Launching Instances with the CLI

Tip

Reading Command Line Interface (CLI) is highly recommended before continuing on the following sections.

Creating an instance with the CLI

To launch an instance inside a reservation, run:

openstack server create \
--image CC-CentOS8 \
--flavor baremetal \
--key-name <key_name> \
--nic net-id=<sharednet1_id> \
--hint reservation=<reservation_id> \
my-instance

The ID of the sharednet1 network can be obtained using the command:

openstack network list

Alternatively, you may look it up in the GUI in the Network > Networks page. You can obtain your reservation ID via the GUI or by running:

openstack reservation lease show <lease_name>

Attention

The reservation ID and the lease ID are different

Running a script on boot

You might want to automatically execute some code after launching an instance, whether it is installing packages, changing configuration files, or running an application. OpenStack provides a mechanism called User Data to pass information to instances. This information can be any data in any format, but if it is a shell script it will be automatically executed after boot by cloudinit. You can provide this shell script either via the GUI in the Configuration tab when launching an instance, or by providing a file to the nova command line using the --user-data option.

Tip

Chameleon supported images are configured with appliance agents, including collectd (for system monitoring) and Heat agents. To turn off appliance agents on boot, in order to remove the potential impact on experimental measurements, pass the following script as user-data.

#!/bin/bash
systemctl stop collectd.service
systemctl disable collectd.service
systemctl stop os-collect-config.service
systemctl disable os-collect-config.service

Turning off collectd will stop collecting system metrics, but you can restart and configure the daemon anytime for monitoring your experiment. For power monitoring capabilities, see Power Monitoring.

Customizing the Kernel

It is easy to customize the operating system kernel or modify the kernel command line. You now have the option of modifying the boot loader configuration (e.g., /boot/grub2/grub.cfg on CentOS 7 images) to point it to a new kernel on the local disk, or specifying kernel parameters and then rebooting using this modified configuration.

To do this, you must be using a whole disk image rather than a partition image. Whole disk images contain their own kernel and ramdisk files and do not have kernel_id and ramdisk_id properties in the image repository, unlike partition images. Most Chameleon base images are whole disk images, giving you a good place to start if you’re interested in custom kernels.

Running virtual machines on bare metal

For cloud computing and virtualization experiments, you might want to run virtual machines on bare hardware that you fully control rather than use the shared OpenStack KVM cloud. There are many different ways to configure networking for virtual machines. The configuration described below will enable you to connect your virtual machines to the Internet using a KVM Public Bridge which you must first configure manually on your host on the default network interface.

First, set up your environment for the OpenStack command line tools by following the instructions. Install the Neutron client in a virtualenv with:

pip install python-neutronclient

Then, for each virtual machine you want to run, request a Neutron port with:

openstack port-create sharednet1

This should display, among other information:

  • A fixed IP in the same private network as the physical nodes

  • A MAC address

Finally, start your virtual machine while assigning it the MAC address provided by OpenStack. If your image is configured to use DHCP, the virtual machine should receive the allocated IP.

Neutron ports allocated this way are not automatically deleted, so delete them after your experiment is over using:

openstack port delete <id>

You may find the ID of your ports using:

openstack port list

Inspecting your node

From within an instance you have already launched, you can discover which node it is running on by executing

curl http://169.254.169.254/openstack/latest/vendor_data.json

This will return a JSON dictionary describing site, cluster, and node.

Customizing networking

In its default configuration, the bare metal deployment system used by Chameleon (OpenStack Ironic <https://docs.openstack.org/ironic/latest/>`_) is restricted to using a single shared network per site. The network configuration features available in the dashboard are not supported (Networks and Routers). On CHI@UC, network layer 2 isolation is optionally available for compute nodes. You may find more details on the documentation for Networking.