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We are using Apache CloudStack to provide VMs-as-a-service to members. Our user documentation is here:

Prerequisite reading:

Official CloudStack documentation:

Rebooting machines

I'm going to start with this first because this is what future sysadmins are most interested in. If you reboot one of the CloudStack guest machines (as of this writing: biloba, ginkgo and chamomile), then I suggest you perform a live migration of all of the VMs on that host to the other other machines (see #Sequential reboot).

If this is not possible (e.g. there is not enough capacity on the other machines), then CloudStack will most likely shut down the VMs automatically. You are responsible for restarting them manually after the reboot. You will also need to manually restart any Kubernetes clusters.

Note: if the cloudstack-agent.service is having trouble reconnecting to the management servers after a reboot, just do a systemctl restart and cross your fingers.

Sequential reboot

If it is possible to reboot the machines one at a time (e.g. for a software upgrade), then it is possible to avoid having any downtime. Login to the web UI as admin, go to Infrastructure > Hosts, hover above the three-dots button for a particular host, then press the "Enable Maintenance Mode" button. Cloudstack-enable-maintenance-mode-button.png

Wait for the VMs to be migrated to the other machines (press the Refresh button to update the table). If you see an error which says "ErrorInPrepareForMaintenance", just wait it out. If more than 20 minutes have passed and there is still no progress, take the host out of maintenance mode, and put it back into maintenance mode. If this still does not work, restart the management server.

When a host is in maintenance mode, it should look like this: Cloudstack-host-in-maintenance-mode.png

Once all VMs have been migrated, do whatever you need to do on the physical host; once it is back up, take it back out of maintenance mode from the web UI. Repeat for any other hosts which need to be taken offline.

Building packages

While CloudStack does provide .deb packages for Ubuntu, unfortunately these don't work on Debian (the 'qemu-kvm' dependency is a virtual package on Debian, but not on Ubuntu). So we're going to build our own packages instead.

We're going to perform the build in a Podman container to avoid polluting the host machine with unnecessary packages. There's a container called cloudstack-build on biloba which you can re-use. If you create a new container, make sure to use the same Podman image as the release for which you're building (e.g. 'debian:bullseye').

The instructions below are adapted from

Inside the container, install the dependencies:

apt install maven openjdk-11-jdk libws-commons-util-java libcommons-codec-java libcommons-httpclient-java liblog4j1.2-java genisoimage devscripts debhelper python3-setuptools

Install Node.js 12 as well (Debian bullseye's version happens to be 12):

apt install nodejs npm

Build the node-sass module (see this issue to see why this is necessary):

cd ui && npm install && npm rebuild node-sass && cd ..

The python3-mysql.connector package is not available in bullseye, so we're going to download and install it from the sid release:

curl -LOJ
apt install ./python3-mysql.connector_8.0.15-2_all.deb

Download the CloudStack source code:

curl -LOJ
tar -jxvf apache-cloudstack-
cd apache-cloudstack-

Download the Maven dependencies:

mvn -P deps

Now open debian/control and perform the following changes:

  • Replace 'qemu-kvm (>=2.5)' with 'qemu-system-x86 (>= 1:5.2)' in the dependencies of cloudstack-agent
  • Remove dh-systemd as a build dependency of cloudstack (it's included in debhelper)

Now open debian/rules and add the following flags to the mvn command:

-Dmaven.test.skip=true -Dclean.skip=true -Dcheckstyle.skip

Now open debian/changelog and change 'unstable' to 'bullseye'.

As of this writing, there is a bug in libvirt which prevents VMs with more than 4GB of RAM from being created on hosts with cgroups2. Until that issue is fixed, we're going to need to modify the source code. Since we're already building a custom CloudStack package, it's easier to patch CloudStack than to patch libvirt, so paste something like the following into debian/patches/fix-cgroups2-cpu-weight.patch:

Description: Workaround for libvirt trying to write a value to the cgroups v2
  cpu.weight controller which is greater than the maximum (10000). The
  libvirt developers are currently discussing a solution.
Forwarded: not-needed
Origin: upstream,
Author: Max Erenberg <>
Last-Update: 2021-12-03
Index: apache-cloudstack-
--- apache-cloudstack-
+++ apache-cloudstack-
@@ -1483,6 +1483,10 @@ public class LibvirtVMDef {
         static final int MAX_PERIOD = 1000000;
         public void setShares(int shares) {
+           // Clamp the value to the cgroups v2 cpu.weight maximum until
+           // upstream libvirt gets fixed:
+           //
+           shares = Math.min(shares, 10000);
             _shares = shares;

I think you have to manually modify that file to incorporate those changes (I could be wrong on this, but that's how I did it).

