1 files changed, 238 insertions, 0 deletions
diff --git a/nixos/modules/virtualisation/nixos-container.pl b/nixos/modules/virtualisation/nixos-container.pl
new file mode 100644
index 000000000000..d7e8c7339b6d
--- /dev/null
+++ b/nixos/modules/virtualisation/nixos-container.pl
@@ -0,0 +1,238 @@
+#! @perl@
+
+use strict;
+use POSIX;
+use File::Path;
+use File::Slurp;
+use Fcntl ':flock';
+use Getopt::Long qw(:config gnu_getopt);
+
+my $socat = '@socat@/bin/socat';
+
+# Parse the command line.
+
+sub showHelp {
+    print <<EOF;
+Usage: nixos-container list
+       nixos-container create <container-name> [--config <string>] [--ensure-unique-name]
+       nixos-container destroy <container-name>
+       nixos-container start <container-name>
+       nixos-container stop <container-name>
+       nixos-container login <container-name>
+       nixos-container root-login <container-name>
+       nixos-container run <container-name> -- args...
+       nixos-container set-root-password <container-name> <password>
+       nixos-container show-ip <container-name>
+EOF
+    exit 0;
+}
+
+my $ensureUniqueName = 0;
+my $extraConfig = "";
+
+GetOptions(
+    "help" => sub { showHelp() },
+    "ensure-unique-name" => \$ensureUniqueName,
+    "config=s" => \$extraConfig
+    ) or exit 1;
+
+my $action = $ARGV[0] or die "$0: no action specified\n";
+
+
+# Execute the selected action.
+
+mkpath("/etc/containers", 0, 0755);
+mkpath("/var/lib/containers", 0, 0700);
+
+if ($action eq "list") {
+    foreach my $confFile (glob "/etc/containers/*.conf") {
+        $confFile =~ /\/([^\/]+).conf$/ or next;
+        print "$1\n";
+    }
+    exit 0;
+}
+
+my $containerName = $ARGV[1] or die "$0: no container name specified\n";
+$containerName =~ /^[a-zA-Z0-9\-]+$/ or die "$0: invalid container name\n";
+
+sub writeNixOSConfig {
+    my ($nixosConfigFile) = @_;
+
+    my $nixosConfig = <<EOF;
+{ config, pkgs, ... }:
+
+with pkgs.lib;
+
+{ boot.isContainer = true;
+  security.initialRootPassword = mkDefault "!";
+  networking.hostName = mkDefault "$containerName";
+  networking.useDHCP = false;
+  $extraConfig
+}
+EOF
+
+    write_file($nixosConfigFile, $nixosConfig);
+}
+
+if ($action eq "create") {
+    # Acquire an exclusive lock to prevent races with other
+    # invocations of ‘nixos-container create’.
+    my $lockFN = "/run/lock/nixos-container";
+    open(my $lock, '>>', $lockFN) or die "$0: opening $lockFN: $!";
+    flock($lock, LOCK_EX) or die "$0: could not lock $lockFN: $!";
+
+    my $confFile = "/etc/containers/$containerName.conf";
+    my $root = "/var/lib/containers/$containerName";
+
+    # Maybe generate a unique name.
+    if ($ensureUniqueName) {
+        my $base = $containerName;
+        for (my $nr = 0; ; $nr++) {
+            $containerName = "$base-$nr";
+            $confFile = "/etc/containers/$containerName.conf";
+            $root = "/var/lib/containers/$containerName";
+            last unless -e $confFile || -e $root;
+        }
+    }
+
+    die "$0: container ‘$containerName’ already exists\n" if -e $confFile;
+
+    # Get an unused IP address.
+    my %usedIPs;
+    foreach my $confFile2 (glob "/etc/containers/*.conf") {
+        my $s = read_file($confFile2) or die;
+        $usedIPs{$1} = 1 if $s =~ /^HOST_ADDRESS=([0-9\.]+)$/m;
+        $usedIPs{$1} = 1 if $s =~ /^LOCAL_ADDRESS=([0-9\.]+)$/m;
+    }
+
+    my ($ipPrefix, $hostAddress, $localAddress);
+    for (my $nr = 1; $nr < 255; $nr++) {
+        $ipPrefix = "10.233.$nr";
+        $hostAddress = "$ipPrefix.1";
+        $localAddress = "$ipPrefix.2";
+        last unless $usedIPs{$hostAddress} || $usedIPs{$localAddress};
+        $ipPrefix = undef;
+    }
+
+    die "$0: out of IP addresses\n" unless defined $ipPrefix;
+
+    my @conf;
+    push @conf, "PRIVATE_NETWORK=1\n";
+    push @conf, "HOST_ADDRESS=$hostAddress\n";
+    push @conf, "LOCAL_ADDRESS=$localAddress\n";
+    write_file($confFile, \@conf);
+
+    close($lock);
+
+    print STDERR "host IP is $hostAddress, container IP is $localAddress\n";
+
+    mkpath("$root/etc/nixos", 0, 0755);
+
+    my $nixosConfigFile = "$root/etc/nixos/configuration.nix";
+    writeNixOSConfig $nixosConfigFile;
+
+    # The per-container directory is restricted to prevent users on
+    # the host from messing with guest users who happen to have the
+    # same uid.
