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Appendix A: OpenStack Orchestration

OpenStack’s orchestration service was excluded from the Certified OpenStack Administrator exam requirements. However, I decided to keep this topic in the book as an annex and parity with the first exam version amount of knowledge.

Heat’s Architecture and Components

The last (but certainly not the least) service covered in this book is Heat. OpenStack’s orchestration service is the “one ring to rule them all.” Heat’s main purpose is to manage the entire infrastructure and applications life cycle within OpenStack clouds. Heat uses templates describing instances, networks, volumes, and so forth for orchestration. Heat can also rule scale-in/scale-out scenarios with Ceilometer’s help.

Two formats of templates can be used.

HOT (Heat Orchestration Template) is an OpenStack-native YAML-based template format.
CFT (AWS CloudFormation Template) is compatible with AWS CloudFormation (http://aws.amazon.com/cloudformation/) JSON-based template format. You can use a lot of templates designed for AWS. A good starting point for research is https://aws.amazon.com/cloudformation/resources/templates/.

OpenStack’s orchestration architecture is shown in Figure A-1. Heat consists of several services implemented as GNU/Linux daemons and CLI commands.

heat-api accepts an OpenStack-native REST API call for template processing. After receiving API calls, heat-api processes them by sending them to the heat-engine via the AMQP protocol.
heat-api-cfn is a CloudFormation API service. It is similar to heat-api by function.
heat-engine is Heat’s main service. The engine does all the work of orchestrating, launching templates, and providing feedback to the client.
heat is a CLI tool that communicates with the heat-api.

Figure A-1
OpenStack Orchestration architecture

Introducing the Heat OpenStack Template

The input information for Heat is a template that describes the stack. Stack is the branch of OpenStack resources that creates an application. Applications can consist of several instances and networks. HOT (Heat OpenStack Template) was originally introduced in the Icehouse release, and it acts as a primary standard for Heat.

Have a look at Figure A-2, where the structure of the HOT is shown. The template is divided into four parts. The first part is a template header. It consists of the HOT version and an optional description for the OpenStack operator. Table A-1 lists the most recent versions of HOT.

Figure A-2
Example of the Heat OpenStack Template (HOT) format

Table A-1

OpenStack Heat OpenStack Templates Versions

Series

HOT Version

Liberty

heat_template_version: 2015-10-15

Mitaka

Newton

Ocata

Pike

Queens

Rocky

Wallaby

heat_template_version: 2016-04-08

heat_template_version: 2017-02-24

heat_template_version: 2018-09-01

heat_template_version: 2018-03-02

heat_template_version: 2016-04-08

heat_template_version: 2021-04-16

The second optional section is the parameters. This section allows you to customize the deployment and specify the input parameters that must be provided when instantiating the template.

The third section is always mandatory. It starts from general resources and defines actual resources that make up a stack. There are more than 100 resource types that can be defined here. You can find a full description of HOT at the OpenStack documentation project site (http://docs.openstack.org/developer/heat/template_guide/index.html). There should be at least one resource definition in this section.

The last section defines the output parameters that should be available to the user after a stack has been created. These output parameters are available from CLI and in the Horizon web client.

Launching a Stack Using a HOT

You can check the template examples at https://github.com/openstack/heat-templates/. There you can find examples of templates that demonstrate core Heat functionality. Here is a listing of a slightly modified “Hello world” example from this repository.

heat_template_version: 2015-10-15

description: >

Apress Certified OpenStack Administrator Study Guide.

One VM Example

parameters:

network:

type: string

description: Network for VM

default: private

image:

type: string

description: Cirros Image for VM

default: cirros

resources:

my_server:

type: OS::Nova::Server

properties:

flavor: m1.tiny

key_name: mykey

networks:

- network: { get_param: network }

image: { get_param: image }

user_data: |

#!/bin/sh

echo "Instance started :)"

user_data_format: RAW

outputs:

instance_name:

description: The name of VM

value: { get_attr: [my_server, name] }

private_ip:

description: The private IP of VM

value: { get_attr: [ my_server, first_address ] }

The example consists of all four main parts of the template. There are two parameters defined: network and image. They have default values, but you can redefine them at the time of stack launching. The only described resource type OS::Nova::Server in this stack is my_server. By the way, you can find descriptions of all the resource types in the Horizon web interface. The results of this example are shown in Figure A-3. The most interesting part of the definition is the example of how to run a specific script when starting the instance. And at the end of the template, the virtual machine’s name and IP output are defined.

