Ansible offers great flexibility. Because of this the community has figured out many useful ways to leverage Ansible modules and playbook structures to automate frequent operations on multiple layers, including using it with OpenStack.
In this blog we’ll cover the many use-cases #for Ansible, the most popular automation software, with OpenStack, the most popular cloud infrastructure software. We’ll help you understand here how and why you should use Ansible to make your life easier, in what we like to call Full-Stack Automation.
Let’s begin by analyzing the layers of Full-Stack Automation, shown in the diagram above. At the bottom, we have the hardware resources (servers, storage area networks, and networking gear). Above, is the operating system (Linux or Windows). On the Linux side, you can install OpenStack to abstract all of your datacenter resources and offer a software-defined version of your compute, network, and storage resources. On top of OpenStack, are the tenant-defined services needed to create the virtual machines where the applications will reside. Finally, you have to manage the operating system (Linux or Windows) to deploy the actual applications and workloads that you really care about (databases, web servers, mobile application backends, etc.). If you use containers (like Docker or Rkt), you’ll package those applications in images that will be deployed on top of your Guest OS. In addition to that, some languages introduce the concept of application servers, which adds another layer (i.e. J2EE).
Ansible management possibilities
With Ansible, you have a module to manage every layer. This is true even for the networking hardware, although technically speaking it’s for the network operating system, like IOS or NXOS (see the full list of Ansible network modules here).
General interaction with the Operating System: install packages, change or enforce file content or permissions, manage services, create/remove users and groups, etc.
Linux and BSD via SSH (the first and most popular use-case)
Windows via PowerShell (since 1.7)
IaaS Software: install the IaaS software and its dependencies (databases, load balancers, configuration files, services, and other helper tools)
OpenStack-ansible installer https://github.com/openstack/openstack-ansible, as used in some upstream-based OpenStack distributions from other vendors. Note that the Red Hat OpenStack Platform does not use Ansible, but Heat and Puppet. Future releases will leverage Ansible to perform certain validations and to help operators perform their updates and upgrades.
CloudStack installer is also an Ansible-based project.
Virtual Resources: define the resource, like a Virtual Machine or Instance, in terms of how big it is, who can access it, what content should it have, what security profile and network access it requires, etc.
OpenStack Ansible modules (since Ansible 2.0): for instance, Nova or Neutron. It’s based on the OpenStack “shade” library, a common tool for all CLI tools in OpenStack.
It can also manage not so virtual network resources, via netconf (since 2.2) https://docs.ansible.com/ansible/netconf_config_module.html
VmWare vSphere Ansible modules
RHV or oVirt or Libvirt for bare KVM
It also has modules for public cloud providers, like Amazon, Google Cloud, Azure and Digital Ocean
Guest OS: the same components as described for the Host OS. But how do you discover how many Guests you have?
Ansible Dynamic Inventory will dynamically interrogate the IaaS/VM layer and discover which instances are currently available. It detects their hostname, IPs, and security settings and replaces the static Inventory concept. This is especially useful if you leverage Auto Scaling Groups in your cloud infrastructure, which makes your list of instances very variable over time.
Containers Engine (optional)
Docker: Note that the old Docker module is deprecated for a new, native version, in Ansible 2.1.
Kubernetes
Atomic Host
Tenant Software: databases, web servers, load balancers, data processing engines, etc.
Ansible Galaxy is the repository of recipes (playbooks) to deploy the most popular software, and it’s the result of the contributions of thousands of community members.
You can also manage web Infrastructure such as JBoss, allowing Ansible to define how an app is deployed in the application server.
How to install the latest Ansible on a Python virtual environment
As you have seen, some features are only available with very recent Ansible versions, like 2.2. However, your OS may not ship it yet. For example, RHEL 7 or CentOS 7 only comes with Ansible 1.9.
Given that Ansible is a command-line tool written in Python, which supports multiple versions on a system, you may not need the security hardening in Ansible that your distribution offers, and you may want to try the latest version instead.
