "27.9880614";
location.longitude = "86.92521";

Tips and Tricks

Location of Options

The Home Manager options are defined in the Home Manager Options Manual.

The global options can be found under services.redshift.

Usage

# If services.redshift.enable is true, the systemd unit redshift.service is provided. 
# It can either be started by the user level service manager like this:
systemctl --user start redshift

# Or permanantly enabled by creating the empty file
~/.config/systemd/user/default.target.wants/redshift.service

# After starting the service, make sure to check its status in the service manager:
systemctl --user status redshift

Troubleshooting

Provider is unable to determine location

It may happen that Redshift gets stuck at "Waiting for initial location to become available..." when using the geoclue2 location provider. This may happen when Geoclue is unable to determine your location due to missing information. In that case, you may resort to setting the location manually or using an alternate location service such as beaconDB, which can take advantage of WiFi scanning.

An example of using beaconDB as an alternative:

❄︎ /etc/nixos/configuration.nix

location.provider = "geoclue2";
services.geoclue2 = {
    enable = true;
    geoProviderUrl = "https://api.beacondb.net/v1/geolocate";
  };