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User-Facing Operations¶
This guide is for OpenStack operators and does not seek to be an exhaustive reference for users, but as an operator, you should have a basic understanding of how to use the cloud facilities. This chapter looks at OpenStack from a basic user perspective, which helps you understand your users’ needs and determine, when you get a trouble ticket, whether it is a user issue or a service issue. The main concepts covered are images, flavors, security groups, block storage, shared file system storage, and instances.
Images¶
OpenStack images can often be thought of as “virtual machine templates.” Images can also be standard installation media such as ISO images. Essentially, they contain bootable file systems that are used to launch instances.
Adding Images¶
Several pre-made images exist and can easily be imported into the Image service. A common image to add is the CirrOS image, which is very small and used for testing purposes. To add this image, simply do:
$ wget http://download.cirros-cloud.net/0.3.5/cirros-0.3.5-x86_64-disk.img
$ openstack image create --file cirros-0.3.5-x86_64-disk.img \
--public --container-format bare \
--disk-format qcow2 "cirros image"
The openstack image create command provides a large set of options
for working with your image. For example, the --min-disk option is
useful for images that require root disks of a certain size (for example,
large Windows images). To view these options, run:
$ openstack help image create
Run the following command to view the properties of existing images:
$ openstack image show IMAGE_NAME_OR_UUID
Adding Signed Images¶
To provide a chain of trust from an end user to the Image service, and the Image service to Compute, an end user can import signed images that can be initially verified in the Image service, and later verified in the Compute service. Appropriate Image service properties need to be set to enable this signature feature.
Note
Prior to the steps below, an asymmetric keypair and certificate must be generated. In this example, these are called private_key.pem and new_cert.crt, respectively, and both reside in the current directory. Also note that the image in this example is cirros-0.3.5-x86_64-disk.img, but any image can be used.
The following are steps needed to create the signature used for the signed images:
Retrieve image for upload
$ wget http://download.cirros-cloud.net/0.3.5/cirros-0.3.5-x86_64-disk.img
Use private key to create a signature of the image
Note
The following implicit values are being used to create the signature in this example:
Signature hash method = SHA-256
Signature key type = RSA-PSS
Note
The following options are currently supported:
Signature hash methods: SHA-224, SHA-256, SHA-384, and SHA-512
Signature key types: DSA, ECC_SECT571K1, ECC_SECT409K1, ECC_SECT571R1, ECC_SECT409R1, ECC_SECP521R1, ECC_SECP384R1, and RSA-PSS
Generate signature of image and convert it to a base64 representation:
$ openssl dgst -sha256 -sign private_key.pem -sigopt rsa_padding_mode:pss \ -out image-file.signature cirros-0.3.5-x86_64-disk.img $ base64 -w 0 image-file.signature > signature_64 $ cat signature_64 'c4br5f3FYQV6Nu20cRUSnx75R/VcW3diQdsUN2nhPw+UcQRDoGx92hwMgRxzFYeUyydRTWCcUS2ZLudPR9X7rM THFInA54Zj1TwEIbJTkHwlqbWBMU4+k5IUIjXxHO6RuH3Z5f/SlSt7ajsNVXaIclWqIw5YvEkgXTIEuDPE+C4='
Note
Using Image API v1 requires ‘-w 0’ above, since multiline image properties are not supported.
Image API v2 supports multiline properties, so this option is not required for v2 but it can still be used.
Create context
$ python >>> from keystoneclient.v3 import client >>> keystone_client = client.Client(username='demo', user_domain_name='Default', password='password', project_name='demo', auth_url='http://localhost:5000/v3') >>> from oslo_context import context >>> context = context.RequestContext(auth_token=keystone_client.auth_token, tenant=keystone_client.project_id)
Encode certificate in DER format
>>> from cryptography import x509 as cryptography_x509 >>> from cryptography.hazmat import backends >>> from cryptography.hazmat.primitives import serialization >>> with open("new_cert.crt", "rb") as cert_file: >>> cert = cryptography_x509.load_pem_x509_certificate( cert_file.read(), backend=backends.default_backend() ) >>> certificate_der = cert.public_bytes(encoding=serialization.Encoding.DER)
Upload Certificate in DER format to Castellan
>>> from castellan.common.objects import x_509 >>> from castellan import key_manager >>> castellan_cert = x_509.X509(certificate_der) >>> key_API = key_manager.API() >>> cert_uuid = key_API.store(context, castellan_cert) >>> cert_uuid u'62a33f41-f061-44ba-9a69-4fc247d3bfce'
Upload Image to Image service, with Signature Metadata
Note
The following signature properties are used:
img_signature uses the signature called signature_64
img_signature_certificate_uuid uses the value from cert_uuid in section 5 above
img_signature_hash_method matches ‘SHA-256’ in section 2 above
img_signature_key_type matches ‘RSA-PSS’ in section 2 above
$ . openrc demo $ export OS_IMAGE_API_VERSION=2 $ openstack image create --property name=cirrosSignedImage_goodSignature \ --property is-public=true --container-format bare --disk-format qcow2 \ --property img_signature='c4br5f3FYQV6Nu20cRUSnx75R/VcW3diQdsUN2nhPw+UcQRDoGx92hwMgRxzFYeUyydRTWCcUS2ZLudPR9X7rMTHFInA54Zj1TwEIbJTkHwlqbWBMU4+k5IUIjXxHO6RuH3Z5fSlSt7ajsNVXaIclWqIw5YvEkgXTIEuDPE+C4=' \ --property img_signature_certificate_uuid='62a33f41-f061-44ba-9a69-4fc247d3bfce' \ --property img_signature_hash_method='SHA-256' \ --property img_signature_key_type='RSA-PSS' < ~/cirros-0.3.5-x86_64-disk.img
Note
The maximum image signature character limit is 255.