However, as any other Python software, there are many dependencies, and it’s very dangerous to mix untested upstream libraries with your system-provided ones. Those libraries may be shared and used in other parts of your system, and untested newer libraries can break other applications. The quick solution is to install the latest Ansible version, with all its dependencies, in a isolated folder under your non-privileged user account. This is called a Python Virtual Environment (virtualenv), and if done properly, allows you to safely play with the latest Ansible modules for a full-stack orchestration. Of course, we do not recommend this practice for any production use-case; consider it a learning exercise to improve your DevOps skills.
1) Install prerequisites (pip, virtualenv)
The only system-wide python library we need here is “virtualenvwrapper”. Other than that, you should not do “sudo pip install” as it will replace system python libraries with untested, newer ones. We only trust one here, “virtualenvwrapper”. The virtual environment method is a good mechanism for installing and testing newer python modules in your non-privileged user account.
$ sudo yum install python-pip
$ sudo pip install virtualenvwrapper
$ sudo yum install python-heatclient python-openstackclient python2-shade
2) Setup a fresh virtualenv, where we’ll install the latest Ansible release
First, create a directory to hold the virtual environments.
$ mkdir $HOME/.virtualenvs
Then, add a line like &8220;export WORKON_HOME=$HOME/.virtualenvs&8221; to your .bashrc. Also, add a line like &8220;source /usr/bin/virtualenvwrapper.sh&8221; to your .bashrc. Now source it.
$ source ~/.bashrc
At this point, wrapper links are created, but only the first time you run it. To see the list of environments, just execute &8220;workon&8221;. Next, we&8217;ll create a new virtualenv named “ansible2” , which will be automatically enabled, with access to the default RPM-installed packages.
$ workon
$ mkvirtualenv ansible2 –system-site-packages
To exit the virtualenv, type &8220;deactivate&8221;, and to re-enter again, use &8220;workon&8221;.
$ deactivate
$ workon ansible2
3) Enter the new virtualenv and install Ansible2 via PIP (as regular user, not root)
You can notice your shell prompt has changed and it shows the virtualenv name in brackets.
(ansible2) $ pip install ansible
The above command will install just the ansible 2 dependencies, leveraging your system-wide RPM-provided python packages (thanks to the –system-site-packages flag we used earlier). Alternatively, if you want to try the development branch:
(ansible2) $ pip install git+git://github.com/ansible/ansible.git@devel
(ansible2) $ ansible –version
If you ever want to remove the virtualenv, and all its dependencies, just use use &8220;rmvirtualenv ansible2&8221;.
4) Install OpenStack client dependencies
The first command below ensures you have the latest stable OpenStack API versions, although you can also try a pip install to get the latest CLI. The second command provides the latest python “shade” library to connect to latest OpenStack API versions using ansible, regardless of the CLI tool.
(ansible2) $ yum install python-openstackclient python-heatclient
(ansible2) $ pip install shade –upgrade
5) Test it
(ansible2) $ ansible -m ping localhost
localhost | SUCCESS => {
“changed”: false,
“ping”: “pong”
}
NOTE: you cannot run this version of ansible outside the virtualenv, so always remember to do “workon ansible2” before usi.
Using Ansible to orchestrate OpenStack
Our savvy readers will notice that using Ansible to orchestrate OpenStack seems to ignore the fact that Heat is the official orchestration module for OpenStack. Indeed, an Ansible Playbook will do almost the same as a HOT template (HOT is the YAML-based syntax for Heat, an evolution of AWS CloudFormation). However, there are many DevOps professionals out there who don’t like to learn new syntax, and they are already consolidating all their process for their hybrid infrastructure.
The Ansible team recognized that and leveraged Shade, the official library from the OpenStack project, to build interfaces to OpenStack APIs. At the time of this writing, Ansible 2.2 includes modules to call the following APIs
Keystone: users, groups, roles, projects
Nova: servers, keypairs, security-groups, flavors
Neutron: ports, network, subnets, routers, floating IPs
Ironic: nodes, introspection
Swift Objects
Cinder volumes
Glance images
From an Ansible perspective, it needs to interact with a server where it can load the OpenStack credentials and open an HTTP connection to the OpenStack APIs. If that server is your machine (localhost), then it will work locally, load the Keystone credentials, and start talking to OpenStack.