Figure A-3
Example of the resource types’ description in Horizon

You can start the stack either in Horizon or in the command line. If you choose Horizon, go to Project ➤ Orchestration ➤ Stacks and click the Launch Stack button. You can use the -P option to define parameters if you use the command line.

$ openstack stack create -t Hello-World.yml --parameter network=private --parameter image=cirros mystack

+---------------------+------------------------------------------+

| Field | Value |

+---------------------+------------------------------------------+

| id | 37160ce4-d98e-4950-82af-873eabd1573e |

| stack_name | mystack |

| description | Apress Certified OpenStack Administrator Study Guide. One VM Example |

| | |

| creation_time | 2022-07-28T14:42:09Z |

| updated_time | None |

| stack_status | CREATE_IN_PROGRESS |

| stack_status_reason | Stack CREATE started |

+---------------------+------------------------------------------+

Then you can issue the openstack stack list command to make sure the stack creation is completed.

$ openstack stack list

+--------------------------------------+------------+-----------------+----------------------+--------------+

+--------------------------------------+------------+-----------------+----------------------+--------------+

+--------------------------------------+------------+-----------------+----------------------+--------------+

You also see the new instance in Nova.

openstack server list

+-----------+-----------+--------+----------+--------+---------+

+-----------+-----------+--------+----------+--------+---------+

+-----------+-----------+--------+----------+--------+---------+

The name of the instance consists of the stack name, instance name, and automatically generated alpha-number appendix. You can show detailed information about running the stack.

$ openstack stack show mystack

+-----------------------+-------------------------------------------------+

| Field | Value |

+-----------------------+-------------------------------------------------+

| id | 37160ce4-d98e-4950-82af-873eabd1573e |

| stack_name | mystack |

| description | Apress Certified OpenStack Administrator Study Guide. One VM Example |

| | |

| creation_time | 2022-07-28T14:42:09Z |

| updated_time | None |

| stack_status | CREATE_COMPLETE |

| stack_status_reason | Stack CREATE completed successfully |

| parameters | OS::project_id: 7c8be1bdcc544e5fa8191b6095e5e595|

| | OS::stack_id: 37160ce4-d98e-4950-82af-873eabd1573e |

| | OS::stack_name: mystack |

| | image: cirros |

| | network: private |

| | |

| outputs | - description: The name of VM |

| | output_key: instance_name |

| | output_value: mystack-my_server-rn4jl7eg3uko |

| | - description: The private IP of VM |

| | output_key: private_ip |

| | output_value: 10.0.0.155 |

| | |

| links | - href: http://192.168.122.10:8004/v1/7c8be1bdcc544e5fa8191b6095e5e595/stacks/mystack/37160ce4-d98e-4950-82af-873eabd1573e |

| | rel: self |

| | |

| deletion_time | None |

| notification_topics | [] |

| capabilities | [] |

| disable_rollback | True |

| timeout_mins | None |

| stack_owner | demo |

| parent | None |

| stack_user_project_id | 2affe18a371844afab2b4cdb685a93fb |

| tags | [] |

| | |

+-----------------------+-------------------------------------------------+

This information is also available in the Horizon web interface (see Figure A-4).

Figure A-4
Example of the stack details in the Horizon web interface

Using CLI and the Dashboard for Heat Service Operations

Let’s examine the most common operations with stacks. If you troubleshoot the stack and want to see what happens with the resources, the heat event-list command is very useful.

$ openstack stack event list mystack

2022-07-28 14:42:09Z [mystack]: CREATE_IN_PROGRESS Stack CREATE started

2022-07-28 14:42:09Z [mystack.my_server]: CREATE_IN_PROGRESS state changed

2022-07-28 14:42:15Z [mystack.my_server]: CREATE_COMPLETE state changed

2022-07-28 14:42:15Z [mystack]: CREATE_COMPLETE Stack CREATE completed successfully

Figure A-5 shows the list of events in the Horizon web interface.