Verify the Keystone URL
Note
The default Keystone configuration assumes that Keystone is in the local host, and it uses
http://localhost:5000/v3as the endpoint URL, which is specified inglance-api.confandnova-api.conffiles:[barbican] auth_endpoint = http://localhost:5000/v3
Note
If Keystone is located remotely instead, edit the
glance-api.confandnova.conffiles. In the[barbican]section, configre theauth_endpointoption:[barbican] auth_endpoint = https://192.168.245.9:5000/v3
Signature verification will occur when Compute boots the signed image
Note
nova-compute servers first need to be updated by the following steps:
Ensure that cryptsetup is installed, and ensure that
pythin-barbicanclientPython package is installedSet up the Key Manager service by editing /etc/nova/nova.conf and adding the entries in the codeblock below
The flag verify_glance_signatures enables Compute to automatically validate signed instances prior to its launch. This validation feature is enabled when the value is set to TRUE
[key_manager] api_class = castellan.key_manager.barbican_key_manager.BarbicanKeyManager [glance] verify_glance_signatures = TRUE
Note
The api_class [keymgr] is deprecated as of Newton, so it should not be included in this release or beyond.
Deleting Images¶
To delete an image, just execute:
$ openstack image delete IMAGE_NAME_OR_UUID
Caution
Generally, deleting an image does not affect instances or snapshots that were based on the image. However, some drivers may require the original image to be present to perform a migration. For example, XenAPI live-migrate will work fine if the image is deleted, but libvirt will fail.
Other CLI Options¶
A full set of options can be found using:
$ glance help
or the Command-Line Interface Reference.
The Image service and the Database¶
The only thing the Image service does not store in a database is the image itself. The Image service database has two main tables:
imagesimage_properties
Working directly with the database and SQL queries can provide you with custom lists and reports of images. Technically, you can update properties about images through the database, although this is not generally recommended.
Example Image service Database Queries¶
One interesting example is modifying the table of images and the owner of that image. This can be easily done if you simply display the unique ID of the owner. This example goes one step further and displays the readable name of the owner:
mysql> select glance.images.id,
glance.images.name, keystone.tenant.name, is_public from
glance.images inner join keystone.tenant on
glance.images.owner=keystone.tenant.id;
Another example is displaying all properties for a certain image:
mysql> select name, value from
image_properties where id = <image_id>
Flavors¶
Virtual hardware templates are called “flavors” in OpenStack, defining sizes for RAM, disk, number of cores, and so on. The default install provides five flavors.
These are configurable by admin users (the rights may also be delegated
to other users by redefining the access controls for
compute_extension:flavormanage in /etc/nova/policy.json on the
nova-api server). To get the list of available flavors on your
system, run:
$ openstack flavor list
+----+-----------+-------+------+-----------+-------+-----------+
| ID | Name | RAM | Disk | Ephemeral | VCPUs | Is Public |
+----+-----------+-------+------+-----------+-------+-----------+
| 1 | m1.tiny | 512 | 1 | 0 | 1 | True |
| 2 | m1.small | 2048 | 20 | 0 | 1 | True |
| 3 | m1.medium | 4096 | 40 | 0 | 2 | True |
| 4 | m1.large | 8192 | 80 | 0 | 4 | True |
| 5 | m1.xlarge | 16384 | 160 | 0 | 8 | True |
+----+-----------+-------+------+-----------+-------+-----------+
The openstack flavor create command allows authorized users to create new flavors. Additional flavor manipulation commands can be shown with the following command:
$ openstack help | grep flavor
Flavors define a number of parameters, resulting in the user having a
choice of what type of virtual machine to run—just like they would have
if they were purchasing a physical server.
Table. Flavor parameters lists the elements that can be set.
Note in particular extra_specs, which can be used to
define free-form characteristics, giving a lot of flexibility beyond just the
size of RAM, CPU, and Disk.