Let’s see an example. We’ll use Ansible OpenStack modules to connect to Nova and start a small instance with the Cirros image. But we’ll first upload the latest Cirros image, if not present. We’ll use an existing SSH key from our current user. You can download this playbook from this github link.
—
# Setup according to Blogpost “Full Stack automation with Ansible and OpenStack”. Execute with “ansible-playbook ansible-openstack-blogpost.yml -c local -vv”
# #
# #
# #
– name: Execute the Blogpost demo tasks
hosts: localhost
tasks:
– name: Download cirros image
get_url:
url: http://download.cirros-cloud.net/0.3.4/cirros-0.3.4-x86_64-disk.img
dest: /tmp/cirros-0.3.4-x86_64-disk.img
– name: Upload cirros image to openstack
os_image:
name: cirros
container_format: bare
disk_format: qcow2
state: present
filename: /tmp/cirros-0.3.4-x86_64-disk.img
– name: Create new keypair from current user’s default SSH key
os_keypair:
state: present
name: ansible_key
public_key_file: “{{ ‘~’ | expanduser }}/.ssh/id_rsa.pub”
– name: Create the test network
os_network:
state: present
name: testnet
external: False
shared: False
#provider_network_type: vlan
#provider_physical_network: datacentre
register: testnet_network
– name: Create the test subnet
os_subnet:
state: present
network_name: “{{ testnet_network.id }}”
name: testnet_sub
ip_version: 4
cidr: 192.168.0.0/24
gateway_ip: 192.168.0.1
enable_dhcp: yes
dns_nameservers:
– 8.8.8.8
register: testnet_sub
– name: Create the test router
ignore_errors: yes for some reasons, re-running this task gives errors
os_router:
state: present
name: testnet_router
network: nova
external_fixed_ips:
– subnet: nova
interfaces:
– testnet_sub
– name: Create a new security group
os_security_group:
state: present
name: secgr
– name: Create a new security group allowing any ICMP
os_security_group_rule:
security_group: secgr
protocol: icmp
remote_ip_prefix: 0.0.0.0/0
– name: Create a new security group allowing any SSH connection
os_security_group_rule:
security_group: secgr
protocol: tcp
port_range_min: 22
port_range_max: 22
remote_ip_prefix: 0.0.0.0/0
– name: Create server instance
os_server:
state: present
name: testServer
image: cirros
flavor: m1.small
security_groups: secgr
key_name: ansible_key
nics:
– net-id: “{{ testnet_network.id }}”
register: testServer
– name: Show Server’s IP
debug: var=testServer.openstack.public_v4
After the execution, we see the IP of the instance. We write it down, and we can now use Ansible to connect into it via SSH. We assume Nova’s default network allows connections from our workstation, in our case via a provider network.
Comparison with OpenStack Heat
Using Ansible instead of Heat has it&8217;s advantages and disadvantages. For instance, with Ansible you must keep track of the resources you create, and manually delete them (in reverse order) once you are done with them. This is especially tricky with Neutron ports, floating IPs and routers. With Heat, you just delete the stack, and all the created resources will be properly deleted.
Compare the above with a similar (but not equivalent) Heat Template, that can be downloaded from this github gist:
heat_template_version: 2015-04-30
description: >
Node template. Launch with “openstack stack create –parameter public_network=nova –parameter ctrl_network=default –parameter secgroups=default –parameter image=cirros –parameter key=ansible_key –parameter flavor=m1.small –parameter name=myserver -t openstack-blogpost-heat.yaml testStack”
parameters:
name:
type: string
description: Name of node
key:
type: string
description: Name of keypair to assign to server
secgroups:
type: comma_delimited_list
description: List of security group to assign to server
image:
type: string
description: Name of image to use for servers
flavor:
type: string
description: Flavor to use for server
availability_zone:
type: string
description: Availability zone for server
default: nova
ctrl_network:
type: string
label: Private network name or ID
description: Network to attach instance to.
public_network:
type: string
label: Public network name or ID
description: Network to attach instance to.