Figure A-5
Example of the stack events list in the Horizon web interface

As the owner of the stack, you can suspend and resume your stacks again.

$ openstack stack suspend mystack

+-----------+------+-----------+------+--------+

+-----------+------+-----------+------+--------+

+-----------+------+-----------+------+--------+

$ openstack stack resume mystack

+-----------+------+----------+------+--------+

+-----------+------+----------+------+--------+

+-----------+------+----------+------+--------+

With Horizon and CLI, it is possible to see the resources of your stack.

$ openstack stack resource list mystack

+---------+-----------+------------+-----------+------+

+---------+-----------+------------+-----------+------+

+---------+-----------+------------+-----------+------+

If you prefer to work with Horizon, you can see the same information. An example of the stack resources in Horizon is shown in Figure A-6.

Figure A-6
Example of the stack resources as shown in the Horizon web interface

As mentioned, openstack stack show mystack shows the information for all the stacks’ properties, including output. You can use another command if you want to see output only.

$ openstack stack output show mystack --all

+---------------+----------------------------------------------------+

| Field | Value |

+---------------+----------------------------------------------------+

| instance_name | { |

| | "output_key": "instance_name", |

| | "description": "The name of VM", |

| | "output_value": "mystack-my_server-rn4jl7eg3uko" |

| | } |

| private_ip | { |

| | "output_key": "private_ip", |

| | "description": "The private IP of VM", |

| | "output_value": "10.0.0.155" |

| | } |

+---------------+----------------------------------------------------+

Also, you can see the template using the command.

$ openstack stack template show mystack

If you update the text of the template file, you may also want to update a stack. Run the following command to update an existing stack from a modified template file.

$ openstack stack update -t Hello-World.yml --parameter network=private --parameter image=cirros mystack

+---------------------+-------------------------------------------------+

| Field | Value |

+---------------------+-------------------------------------------------+

| id | 37160ce4-d98e-4950-82af-873eabd1573e |

| stack_name | mystack |

| description | Apress Certified OpenStack Administrator Study Guide. One VM Example |

| | |

| creation_time | 2022-07-28T14:42:09Z |

| updated_time | 2022-07-28T16:01:34Z |

| stack_status | UPDATE_IN_PROGRESS |

| stack_status_reason | Stack UPDATE started |

+---------------------+-------------------------------------------------+

Some resources are updated in place, while others are replaced with new resources. Finally, you can also delete a stack.

$ openstack stack delete mystack

Are you sure you want to delete this stack(s) [y/N]? y

The Topology subtab on the Project details page is very useful for an overall view of the stack resources and links between them. An example of a two-instance stack topology is shown in Figure A-7.

Figure A-7
Example of the stack topology

Index

A, B

Access control lists (ACLs)

Ceilometer

Certified OpenStack Administrator (COA)

architecture and components

command key bindings

commands

distributions

download links

exam facts

exam requirements

hypervisor

kernel modules

KVM

Nova

production operations, enterprises

vs. Red Hat

services

technical documentation

tmux multiplexers

vendor’s contribution

versions

virtualization hardware support

website

Cinder

architecture

configuration options

LVM volume group

OpenStack node

openstack volume service list

quotas

configuration options

demo project

Horizon

name/number

results

services

snapshots

backing up

volume

storage pools

storage providers

test environments

volumes

admin users

apresstest1

backing up

cinder command

creation

deletion

Glance’s image

lvs command

openstack command

regular users

VM instance

CloudFormation Template (CFT)

Cloud service models

Command-line interface (CLI)

clients

help option

keypair create subcommand

packet manager

python3-openstackclient

Dashboard

Domains

Dynamic Host Configuration Protocol (DHCP)

Ethernet interface

Flavors

addition

deletion

details

managing

public

Glance

architecture

components

connection URL

disk formats

files

glance-api

glance-registry service

images

back ends

CLI commands

--debug option

deletion

metadata

operations

set up

Keystone

metadata

Nova

OpenStack controller

storage

GNU/Linux distributions

Heat

architecture/components

template

Heat Orchestration Template (HOT)

