openstack/openstack-ansible
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openstack-ansible/doc/source/admin/openstack-operations/managing-instances.rst
Jean-Philippe Evrard c4d221e29b [Docs] Simplify structure of operations guide 
This is a first step towards inclusion of the major upgrades
into the operations guide.

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Managing instances
==================
This chapter describes how to create and access instances.
Creating an instance using the Dashboard
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Using an image, create a new instance via the Dashboard options.
#. Log into the Dashboard, and select the **Compute** project from the
drop down list.
#. Click the **Images** option.
#. Locate the image that will act as the instance base from the
**Images** table.
#. Click **Launch** from the **Actions** column.
#. Check the **Launch Instances** dialog, and find the **details** tab.
Enter the appropriate values for the instance.
#. In the Launch Instance dialog, click the **Access & Security** tab.
Select the keypair. Set the security group as "default".
#. Click the **Networking tab**. This tab will be unavailable if
OpenStack networking (neutron) has not been enabled. If networking
is enabled, select the networks on which the instance will
reside.
#. Click the **Volume Options tab**. This tab will only be available
if a Block Storage volume exists for the instance. Select
**Don't boot from a volume** for now.
For more information on attaching Block Storage volumes to
instances for persistent storage, see the
*Managing volumes for persistent storage* section below.
#. Add customisation scripts, if needed, by clicking the
**Post-Creation** tab. These run after the instance has been
created. Some instances support user data, such as root passwords,
or admin users. Enter the information specific to the instance
here if required.
#. Click **Advanced Options**. Specify whether the instance uses a
configuration drive to store metadata by selecting a disk
partition type.
#. Click **Launch** to create the instance. The instance will start on a
compute node. The **Instance** page will open and start creating a
new instance. The **Instance** page that opens will list the instance
name, size, status, and task. Power state and public and private IP
addresses are also listed here.
The process will take less than a minute to complete. Instance
creation is complete when the status is listed as active. Refresh the
page to see the new active instance.
.. list-table:: **Launching an instance options**
:widths: 33 33 33
:header-rows: 1
* - Field Name
- Required
- Details
* - **Availability Zone**
- Optional
- The availability zone in which the image service creates the instance.
If no availability zones is defined, no instances will be found. The
cloud provider sets the availability zone to a specific value.
* - **Instance Name**
- Required
- The name of the new instance, which becomes the initial host name of the
server. If the server name is changed in the API or directly changed,
the Dashboard names remain unchanged
* - **Image**
- Required
- The type of container format, one of ``ami``, ``ari``, ``aki``,
``bare``, or ``ovf``
* - **Flavor**
- Required
- The vCPU, Memory, and Disk configuration. Note that larger flavors can
take a long time to create. If creating an instance for the first time
and want something small with which to test, select ``m1.small``.
* - **Instance Count**
- Required
- If creating multiple instances with this configuration, enter an integer
up to the number permitted by the quota, which is ``10`` by default.
* - **Instance Boot Source**
- Required
- Specify whether the instance will be based on an image or a snapshot. If
it is the first time creating an instance, there will not yet be any
snapshots available.
* - **Image Name**
- Required
- The instance will boot from the selected image. This option will be
pre-populated with the instance selected from the table. However, choose
``Boot from Snapshot`` in **Instance Boot Source**, and it will default
to ``Snapshot`` instead.
* - **Security Groups**
- Optional
- This option assigns security groups to an instance.
The default security group activates when no customised group is
specified here. Security Groups, similar to a cloud firewall, define
which incoming network traffic is forwarded to instances.
* - **Keypair**
- Optional
- Specify a key pair with this option. If the image uses a static key set
(not recommended), a key pair is not needed.
* - **Selected Networks**
- Optional
- To add a network to an instance, click the **+** in the **Networks
field**.
* - **Customisation Script**
- Optional
- Specify a customisation script. This script runs after the instance
launches and becomes active.