Column |
Description |
|---|---|
ID |
Unique ID (integer or UUID) for the flavor. |
Name |
A descriptive name, such as xx.size_name, is conventional but not required, though some third-party tools may rely on it. |
Memory_MB |
Virtual machine memory in megabytes. |
Disk |
Virtual root disk size in gigabytes. This is an ephemeral disk the base image is copied into. You don’t use it when you boot from a persistent volume. The “0” size is a special case that uses the native base image size as the size of the ephemeral root volume. |
Ephemeral |
Specifies the size of a secondary ephemeral data disk. This is an empty, unformatted disk and exists only for the life of the instance. |
Swap |
Optional swap space allocation for the instance. |
VCPUs |
Number of virtual CPUs presented to the instance. |
RXTX_Factor |
Optional property that allows created servers to have a different bandwidth cap from that defined in the network they are attached to. This factor is multiplied by the rxtx_base property of the network. Default value is 1.0 (that is, the same as the attached network). |
Is_Public |
Boolean value that indicates whether the flavor is available to
all users or private. Private flavors do not get the current
tenant assigned to them. Defaults to |
extra_specs |
Additional optional restrictions on which compute nodes the flavor can run on. This is implemented as key-value pairs that must match against the corresponding key-value pairs on compute nodes. Can be used to implement things like special resources (such as flavors that can run only on compute nodes with GPU hardware). |
Private Flavors¶
A user might need a custom flavor that is uniquely tuned for a project she is working on. For example, the user might require 128 GB of memory. If you create a new flavor as described above, the user would have access to the custom flavor, but so would all other tenants in your cloud. Sometimes this sharing isn’t desirable. In this scenario, allowing all users to have access to a flavor with 128 GB of memory might cause your cloud to reach full capacity very quickly. To prevent this, you can restrict access to the custom flavor using the nova flavor-access-add command:
$ nova flavor-access-add FLAVOR_ID PROJECT_ID
To view a flavor’s access list, do the following:
$ nova flavor-access-list [--flavor FLAVOR_ID]
Tip
Once access to a flavor has been restricted, no other projects besides the ones granted explicit access will be able to see the flavor. This includes the admin project. Make sure to add the admin project in addition to the original project.
It’s also helpful to allocate a specific numeric range for custom and private flavors. On UNIX-based systems, nonsystem accounts usually have a UID starting at 500. A similar approach can be taken with custom flavors. This helps you easily identify which flavors are custom, private, and public for the entire cloud.
How Do I Modify an Existing Flavor?¶
The OpenStack dashboard simulates the ability to modify a flavor by deleting an existing flavor and creating a new one with the same name.
Security Groups¶
A common new-user issue with OpenStack is failing to set an appropriate security group when launching an instance. As a result, the user is unable to contact the instance on the network.
Security groups are sets of IP filter rules that are applied to an instance’s networking. They are project specific, and project members can edit the default rules for their group and add new rules sets. All projects have a “default” security group, which is applied to instances that have no other security group defined. Unless changed, this security group denies all incoming traffic.
Tip
As noted in the previous chapter, the number of rules per security
group is controlled by the quota_security_group_rules, and the
number of allowed security groups per project is controlled by the
quota_security_groups quota.
End-User Configuration of Security Groups¶
Security groups for the current project can be found on the OpenStack dashboard under Access & Security. To see details of an existing group, select the Edit Security Group action for that security group. Obviously, modifying existing groups can be done from this edit interface. There is a Create Security Group button on the main Access & Security page for creating new groups. We discuss the terms used in these fields when we explain the command-line equivalents.
Setting with openstack command
If your environment is using Neutron, you can configure security groups settings using the openstack command. Get a list of security groups for the project you are acting in, by using following command:
$ openstack security group list
+------------------------+---------+------------------------+-------------------------+
| ID | Name | Description | Project |
+------------------------+---------+------------------------+-------------------------+
| 3bef30ed-442d-4cf1 | default | Default security group | 35e3820f7490493ca9e3a5e |
| -b84d-2ba50a395599 | | | 685393298 |
| aaf1d0b7-98a0-41a3-ae1 | default | Default security group | 32e9707393c34364923edf8 |
| 6-a58b94503289 | | | f5029cbfe |
+------------------------+---------+------------------------+-------------------------+
To view the details of a security group:
$ openstack security group show 3bef30ed-442d-4cf1-b84d-2ba50a395599
+-----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Field | Value |
+-----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| created_at | 2016-11-08T21:55:19Z |
| description | Default security group |
| id | 3bef30ed-442d-4cf1-b84d-2ba50a395599 |
| name | default |
| project_id | 35e3820f7490493ca9e3a5e685393298 |
| project_id | 35e3820f7490493ca9e3a5e685393298 |
| revision_number | 1 |
| rules | created_at='2016-11-08T21:55:19Z', direction='egress', ethertype='IPv6', id='1dca4cac-d4f2-46f5-b757-d53c01a87bdf', project_id='35e3820f7490493ca9e3a5e685393298', |
| | revision_number='1', updated_at='2016-11-08T21:55:19Z' |
| | created_at='2016-11-08T21:55:19Z', direction='egress', ethertype='IPv4', id='2d83d6f2-424e-4b7c-b9c4-1ede89c00aab', project_id='35e3820f7490493ca9e3a5e685393298', |
| | revision_number='1', updated_at='2016-11-08T21:55:19Z' |
| | created_at='2016-11-08T21:55:19Z', direction='ingress', ethertype='IPv4', id='62b7d1eb-b98d-4707-a29f-6df379afdbaa', project_id='35e3820f7490493ca9e3a5e685393298', remote_group_id |
| | ='3bef30ed-442d-4cf1-b84d-2ba50a395599', revision_number='1', updated_at='2016-11-08T21:55:19Z' |
| | created_at='2016-11-08T21:55:19Z', direction='ingress', ethertype='IPv6', id='f0d4b8d6-32d4-4f93-813d-3ede9d698fbb', project_id='35e3820f7490493ca9e3a5e685393298', remote_group_id |
| | ='3bef30ed-442d-4cf1-b84d-2ba50a395599', revision_number='1', updated_at='2016-11-08T21:55:19Z' |
| updated_at | 2016-11-08T21:55:19Z |
+-----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
These rules are all “allow” type rules, as the default is deny. This example shows the full port range for all protocols allowed from all IPs. This section describes the most common security group rule parameters:
- direction
The direction in which the security group rule is applied. Valid values are
ingressoregress.- remote_ip_prefix
This attribute value matches the specified IP prefix as the source IP address of the IP packet.