Then paste the following into debian/patches/00list:


Finally, import your GPG key into the container (make sure to delete it afterwards!), and build the packages:

debuild -k<YOUR_GPG_KEY_ID>

There should already be a .dupload.conf in the /root directory in the cloudstack-build container; if you need need another copy, ask a syscom member. Open /root/.ssh/config and change the User parameter to your username. Finally, go to /root and upload the packages to potassium-benzoate (replace the version number):

dupload cloudstack_4.16.0.0+1_amd64.changes

Database setup

We are using master-master replication between two MariaDB instances on biloba and chamomile. See here and here for instructions on how to set this up.

To avoid split-brain syndrome, points to a virtual IP shared by biloba and chamomile via keepalived. This means that only one host is actually handling requests at any moment; the other is a hot standby.

Also add the following parameters to /etc/mysql/my.cnf on the hosts running MariaDB:

binlog-format = 'ROW'

Also comment out (or remove) the following line in /etc/mysql/mariadb.conf.d/50-server.cnf:

bind-address =

Now restart MariaDB.

Management server setup

Install the management server from our Debian repository:

apt install cloudstack-management

Run the database scripts:

cloudstack-setup-databases cloud:password@localhost --deploy-as=root

(Replace 'password' by a strong password.)

Open /etc/cloudstack/management/ and replace all instances of 'localhost' by ''.

Open /etc/cloudstack/management/ and set 'bind-interface' to (CloudStack is being reverse proxied behind NGINX).

Run some more scripts:


Mount the cloudstack-secondary CephFS volume at /mnt/cloudstack-secondary:

mkdir /mnt/cloudstack-secondary
mount -t nfs4 -o port=2049 /mnt/cloudstack-secondary

Now download the management VM template:

/usr/share/cloudstack-common/scripts/storage/secondary/cloud-install-sys-tmplt -m /mnt/cloudstack-secondary/ -u -h kvm -F

The management server will run on port 8080 by default, so reverse proxy it from NGINX:

location / {
  proxy_pass http://localhost:8080;

Compute node setup

Install packages:

apt install cloudstack-agent libvirt-daemon-driver-storage-rbd qemu-block-extra

Create a new user for CloudStack:

useradd -s /bin/bash -d /nonexistent -M cloudstack
# set the password
passwd cloudstack

Add the following to /etc/sudoers:

cloudstack ALL=(ALL) NOPASSWD:ALL     
Defaults:cloudstack !requiretty

(There is a way to restrict this, but I was never able to get it to work.)

Network setup

The /etc/network/interfaces file should look something like this (taking ginkgo as an example):

auto enp3s0f0
iface enp3s0f0 inet manual

auto ens1f0np0
iface ens1f0np0 inet manual

# csc-cloud management
auto enp3s0f0.529
iface enp3s0f0.529 inet manual

auto br529
iface br529 inet static
    bridge_ports enp3s0f0.529
iface br529 inet6 static
    bridge_ports enp3s0f0.529
    address fd74:6b6a:8eca:4902::22/64

# csc-cloud provider
auto ens1f0np0.425
iface ens1f0np0.425 inet manual

auto br425
iface br425 inet manual
    bridge_ports ens1f0np0.425

# csc server network
auto ens1f0np0.134
iface ens1f0np0.134 inet manual

auto br134
iface br134 inet static
    bridge_ports ens1f0np0.134
iface br134 inet6 static
    bridge_ports ens1f0np0.134
    address 2620:101:f000:4901:c5c::148/64
    gateway 2620:101:f000:4901::1

Add/modify the following lines to /etc/cloudstack/

libvirtd setup

Add/modify the following lines in /etc/libvirt/libvirtd.conf:

listen_tls = 0
listen_tcp = 1
tcp_port = "16509"
auth_tcp = "none"
mdns_adv = 0

Uncomment the following line in /etc/default/libvirtd:


Make sure the following lines are present in /etc/libvirt/qemu.conf:


Now run:

systemctl mask libvirtd.socket
systemctl mask libvirtd-ro.socket
systemctl mask libvirtd-admin.socket
systemctl restart libvirtd

Management server setup (cont'd)

Now start the cloudstack-management systemd service and visit the web UI ( The login credentials are 'admin' for both the username and password. Start the setup walkthrough (you will be prompted to change the password). Make sure to choose Basic Networking.

