9.2 KiB
Orchestration
This chapter explains the importance of durability and scalability for your cloud-based applications. In most cases, really achieving these qualities means automating tasks such as scaling and other operational tasks.
The Orchestration module provides a template-based way to describe a cloud application, then coordinates running the needed OpenStack API calls to run cloud applications. The templates enable you to create most OpenStack resource types, such as instances, networking information, volumes, security groups, and even users. It also provides more advanced functionality, such as instance high availability, instance auto-scaling, and nested stacks.
The OpenStack Orchestration API contains these constructs:
- Stacks
- Resources
- Templates
You create stacks from templates, which contain resources. Resources
are an abstraction in the HOT (Heat Orchestration Template) template
language, which enables you to define different cloud resources by
setting the type attribute.
For example, you might use the Orchestration API to create two
compute instances by creating a stack and by passing a template to the
Orchestration API. That template would contain two resources with the
type attribute set to OS::Nova::Server.
That is a simplistic example, of course, but the flexibility of the resource object enables the creation of templates that contain all the required cloud infrastructure to run an application, such as load balancers, block storage volumes, compute instances, networking topology, and security policies.
Note
The Orchestration module is not deployed by default in every cloud. If these commands do not work, it means the Orchestration API is not available; ask your support team for assistance.
This section introduces the HOT templating language, and takes you through some common OpenStack Orchestration calls.
In previous sections of this guide, you used your SDK to programatically interact with OpenStack. In this section you work from the command line to use the Orchestration API directly through template files.
Install the 'heat' command-line client by following this guide: http://docs.openstack.org/cli-reference/content/install_clients.html
Then, use this guide to set up the necessary variables for your cloud in an 'openrc' file: http://docs.openstack.org/cli-reference/content/cli_openrc.html
dotnet
Warning
the .NET SDK does not currently support OpenStack Orchestration.
fog
Note
jclouds
Warning
Jclouds does not currently support OpenStack Orchestration. See this bug report.
libcloud
Warning
libcloud does not currently support OpenStack Orchestration.
pkgcloud
Note
Pkgcloud supports OpenStack Orchestration :D:D:D but this section is not written yet
openstacksdk
Warning
The OpenStack SDK does not currently support OpenStack Orchestration.
phpopencloud
Note
PHP-opencloud supports OpenStack Orchestration :D:D:D but this section is not written yet.
HOT templating language
To learn about the template syntax for OpenStack Orchestration, how to create basic templates, and their inputs and outputs, see Heat Orchestration Template (HOT) Guide.
Work with stacks: Basics
Stack create
The following example uses the hello_faafo Hot template to demonstrate how to create a compute instance that builds and runs the Fractal application as an all-in-one installation. These configuration settings are passed in as parameters:
- The flavor to use
- Your ssh key name
- The unique identifier (UUID) of the image to use
$ wget https://git.openstack.org/cgit/openstack/api-site/plain/firstapp/samples/heat/hello_faafo.yaml
$ heat stack-create --template-file hello_faafo.yaml \
--parameters flavor=m1.small\;key_name=test\;image_id=5bbe4073-90c0-4ec9-833c-092459cc4539 hello_faafo
+--------------------------------------+-------------+--------------------+----------------------+
| id | stack_name | stack_status | creation_time |
+--------------------------------------+-------------+--------------------+----------------------+
| 0db2c026-fb9a-4849-b51d-b1df244096cd | hello_faafo | CREATE_IN_PROGRESS | 2015-04-01T03:20:25Z |
+--------------------------------------+-------------+--------------------+----------------------+The resulting stack automatically creates a Nova instance, as follows:
$ nova list
+--------------------------------------+---------------------------------+--------+------------+-------------+------------------+
| ID | Name | Status | Task State | Power State | Networks |
+--------------------------------------+---------------------------------+--------+------------+-------------+------------------+
| 9bdf0e2f-415e-43a0-90ea-63a5faf86cf9 | hello_faafo-server-dwmwhzfxgoor | ACTIVE | - | Running | private=10.0.0.3 |
+--------------------------------------+---------------------------------+--------+------------+-------------+------------------+Use the following command to verify that the stack was successfully created:
$ heat stack-list
+--------------------------------------+-------------+-----------------+----------------------+
| id | stack_name | stack_status | creation_time |
+--------------------------------------+-------------+-----------------+----------------------+
| 0db2c026-fb9a-4849-b51d-b1df244096cd | hello_faafo | CREATE_COMPLETE | 2015-04-01T03:20:25Z |
+--------------------------------------+-------------+-----------------+----------------------+The stack reports an initial CREATE_IN_PROGRESS status.
When all software has been installed, the status changes to
CREATE_COMPLETE.
You might have to run the stack-list command a few times
before the stack creation is complete.
Show information about the stack
Run this command to get more information about the stack:
$ heat stack-show hello_faafoThe outputs property shows the URL through which you can access the Fractal app. You can SSH into the instance.
Remove the stack
$ heat stack-delete hello_faafo
+--------------------------------------+-------------+--------------------+----------------------+
| id | stack_name | stack_status | creation_time |
+--------------------------------------+-------------+--------------------+----------------------+
| 0db2c026-fb9a-4849-b51d-b1df244096cd | hello_faafo | DELETE_IN_PROGRESS | 2015-04-01T03:20:25Z |
+--------------------------------------+-------------+--------------------+----------------------+Verify the nova instance was deleted when the stack was removed:
$ nova list
+----+------+--------+------------+-------------+----------+
| ID | Name | Status | Task State | Power State | Networks |
+----+------+--------+------------+-------------+----------+
+----+------+--------+------------+-------------+----------+While this stack starts a single instance that builds and runs the Fractal app as an all-in-one installation, you can make very complicated templates that impact dozens of instances or that add and remove instances on demand. Continue to the next section to learn more.
Work with stacks: Advanced
needs more explanatory material
needs a heat template that uses fractal app
With the Orchestration API, the Fractal app can create an auto-scaling group for all parts of the application to dynamically provision more compute resources during periods of heavy utilization, and also terminate compute instances to scale down as demand decreases.
To learn about auto-scaling with the Orchestration API, read these articles:
- http://superuser.openstack.org/articles/simple-auto-scaling-environment-with-heat
- http://superuser.openstack.org/articles/understanding-openstack-heat-auto-scaling
For an example template that creates an auto-scaling Wordpress instance, see the heat template repository
Next steps
You should now be fairly confident working with the Orchestration service. To see the calls that we did not cover and more, see the volume documentation of your SDK. Or, try one of these steps in the tutorial:
/networking: Learn about complex networking./advice: Get advice about operations./craziness: Learn some crazy things that you might not think to do ;)