Creating a CentOS 7 Morpheus Image

Overview

Morpheus comes out of the box with a default set of blueprints for use in many modern deployment scenarios. These consist mostly of base operating system images with a few additional adjustments. These adjustments typically include the addition of cloud-init (which is highly recommended to be used in most environments, but not mandatory). However, in many on-premise deployments there are custom image requirements as well as networking requirements. This guide will go over how to create a base CentOS 7 Image for use within Morpheus .

Creating a CentOS 7 Morpheus VMware Image

VMWare

When running in VMWare it is highly recommended that VMware Tools be installed. Without it, Morpheus will have difficulty assessing the host ip address and performing some additional automation tasks for the operating system.

Cloud-Init

To get started with a base CentOS image we first install cloud-init. This is a relatively simple process using yum:

yum -y install epel-release
yum -y install git wget ntp curl cloud-init dracut-modules-growroot
rpm -qa kernel | sed 's/^kernel-//'  | xargs -I {} dracut -f /boot/initramfs-{}.img {}

There are two parts to this yum installation. We are first ensuring some core dependencies are installed for automation as well as cloud-init. git for example is installed for use by ansible playbook automation down the line and is therefore optional if not using ansible. The dracut-modules-growroot is responsible for resizing the root partition upon first boot to match the virtual disk size that was potentially adjusted during provisioning.

A great benefit to using cloud-init is credentials don’t have to be locked into the blueprint. It is advisable, within Morpheus , to configure the default cloud-init user that gets created when the vm boots automatically by cloud-init. This is located in the Administration -> Provisioning -> Cloud-Init Settings section.

Network Interfaces

A slightly annoying change with centOS 7 is that the network interfaces have changed naming convention. You may notice when running ifconfig that the primary network interface is set to something like ens2344 or some other random number. This naming is dynamic typically by hardware id and we don’t want this to fluctuate when provisioning the blueprint in various VMware environments. Fortunately, there is a way to turn this functionality off and restore the interface back to eth0.

Firstly we need to adjust our bootloader to disable interface naming like this.

sed -i -e 's/quiet/quiet net.ifnames=0 biosdevname=0/' /etc/default/grub
grub2-mkconfig -o /boot/grub2/grub.cfg

The above command adds a few arguments to the kernel args list (namely net.ifnames=0 and biosdevname=0. It may be useful to view the /etc/default/grub file and ensure these settings were indeed applied.

The next step is to adjust the network-scripts in centOS. we need to ensure we have a file called /etc/sysconfig/network-scripts/ifcfg-eth0

Below is a script that we run on our packer builds to prepare the machines network configuration files.

export iface_file=$(basename "$(find /etc/sysconfig/network-scripts/ -name 'ifcfg*' -not -name 'ifcfg-lo' | head -n 1)")
export iface_name=${iface_file:6}
echo $iface_file
echo $iface_name
sudo mv /etc/sysconfig/network-scripts/$iface_file /etc/sysconfig/network-scripts/ifcfg-eth0
sudo sed -i -e "s/$iface_name/eth0/" /etc/sysconfig/network-scripts/ifcfg-eth0
sudo bash -c 'echo NM_CONTROLLED=\"no\" >> /etc/sysconfig/network-scripts/ifcfg-eth0'

This script tries to ensure there is a new ifcfg-eth0 config created to replace the old ens config file. Please do verify this config exists after running. If it does not you will have to be sure to build one on your own.

TYPE=Ethernet
DEVICE=eth0
NAME=eth0
ONBOOT=yes
NM_CONTROLLED="no"
BOOTPROTO="dhcp"
DEFROUTE=yes

Gotyas

SELinux can cause issues with cloud-init when in enforced mode. It may be advisable to set this to permissive unless it is mandatory within your organization to use an enforced SELinux configuration. If that is the case please see the documentation for the cloud_init_t security policies.

Network Manager will also prevent the required restart of the Network Service when assigning static IP’s. Disable Network Manager when possible or Static IP assignment may not work until the Network Service is restarted manually.

A Note on Proxies

Proxy configurations are known to vary in some organizations and makes building a base blueprint a little more difficult. In order to fully configure proxies a few environment variables must be set in the /etc/environment file (This can be done automatically in a default user-data script for cloud-init as well in edit cloud).

http_proxy="http://myproxyaddress:8080"
https_proxy="http://myproxyaddress:8080"
ftp_proxy="http://myproxyaddress:8080"
no_proxy=127.0.0.1,localhost,applianceUrl
https_no_proxy=127.0.0.1,localhost,applianceUrl

Important

It is very important to properly set the no_proxy list (applianceUrl) should be replaced with the actual appliance url. In future releases, morpheus plans to automatically take care of this.

Note

If using cloud-init agent install mode these settings need to be set in the custom Cloud-Init User data section of “Edit Cloud” or “Edit Virtual Image”

Important

If using this virtual machine as a docker host, proxy settings must also be configured in the docker config. See Docker guides for instructions on how to properly set this. If necessary this can be wrapped in a task automation workflow for your own use.