The walkthrough is almost certainly going to fail (at least, it did for me). Don't panic when this happens; just abort the walkthrough, and set up everything else manually. Once primary and secondary storage have been setup, and at least one host has been added, enable the Pod, Cluster and Zone (there should only be one of each).

Primary Storage

Secondary Storage

  • Type: NFS
  • Host:
  • Path: /cloudstack-secondary

Global settings

Some global settings which you'll need to set from the web UI:

  • ca.plugin.root.auth.strictness: false (this always caused issues for me, so I just disabled it)
  • host:, (the VLAN 529 addresses of biloba and chamomile)

Adding a host

This is an extremely painful process which I am almost certainly doing wrong. It usually takes me 7-8 attempts to add a single host (that's not an exaggeration). This is what it looks like:

  • Stop cloudstack-agent service
  • Configure /etc/cloudstack-agent/
  • Add a host from the CloudStack UI
  • Start cloudstack-agent.service

The reason why this takes several attempts is because cloudstack-agent actually overwrites your file. If/when you notice that this happens, restart the whole process again.

Accessing the System VMs

If you need to SSH into one of the System VMs, get its link-local address from the web UI, and run e.g.

ssh -i /var/lib/cloudstack/management/.ssh/id_rsa -p 3922 root@

Some more global settings

allow.user.expunge.recover.vm = true
allow.user.view.destroyed.vm = true
expunge.delay = 1
expunge.interval = 1
network.securitygroups.defaultadding = false
allow.public.user.templates = false = 0
network.throttling.rate = 0
cpu.overprovisioning.factor = 4.0
allow.user.create.projects = false
max.project.cpus = 8
max.project.memory = 8192 = 40 = 20
max.account.cpus = 8
max.account.memory = 8192 = 40 = 20


Since we disabled certificate validation from the clients, we're going to use some iptables-fu on all of the CloudStack hosts (to make our lives easier, we're going to use the same rules on the management and agent servers):

iptables -A CLOUDSTACK-SERVICES -p tcp -m multiport --dports 16509,16514,45335,41047,8250 -j REJECT
iptables-save > /etc/iptables/rules.v4

ip6tables -A CLOUDSTACK-SERVICES -s fd74:6b6a:8eca:4902::/64 -j RETURN
ip6tables -A CLOUDSTACK-SERVICES -p tcp -m multiport --dports 16509,16514,45335,41047,8250 -j REJECT
ip6tables-save > /etc/iptables/rules.v6

LDAP authentication

Go to Global Settings in the UI, type 'ldap' in the search bar, and configure the parameters as needed. Make sure the mail attribute is set to 'mailLocalAddress'.

Create a new domain called 'Members'. Then go to 'LDAP Configuration', click the 'Configure LDAP +' button, and add a new LDAP config linked to the domain you just created.

ceo handles the creation of CloudStack accounts, so create an API key + secret token and add it to /etc/csc/ceod.ini on biloba.


This deserves an entire page of its own - see CloudStack Templates.


This deserves an entire page of its own - see Kubernetes.

Upgrading CloudStack

Please be extremely careful if you decide to upgrade CloudStack. The last time I tried to perform an upgrade (from 4.15 to 4.16), the agents refused to connect to the management servers (or maybe it was the other way around?), and I ended up having to wipe the entire CloudStack installation clean and start again from scratch. Therefore it is fair to say that nobody has ever managed to successfully upgrade CloudStack on our machines. Do this at your own risk.

If you decide to perform an upgrade, then at the very least, you will need to backup the MariaDB databases ('cloud' and 'cloud_usage'), as well as the /etc/cloudstack and /var/lib/cloudstack folders on each of biloba, chamomile and ginkgo. Also, good luck.