25 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 service 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 uses the stacks, resources, and templates constructs.
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 contains two resources with the
type attribute set to OS::Nova::Server.
That example is simplistic, 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 service 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, you used your SDK to programatically interact with OpenStack. In this section, you use the 'heat' command-line client to access the Orchestration API directly through template files.
Install the 'heat' command-line client by following this guide: http://docs.openstack.org/cli-reference/common/cli_install_openstack_command_line_clients.html#install-the-clients
Use this guide to set up the necessary variables for your cloud in an 'openrc' file: http://docs.openstack.org/cli-reference/common/cli_set_environment_variables_using_openstack_rc.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 hello_faafo Hot template demonstrates how to create a compute instance that builds and runs the Fractal application as an all-in-one installation.
You pass in these configuration settings as parameters:
- The flavor
- Your ssh key name
- The unique identifier (UUID) of the image
$ wget https://git.openstack.org/cgit/openstack/api-site/plain/firstapp/samples/heat/hello_faafo.yaml
$ openstack stack create -t hello_faafo.yaml \
--parameter flavor=m1.small\;key_name=test\;image_id=5bbe4073-90c0-4ec9-833c-092459cc4539 hello_faafo
+---------------------+-----------------------------------------------------------------------+
| Field | Value |
+---------------------+-----------------------------------------------------------------------+
| id | 0db2c026-fb9a-4849-b51d-b1df244096cd |
| stack_name | hello_faafo |
| description | A template to bring up the faafo application as an all in one install |
| | |
| creation_time | 2015-04-01T03:20:25 |
| updated_time | None |
| stack_status | CREATE_IN_PROGRESS |
| stack_status_reason | |
+---------------------+-----------------------------------------------------------------------+The 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 |
+--------------------------------------+---------------------------------+--------+------------+-------------+------------------+Verify that the stack was successfully created:
$ openstack stack list
+--------------------------------------+-------------+-----------------+---------------------+--------------+
| ID | Stack Name | Stack Status | Creation Time | Updated Time |
+--------------------------------------+-------------+-----------------+---------------------+--------------+
| 0db2c026-fb9a-4849-b51d-b1df244096cd | hello_faafo | CREATE_COMPLETE | 2015-04-01T03:20:25 | None |
+--------------------------------------+-------------+-----------------+---------------------+--------------+The stack reports an initial CREATE_IN_PROGRESS status.
When all software is installed, the status changes to
CREATE_COMPLETE.
You might have to run the openstack stack list command a few times before
the stack creation is complete.
Show information about the stack
Get more information about the stack:
$ openstack stack show hello_faafoThe outputs property shows the URL through which you can access the Fractal application. You can SSH into the instance.
Remove the stack
$ openstack stack delete hello_faafo
Are you sure you want to delete this stack(s) [y/N]?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 application 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
With the Orchestration API, the Fractal application 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
Initially, the focus is on scaling the workers because they consume the most resources.
The example template depends on the ceilometer project, which is part of the Telemetry service.
Note
The Telemetry service is not deployed by default in every cloud. If the ceilometer commands do not work, this example does not work; ask your support team for assistance.
To better understand how the template works, use this guide to install the 'ceilometer' command-line client:
To set up the necessary variables for your cloud in an 'openrc' file, use this guide:
- http://docs.openstack.org/cli-reference/common/cli_set_environment_variables_using_openstack_rc.html
The Telemetry service uses meters to measure a given aspect of a
resources usage. The meter that we are interested in is the
cpu_util meter.
The value of a meter is regularly sampled and saved with a timestamp.
These saved samples are aggregated to produce a statistic. The statistic that we are interested in is avg: the average of the samples over a given period.
We are interested because the Telemetry service supports alarms: an alarm is fired when our average statistic breaches a configured threshold. When the alarm fires, an associated action is performed.
The stack we will be building uses the firing of alarms to control the addition or removal of worker instances.