+    my $profileDir = "/nix/var/nix/profiles/per-container";
+    mkpath($profileDir, 0, 0700);
+    $profileDir = "$profileDir/$containerName";
+    mkpath($profileDir, 0, 0755);
+
+    system("nix-env", "-p", "$profileDir/system",
+           "-I", "nixos-config=$nixosConfigFile", "-f", "<nixpkgs/nixos>",
+           "--set", "-A", "system") == 0
+        or die "$0: failed to build initial container configuration\n";
+
+    print "$containerName\n" if $ensureUniqueName;
+    exit 0;
+}
+
+my $root = "/var/lib/containers/$containerName";
+my $profileDir = "/nix/var/nix/profiles/per-container/$containerName";
+my $confFile = "/etc/containers/$containerName.conf";
+die "$0: container ‘$containerName’ does not exist\n" if !-e $confFile;
+
+sub isContainerRunning {
+    my $status = `systemctl show 'container\@$containerName'`;
+    return $status =~ /ActiveState=active/;
+}
+
+sub stopContainer {
+    system("systemctl", "stop", "container\@$containerName") == 0
+        or die "$0: failed to stop container\n";
+}
+
+if ($action eq "destroy") {
+    die "$0: cannot destroy declarative container (remove it from your configuration.nix instead)\n"
+        unless POSIX::access($confFile, &POSIX::W_OK);
+
+    stopContainer if isContainerRunning;
+
+    rmtree($profileDir) if -e $profileDir;
+    rmtree($root) if -e $root;
+    unlink($confFile) or die;
+}
+
+elsif ($action eq "start") {
+    system("systemctl", "start", "container\@$containerName") == 0
+        or die "$0: failed to start container\n";
+}
+
+elsif ($action eq "stop") {
+    stopContainer;
+}
+
+elsif ($action eq "update") {
+    my $nixosConfigFile = "$root/etc/nixos/configuration.nix";
+
+    # FIXME: may want to be more careful about clobbering the existing
+    # configuration.nix.
+    writeNixOSConfig $nixosConfigFile if defined $extraConfig;
+
+    system("nix-env", "-p", "$profileDir/system",
+           "-I", "nixos-config=$nixosConfigFile", "-f", "<nixpkgs/nixos>",
+           "--set", "-A", "system") == 0
+        or die "$0: failed to build container configuration\n";
+
+    if (isContainerRunning) {
+        print STDERR "reloading container...\n";
+        system("systemctl", "reload", "container\@$containerName") == 0
+            or die "$0: failed to reload container\n";
+    }
+}
+
+elsif ($action eq "login") {
+    exec($socat, "unix:$root/var/lib/login.socket", "-,echo=0,raw");
+}
+
+elsif ($action eq "root-login") {
+    exec($socat, "unix:$root/var/lib/root-login.socket", "-,echo=0,raw");
+}
+
+elsif ($action eq "run") {
+    shift @ARGV; shift @ARGV;
+    open(SOCAT, "|-", $socat, "unix:$root/var/lib/run-command.socket", "-");
+    print SOCAT join(' ', map { "'$_'" } @ARGV), "\n";
+    close(SOCAT);
+}
+
+elsif ($action eq "set-root-password") {
+    # FIXME: don't get password from the command line.
+    my $password = $ARGV[2] or die "$0: no password given\n";
+    open(SOCAT, "|-", $socat, "unix:$root/var/lib/run-command.socket", "-");
+    print SOCAT "passwd\n";
+    print SOCAT "$password\n";
+    print SOCAT "$password\n";
+    close(SOCAT);
+}
+
+elsif ($action eq "show-ip") {
+    my $s = read_file($confFile) or die;
+    $s =~ /^LOCAL_ADDRESS=([0-9\.]+)$/m or die "$0: cannot get IP address\n";
+    print "$1\n";
+}
+
+else {
+    die "$0: unknown action ‘$action’\n";
+}