liminix/modules/health-check/default.nix

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## Health check
##
## Runs a service and a separate periodic health process. When the
## health check starts failing over a period of time, kill the service.
## (Usually that means the supervisor will restart it, but you can
## have other behaviours by e.g. combining this service with a round-robin
## for failover)
{ lib, pkgs, config, ...}:
let
inherit (lib) mkOption types;
inherit (pkgs) liminix;
# inherit (pkgs.liminix.services) longrun;
in {
options = {
system.service.health-check = mkOption {
description = "run a service while periodically checking it is healthy";
type = liminix.lib.types.serviceDefn;
};
};
config.system.service.health-check = config.system.callService ./service.nix {
service = mkOption {
type = liminix.lib.types.service;
};
interval = mkOption {
description = "interval between checks, in seconds";
type = types.int;
default = 10;
example = 10;
};
threshold = mkOption {
description = "number of consecutive failures required for the service to be kicked";
type = types.int;
example = 3;
};
healthCheck = mkOption {
description = "health check command or script. Expected to exit 0 if the service is healthy or any other exit status otherwise";
type = types.path;
};
};
config.programs.busybox.applets = ["expr"];
}