To verify that ceilometer is installed, list the known meters:
$ ceilometer meter-listThis command returns a very long list of meters. Once a meter is created, it is never thrown away!
Launch the stack with auto-scaling workers:
$ wget https://git.openstack.org/cgit/openstack/api-site/plain/firstapp/samples/heat/faafo_autoscaling_workers.yaml
$ openstack stack create -t faafo_autoscaling_workers.yaml \
--parameters flavor=m1.small\;key_name=test\;image_id=5bbe4073-90c0-4ec9-833c-092459cc4539 \
faafo_autoscaling_workers
+---------------------+-----------------------------------------------------------------------+
| Field | Value |
+---------------------+-----------------------------------------------------------------------+
| id | 0db2c026-fb9a-4849-b51d-b1df244096cd |
| stack_name | faafo_autoscaling_workers |
| description | A template to bring up the faafo application as an all in one install |
| | |
| creation_time | 2015-11-17T05:12:06 |
| updated_time | None |
| stack_status | CREATE_IN_PROGRESS |
| stack_status_reason | |
+---------------------+-----------------------------------------------------------------------+As before, pass in configuration settings as parameters.
And as before, the stack takes a few minutes to build!
Wait for it to reach the CREATE_COMPLETE status:
$ openstack stack list
+--------------------------------------+---------------------------+-----------------+---------------------+--------------+
| ID | Stack Name | Stack Status | Creation Time | Updated Time |
+--------------------------------------+---------------------------+-----------------+---------------------+--------------+
| 0db2c026-fb9a-4849-b51d-b1df244096cd | faafo_autoscaling_workers | CREATE_COMPLETE | 2015-11-17T05:12:06 | None |
+--------------------------------------+---------------------------+-----------------+---------------------+--------------+Run the nova list command. This template created three
instances:
$ nova list
+--------------------------------------+----------+--------+------------+-------------+----------------------+
| ID | Name | Status | Task State | Power State | Networks |
+--------------------------------------+----------+--------+------------+-------------+----------------------+
| 0de89b0a-5bfd-497b-bfa2-c13f6ef7a67e | api | ACTIVE | - | Running | public=115.146.89.75 |
| a6b9b334-e8ba-4c56-ab53-cacfc6f3ad43 | services | ACTIVE | - | Running | public=115.146.89.74 |
| 10122bfb-881b-4122-9955-7e801dfc5a22 | worker | ACTIVE | - | Running | public=115.146.89.80 |
+--------------------------------------+----------+--------+------------+-------------+----------------------+Note that the worker instance is part of an
OS::Heat::AutoScalingGroup.
Confirm that the stack created two alarms:
$ ceilometer alarm-list
+--------------------------------------+---------------------------------------+-------+----------+---------+------------+--------------------------------+------------------+
| Alarm ID | Name | State | Severity | Enabled | Continuous | Alarm condition | Time constraints |
+--------------------------------------+---------------------------------------+-------+----------+---------+------------+--------------------------------+------------------+
| 2bc8433f-9f8a-4c2c-be88-d841d9de1506 | testFaafo-cpu_alarm_low-torkcwquons4 | ok | low | True | True | cpu_util < 15.0 during 1 x 60s | None |
| 7755cc9a-26f3-4e2b-a9af-a285ec8524da | testFaafo-cpu_alarm_high-qqtbvk36l6nq | ok | low | True | True | cpu_util > 90.0 during 1 x 60s | None |
+--------------------------------------+---------------------------------------+-------+----------+---------+------------+--------------------------------+------------------+Note
If either alarm reports the insufficient data state, the
default sampling period of the stack is probably too low for your cloud;
ask your support team for assistance. You can set the period through the
period parameter of the stack to match your clouds
requirements.
Use the stack ID to get more information about the stack:
$ openstack stack show 0db2c026-fb9a-4849-b51d-b1df244096cdThe outputs section of the stack contains two ceilometer command-line queries:
ceilometer_sample_query: shows the samples used to build the statistics.ceilometer_statistics_query: shows the statistics used to trigger the alarms.
