Architecture¶
Computing nodes and resources¶
The advantage of virtual machines over physical ma- chines is that various computing environments can co-exist on a single physical machine. A setup with fewer physical machines but with multiple virtual environments is more economical and occupies a smaller space in the server racks. Thanks to a virtualisation layer and a hypervisor monitoring the health, new virtual machines can be created or deleted on demand and based on the available capacity of the physical server.
The Jenkins virtual machine running the Linux Ubuntu operating system is a shared resource, is referred to as the master node, handles HTTPs requests, and orchestrates the slave nodes. The Linux (Debian based), Windows 7, and Windows 10 operating systems are virtual machines and are running on the same physical computing node, whereas the macOS operating system is running on a dedicated physical machine. The specifications of the computing nodes are:
# |
Name |
Type |
Mode |
Memory |
cores |
OS |
Storage (GB) |
|---|---|---|---|---|---|---|---|
1 |
Prince |
Virtual |
master |
8GB ECC |
4 |
Ubuntu 16.04 |
34+120 |
2 |
Linux |
Virtual |
slave |
18GB ECC |
20 |
Ubuntu 16.04 |
46+200 |
2 |
Windows 7 |
Virtual |
slave |
18GB ECC |
20 |
Windows 7 |
60+200 |
2 |
Windows 10 |
Virtual |
slave |
18GB ECC |
20 |
Windows 10 |
50+200 |
3 |
Mac |
Physical |
slave |
24GB ECC |
12 |
macOS 10.12 |
250 |
A limited amount of storage is usually provided to each virtual machine and only satisfies the need to run and store small amount of data. For larger data, such as build data, an NFS (Network File System) or SMB (Server Message Block) mount point is provided on a central storage system.
Virtual machine management and access control¶
Security and appropriate access control to each virtual machine and associated services is provided through FreeIPA. FreeIPA provides a centralised resource to control authentication, authorisation and account information by storing all information about a user, virtual machine and other sets of objects required to manage the security of the virtual machine.
In order to reduce maintenance and initialisation time of new virtual machines, the virtual machines are deployed using Foreman, a virtual- isation environment agnostic web tool typically used to manage the complete lifecycle of virtual machines.
All physical and virtual servers (except the macOS node) are configured via Puppet, which is a configuration management tool that facilitates standard- ised configurations across a pool of servers such as firewall definitions, administration SSH (Secure Shell) keys, default packages, and other settings. In the current setup, the compliance of all machine configurations is constantly monitored, while periodic health reports are provided to Foreman. Besides the configuration monitoring and deployment, the performance of the virtual machines is monitored using netdata, which is particularly useful when evaluating the performance of the continuous integration test suite.
Virtualisation layer¶
Hypervisor software runs on a server handling virtual machines (VMs). In the present case, oVirt is installed on each of the physical servers, and is a key element in VM management. Kernel-based Virtual Machine (KVM), a virtualisation infrastructure, is used as the hypervisor layer. oVirt provides a graphical user interface (GUI) to manage all physical and logical resources needed for the virtual infrastructure (e.g storage, network, data centres). In the current continuous integration system, the 2 physical servers (not the macOS node) are running CentOS 7.3 and are virtualised using oVirt 4.1.0.