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Host Configuration

This section covers configuration of hosts. It does not cover configuration or deployment of containers. Hosts that are configured by Kayobe include:

Seed hypervisor (kayobe seed hypervisor host configure)
Seed (kayobe seed host configure)
Overcloud (kayobe overcloud host configure)

Unless otherwise stated, all host configuration described here is applied to each of these types of host.

Configuration Location

Some host configuration options are set via global variables, and others have a variable for each type of host. The latter variables are included in the following files under ${KAYOBE_CONFIG_PATH}:

seed-hypervisor.yml
seed.yml
compute.yml
controller.yml
monitoring.yml
storage.yml

Note that any variable may be set on a per-host or per-group basis, by using inventory host or group variables - these delineations are for convenience.

Paths

Several directories are used by Kayobe on the remote hosts. There is a hierarchy of variables in ${KAYOBE_CONFIG_PATH}/globals.yml that can be used to control where these are located.

base_path (default /opt/kayobe/) sets the default base path for various directories.
config_path (default {{ base_path }}/etc) is a path in which to store configuration files.
image_cache_path (default {{ base_path }}/images) is a path in which to cache downloaded or built images.
source_checkout_path (default {{ base_path }}/src) is a path into which to store clones of source code repositories.
virtualenv_path (default {{ base_path }}/venvs) is a path in which to create Python virtual environments.

SSH Known Hosts

While strictly this configuration is applied to the Ansible control host (localhost), it is applied during the host configure commands. The ansible_host of each host is added as an SSH known host. This is typically the host's IP address on the admin network (admin_oc_net_name), as defined in ${KAYOBE_CONFIG_PATH}/network-allocation.yml (see configuration-network-ip-allocation).

Kayobe User Bootstrapping

Kayobe uses a user account defined by the kayobe_ansible_user variable (in ${KAYOBE_CONFIG_PATH}/globals.yml) for remote SSH access. By default, this is stack.

Typically, the image used to provision these hosts will not include this user account, so Kayobe performs a bootstrapping step to create it, as a different user. In cloud images, there is often a user named after the OS distro, e.g. centos or ubuntu. This user defaults to the name of the user running Kayobe, but may be set via the following variables:

seed_hypervisor_bootstrap_user
seed_bootstrap_user
compute_bootstrap_user
controller_bootstrap_user
monitoring_bootstrap_user
storage_bootstrap_user

For example, to set the bootstrap user for controllers to centos:

controller_bootstrap_user: centos

PyPI Mirror

Kayobe supports configuration of a PyPI mirror, via variables in ${KAYOBE_CONFIG_PATH}/pip.yml. This functionality is enabled by setting the pip_local_mirror variable to true.

Kayobe will generate configuration for pip and easy_install to use the mirror, for the list of users defined by pip_applicable_users (default kayobe_ansible_user and root), in addition to the user used for Kolla Ansible (kolla_ansible_user). The mirror URL is configured via pip_index_url, and pip_trusted_hosts is a list of 'trusted' hosts, for which SSL verification will be disabled.

For example, to configure use of the test PyPI mirror at https://test.pypi.org/simple/:

pip_local_mirror: true
pip_index_url: https://test.pypi.org/simple/

Kayobe Remote Virtual Environment

By default, Ansible executes modules remotely using the system python interpreter, even if the Ansible control process is executed from within a virtual environment (unless the local connection plugin is used). This is not ideal if there are python dependencies that must be installed with isolation from the system python packages. Ansible can be configured to use a virtualenv by setting the host variable ansible_python_interpreter to a path to a python interpreter in an existing virtual environment.

If kayobe detects that ansible_python_interpreter is set and references a virtual environment, it will create the virtual environment if it does not exist. Typically this variable should be set via a group variable in the inventory for hosts in the seed, seed-hypervisor, and/or overcloud groups.

The default Kayobe configuration in the kayobe-config repository sets ansible_python_interpreter to {{ virtualenv_path }}/kayobe/bin/python for the seed, seed-hypervisor, and overcloud groups.

Disk Wiping

Using hosts that may have stale data on their disks could affect the deployment of the cloud. This is not a configuration option, since it should only be performed once to avoid losing useful data. It is triggered by passing the --wipe-disks argument to the host configure commands.

Users and Groups

Linux user accounts and groups can be configured using the users_default variable in ${KAYOBE_CONFIG_PATH}/users.yml. The format of the list is that used by the users variable of the singleplatform-eng.users role. The following variables can be used to set the users for specific types of hosts:

seed_hypervisor_users
seed_users
compute_users
controller_users
monitoring_users
storage_users

In the following example, a single user named bob is created. A password hash has been generated via mkpasswd --method=sha-512. The user is added to the wheel group, and an SSH key is authorised. The SSH public key should be added to the Kayobe configuration.

users_default:
 - username: bob
   name: Bob
   password: "$6$wJt9MLWrHlWN8$oXJHbdaslm9guD5EC3Dry1mphuqF9NPeQ43OXk3cXZa2ze/F9FOTxm2KvvDkbdxBDs7ouwdiLTUJ1Ff40.cFU."
   groups:
     - wheel
   append: True
   ssh_key:
     - "{{ lookup('file', kayobe_config_path ~ '/ssh-keys/id_rsa_bob.pub') }}"

Package Repositories

Kayobe supports configuration of package repositories via Yum, via variables in ${KAYOBE_CONFIG_PATH}/yum.yml.