These queries provide a view into the behavior of the stack.
In a new Terminal window, SSH into the 'api' API instance. Use the key pair name that you passed in as a parameter.
$ ssh -i ~/.ssh/test USERNAME@IP_APIIn your SSH session, confirm that no fractals were generated:
$ faafo list
201-11-18 11:07:20.464 8079 INFO faafo.client [-] listing all fractals
+------+------------+----------+
| UUID | Dimensions | Filesize |
+------+------------+----------+
+------+------------+----------+Then, create a pair of large fractals:
$ faafo create --height 9999 --width 9999 --tasks 2In the Terminal window where you run ceilometer, run
ceilometer_sample_query to see the samples.
$ ceilometer sample-list -m cpu_util -q metadata.user_metadata.stack=0db2c026-fb9a-4849-b51d-b1df244096cd
+--------------------------------------+----------+-------+----------------+------+---------------------+
| Resource ID | Name | Type | Volume | Unit | Timestamp |
+--------------------------------------+----------+-------+----------------+------+---------------------+
| 10122bfb-881b-4122-9955-7e801dfc5a22 | cpu_util | gauge | 100.847457627 | % | 2015-11-18T00:15:50 |
| 10122bfb-881b-4122-9955-7e801dfc5a22 | cpu_util | gauge | 82.4754098361 | % | 2015-11-18T00:14:51 |
| 10122bfb-881b-4122-9955-7e801dfc5a22 | cpu_util | gauge | 0.45 | % | 2015-11-18T00:13:50 |
| 10122bfb-881b-4122-9955-7e801dfc5a22 | cpu_util | gauge | 0.466666666667 | % | 2015-11-18T00:12:50 |
+--------------------------------------+----------+-------+----------------+------+---------------------+The CPU utilization across workers increases as workers start to create the fractals.
Run the ceilometer_statistics_query: command to see the
derived statistics.
$ ceilometer statistics -m cpu_util -q metadata.user_metadata.stack=0db2c026-fb9a-4849-b51d-b1df244096cd -p 60 -a avg
+--------+---------------------+---------------------+----------------+----------+---------------------+---------------------+
| Period | Period Start | Period End | Avg | Duration | Duration Start | Duration End |
+--------+---------------------+---------------------+----------------+----------+---------------------+---------------------+
| 60 | 2015-11-18T00:12:45 | 2015-11-18T00:13:45 | 0.466666666667 | 0.0 | 2015-11-18T00:12:50 | 2015-11-18T00:12:50 |
| 60 | 2015-11-18T00:13:45 | 2015-11-18T00:14:45 | 0.45 | 0.0 | 2015-11-18T00:13:50 | 2015-11-18T00:13:50 |
| 60 | 2015-11-18T00:14:45 | 2015-11-18T00:15:45 | 82.4754098361 | 0.0 | 2015-11-18T00:14:51 | 2015-11-18T00:14:51 |
| 60 | 2015-11-18T00:15:45 | 2015-11-18T00:16:45 | 100.847457627 | 0.0 | 2015-11-18T00:15:50 | 2015-11-18T00:15:50 |
+--------+---------------------+---------------------+----------------+----------+---------------------+---------------------+Note
The samples and the statistics are listed in opposite time order!
