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nova-image: use wget instead of cloud-init (via EC2 API)

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The Openstack metadata service exposes the EC2 API. We use the
existing `ec2.nix` module to configure the hostname and ssh keys of an
Openstack Instance.

A test checks the ssh server is well configured.

This is mainly to reduce the size of the image (700MB). Also,
declarative features provided by cloud-init are not really useful
since we would prefer to use our `configuration.nix` file instead.
This commit is contained in:
Antoine Eiche 2019-01-28 11:59:18 +01:00
parent bf041c3f1d
commit 2858b35100
4 changed files with 160 additions and 83 deletions
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62
nixos/modules/virtualisation/nova-config.nix
View file

@ -1,4 +1,4 @@
{ lib, ... }:
{ pkgs, lib, ... }:
with lib;
@ -6,6 +6,8 @@ with lib;
imports = [
../profiles/qemu-guest.nix
../profiles/headless.nix
# The Openstack Metadata service exposes data on an EC2 API also.
./ec2-data.nix
];
config = {
@ -26,35 +28,41 @@ with lib;
passwordAuthentication = mkDefault false;
};
services.cloud-init.enable = true;
systemd.services.nova-init = {
path = [ pkgs.wget ];
description = "Fetch Metadata on startup";
wantedBy = [ "multi-user.target" ];
before = [ "apply-ec2-data.service" ];
wants = [ "network-online.target" ];
after = [ "network-online.target" ];
script =
''
metaDir=/etc/ec2-metadata
mkdir -m 0755 -p "$metaDir"
# Put /tmp and /var on /ephemeral0, which has a lot more space.
# Unfortunately we can't do this with the `fileSystems' option
# because it has no support for creating the source of a bind
# mount. Also, "move" /nix to /ephemeral0 by layering a unionfs-fuse
# mount on top of it so we have a lot more space for Nix operations.
echo "getting Openstack instance metadata (via EC2 API)..."
if ! [ -e "$metaDir/ami-manifest-path" ]; then
wget --retry-connrefused -O "$metaDir/ami-manifest-path" http://169.254.169.254/1.0/meta-data/ami-manifest-path
fi
/*
boot.initrd.postMountCommands =
''
mkdir -m 1777 -p $targetRoot/ephemeral0/tmp
mkdir -m 1777 -p $targetRoot/tmp
mount --bind $targetRoot/ephemeral0/tmp $targetRoot/tmp
if ! [ -e "$metaDir/user-data" ]; then
wget --retry-connrefused -O "$metaDir/user-data" http://169.254.169.254/1.0/user-data && chmod 600 "$metaDir/user-data"
fi
mkdir -m 755 -p $targetRoot/ephemeral0/var
mkdir -m 755 -p $targetRoot/var
mount --bind $targetRoot/ephemeral0/var $targetRoot/var
if ! [ -e "$metaDir/hostname" ]; then
wget --retry-connrefused -O "$metaDir/hostname" http://169.254.169.254/1.0/meta-data/hostname
fi
mkdir -p /unionfs-chroot/ro-nix
mount --rbind $targetRoot/nix /unionfs-chroot/ro-nix
mkdir -p /unionfs-chroot/rw-nix
mkdir -m 755 -p $targetRoot/ephemeral0/nix
mount --rbind $targetRoot/ephemeral0/nix /unionfs-chroot/rw-nix
unionfs -o allow_other,cow,nonempty,chroot=/unionfs-chroot,max_files=32768 /rw-nix=RW:/ro-nix=RO $targetRoot/nix
'';
boot.initrd.supportedFilesystems = [ "unionfs-fuse" ];
*/
if ! [ -e "$metaDir/public-keys-0-openssh-key" ]; then
wget --retry-connrefused -O "$metaDir/public-keys-0-openssh-key" http://169.254.169.254/1.0/meta-data/public-keys/0/openssh-key
fi
'';
restartIfChanged = false;
unitConfig.X-StopOnRemoval = false;
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
};
};
};
}