- protocol
The protocol that is matched by the security group rule. Valid values are
null,tcp,udp,icmp, andicmpv6.- port_range_min
The minimum port number in the range that is matched by the security group rule. If the protocol is TCP or UDP, this value must be less than or equal to the
port_range_maxattribute value. If the protocol is ICMP or ICMPv6, this value must be an ICMP or ICMPv6 type, respectively.- port_range_max
The maximum port number in the range that is matched by the security group rule. The
port_range_minattribute constrains theport_range_maxattribute. If the protocol is ICMP or ICMPv6, this value must be an ICMP or ICMPv6 type, respectively.- ethertype
Must be
IPv4orIPv6, and addresses represented in CIDR must match the ingress or egress rules.
When adding a new security group, you should pick a descriptive but
brief name. This name shows up in brief descriptions of the instances
that use it where the longer description field often does not. Seeing
that an instance is using security group http is much easier to
understand than bobs_group or secgrp1.
This example creates a security group that allows web traffic anywhere
on the Internet. We’ll call this group global_http, which is clear
and reasonably concise, encapsulating what is allowed and from where.
From the command line, do:
$ openstack security group create global_http --description "allow web traffic from the Internet"
Created a new security_group:
+-----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Field | Value |
+-----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| created_at | 2016-11-10T16:09:18Z |
| description | allow web traffic from the Internet |
| headers | |
| id | 70675447-1b92-4102-a7ea-6a3ca99d2290 |
| name | global_http |
| project_id | 32e9707393c34364923edf8f5029cbfe |
| project_id | 32e9707393c34364923edf8f5029cbfe |
| revision_number | 1 |
| rules | created_at='2016-11-10T16:09:18Z', direction='egress', ethertype='IPv4', id='e440b13a-e74f-4700-a36f-9ecc0de76612', project_id='32e9707393c34364923edf8f5029cbfe', |
| | revision_number='1', updated_at='2016-11-10T16:09:18Z' |
| | created_at='2016-11-10T16:09:18Z', direction='egress', ethertype='IPv6', id='0debf8cb-9f1d-45e5-98db-ee169c0715fe', project_id='32e9707393c34364923edf8f5029cbfe', |
| | revision_number='1', updated_at='2016-11-10T16:09:18Z' |
| updated_at | 2016-11-10T16:09:18Z |
+-----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
Immediately after create, the security group has only an allow egress rule. To make it do what we want, we need to add some rules:
$ openstack security group rule create --help
usage: openstack security group rule create [-h]
[-f {json,shell,table,value,yaml}]
[-c COLUMN]
[--max-width <integer>]
[--noindent] [--prefix PREFIX]
[--remote-ip <ip-address> | --remote-group <group>]
[--dst-port <port-range>]
[--icmp-type <icmp-type>]
[--icmp-code <icmp-code>]
[--protocol <protocol>]
[--ingress | --egress]
[--ethertype <ethertype>]
[--project <project>]
[--project-domain <project-domain>]
<group>
$ openstack security group rule create --ingress --ethertype IPv4 \
--protocol tcp --remote-ip 0.0.0.0/0 global_http
Created a new security group rule:
+-------------------+--------------------------------------+
| Field | Value |
+-------------------+--------------------------------------+
| created_at | 2016-11-10T16:12:27Z |
| description | |
| direction | ingress |
| ethertype | IPv4 |
| headers | |
| id | 694d30b1-1c4d-4bb8-acbe-7f1b3de2b20f |
| port_range_max | None |
| port_range_min | None |
| project_id | 32e9707393c34364923edf8f5029cbfe |
| project_id | 32e9707393c34364923edf8f5029cbfe |
| protocol | tcp |
| remote_group_id | None |
| remote_ip_prefix | 0.0.0.0/0 |
| revision_number | 1 |
| security_group_id | 70675447-1b92-4102-a7ea-6a3ca99d2290 |
| updated_at | 2016-11-10T16:12:27Z |
+-------------------+--------------------------------------+
Despite only outputting the newly added rule, this operation is additive:
$ openstack security group show global_http
+-----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Field | Value |
+-----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| created_at | 2016-11-10T16:09:18Z |
| description | allow web traffic from the Internet |
| id | 70675447-1b92-4102-a7ea-6a3ca99d2290 |
| name | global_http |
| project_id | 32e9707393c34364923edf8f5029cbfe |
| project_id | 32e9707393c34364923edf8f5029cbfe |
| revision_number | 2 |
| rules | created_at='2016-11-10T16:09:18Z', direction='egress', ethertype='IPv6', id='0debf8cb-9f1d-45e5-98db-ee169c0715fe', project_id='32e9707393c34364923edf8f5029cbfe', |
| | revision_number='1', updated_at='2016-11-10T16:09:18Z' |
| | created_at='2016-11-10T16:12:27Z', direction='ingress', ethertype='IPv4', id='694d30b1-1c4d-4bb8-acbe-7f1b3de2b20f', project_id='32e9707393c34364923edf8f5029cbfe', protocol='tcp', |
| | remote_ip_prefix='0.0.0.0/0', revision_number='1', updated_at='2016-11-10T16:12:27Z' |
| | created_at='2016-11-10T16:09:18Z', direction='egress', ethertype='IPv4', id='e440b13a-e74f-4700-a36f-9ecc0de76612', project_id='32e9707393c34364923edf8f5029cbfe', |