Creating an instance using the command line
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
On the command line, instance creation is managed with the **openstack server
create** command. Before launching an instance, determine what images and
flavors are available to create a new instance using the **openstack image
list** and **openstack flavor list** commands.
#. Log in to any utility container.
#. Issue the **openstack server create** command with a name for the instance,
along with the name of the image and flavor to use:
.. code::
$ openstack server create --image precise-image --flavor 2 --key-name example-key example-instance
+-------------------------------------+--------------------------------------+
| Property | Value |
+-------------------------------------+--------------------------------------+
| OS-DCF:diskConfig | MANUAL |
| OS-EXT-SRV-ATTR:host | None |
| OS-EXT-SRV-ATTR:hypervisor_hostname | None |
| OS-EXT-SRV-ATTR:instance_name | instance-0000000d |
| OS-EXT-STS:power_state | 0 |
| OS-EXT-STS:task_state | scheduling |
| OS-EXT-STS:vm_state | building |
| accessIPv4 | |
| accessIPv6 | |
| adminPass | ATSEfRY9fZPx |
| config_drive | |
| created | 2012-08-02T15:43:46Z |
| flavor | m1.small |
| hostId | |
| id | 5bf46a3b-084c-4ce1-b06f-e460e875075b |
| image | precise-image |
| key_name | example-key |
| metadata | {} |
| name | example-instance |
| progress | 0 |
| status | BUILD |
| tenant_id | b4769145977045e2a9279c842b09be6a |
| updated | 2012-08-02T15:43:46Z |
| user_id | 5f2f2c28bdc844f9845251290b524e80 |
+-------------------------------------+--------------------------------------+
#. To check that the instance was created successfully, issue the **openstack
server list** command:
.. code::
$ openstack server list
+------------------+------------------+--------+-------------------+---------------+
| ID | Name | Status | Networks | Image Name |
+------------------+------------------+--------+-------------------+---------------+
| [ID truncated] | example-instance | ACTIVE | public=192.0.2.0 | precise-image |
+------------------+------------------+--------+-------------------+---------------+
Managing an instance
~~~~~~~~~~~~~~~~~~~~
#. Log in to the Dashboard. Select one of the projects, and click
**Instances**.
#. Select an instance from the list of available instances.
#. Check the **Actions** column, and click on the **More** option.
Select the instance state.
The **Actions** column includes the following options:
- Resize or rebuild any instance
- View the instance console log
- Edit the instance
- Modify security groups
- Pause, resume, or suspend the instance
- Soft or hard reset the instance
.. note::
Terminate the instance under the **Actions** column.
Managing volumes for persistent storage
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Volumes attach to instances, enabling persistent storage. Volume
storage provides a source of memory for instances. Administrators can
attach volumes to a running instance, or move a volume from one
instance to another.
Nova instances live migration
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Nova is capable of live migration instances from one host to
a different host to support various operational tasks including:
* Host Maintenance
* Host capacity management
* Resizing and moving instances to better hardware
Nova configuration drive implication
------------------------------------
Depending on the OpenStack-Ansible version in use, Nova can
be configured to force configuration drive attachments to instances.
In this case, a ISO9660 CD-ROM image will be made available to the
instance via the ``/mnt`` mount point. This can be used by tools,
such as cloud-init, to gain access to instance metadata. This is
an alternative way of accessing the Nova EC2-style Metadata.
To allow live migration of Nova instances, this forced provisioning
of the config (CD-ROM) drive needs either be turned off, or the format of
the configuration drive needs to be changed to a disk format like vfat, a
format which both Linux and Windows instances can access.
This work around is required for all Libvirt versions prior 1.2.17.