See the state of the alarms set up by the template:
$ ceilometer alarm-list
+--------------------------------------+---------------------------------------+-------+----------+---------+------------+--------------------------------+------------------+
| Alarm ID | Name | State | Severity | Enabled | Continuous | Alarm condition | Time constraints |
+--------------------------------------+---------------------------------------+-------+----------+---------+------------+--------------------------------+------------------+
| 56c3022e-f23c-49ad-bf59-16a6875f3bdf | testFaafo-cpu_alarm_low-miw5tmomewot | ok | low | True | True | cpu_util < 15.0 during 1 x 60s | None |
| 70ff7b00-d56d-4a43-bbb2-e18952ae6605 | testFaafo-cpu_alarm_high-ffhsmylfzx43 | alarm | low | True | True | cpu_util > 90.0 during 1 x 60s | None |
+--------------------------------------+---------------------------------------+-------+----------+---------+------------+--------------------------------+------------------+Run the nova list command to confirm that the
OS::Heat::AutoScalingGroup has created more instances:
$ nova list
+--------------------------------------+----------+--------+------------+-------------+----------------------+
| ID | Name | Status | Task State | Power State | Networks |
+--------------------------------------+----------+--------+------------+-------------+----------------------+
| 0de89b0a-5bfd-497b-bfa2-c13f6ef7a67e | api | ACTIVE | - | Running | public=115.146.89.96 |
| a6b9b334-e8ba-4c56-ab53-cacfc6f3ad43 | services | ACTIVE | - | Running | public=115.146.89.95 |
| 10122bfb-881b-4122-9955-7e801dfc5a22 | worker | ACTIVE | - | Running | public=115.146.89.97 |
| 31e7c020-c37c-4311-816b-be8afcaef8fa | worker | ACTIVE | - | Running | public=115.146.89.99 |
| 3fff2489-488c-4458-99f1-0cc50363ae33 | worker | ACTIVE | - | Running | public=115.146.89.98 |
+--------------------------------------+----------+--------+------------+-------------+----------------------+Now, wait until all the fractals are generated and the instances have idled for some time.
Run the nova list command to confirm that the
OS::Heat::AutoScalingGroup removed the unneeded
instances:
$ nova list
+--------------------------------------+----------+--------+------------+-------------+----------------------+
| ID | Name | Status | Task State | Power State | Networks |
+--------------------------------------+----------+--------+------------+-------------+----------------------+
| 0de89b0a-5bfd-497b-bfa2-c13f6ef7a67e | api | ACTIVE | - | Running | public=115.146.89.96 |
| a6b9b334-e8ba-4c56-ab53-cacfc6f3ad43 | services | ACTIVE | - | Running | public=115.146.89.95 |
| 3fff2489-488c-4458-99f1-0cc50363ae33 | worker | ACTIVE | - | Running | public=115.146.89.98 |
+--------------------------------------+----------+--------+------------+-------------+----------------------+Note
The OS::Heat::AutoScalingGroup removes instances in
creation order. So the worker instance that was created first is the
first instance to be removed.
In the outputs section of the stack, you can run these web API calls:
scale__workers_up_url: A post to this url will add worker instances.scale_workers_down_url: A post to this url will remove worker instances.
These demonstrate how the Ceilometer alarms add and remove instances. To use them:
$ curl -X POST "Put the very long url from the template outputs section between these quotes"To recap:
The auto-scaling stack sets up an API instance, a services instance, and an auto-scaling group with a single worker instance. It also sets up ceilometer alarms that add worker instances to the auto-scaling group when it is under load, and removes instances when the group is idling. To do this, the alarms post to URLs.
In this template, the alarms use metadata that is attached to each
worker instance. The metadata is in the
metering.stack=stack_id format.
The prefix is metering. For example, metering.some_name.
$ nova show <instance_id>
...
| metadata | {"metering.some_name": "some_value"} |
...You can aggregate samples and calculate statistics across all instances with the metering.some_name metadata that has some_value by using a query of the form:
-q metadata.user_metadata.some_name=some_valueFor example:
$ ceilometer sample-list -m cpu_util -q metadata.user_metadata.some_name=some_value
$ ceilometer statistics -m cpu_util -q metadata.user_metadata.some_name=some_value -p 6The alarms have the form:
matching_metadata: {'metadata.user_metadata.stack': {get_param: "OS::stack_id"}}Spend some time playing with the stack and the Fractal app to see how it works.
Note
The message queue can take a while to notice that worker instances have died.
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 ;)