nixos-container: Rewrite in Perl
Also fix race condition when multiple containers are created simultaneously (as NixOps tends to do).
This commit is contained in:
Eelco Dolstra
parent
bdb658d033
commit
6da72a4456
@ -18,8 +18,9 @@ let
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name = "nixos-container";
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dir = "bin";
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isExecutable = true;
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src = ./nixos-container.sh;
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inherit (pkgs) bash socat;
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src = ./nixos-container.pl;
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perl = "${pkgs.perl}/bin/perl -I${pkgs.perlPackages.FileSlurp}/lib/perl5/site_perl";
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inherit (pkgs) socat;
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};
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in
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198
nixos/modules/virtualisation/nixos-container.pl
Normal file
198
nixos/modules/virtualisation/nixos-container.pl
Normal file
@ -0,0 +1,198 @@
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#! @perl@
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use strict;
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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 $socat = '@socat@/bin/socat';
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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> [--config <string>] [--ensure-unique-name]
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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 login <container-name>
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nixos-container root-shell <container-name>
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nixos-container set-root-password <container-name> <password>
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nixos-container show-ip <container-name>
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EOF
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exit 0;
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}
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my $ensureUniqueName = 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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"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 "$0: invalid container name\n";
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if ($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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# 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=$localAddress\n";
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write_file($confFile, \@conf);
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close($lock);
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print STDERR "host IP is $hostAddress, container IP is $localAddress\n";
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mkpath("$root/etc/nixos", 0, 0755);
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my $nixosConfig = <<EOF;
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{ config, pkgs, ... }:
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with pkgs.lib;
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{ boot.isContainer = true;
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security.initialRootPassword = mkDefault "!";
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networking.hostName = mkDefault "$containerName";
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networking.useDHCP = false;
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imports = [ <nixpkgs/nixos/modules/virtualisation/container-login.nix> ];
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$extraConfig
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}
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EOF
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my $nixosConfigFile = "$root/etc/nixos/configuration.nix";
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write_file($nixosConfigFile, $nixosConfig);
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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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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 "$0: failed to build initial container configuration\n";
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print "$containerName\n" if $ensureUniqueName;
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exit 0;
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}
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my $confFile = "/etc/containers/$containerName.conf";
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die "$0: container ‘$containerName’ does not exist\n" if !-e $confFile;
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sub stopContainer {
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system("systemctl", "stop", "container\@$containerName") == 0
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or die "$0: failed to stop container\n";
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}
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if ($action eq "destroy") {
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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 $status = `systemctl show 'container\@$containerName'`;
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stopContainer if $status =~ /ActiveState=active/;
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rmtree($profileDir) if -e $profileDir;
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rmtree($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 ($action eq "login") {
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exec($socat, "unix:/var/lib/containers/$containerName/var/lib/login.socket", "-,echo=0,raw");
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}
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elsif ($action eq "root-shell") {
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exec($socat, "unix:/var/lib/containers/$containerName/var/lib/root-shell.socket", "-");
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}
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elsif ($action eq "set-root-password") {
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# FIXME: don't get password from the command line.
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my $password = $ARGV[2] or die "$0: no password given\n";
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open(SOCAT, "|-", $socat, "unix:/var/lib/containers/$containerName/var/lib/root-shell.socket", "-");
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print SOCAT "passwd\n";
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print SOCAT "$password\n";
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print SOCAT "$password\n";
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close(SOCAT);
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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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else {
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die "$0: unknown action ‘$action’\n";
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}
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@ -1,171 +0,0 @@
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#! @bash@/bin/sh -e
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usage() {
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echo "Usage: $0 list" >&2
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echo " $0 create <container-name> [--config <string>] [--ensure-unique-name]" >&2
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echo " $0 update <container-name>" >&2
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echo " $0 destroy <container-name>" >&2
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echo " $0 login <container-name>" >&2
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echo " $0 root-shell <container-name>" >&2
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echo " $0 set-root-password <container-name> <password>" >&2
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echo " $0 show-ip <container-name>" >&2
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}
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args="`getopt --options '' -l help -l config: -l ensure-unique-name -- "$@"`"
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eval "set -- $args"
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extraConfig=
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ensureUniqueName=
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while [ $# -gt 0 ]; do
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case "$1" in
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(--help) usage; exit 0;;
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(--config) shift; extraConfig=$1;;
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(--ensure-unique-name) ensureUniqueName=1;;
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(--) shift; break;;
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(*) break;;