resources:
ctrl_port:
type: OS::Neutron::Port
properties:
network: { get_param: ctrl_network }
security_groups: { get_param: secgroups }
floating_ip:
type: OS::Neutron::FloatingIP
properties:
floating_network: { get_param: public_network }
port_id: { get_resource: ctrl_port }
instance:
type: OS::Nova::Server
properties:
name: { get_param: name }
image: { get_param: image }
flavor: { get_param: flavor }
availability_zone: { get_param: availability_zone }
key_name: { get_param: key }
networks:
– port: { get_resource: ctrl_port }
Combining Dynamic Inventory with the OpenStack modules
Now let’s see what happens when we create many instances, but forget to write down their IP’s. The perfect example to leverage Dynamic Inventory for OpenStack is to learn the current state of our tenant virtualized resources, and gather all server IP’s so we can check their kernel version, for instance. This is transparently done by Ansible Tower, for instance, which will periodically run the inventory and collect the updated list of OpenStack servers to manage.
Before you execute this, #ensure you don’t have stale cloud.yaml files in either ~/.config/openstack, /etc/openstack, or /etc/ansible. The Dynamic Inventory script will look for environment variables first (OS_*), and then it will search for those files.
ensure you are using latest ansible version
$ workon ansible2
$ wget https://raw.githubusercontent.com/ansible/ansible/devel/contrib/inventory/openstack.py
$ chmod +x openstack.py
$ ansible -i openstack.py all -m ping
bdef428a-10fe-4af7-ae70-c78a0aba7a42 | SUCCESS => {
“changed”: false,
“ping”: “pong”
}
343c6e76-b3f6-4e78-ae59-a7cf31f8cc44 | SUCCESS => {
“changed”: false,
“ping”: “pong”
}
You can have fun by looking at all the information that the Inventory script above returns if you just executed as follows:
$ ./openstack.py &8211;list
{
“”: [
“777a3e02-a7e1-4bec-86b7-47ae7679d214″,
“bdef428a-10fe-4af7-ae70-c78a0aba7a42″,
“0a0c2f0e-4ac6-422d-8d9b-12b7a87daa72″,
“9d4ee5c0-b53d-4cdb-be0f-c77fece0a8b9″,
“343c6e76-b3f6-4e78-ae59-a7cf31f8cc44″
],
“_meta”: {
“hostvars”: {
“0a0c2f0e-4ac6-422d-8d9b-12b7a87daa72″: {
“ansible_ssh_host”: “172.31.1.42”,
“openstack”: {
“HUMAN_ID”: true,
“NAME_ATTR”: “name”,
“OS-DCF:diskConfig”: “MANUAL”,
“OS-EXT-AZ:availability_zone”: “nova”,
“OS-EXT-SRV-ATTR:host”: “compute-0.localdomain”,
“OS-EXT-SRV-ATTR:hypervisor_hostname”: “compute-0.localdomain”,
“OS-EXT-SRV-ATTR:instance_name”: “instance-000003e7″,
“OS-EXT-STS:power_state”: 1,
“OS-EXT-STS:task_state”: null,
“OS-EXT-STS:vm_state”: “active”,
“OS-SRV-USG:launched_at”: “2016-10-10T21:13:24.000000″,
“OS-SRV-USG:terminated_at”: null,
“accessIPv4″: “172.31.1.42”,
“accessIPv6″: “”,
(….)
Conclusion
Even though Heat is very useful, some people may prefer to learn Ansible to do their workload orchestration, as it offers a common language to define and automate the full stack of I.T. resources. I hope this article has provided you with a practical example, with a very basic use case for Ansible to launch OpenStack resources. If you are interested in trying Ansible and Ansible Tower, please visit https://www.ansible.com/openstack. A good starting point would be connecting Heat with Ansible Tower callbacks, as described in this other blog post
Also, if you want to learn more about Red Hat OpenStack Platform, you&8217;ll find lots of valuable resources (including videos and whitepapers) on our website. https://www.redhat.com/en/technologies/linux-platforms/openstack-platform
Quelle: RedHat Stack