CentOS and EPEL Mirrors

CentOS and EPEL mirrors can be enabled by setting yum_use_local_mirror to true. CentOS repository mirrors are configured via the following variables:

yum_centos_mirror_host (default mirror.centos.org) is the mirror hostname.
yum_centos_mirror_directory (default centos) is a directory on the mirror in which repositories may be accessed.

EPEL repository mirrors are configured via the following variables:

yum_epel_mirror_host (default download.fedoraproject.org) is the mirror hostname.
yum_epel_mirror_directory (default pub/epel) is a directory on the mirror in which repositories may be accessed.

For example, to configure CentOS and EPEL mirrors at mirror.example.com:

yum_use_local_mirror: true
yum_centos_mirror_host: mirror.example.com
yum_epel_mirror_host: mirror.example.com

Custom Yum Repositories

It is also possible to configure a list of custom Yum repositories via the yum_custom_repos variable. The format is a dict/map, with repository names mapping to a dict/map of arguments to pass to the Ansible yum module.

For example, the following configuration defines a single Yum repository called widgets.

yum_custom_repos:
  widgets:
    baseurl: http://example.com/repo
    file: widgets
    gpgkey: http://example.com/gpgkey
    gpgcheck: yes

Disabling EPEL

It is possible to disable the EPEL Yum repository by setting yum_install_epel to false.

SELinux

SELinux is not supported by Kolla Ansible currently, so it is disabled by Kayobe. If necessary, Kayobe will reboot systems in order to apply a change to the SELinux configuration. The timeout for waiting for systems to reboot is disable_selinux_reboot_timeout. Alternatively, the reboot may be avoided by setting disable_selinux_do_reboot to false.

Network Configuration

Configuration of host networking is covered in depth in configuration-network.

Sysctls

Arbitrary sysctl configuration can be applied to hosts. The variable format is a dict/map, mapping parameter names to their required values. The following variables can be used to set sysctl configuration specific types of hosts:

seed_hypervisor_sysctl_parameters
seed_sysctl_parameters
compute_sysctl_parameters
controller_sysctl_parameters
monitoring_sysctl_parameters
storage_sysctl_parameters

For example, to set the net.ipv4.ip_forward parameter to 1 on controllers:

controller_sysctl_parameters:
  net.ipv4.ip_forward: 1

Disable cloud-init

cloud-init is a popular service for performing system bootstrapping. If you are not using cloud-init, this section can be skipped.

If using the seed's Bifrost service to provision the control plane hosts, the use of cloud-init may be configured via the kolla_bifrost_dib_init_element variable.

cloud-init searches for network configuration in order of increasing precedence; each item overriding the previous. In some cases, on subsequent boots cloud-init can automatically reconfigure network interfaces and cause some issues in network configuration. To disable cloud-init from running after the initial server bootstrapping, set disable_cloud_init to true in ${KAYOBE_CONFIG_PATH}/overcloud.yml.

Disable Glean

The glean service can be used to perform system bootstrapping, serving a similar role to cloud-init. If you are not using glean, this section can be skipped.

If using the seed's Bifrost service to provision the control plane hosts, the use of glean may be configured via the kolla_bifrost_dib_init_element variable.

After the initial server bootstrapping, the glean service can cause problems as it attempts to enable all network interfaces, which can lead to timeouts while booting. To avoid this, the glean service is disabled. Additionally, any network interface configuration files generated by glean and not overwritten by Kayobe are removed.

Timezone

The timezone can be configured via the timezone variable in ${KAYOBE_CONFIG_PATH}/ntp.yml. The value must be a valid Linux timezone. For example:

timezone: Europe/London

NTP

Network Time Protocol (NTP) may be configured via variables in ${KAYOBE_CONFIG_PATH}/ntp.yml. The list of NTP servers is configured via ntp_config_server, and by default the pool.ntp.org servers are used. A list of restrictions may be added via ntp_config_restrict, and a list of interfaces to listen on via ntp_config_listen. Other options and their default values may be found in the resmo.ntp Ansible role.

ntp_config_server:
  - 1.ubuntu.pool.ntp.org
  - 2.ubuntu.pool.ntp.org

ntp_config_restrict:
  - '-4 default kod notrap nomodify nopeer noquery'

ntp_config_listen:
  - eth0

The NTP service may be disabled as follows:

ntp_package_state: absent
ntp_service_state: stopped
ntp_service_enabled: false

LVM

Logical Volume Manager (LVM) physical volumes, volume groups, and logical volumes may be configured via the lvm_groups variable. For convenience, this is mapped to the following variables:

seed_lvm_groups
compute_lvm_groups
controller_lvm_groups
monitoring_lvm_groups
storage_lvm_groups

Note that LVM is not configured on the seed hypervisor.