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esac
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shift
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done
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action="$1"
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if [ -z "$action" ]; then usage; exit 1; fi
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shift
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getContainerRoot() {
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root="/var/lib/containers/$container"
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if ! [ -d "$root" ]; then
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echo "$0: container ‘$container’ does not exist" >&2
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exit 1
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fi
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}
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if [ $action = list ]; then
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for i in $(cd /etc/containers && echo *.conf); do
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echo "$(basename "$i" .conf)"
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done
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exit 0
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fi
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container="$1"
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if [ -z "$container" ]; then usage; exit 1; fi
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shift
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if [ $action = create ]; then
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if [ -n "$ensureUniqueName" ]; then
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# FIXME: race
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nr=0
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while [ -e "/etc/containers/$container-$nr.conf" -o -e "/var/lib/containers/$container-$nr" ]; do
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: $((nr++))
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done
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container="$container-$nr"
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fi
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confFile="/etc/containers/$container.conf"
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root="/var/lib/containers/$container"
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if [ -e "$confFile" -o -e "$root/nix" ]; then
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echo "$0: container ‘$container’ already exists" >&2
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exit 1
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fi
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profileDir="/nix/var/nix/profiles/per-container/$container"
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mkdir -m 0755 -p "$root/etc/nixos" "$profileDir"
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config="
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{ config, pkgs, ... }:
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with pkgs.lib;
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{ boot.isContainer = true;
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security.initialRootPassword = mkDefault \"!\";
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networking.hostName = mkDefault \"$container\";
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networking.useDHCP = false;
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imports = [ <nixpkgs/nixos/modules/virtualisation/container-login.nix> ];
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$extraConfig
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}"
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configFile="$root/etc/nixos/configuration.nix"
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echo "$config" > "$configFile"
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nix-env -p "$profileDir/system" -I "nixos-config=$configFile" -f '<nixpkgs/nixos>' --set -A system
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# Allocate a new /8 network in the 10.233.* range. FIXME: race
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network="$(sed -e 's/.*_ADDRESS=10\.233\.\(.*\)\..*/\1/; t; d' /etc/containers/*.conf | sort -n | tail -n1)"
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if [ -z "$network" ]; then network=0; else : $((network++)); fi
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hostAddress="10.233.$network.1"
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localAddress="10.233.$network.2"
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echo "host IP is $hostAddress, container IP is $localAddress" >&2
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cat > "$confFile" <<EOF
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PRIVATE_NETWORK=1
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HOST_ADDRESS=$hostAddress
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LOCAL_ADDRESS=$localAddress
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EOF
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echo "starting container@$container.service..." >&2
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systemctl start "container@$container.service"
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# Print generated container name on stdout.
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if [ -n "$ensureUniqueName" ]; then
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echo "$container"
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fi
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elif [ $action = update ]; then
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getContainerRoot
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configFile="$root/etc/nixos/configuration.nix"
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profileDir="/nix/var/nix/profiles/per-container/$container"
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nix-env -p "$profileDir/system" -I "nixos-config=$configFile" -f '<nixpkgs/nixos>' --set -A system
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echo "reloading container@$container.service..." >&2
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systemctl reload "container@$container.service"
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elif [ $action = destroy ]; then
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getContainerRoot
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confFile="/etc/containers/$container.conf"
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if [ -e "$confFile" -a ! -w "$confFile" ]; then
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echo "$0: cannot destroy declarative container (remove it from your configuration.nix instead)"
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exit 1
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fi
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if systemctl show "container@$container.service" | grep -q ActiveState=active; then
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echo "stopping container@$container.service..." >&2
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systemctl stop "container@$container.service"
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fi
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rm -f "$confFile"
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rm -rf "$root"
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elif [ $action = login ]; then
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getContainerRoot
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exec @socat@/bin/socat "unix:$root/var/lib/login.socket" -,echo=0,raw
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elif [ $action = root-shell ]; then
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getContainerRoot
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exec @socat@/bin/socat "unix:$root/var/lib/root-shell.socket" -
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elif [ $action = set-root-password ]; then
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password="$1"
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if [ -z "$password" ]; then usage; exit 1; fi
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# FIXME: not very secure.
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getContainerRoot
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(echo "passwd"; echo "$password"; echo "$password") | @socat@/bin/socat "unix:$root/var/lib/root-shell.socket" -
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elif [ $action = show-ip ]; then
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getContainerRoot
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. "/etc/containers/$container.conf"
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echo "$LOCAL_ADDRESS"
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else
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echo "$0: unknown action ‘$action’" >&2
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exit 1
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fi
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