61
nixos/tests/common/ec2.nix Normal file
View file

@ -0,0 +1,61 @@
{ pkgs, makeTest }:
with pkgs.lib;
{
makeEc2Test = { name, image, userData, script, hostname ? "ec2-instance", sshPublicKey ? null }:
let
metaData = pkgs.stdenv.mkDerivation {
name = "metadata";
buildCommand = ''
mkdir -p $out/1.0/meta-data
ln -s ${pkgs.writeText "userData" userData} $out/1.0/user-data
echo "${hostname}" > $out/1.0/meta-data/hostname
echo "(unknown)" > $out/1.0/meta-data/ami-manifest-path
'' + optionalString (sshPublicKey != null) ''
mkdir -p $out/1.0/meta-data/public-keys/0
ln -s ${pkgs.writeText "sshPublicKey" sshPublicKey} $out/1.0/meta-data/public-keys/0/openssh-key
'';
};
in makeTest {
name = "ec2-" + name;
nodes = {};
testScript =
''
my $imageDir = ($ENV{'TMPDIR'} // "/tmp") . "/vm-state-machine";
mkdir $imageDir, 0700;
my $diskImage = "$imageDir/machine.qcow2";
system("qemu-img create -f qcow2 -o backing_file=${image}/nixos.qcow2 $diskImage") == 0 or die;
system("qemu-img resize $diskImage 10G") == 0 or die;
# Note: we use net=169.0.0.0/8 rather than
# net=169.254.0.0/16 to prevent dhcpcd from getting horribly
# confused. (It would get a DHCP lease in the 169.254.*
# range, which it would then configure and prompty delete
# again when it deletes link-local addresses.) Ideally we'd
# turn off the DHCP server, but qemu does not have an option
# to do that.
my $startCommand = "qemu-kvm -m 768";
$startCommand .= " -device virtio-net-pci,netdev=vlan0";
$startCommand .= " -netdev 'user,id=vlan0,net=169.0.0.0/8,guestfwd=tcp:169.254.169.254:80-cmd:${pkgs.micro-httpd}/bin/micro_httpd ${metaData}'";
$startCommand .= " -drive file=$diskImage,if=virtio,werror=report";
$startCommand .= " \$QEMU_OPTS";
my $machine = createMachine({ startCommand => $startCommand });
${script}
'';
};
snakeOilPrivateKey = ''
-----BEGIN OPENSSH PRIVATE KEY-----
b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAMwAAAAtzc2gtZW
QyNTUxOQAAACDEPmwZv5dDPrMUaq0dDP+6eBTTe+QNrz14KBEIdhHd1QAAAJDufJ4S7nye
EgAAAAtzc2gtZWQyNTUxOQAAACDEPmwZv5dDPrMUaq0dDP+6eBTTe+QNrz14KBEIdhHd1Q
AAAECgwbDlYATM5/jypuptb0GF/+zWZcJfoVIFBG3LQeRyGsQ+bBm/l0M+sxRqrR0M/7p4
FNN75A2vPXgoEQh2Ed3VAAAADEVDMiB0ZXN0IGtleQE=
-----END OPENSSH PRIVATE KEY-----
'';
snakeOilPublicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIMQ+bBm/l0M+sxRqrR0M/7p4FNN75A2vPXgoEQh2Ed3V EC2 test key";
}