| | revision_number='1', updated_at='2016-11-10T16:09:18Z' |
| updated_at | 2016-11-10T16:12:27Z |
+-----------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
The inverse operation is called openstack security group rule delete, specifying security-group-rule ID. Whole security groups can be removed with openstack security group delete.
To create security group rules for a cluster of instances, use RemoteGroups.
RemoteGroups are a dynamic way of defining the CIDR of allowed sources. The user specifies a RemoteGroup (security group name) and then all the users’ other instances using the specified RemoteGroup are selected dynamically. This dynamic selection alleviates the need for individual rules to allow each new member of the cluster.
The code is similar to the above example of
openstack security group rule create. To use RemoteGroup, specify
--remote-group instead of --remote-ip.
For example:
$ openstack security group rule create --ingress \
--ethertype IPv4 --protocol tcp \
--remote-group global_http cluster
The “cluster” rule allows SSH access from any other instance that uses
the global-http group.
Block Storage¶
OpenStack volumes are persistent block-storage devices that may be attached and detached from instances, but they can be attached to only one instance at a time. Similar to an external hard drive, they do not provide shared storage in the way a network file system or object store does. It is left to the operating system in the instance to put a file system on the block device and mount it, or not.
As with other removable disk technology, it is important that the operating system is not trying to make use of the disk before removing it. On Linux instances, this typically involves unmounting any file systems mounted from the volume. The OpenStack volume service cannot tell whether it is safe to remove volumes from an instance, so it does what it is told. If a user tells the volume service to detach a volume from an instance while it is being written to, you can expect some level of file system corruption as well as faults from whatever process within the instance was using the device.
There is nothing OpenStack-specific in being aware of the steps needed
to access block devices from within the instance operating system,
potentially formatting them for first use and being cautious when
removing them. What is specific is how to create new volumes and attach
and detach them from instances. These operations can all be done from
the Volumes page of the dashboard or by using the openstack
command-line client.
To add new volumes, you need only a volume size in gigabytes. Either put these into the Create Volume web form or use the command line:
$ openstack volume create volume1 --size 10
This creates a 10 GB volume. To list existing volumes and the instances they are connected to, if any:
$ openstack volume list
+--------------------------------------+--------------+--------+------+-------------+
| ID | Display Name | Status | Size | Attached to |
+--------------------------------------+--------------+--------+------+-------------+
| 6cf4114a-56b2-476b-acf7-7359d8334aa2 | volume1 | error | 10 | |
+--------------------------------------+--------------+--------+------+-------------+
OpenStack Block Storage also allows creating snapshots of volumes. Remember that this is a block-level snapshot that is crash consistent, so it is best if the volume is not connected to an instance when the snapshot is taken and second best if the volume is not in use on the instance it is attached to. If the volume is under heavy use, the snapshot may have an inconsistent file system. In fact, by default, the volume service does not take a snapshot of a volume that is attached to an image, though it can be forced to. To take a volume snapshot, either select Create Snapshot from the actions column next to the volume name on the dashboard Volumes page, or run this from the command line:
$ openstack help snapshot create
usage: openstack snapshot create [-h] [-f {json,shell,table,value,yaml}]
[-c COLUMN] [--max-width <integer>]
[--noindent] [--prefix PREFIX]
[--name <name>] [--description <description>]
[--force] [--property <key=value>]
<volume>
Create new snapshot
positional arguments:
<volume> Volume to snapshot (name or ID)
optional arguments:
-h, --help show this help message and exit
--name <name> Name of the snapshot
--description <description>
Description of the snapshot
--force Create a snapshot attached to an instance. Default is
False
--property <key=value>
Set a property to this snapshot (repeat option to set
multiple properties)
output formatters:
output formatter options
-f {json,shell,table,value,yaml}, --format {json,shell,table,value,yaml}
the output format, defaults to table
-c COLUMN, --column COLUMN
specify the column(s) to include, can be repeated
table formatter:
--max-width <integer>
Maximum display width, <1 to disable. You can also use
the CLIFF_MAX_TERM_WIDTH environment variable, but the
parameter takes precedence.