To turn off the forced provisioning of the config drive, add the following
override to the ``/etc/openstack_deploy/user_variables.yml`` file:
.. code-block:: yaml
nova_force_config_drive: False
To change the format of the configuration drive, to a hard disk style format,
use the following configuration inside the same
``/etc/openstack_deploy/user_variables.yml`` file:
.. code-block:: yaml
nova_nova_conf_overrides:
DEFAULT:
config_drive_format: vfat
force_config_drive: false
Tunneling versus direct transport
---------------------------------
In the default configuration, Nova determines the correct transport
URL for how to transfer the data from one host to the other.
Depending on the ``nova_virt_type`` override the following configurations
are used:
* kvm defaults to ``qemu+tcp://%s/system``
* qemu defaults to ``qemu+tcp://%s/system``
* xen defaults to ``xenmigr://%s/system``
Libvirt TCP port to transfer the data to migrate.
OpenStack-Ansible changes the default setting and used a encrypted SSH
connection to transfer the instance data.
.. code-block:: yaml
live_migration_uri = "qemu+ssh://nova@%s/system?no_verify=1&keyfile={{ nova_system_home_folder }}/.ssh/id_rsa"
Other configurations can be configured inside the
``/etc/openstack_deploy/user_variables.yml`` file:
.. code-block:: yaml
nova_nova_conf_overrides:
libvirt:
live_migration_completion_timeout: 0
live_migration_progress_timeout: 0
live_migration_uri: "qemu+ssh://nova@%s/system?keyfile=/var/lib/nova/.ssh/id_rsa&no_verify=1"
Local versus shared storage
---------------------------
By default, live migration assumes that your Nova instances are stored
on shared storage and KVM/Libvirt only need to synchronize the
memory and base image of the Nova instance to the new host.
Live migrations on local storage will fail as a result of that assumption.
Migrations with local storage can be accomplished by allowing instance disk
migrations with the ``--block-migrate`` option.
Additional Nova flavor features like ephemeral storage or swap have an
impact on live migration performance and success.
Cinder attached volumes also require a Libvirt version larger or equal to
1.2.17.
Executing the migration
-----------------------
The live migration is accessible via the nova client.
.. code-block:: console
nova live-migration [--block-migrate] [--force] <uuid> [<host>]
Examplarery live migration on a local storage:
.. code-block:: console
nova live-migration --block-migrate <uuid of the instance> <nova host>
Monitoring the status
---------------------
Once the live migration request has been accepted, the status can be
monitored with the nova client:
.. code-block:: console
nova migration-list
+-----+------------+-----------+----------------+--------------+-----------+-----------+---------------+------------+------------+------------+------------+-----------------+
| Id | Source Node | Dest Node | Source Compute | Dest Compute | Dest Host | Status | Instance UUID | Old Flavor | New Flavor | Created At | Updated At | Type |
+----+-------------+-----------+----------------+--------------+-----------+-----------+---------------+------------+------------+------------+------------+-----------------+
| 6 | - | - | compute01 | compute02 | - | preparing | f95ee17a-d09c | 7 | 7 | date | date | live-migration |
+----+-------------+-----------+----------------+--------------+-----------+-----------+---------------+------------+------------+------------+------------+-----------------+
To filter the list, the options ``--host`` or ``--status`` can be used:
.. code-block:: console
nova migration-list --status error
In cases where the live migration fails, both the source and destination
compute nodes need to be checked for errors. Usually it is sufficient
to search for the instance UUID only to find errors related to the
live migration.
Other forms of instance migration
---------------------------------
Besides the live migration, Nova offers the option to migrate entire hosts
in a online (live) or offline (cold) migration.
The following nova client commands are provided:
* ``host-evacuate-live``
Live migrate all instances of the specified host
to other hosts if resource utilzation allows.
It is best to use shared storage like Ceph or NFS
for host evacuation.
* ``host-servers-migrate``
This command is similar to host evacuation but
migrates all instances off the specified host while
they are shutdown.
* ``resize``
Changes the flavor of an Nova instance (increase) while rebooting
and also migrates (cold) the instance to a new host to accommodate
the new resource requirements. This operation can take considerate
amount of time, depending disk image sizes.
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