300 lines
9 KiB
Perl
300 lines
9 KiB
Perl
#! @perl@
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use strict;
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use POSIX;
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use File::Path;
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use File::Slurp;
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use Fcntl ':flock';
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use Getopt::Long qw(:config gnu_getopt);
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my $nsenter = "@utillinux@/bin/nsenter";
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my $su = "@su@";
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# Ensure a consistent umask.
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umask 0022;
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# Parse the command line.
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sub showHelp {
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print <<EOF;
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Usage: nixos-container list
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nixos-container create <container-name> [--system-path <path>] [--config <string>] [--ensure-unique-name] [--auto-start]
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nixos-container destroy <container-name>
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nixos-container start <container-name>
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nixos-container stop <container-name>
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nixos-container status <container-name>
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nixos-container update <container-name> [--config <string>]
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nixos-container login <container-name>
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nixos-container root-login <container-name>
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nixos-container run <container-name> -- args...
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nixos-container show-ip <container-name>
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nixos-container show-host-key <container-name>
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EOF
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exit 0;
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}
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my $systemPath;
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my $ensureUniqueName = 0;
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my $autoStart = 0;
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my $extraConfig;
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GetOptions(
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"help" => sub { showHelp() },
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"ensure-unique-name" => \$ensureUniqueName,
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"auto-start" => \$autoStart,
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"system-path=s" => \$systemPath,
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"config=s" => \$extraConfig
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) or exit 1;
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my $action = $ARGV[0] or die "$0: no action specified\n";
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# Execute the selected action.
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mkpath("/etc/containers", 0, 0755);
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mkpath("/var/lib/containers", 0, 0700);
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if ($action eq "list") {
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foreach my $confFile (glob "/etc/containers/*.conf") {
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$confFile =~ /\/([^\/]+).conf$/ or next;
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print "$1\n";
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}
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exit 0;
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}
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my $containerName = $ARGV[1] or die "$0: no container name specified\n";
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$containerName =~ /^[a-zA-Z0-9\-]+$/ or die "$0: invalid container name\n";
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sub writeNixOSConfig {
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my ($nixosConfigFile) = @_;
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my $nixosConfig = <<EOF;
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{ config, lib, pkgs, ... }:
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with lib;
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{ boot.isContainer = true;
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networking.hostName = mkDefault "$containerName";
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networking.useDHCP = false;
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$extraConfig
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}
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EOF
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write_file($nixosConfigFile, $nixosConfig);
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}
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if ($action eq "create") {
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# Acquire an exclusive lock to prevent races with other
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# invocations of ‘nixos-container create’.
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my $lockFN = "/run/lock/nixos-container";
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open(my $lock, '>>', $lockFN) or die "$0: opening $lockFN: $!";
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flock($lock, LOCK_EX) or die "$0: could not lock $lockFN: $!";
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my $confFile = "/etc/containers/$containerName.conf";
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my $root = "/var/lib/containers/$containerName";
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# Maybe generate a unique name.
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if ($ensureUniqueName) {
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my $base = $containerName;
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for (my $nr = 0; ; $nr++) {
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$containerName = "$base-$nr";
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$confFile = "/etc/containers/$containerName.conf";
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$root = "/var/lib/containers/$containerName";
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last unless -e $confFile || -e $root;
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}
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}
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die "$0: container ‘$containerName’ already exists\n" if -e $confFile;
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# Due to interface name length restrictions, container names must
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# be restricted too.
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die "$0: container name ‘$containerName’ is too long\n" if length $containerName > 11;
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# Get an unused IP address.
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my %usedIPs;
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foreach my $confFile2 (glob "/etc/containers/*.conf") {
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my $s = read_file($confFile2) or die;
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$usedIPs{$1} = 1 if $s =~ /^HOST_ADDRESS=([0-9\.]+)$/m;
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$usedIPs{$1} = 1 if $s =~ /^LOCAL_ADDRESS=([0-9\.]+)$/m;
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}
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my ($ipPrefix, $hostAddress, $localAddress);
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for (my $nr = 1; $nr < 255; $nr++) {
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$ipPrefix = "10.233.$nr";
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$hostAddress = "$ipPrefix.1";
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$localAddress = "$ipPrefix.2";
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last unless $usedIPs{$hostAddress} || $usedIPs{$localAddress};
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$ipPrefix = undef;
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}
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die "$0: out of IP addresses\n" unless defined $ipPrefix;
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my @conf;
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push @conf, "PRIVATE_NETWORK=1\n";
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push @conf, "HOST_ADDRESS=$hostAddress\n";
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push @conf, "LOCAL_ADDRESS=$localAddress\n";
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push @conf, "AUTO_START=$autoStart\n";
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write_file($confFile, \@conf);
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close($lock);
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print STDERR "host IP is $hostAddress, container IP is $localAddress\n";
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# The per-container directory is restricted to prevent users on
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# the host from messing with guest users who happen to have the
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# same uid.
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my $profileDir = "/nix/var/nix/profiles/per-container";
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mkpath($profileDir, 0, 0700);
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$profileDir = "$profileDir/$containerName";
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mkpath($profileDir, 0, 0755);
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# Build/set the initial configuration.