json formatter:
--noindent whether to disable indenting the JSON
shell formatter:
a format a UNIX shell can parse (variable="value")
--prefix PREFIX add a prefix to all variable names
Note
For more information about updating Block Storage volumes (for example, resizing or transferring), see the OpenStack End User Guide.
Block Storage Creation Failures¶
If a user tries to create a volume and the volume immediately goes into an error state, the best way to troubleshoot is to grep the cinder log files for the volume’s UUID. First try the log files on the cloud controller, and then try the storage node where the volume was attempted to be created:
# grep 903b85d0-bacc-4855-a261-10843fc2d65b /var/log/cinder/*.log
Instances¶
Instances are the running virtual machines within an OpenStack cloud. This section deals with how to work with them and their underlying images, their network properties, and how they are represented in the database.
Starting Instances¶
To launch an instance, you need to select an image, a flavor, and a name. The name needn’t be unique, but your life will be simpler if it is because many tools will use the name in place of the UUID so long as the name is unique. You can start an instance from the dashboard from the Launch Instance button on the Instances page or by selecting the Launch action next to an image or a snapshot on the Images page.
On the command line, do this:
$ openstack server create --flavor FLAVOR --image IMAGE_NAME_OR_ID
There are a number of optional items that can be specified. You should read the rest of this section before trying to start an instance, but this is the base command that later details are layered upon.
To delete instances from the dashboard, select the Delete Instance action next to the instance on the Instances page.
Note
In releases prior to Mitaka, select the equivalent Terminate instance action.
From the command line, do this:
$ openstack server delete INSTANCE_ID
It is important to note that powering off an instance does not terminate it in the OpenStack sense.
Instance Boot Failures¶
If an instance fails to start and immediately moves to an error state, there are a few different ways to track down what has gone wrong. Some of these can be done with normal user access, while others require access to your log server or compute nodes.
The simplest reasons for nodes to fail to launch are quota violations or the scheduler being unable to find a suitable compute node on which to run the instance. In these cases, the error is apparent when you run a openstack server show on the faulted instance:
$ openstack server show test-instance
+--------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------+
| Field | Value |
+--------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------+
| OS-DCF:diskConfig | AUTO |
| OS-EXT-AZ:availability_zone | nova |
| OS-EXT-SRV-ATTR:host | None |
| OS-EXT-SRV-ATTR:hypervisor_hostname | None |
| OS-EXT-SRV-ATTR:instance_name | instance-0000000a |
| OS-EXT-STS:power_state | NOSTATE |
| OS-EXT-STS:task_state | None |
| OS-EXT-STS:vm_state | error |
| OS-SRV-USG:launched_at | None |
| OS-SRV-USG:terminated_at | None |
| accessIPv4 | |
| accessIPv6 | |
| addresses | |
| config_drive | |
| created | 2016-11-23T07:51:53Z |
| fault | {u'message': u'Build of instance 6ec42311-a121-4887-aece-48fb93a4a098 aborted: Failed to allocate the network(s), not rescheduling.', |
| | u'code': 500, u'details': u' File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 1779, in |
| | _do_build_and_run_instance\n filter_properties)\n File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 1960, in |
| | _build_and_run_instance\n reason=msg)\n', u'created': u'2016-11-23T07:57:04Z'} |
| flavor | m1.tiny (1) |
| hostId | |
| id | 6ec42311-a121-4887-aece-48fb93a4a098 |
| image | cirros (9fef3b2d-c35d-4b61-bea8-09cc6dc41829) |
| key_name | None |
| name | test-instance |
| os-extended-volumes:volumes_attached | [] |
| project_id | 5669caad86a04256994cdf755df4d3c1 |
| properties | |
| status | ERROR |
| updated | 2016-11-23T07:57:04Z |
| user_id | c36cec73b0e44876a4478b1e6cd749bb |
+--------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------+
In this case, looking at the fault message shows NoValidHost,
indicating that the scheduler was unable to match the instance
requirements.
