146 lines
3.5 KiB
Nix
146 lines
3.5 KiB
Nix
{ config, pkgs, ... }:
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with pkgs.lib;
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let
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cfg = config.services.cgroups;
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cgconfigConf = pkgs.writeText "cgconfig.conf" cfg.groups;
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cgrulesConf = pkgs.writeText "cgrules.conf" cfg.rules;
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in
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{
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###### interface
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options = {
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services.cgroups.enable = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Whether to enable support for control groups, a Linux kernel
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feature for resource management. It allows you to assign
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processes to groups that share certain resource limits (e.g.,
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CPU or memory). The <command>cgrulesengd</command> daemon
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automatically assigns processes to the right cgroup depending
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on the rules defined in
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<option>services.cgroups.rules</option>.
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'';
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};
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services.cgroups.groups = mkOption {
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type = types.string;
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default =
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''
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mount {
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cpu = /sys/fs/cgroup/cpu;
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}
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'';
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example =
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''
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mount {
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cpu = /sys/fs/cgroup/cpu;
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cpuacct = /sys/fs/cgroup/cpuacct;
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}
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# Create a "www" cgroup with a lower share of the CPU (the
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# default is 1024).
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group www {
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cpu {
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cpu.shares = "500";
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}
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}
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'';
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description = ''
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The contents of the <filename>cgconfig.conf</filename>
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configuration file, which defines the cgroups.
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'';
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};
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services.cgroups.rules = mkOption {
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type = types.string;
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default = "";
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example =
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''
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# All processes executed by the "wwwrun" uid should be
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# assigned to the "www" CPU cgroup.
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wwwrun cpu www
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'';
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description = ''
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The contents of the <filename>cgrules.conf</filename>
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configuration file, which determines to which cgroups
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processes should be assigned by the
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<command>cgrulesengd</command> daemon.
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'';
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};
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};
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###### implementation
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config = mkIf cfg.enable {
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environment.systemPackages = [ pkgs.libcgroup ];
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environment.etc =
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[ { source = cgconfigConf;
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target = "cgconfig.conf";
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}
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{ source = cgrulesConf;
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target = "cgrules.conf";
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}
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];
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# The daemon requires the userspace<->kernelspace netlink
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# connector.
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boot.kernelModules = [ "cn" ];
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jobs.cgroups =
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{ startOn = "startup";
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description = "Control groups daemon";
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path = [ pkgs.libcgroup pkgs.procps pkgs.utillinux ];
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preStart =
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''
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if [ -d /sys/fs/cgroup ]; then
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if ! mountpoint -q /sys/fs/cgroup; then
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mount -t tmpfs -o mode=755 /dev/cgroup /sys/fs/cgroup
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fi
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fi
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cgclear || true
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# Mount the cgroup hierarchies. Note: we refer to the
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# store path of cgconfig.conf here to ensure that the job
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# gets reloaded if the configuration changes.
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cgconfigparser -l ${cgconfigConf}
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# Move existing processes to the right cgroup.
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cgclassify --cancel-sticky $(ps --no-headers -eL o tid) || true
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# Force a restart if the rules change:
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# ${cgrulesConf}
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'';
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# Run the daemon that moves new processes to the right cgroup.
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exec = "cgrulesengd";
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daemonType = "fork";
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postStop =
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''
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cgclear
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'';
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};
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};
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}
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