138 lines
4.1 KiB
Nix
138 lines
4.1 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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ascensionsDir = "/var/lib/ascensions";
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ascensionType = { name, ... }: {
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options = {
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incantations = mkOption {
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type = with types; functionTo (listOf package);
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default = [];
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};
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distributed = mkOption {
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type = types.bool;
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default = false;
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description = "Whether to perform a distributed ascension using Consul KV.";
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};
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requiredBy = mkOption {
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type = with types; listOf str;
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default = [ "${name}.service" ];
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description = "Services that require this ascension.";
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};
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before = mkOption {
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type = with types; listOf str;
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default = [];
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description = "Run the ascension before these services.";
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};
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after = mkOption {
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type = with types; listOf str;
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default = [];
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description = "Run the ascension after these services.";
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};
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};
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};
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builtinIncantations = with pkgs; rec {
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execShellWith = extraPackages: script: writeShellScript "incantation" ''
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export PATH='${makeBinPath ([ coreutils ] ++ extraPackages)}'
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${script}
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'';
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execShell = execShellWith [];
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multiple = incantations: execShell (concatStringsSep " && " incantations);
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move = from: to: execShell ''
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test -e ${escapeShellArg from} && rm -rf ${escapeShellArg to}
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mkdir -p "$(dirname ${escapeShellArg to})"
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mv ${escapeShellArgs [ from to ]}
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'';
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chmod = mode: target: "chmod -R ${escapeShellArgs [ mode target ]}";
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};
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allIncantations = builtinIncantations // mapAttrs (_: mk: mk allIncantations) config.system.extraIncantations;
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runIncantations = f: f allIncantations;
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consul = config.services.consul.package;
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in
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{
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options.system = {
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ascensions = mkOption {
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type = with types; attrsOf (submodule ascensionType);
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default = {};
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};
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extraIncantations = mkOption {
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type = with types; attrsOf (functionTo raw);
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default = {};
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};
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};
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config = {
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systemd = {
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tmpfiles.rules = [
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"d ${ascensionsDir} 0755 root root - -"
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];
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services = mapAttrs' (name: asc: {
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name = "ascend-${name}";
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value = let
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incantations = runIncantations asc.incantations;
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targetLevel = toString (length incantations);
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in {
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description = "Ascension for ${name}";
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wantedBy = [ "multi-user.target" ];
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inherit (asc) requiredBy before;
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after = asc.after ++ (lib.optional asc.distributed "consul-ready.service");
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requires = lib.optional asc.distributed "consul-ready.service";
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serviceConfig.Type = "oneshot";
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distributed.enable = asc.distributed;
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script = ''
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incantations=(${concatStringsSep " " incantations})
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${if asc.distributed then /*bash*/ ''
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getLevel() {
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${consul}/bin/consul kv get 'ascensions/${name}/currentLevel'
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}
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setLevel() {
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${consul}/bin/consul kv put 'ascensions/${name}/currentLevel' "$1" >/dev/null
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}
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isEmpty() {
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! getLevel >/dev/null 2>/dev/null
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}
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'' else /*bash*/ ''
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levelFile='${ascensionsDir}/${name}'
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getLevel() {
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echo "$(<"$levelFile")"
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}
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setLevel() {
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echo "$1" > "$levelFile"
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}
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isEmpty() {
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[[ ! -e "$levelFile" ]]
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}
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''
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}
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if isEmpty; then
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setLevel '${targetLevel}'
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echo Initializing at level ${targetLevel}
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exit 0
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fi
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cur=$(getLevel)
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echo Current level: $cur
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for lvl in $(seq $(($cur+1)) ${targetLevel}); do
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echo Running incantation for level $lvl...
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''${incantations[$((lvl-1))]}
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setLevel "$lvl"
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done
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echo All incantations complete, ascended to level $(getLevel)
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'';
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};
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}) config.system.ascensions;
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};
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};
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}
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