If openstack server show does not sufficiently explain the failure,
searching for the instance UUID in the nova-compute.log on the compute
node it was scheduled on or the nova-scheduler.log on your scheduler hosts
is a good place to start looking for lower-level problems.
Using openstack server show as an admin user will show the compute
node the instance was scheduled on as hostId. If the instance failed
during scheduling, this field is blank.
Using Instance-Specific Data¶
There are two main types of instance-specific data: metadata and user data.
Instance metadata¶
For Compute, instance metadata is a collection of key-value pairs associated with an instance. Compute reads and writes to these key-value pairs any time during the instance lifetime, from inside and outside the instance, when the end user uses the Compute API to do so. However, you cannot query the instance-associated key-value pairs with the metadata service that is compatible with the Amazon EC2 metadata service.
For an example of instance metadata, users can generate and register SSH keys using the openstack keypair create command:
$ openstack keypair create mykey > mykey.pem
This creates a key named mykey, which you can associate with
instances. The file mykey.pem is the private key, which should be
saved to a secure location because it allows root access to instances
the mykey key is associated with.
Use this command to register an existing key with OpenStack:
$ openstack keypair create --public-key mykey.pub mykey
Note
You must have the matching private key to access instances associated with this key.
To associate a key with an instance on boot, add --key-name mykey to
your command line. For example:
$ openstack server create --image ubuntu-cloudimage --flavor 2 \
--key-name mykey myimage
When booting a server, you can also add arbitrary metadata so that you
can more easily identify it among other running instances. Use the
--property option with a key-value pair, where you can make up
the string for both the key and the value. For example, you could add a
description and also the creator of the server:
$ openstack server create --image=test-image --flavor=1 \
--property description='Small test image' smallimage
When viewing the server information, you can see the metadata included on the metadata line:
$ openstack server show smallimage
+--------------------------------------+----------------------------------------------------------+
| Field | Value |
+--------------------------------------+----------------------------------------------------------+
| OS-DCF:diskConfig | MANUAL |
| OS-EXT-AZ:availability_zone | nova |
| OS-EXT-SRV-ATTR:host | rdo-newton.novalocal |
| OS-EXT-SRV-ATTR:hypervisor_hostname | rdo-newton.novalocal |
| OS-EXT-SRV-ATTR:instance_name | instance-00000002 |
| OS-EXT-STS:power_state | Running |
| OS-EXT-STS:task_state | None |
| OS-EXT-STS:vm_state | active |
| OS-SRV-USG:launched_at | 2016-12-07T11:20:08.000000 |
| OS-SRV-USG:terminated_at | None |
| accessIPv4 | |
| accessIPv6 | |
| addresses | public=172.24.4.227 |
| config_drive | |
| created | 2016-12-07T11:17:44Z |
| flavor | m1.tiny (1) |
| hostId | aca973d5b7981faaf8c713a0130713bbc1e64151be65c8dfb53039f7 |
| id | 4f7c6b2c-f27e-4ccd-a606-6bfc9d7c0d91 |
| image | cirros (01bcb649-45d7-4e3d-8a58-1fcc87816907) |
| key_name | None |
| name | smallimage |
| os-extended-volumes:volumes_attached | [] |
| progress | 0 |
| project_id | 2daf82a578e9437cab396c888ff0ca57 |
| properties | description='Small test image' |
| security_groups | [{u'name': u'default'}] |
| status | ACTIVE |
| updated | 2016-12-07T11:20:08Z |
| user_id | 8cbea24666ae49bbb8c1641f9b12d2d2 |
+--------------------------------------+----------------------------------------------------------+
Instance user data¶
The user-data key is a special key in the metadata service that
holds a file that cloud-aware applications within the guest instance can
access. For example,
cloudinit is an open
source package from Ubuntu, but available in most distributions, that
handles early initialization of a cloud instance that makes use of this
user data.
This user data can be put in a file on your local system and then passed
in at instance creation with the flag
--user-data <user-data-file>.
For example
$ openstack server create --image ubuntu-cloudimage --flavor 1 \
--user-data mydata.file mydatainstance
To understand the difference between user data and metadata, realize that user data is created before an instance is started. User data is accessible from within the instance when it is running. User data can be used to store configuration, a script, or anything the tenant wants.
File injection¶
Arbitrary local files can also be placed into the instance file system
at creation time by using the --file <dst-path=src-path> option.
You may store up to five files.
For example, let’s say you have a special authorized_keys file named
special_authorized_keysfile that for some reason you want to put on
the instance instead of using the regular SSH key injection. In this
case, you can use the following command:
$ openstack server create --image ubuntu-cloudimage --flavor 1 \
--file /root/.ssh/authorized_keys=special_authorized_keysfile \
authkeyinstance
Associating Security Groups¶
Security groups, as discussed earlier, are typically required to allow network traffic to an instance, unless the default security group for a project has been modified to be more permissive.
Adding security groups is typically done on instance boot. When launching from the dashboard, you do this on the Access & Security tab of the Launch Instance dialog.