Hello world

Horizon web interface

information

Launch Stack button

Nova

openstack stack list command

parameters

Heat Service operations

events list

heat event-list command

stack

deletion

Horizon web interface

output

resources

suspend/resume

topology

updation

template

Horizon

dashboard

project members

users

Horizon’s architecture

Host/Guest OS and instance status

information

instances page

lists

nova command

openstack command

openstack host show command

usage summary

hypervisors

OpenStack

I, J

Identity service

Keystone

operations, managing/verification

Image management service

CirrOS

Cloud-ready images

deployment

image

creation

list

Project view

information

openstack image show command

qemu-img command

Infrastructure as a service (IaaS)

Instances

console, browser

current state

deletion

error

--hard option

information

key pairs

launching

network list

network specification

reboot

snapshots

URL

Kernel-based virtual machines (KVMs)

Keystone

Apache web server

catalog services/endpoints

creation

Horizon

openstack service delete command

openstack service list command

run

script execution

service record

text editor

configuration file

terms

Lightweight Directory Access Protocol (LDAP)

Linux From Scratch (LFS) project

Linux Logical Volume Manager (LVM)

Log files

Mailing lists

Messaging server

Mirantis company

mysqldump command

National Institute of Standards and Technology’s (NIST)

Network address translation (NAT)

Network interfaces

Network resources

commands

external IP/virtual machine

ext-net

floating IP

Horizon

information

locate IP

networks list

networks screen

ports

subnet

tenant network

tenant subnet

topology

virtual router

Network status

demo-net

log file

network page

neutron command

Neutron agent list

neutron command

Neutron service

opensrtack port list command

opensrtack port show command

overview details

routers

topology tab

Neutron

agents

architecture

components

extension

log file

objects

Open vSwitch (OVS)

bridges

components

neutron-openvswitch-agent

ovs-vsctl show

physical interface

OVN

services

Nova

--all-projects option

configuration options

connections

/etc/httpd/conf.d/ directory

goal

hosts

hypervisors

Keystone services catalog

nova command

log files/services

OpenStack documentation

process

resource usage

services

systemctl command

tenant summary

troubleshooting

workflow

OpenInfra Foundation

Opening Virtual Networking (OVN)

metadata agent

Neutron agents

northbound (NB) database

OpenFlow protocol

vs. OVS

southbound (NB) database

OpenStack

block storage services

computer services

databases

documentation

network ports

port numbers

services information

supporting services

systemctl command

vendors

versions

website

Operators

Platform as a service (PaaS)

Projects

Apress projects

creation

--domain option

Horizon

list/details

openstack command

Project security group rules

adding rule

command

creation

Horizon

instances

iptables rules

removing group

Quotas

checking

default network quotas

modification

openstack quota list command

openstack quota set command

openstack quota show command

openstack quota show--default command

overview

resources

RabbitMQ server

graphical web console

settings

status

users

web plug-in

RDO OpenStack, PackStack

adding server

answer file

CentOS Stream 9

Heat

hypervisors

installation

IP address

nodes

NTP server

options

packstack--allinone command

Puppet modules

repositories

SELinux enforcing mode

SELinux permissive mode

tasks/reports

updation/rebooting

Red Hat documentation

Red Hat Enterprise Linux (RHEL)

Red Hat OpenStack Platform (RH OSP)

Representational state transfer application program interfaces (REST APIs)

Roles

RPM Distribution of OpenStack (RDO)

Run control (RC) files

Secure Shell (SSH)

Software as a service (SaaS)

Software Defined Storage (SDS) system

Superuser

Swift

cluster monitoring

container

cURL tool

expiring objects

identification

levels

objects

object storage

swift download command

swift list command

swift stat command

user interface

Troubleshooting

GNU/Linux commands

steps

Ubuntu OpenStack, MicroStack

alias

commands

initialization

installation

Users

creation

Horizon dashboard

keystonerc file

multi-domain model

V, W, X, Y, Z

Vanilla OpenStack, DevStack tool

installation/downloading

local.conf file

stack.sh script

Virtual Machine Manager

website

Virtual desktop environment

Virtual private network (VPN)

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