The format of these variables is as defined by the lvm_groups variable of the mrlesmithjr.manage-lvm Ansible role.

LVM for Docker

The default LVM configuration is optimised for the devicemapper Docker storage driver, which requires a thin provisioned LVM volume. A second logical volume is used for storing Docker volume data, mounted at /var/lib/docker/volumes. Both logical volumes are created from a single data volume group.

To use this configuration, a list of disks must be configured via the following variables:

seed_lvm_group_data_disks
compute_lvm_group_data_disks
controller_lvm_group_data_disks
monitoring_lvm_group_data_disks
storage_lvm_group_data_disks

For example, to configure two of the seed's disks for use by LVM:

seed_lvm_group_data_disks:
  - /dev/sdb
  - /dev/sdc

The Docker volumes LVM volume is assigned a size given by the following variables, with a default value of 75% (of the volume group's capacity):

seed_lvm_group_data_lv_docker_volumes_size
compute_lvm_group_data_lv_docker_volumes_size
controller_lvm_group_data_lv_docker_volumes_size
monitoring_lvm_group_data_lv_docker_volumes_size
storage_lvm_group_data_lv_docker_volumes_size

If using a Docker storage driver other than devicemapper, the remaining 25% of the volume group can be used for Docker volume data. In this case, the LVM volume's size can be increased to 100%:

controller_lvm_group_data_lv_docker_volumes_size: 100%

If using a Docker storage driver other than devicemapper, it is possible to avoid using LVM entirely, thus avoiding the requirement for multiple disks. In this case, set the appropriate <host>_lvm_groups variable to an empty list:

storage_lvm_groups: []

Custom LVM

To define additional logical logical volumes in the default data volume group, modify one of the following variables:

seed_lvm_group_data_lvs
compute_lvm_group_data_lvs
controller_lvm_group_data_lvs
monitoring_lvm_group_data_lvs
storage_lvm_group_data_lvs

Include the variable <host>_lvm_group_data_lv_docker_volumes in the list to include the LVM volume for Docker volume data:

monitoring_lvm_group_data_lvs:
  - "{{ monitoring_lvm_group_data_lv_docker_volumes }}"
  - lvname: other-vol
    size: 1%
    create: true
    filesystem: ext4
    mount: true
    mntp: /path/to/mount

It is possible to define additional LVM volume groups via the following variables:

seed_lvm_groups_extra
compute_lvm_groups_extra
controller_lvm_groups_extra
monitoring_lvm_groups_extra
storage_lvm_groups_extra

For example:

compute_lvm_groups_extra:
  - vgname: other-vg
    disks: /dev/sdb
    create: true
    lvnames:
      - lvname: other-vol
        size: 100%
        create: true
        mount: false

Alternatively, replace the entire volume group list via one of the <host>_lvm_groups variables to replace the default configuration with a custom one.

controller_lvm_groups:
  - vgname: only-vg
    disks: /dev/sdb
    create: true
    lvnames:
      - lvname: only-vol
        size: 100%
        create: true
        mount: false

Kolla-ansible bootstrap-servers

Kolla Ansible provides some host configuration functionality via the bootstrap-servers command, which may be leveraged by Kayobe. Due to the bootstrapping nature of the command, Kayobe uses kayobe_ansible_user to execute it, and uses the Kayobe remote Python virtual environment (or the system Python interpreter if no virtual environment is in use).

See the Kolla Ansible documentation for more information on the functions performed by this command, and how to configure it.

Kolla-ansible Remote Virtual Environment

See configuration-kolla-ansible-venv for information about remote Python virtual environments for Kolla Ansible.

Docker Engine

Docker engine configuration is applied by both Kayobe and Kolla Ansible (during bootstrap-servers).

The docker_storage_driver variable sets the Docker storage driver, and by default the devicemapper driver is used. If using this driver, see configuration-hosts-lvm for information about configuring LVM for Docker.

Various options are defined in ${KAYOBE_CONFIG_PATH}/docker.yml for configuring the devicemapper storage.

A private Docker registry may be configured via docker_registry, with a Certificate Authority (CA) file configured via docker_registry_ca.

To use one or more Docker Registry mirrors, use the docker_registry_mirrors variable.

If using an MTU other than 1500, docker_daemon_mtu can be used to configure this. This setting does not apply to containers using net=host (as Kolla Ansible's containers do), but may be necessary when building images.

Docker's live restore feature can be configured via docker_daemon_live_restore, although it is disabled by default due to issues observed.

Ceph Block Devices

If using Kolla Ansible to deploy Ceph, some preparation of block devices is required. The list of disks to configure for use by Ceph is specified via ceph_disks. This is mapped to the following variables:

compute_ceph_disks
controller_ceph_disks
storage_ceph_disks

The format of the variable is a list of dict/mapping objects. Each mapping should contain an osd item that defines the full path to a block device to use for data. Optionally, each mapping may contain a journal item that specifies the full path to a block device to use for journal data.

The following example defines two OSDs for use by controllers, one of which has a journal:

controller_ceph_disks:
  - osd: /dev/sdb
  - osd: /dev/sdc
    journal: /dev/sdd

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