Albatross: Managing virtual machines
A set of binaries to manage, provision, and deploy virtual machine images. This is very much work in progress, don't expect anything stable.
Please read the blog article for motivation and an overview.
The implementation uses explicit errors (no exceptions), and make mostly use of
the (blocking!) Bos library for operating system commands. A thin layer of Lwt
is used on top to (more gracefully) handle multiple connection, and to have a
watching thread (in
waitpid(2)) for every virtual machine started by vmmd.
To install Albatross, run
opam pin add albatross https://github.com/hannesm/albatross. On FreeBSD,
opam pin add solo5-kernel-ukvm --dev is needed as well.
The following elaborates on how to get the software up and running, following by
provisioning and deploying some unikernels. There is a server (
component which needs six binaries: vmm_console, vmm_log, vmm_stats_lwt, vmmd,
ukvm-bin.none, and ukvm-bin.net; a
CA machine (which should be air-gapped, or
at least use some hardware token) for provisioning which needs vmm_sign, and
vmm_gen_ca; and a development (
DEV) machine which has a fully featured OCaml
and MirageOS environment. Each step is prefixed with the machine it is supposed
to be executed on. Of course you can conflate everything into a single
development system or your server, all up to you and your security scenario.
Exact file transfer operations between these machines is not in scope of this
document, but kept abstract as
COPY. Some commands require superuser
doas), I prefixed them with
File endings used in this document:
.dbfor CA databases
.pemfor (PEM-encoded) signed certificates
.keyfor (PEM-encoded) private keys
.reqfor (PEM-encoded) certificate signing requests
Setup a certificate authority
The first step is to setup a certificate authority (private key and CA certificate). The CA private key can sign and revoke everything, you should better keep it in a safe place (air-gapped machine etc.) - not on the server!
CA> vmm_gen_ca ca ca.db [--days 3650] [--server "server"] [--server-days 365]
This generated five files:
ca.keywhich is the CA private key
cacert.pemwhich is the CA certificate
ca.dbwhich contains a map between serial number and name of issued certificates
server.pemis the server certificate
server.keyis the private key of the server
If you have installed this package on your development machine, follow some more steps to produce the remaining required binaries:
CA> COPY cacert.pem server.pem server.key SRV: DEV> git clone https://github.com/mirage/mirage-skeleton.git DEV> cd mirage-skeleton/tutorial/hello DEV> mirage configure -t ukvm DEV> mirage build DEV> mv ukvm-bin /tmp/ukvm-bin.none DEV> cd ../device-usage/network DEV> mirage configure -t ukvm DEV> mirage build DEV> mv ukvm-bin /tmp/ukvm-bin.net DEV> cd ../../.. DEV> COPY /tmp/ukvm-bin.none /tmp/ukvm-bin.net SRV:/var/db/albatross DEV> COPY vmm_console vmm_log vmm_stats_lwt vmmd SRV:/opt/bin/
SRV> vmm_console -vv & SRV> vmm_log -vv & SRV> vmm_stats_lwt -vv & #optional SRV# vmmd -vv cacert.pem server.pem server.key
Some setup for network interfaces is needed, depending on your operating system. You can also add NAT to allow your virtual machines to talk to the outside world, or add your external interface to the bridge directly, or just keep your VMs local.
# FreeBSD SRV# ifconfig bridge create #should output bridge0 SRV# ifconfig bridge0 name ext SRV# sysctl net.link.tap.up_on_open=1 # Linux SRV# brctl addbr ext
At least on FreeBSD, in order to monitor unikernels write permissions to
/dev/vmm/<vm> are needed. To achieve this (otherwise
vmm_stats won't be
able to collect statistics unless running as a privileged user, the following
devfs ruleset can be used in
/etc/devfs.rules (in case you created an
[albatross=10] add path 'vmm/ukvm*' mode 0660 group albatross
Also need to activate by adding
service devd restart on the host system.
Provision our first virtual machine
We will delegate some resource to a certificate and key we keep on our development machine.
DEV> vmm_req_delegation dev 2 1024 --cpu 1 --bridge ext/10.0.0.2/10.0.0.5/10.0.0.1/24 DEV> COPY dev.req CA:
This produced two files, dev.req and dev.key. Keep the key in a safe place!
CA> vmm_sign ca.db cacert.pem ca.key dev.req [--days 10] CA> COPY dev.pem DEV:
Now, our DEV machine can use its delegation certificate for issuing other certificates. We'll create a certificate for interactive use, and one containing the hello unikernel.
DEV> vmm_req_permissions admin --permission all DEV> vmm_sign dev.db dev.pem dev.key admin.req
This produced in the first step two files,
admin.key, and in
the second step two more files,
DEV> vmm_req_vm hello mirage-skeleton/tutorial/hello/hello.ukvm 12 1 DEV> vmm_sign dev.db dev.pem dev.key hello.req
This generates a private key
hello.key and a certificate signing request named
hello.req including the virtual machine image
hello.ukvm, which gets 12MB
memory and CPU id 1. The second command used the
dev.key to sign the signing
request and output a
--force can be passed to
vmm_req_vm. This means: if there already
exists a running virtual machine with the same name, kill it and start the new
one provided in the certificate.
To actually deploy anything, the server needs the chain (i.e. the vm certificate and the delegation certificate). Our client needs the main CA certificate to authenticate the server itself.
CA> COPY cacert.pem DEV: DEV> cat admin.pem dev.pem > admin.bundle DEV> cat hello.pem dev.pem > hello.bundle
And deploying (watch the output of the processes started on the server above!):
DEV> vmm_client cacert.pem hello.bundle hello.key SRV:1025 DEV> vmm_client cacert.pem admin.bundle admin.key SRV:1025 --db dev.db
Commands are at the moment