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if (defined $systemPath) {
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system("nix-env", "-p", "$profileDir/system", "--set", $systemPath) == 0
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or die "$0: failed to set initial container configuration\n";
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} else {
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mkpath("$root/etc/nixos", 0, 0755);
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my $nixosConfigFile = "$root/etc/nixos/configuration.nix";
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writeNixOSConfig $nixosConfigFile;
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system("nix-env", "-p", "$profileDir/system",
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"-I", "nixos-config=$nixosConfigFile", "-f", "<nixpkgs/nixos>",
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"--set", "-A", "system") == 0
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or die "$0: failed to build initial container configuration\n";
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}
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print "$containerName\n" if $ensureUniqueName;
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exit 0;
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}
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my $root = "/var/lib/containers/$containerName";
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my $profileDir = "/nix/var/nix/profiles/per-container/$containerName";
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my $gcRootsDir = "/nix/var/nix/gcroots/per-container/$containerName";
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my $confFile = "/etc/containers/$containerName.conf";
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if (!-e $confFile) {
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if ($action eq "destroy") {
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exit 0;
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} elsif ($action eq "status") {
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print "gone\n";
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}
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die "$0: container ‘$containerName’ does not exist\n" ;
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}
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sub isContainerRunning {
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my $status = `systemctl show 'container\@$containerName'`;
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return $status =~ /ActiveState=active/;
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}
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sub stopContainer {
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system("systemctl", "stop", "container\@$containerName") == 0
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or die "$0: failed to stop container\n";
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}
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# Return the PID of the init process of the container.
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sub getLeader {
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my $s = `machinectl show "$containerName" -p Leader`;
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chomp $s;
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$s =~ /^Leader=(\d+)$/ or die "unable to get container's main PID\n";
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return int($1);
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}
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# Run a command in the container.
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sub runInContainer {
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my @args = @_;
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my $leader = getLeader;
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exec($nsenter, "-t", $leader, "-m", "-u", "-i", "-n", "-p", "--", @args);
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die "cannot run ‘nsenter’: $!\n";
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}
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# Remove a directory while recursively unmounting all mounted filesystems within
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# that directory and unmounting/removing that directory afterwards as well.
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#
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# NOTE: If the specified path is a mountpoint, its contents will be removed,
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# only mountpoints underneath that path will be unmounted properly.
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sub safeRemoveTree {
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my ($path) = @_;
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system("find", $path, "-mindepth", "1", "-xdev",
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"(", "-type", "d", "-exec", "mountpoint", "-q", "{}", ";", ")",
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"-exec", "umount", "-fR", "{}", "+");
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system("rm", "--one-file-system", "-rf", $path);
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if (-e $path) {
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system("umount", "-fR", $path);
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system("rm", "--one-file-system", "-rf", $path);
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}
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}
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if ($action eq "destroy") {
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die "$0: cannot destroy declarative container (remove it from your configuration.nix instead)\n"
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unless POSIX::access($confFile, &POSIX::W_OK);
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stopContainer if isContainerRunning;
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safeRemoveTree($profileDir) if -e $profileDir;
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safeRemoveTree($gcRootsDir) if -e $gcRootsDir;
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safeRemoveTree($root) if -e $root;
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unlink($confFile) or die;
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}
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elsif ($action eq "start") {
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system("systemctl", "start", "container\@$containerName") == 0
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or die "$0: failed to start container\n";
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}
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elsif ($action eq "stop") {
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stopContainer;
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}
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elsif ($action eq "status") {
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print isContainerRunning() ? "up" : "down", "\n";
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}
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elsif ($action eq "update") {
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my $nixosConfigFile = "$root/etc/nixos/configuration.nix";
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# FIXME: may want to be more careful about clobbering the existing
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# configuration.nix.
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writeNixOSConfig $nixosConfigFile if (defined $extraConfig && $extraConfig ne "");
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system("nix-env", "-p", "$profileDir/system",
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"-I", "nixos-config=$nixosConfigFile", "-f", "<nixpkgs/nixos>",
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"--set", "-A", "system") == 0
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or die "$0: failed to build container configuration\n";
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if (isContainerRunning) {
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print STDERR "reloading container...\n";
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system("systemctl", "reload", "container\@$containerName") == 0
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or die "$0: failed to reload container\n";
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}
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}
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elsif ($action eq "login") {
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exec("machinectl", "login", "--", $containerName);
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}
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elsif ($action eq "root-login") {
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runInContainer("@su@", "root", "-l");
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}
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elsif ($action eq "run") {
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shift @ARGV; shift @ARGV;
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# Escape command.
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my $s = join(' ', map { s/'/'\\''/g; "'$_'" } @ARGV);
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runInContainer("@su@", "root", "-l", "-c", "exec " . $s);
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}
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elsif ($action eq "show-ip") {
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my $s = read_file($confFile) or die;
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$s =~ /^LOCAL_ADDRESS=([0-9\.]+)$/m or die "$0: cannot get IP address\n";
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print "$1\n";
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}
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elsif ($action eq "show-host-key") {
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my $fn = "$root/etc/ssh/ssh_host_ecdsa_key.pub";
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exit 1 if ! -f $fn;
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print read_file($fn);
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}
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else {
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die "$0: unknown action ‘$action’\n";
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}
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