60
nixos/tests/ec2.nix
View file

@ -6,6 +6,8 @@
with import ../lib/testing.nix { inherit system pkgs; };
with pkgs.lib;
with import common/ec2.nix { inherit makeTest pkgs; };
let
image =
(import ../lib/eval-config.nix {
@ -39,65 +41,10 @@ let
];
}).config.system.build.amazonImage;
makeEc2Test = { name, userData, script, hostname ? "ec2-instance", sshPublicKey ? null }:
let
metaData = pkgs.stdenv.mkDerivation {
name = "metadata";
buildCommand = ''
mkdir -p $out/1.0/meta-data
ln -s ${pkgs.writeText "userData" userData} $out/1.0/user-data
echo "${hostname}" > $out/1.0/meta-data/hostname
echo "(unknown)" > $out/1.0/meta-data/ami-manifest-path
'' + optionalString (sshPublicKey != null) ''
mkdir -p $out/1.0/meta-data/public-keys/0
ln -s ${pkgs.writeText "sshPublicKey" sshPublicKey} $out/1.0/meta-data/public-keys/0/openssh-key
'';
};
in makeTest {
name = "ec2-" + name;
nodes = {};
testScript =
''
my $imageDir = ($ENV{'TMPDIR'} // "/tmp") . "/vm-state-machine";
mkdir $imageDir, 0700;
my $diskImage = "$imageDir/machine.qcow2";
system("qemu-img create -f qcow2 -o backing_file=${image}/nixos.qcow2 $diskImage") == 0 or die;
system("qemu-img resize $diskImage 10G") == 0 or die;
# Note: we use net=169.0.0.0/8 rather than
# net=169.254.0.0/16 to prevent dhcpcd from getting horribly
# confused. (It would get a DHCP lease in the 169.254.*
# range, which it would then configure and prompty delete
# again when it deletes link-local addresses.) Ideally we'd
# turn off the DHCP server, but qemu does not have an option
# to do that.
my $startCommand = "qemu-kvm -m 768";
$startCommand .= " -device virtio-net-pci,netdev=vlan0";
$startCommand .= " -netdev 'user,id=vlan0,net=169.0.0.0/8,guestfwd=tcp:169.254.169.254:80-cmd:${pkgs.micro-httpd}/bin/micro_httpd ${metaData}'";
$startCommand .= " -drive file=$diskImage,if=virtio,werror=report";
$startCommand .= " \$QEMU_OPTS";
my $machine = createMachine({ startCommand => $startCommand });
${script}
'';
};
snakeOilPrivateKey = ''
-----BEGIN OPENSSH PRIVATE KEY-----
b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAMwAAAAtzc2gtZW
QyNTUxOQAAACDEPmwZv5dDPrMUaq0dDP+6eBTTe+QNrz14KBEIdhHd1QAAAJDufJ4S7nye
EgAAAAtzc2gtZWQyNTUxOQAAACDEPmwZv5dDPrMUaq0dDP+6eBTTe+QNrz14KBEIdhHd1Q
AAAECgwbDlYATM5/jypuptb0GF/+zWZcJfoVIFBG3LQeRyGsQ+bBm/l0M+sxRqrR0M/7p4
FNN75A2vPXgoEQh2Ed3VAAAADEVDMiB0ZXN0IGtleQE=
-----END OPENSSH PRIVATE KEY-----
'';
snakeOilPublicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIMQ+bBm/l0M+sxRqrR0M/7p4FNN75A2vPXgoEQh2Ed3V EC2 test key";
in {
boot-ec2-nixops = makeEc2Test {
name = "nixops-userdata";
inherit image;
sshPublicKey = snakeOilPublicKey; # That's right folks! My user's key is also the host key!
userData = ''
@ -142,6 +89,7 @@ in {
boot-ec2-config = makeEc2Test {
name = "config-userdata";
inherit image;
sshPublicKey = snakeOilPublicKey;
# ### http://nixos.org/channels/nixos-unstable nixos

60
nixos/tests/nova-image.nix Normal file
View file

@ -0,0 +1,60 @@
{ system ? builtins.currentSystem,
config ? {},
pkgs ? import ../.. { inherit system config; }
}:
with import ../lib/testing.nix { inherit system pkgs; };
with pkgs.lib;
with import common/ec2.nix { inherit makeTest pkgs; };
let
image =
(import ../lib/eval-config.nix {
inherit system;
modules = [
../maintainers/scripts/openstack/nova-image.nix
../modules/testing/test-instrumentation.nix
../modules/profiles/qemu-guest.nix
];
}).config.system.build.novaImage;
in
makeEc2Test {
name = "nova-ec2-metadata";
inherit image;
sshPublicKey = snakeOilPublicKey; # That's right folks! My user's key is also the host key!
userData = ''
SSH_HOST_ED25519_KEY_PUB:${snakeOilPublicKey}
SSH_HOST_ED25519_KEY:${replaceStrings ["\n"] ["|"] snakeOilPrivateKey}
'';
script = ''
$machine->start;
$machine->waitForFile("/etc/ec2-metadata/user-data");
$machine->waitForUnit("sshd.service");
$machine->succeed("grep unknown /etc/ec2-metadata/ami-manifest-path");
# We have no keys configured on the client side yet, so this should fail
$machine->fail("ssh -o BatchMode=yes localhost exit");
# Let's install our client private key
$machine->succeed("mkdir -p ~/.ssh");
$machine->succeed("echo '${snakeOilPrivateKey}' > ~/.ssh/id_ed25519");
$machine->succeed("chmod 600 ~/.ssh/id_ed25519");
# We haven't configured the host key yet, so this should still fail
$machine->fail("ssh -o BatchMode=yes localhost exit");
# Add the host key; ssh should finally succeed
$machine->succeed("echo localhost,127.0.0.1 ${snakeOilPublicKey} > ~/.ssh/known_hosts");
$machine->succeed("ssh -o BatchMode=yes localhost exit");
# Just to make sure resizing is idempotent.
$machine->shutdown;
$machine->start;
$machine->waitForFile("/etc/ec2-metadata/user-data");
'';
}