It is also possible to add and remove security groups when an instance is running. Currently this is only available through the command-line tools. Here is an example:
$ openstack server add security group SERVER SECURITY_GROUP_NAME_OR_ID
$ openstack server remove security group SERVER SECURITY_GROUP_NAME_OR_ID
Floating IPs¶
Where floating IPs are configured in a deployment, each project will have a limited number of floating IPs controlled by a quota. However, these need to be allocated to the project from the central pool prior to their use—usually by the administrator of the project. To allocate a floating IP to a project, use the Allocate IP To Project button on the Floating IPs tab of the Access & Security page of the dashboard. The command line can also be used:
$ openstack floating ip create NETWORK_NAME_OR_ID
Once allocated, a floating IP can be assigned to running instances from the dashboard either by selecting Associate from the actions drop-down next to the IP on the Floating IPs tab of the Access & Security page or by making this selection next to the instance you want to associate it with on the Instances page. The inverse action, Dissociate Floating IP, is available from the Floating IPs tab of the Access & Security page and from the Instances page.
To associate or disassociate a floating IP with a server from the command line, use the following commands:
$ openstack server add floating ip SERVER IP_ADDRESS
$ openstack server remove floating ip SERVER IP_ADDRESS
Attaching Block Storage¶
You can attach block storage to instances from the dashboard on the Volumes page. Click the Manage Attachments action next to the volume you want to attach.
To perform this action from command line, run the following command:
$ openstack server add volume SERVER VOLUME_NAME_OR_ID --device DEVICE
You can also specify block deviceblock device mapping at instance boot time through the nova command-line client with this option set:
--block-device-mapping <dev-name=mapping>
The block device mapping format is
<dev-name>=<id>:<type>:<size(GB)>:<delete-on-terminate>,
where:
- dev-name
A device name where the volume is attached in the system at
/dev/dev_name- id
The ID of the volume to boot from, as shown in the output of openstack volume list
- type
Either
snap, which means that the volume was created from a snapshot, or anything other thansnap(a blank string is valid). In the preceding example, the volume was not created from a snapshot, so we leave this field blank in our following example.- size (GB)
The size of the volume in gigabytes. It is safe to leave this blank and have the Compute Service infer the size.
- delete-on-terminate
A boolean to indicate whether the volume should be deleted when the instance is terminated. True can be specified as
Trueor1. False can be specified asFalseor0.
The following command will boot a new instance and attach a volume at
the same time. The volume of ID 13 will be attached as /dev/vdc. It
is not a snapshot, does not specify a size, and will not be deleted when
the instance is terminated:
$ openstack server create --image 4042220e-4f5e-4398-9054-39fbd75a5dd7 \
--flavor 2 --key-name mykey --block-device-mapping vdc=13:::0 \
boot-with-vol-test
If you have previously prepared block storage with a bootable file
system image, it is even possible to boot from persistent block storage.
The following command boots an image from the specified volume. It is
similar to the previous command, but the image is omitted and the volume
is now attached as /dev/vda:
$ openstack server create --flavor 2 --key-name mykey \
--block-device-mapping vda=13:::0 boot-from-vol-test
Read more detailed instructions for launching an instance from a bootable volume in the OpenStack End User Guide.
To boot normally from an image and attach block storage, map to a device other than vda. You can find instructions for launching an instance and attaching a volume to the instance and for copying the image to the attached volume in the OpenStack End User Guide.
Taking Snapshots¶
The OpenStack snapshot mechanism allows you to create new images from running instances. This is very convenient for upgrading base images or for taking a published image and customizing it for local use. To snapshot a running instance to an image using the CLI, do this:
$ openstack image create IMAGE_NAME --volume VOLUME_NAME_OR_ID
The dashboard interface for snapshots can be confusing because the
snapshots and images are displayed in the Images page. However, an
instance snapshot is an image. The only difference between an image
that you upload directly to the Image Service and an image that you
create by snapshot is that an image created by snapshot has additional
properties in the glance database. These properties are found in the
image_properties table and include:
Name |
Value |
|---|---|
|
snapshot |
|
<uuid of instance that was snapshotted> |
|
<uuid of original image of instance that was snapshotted> |
|
snapshot |
Live Snapshots¶
Live snapshots is a feature that allows users to snapshot the running virtual machines without pausing them. These snapshots are simply disk-only snapshots. Snapshotting an instance can now be performed with no downtime (assuming QEMU 1.3+ and libvirt 1.0+ are used).
Note
If you use libvirt version 1.2.2, you may experience
intermittent problems with live snapshot creation.
To effectively disable the libvirt live snapshotting, until the problem is resolved, add the below setting to nova.conf.
[workarounds]
disable_libvirt_livesnapshot = True
Ensuring Snapshots of Linux Guests Are Consistent
The following section is from Sébastien Han’s OpenStack: Perform Consistent Snapshots blog entry.
A snapshot captures the state of the file system, but not the state of the memory. Therefore, to ensure your snapshot contains the data that you want, before your snapshot you need to ensure that:
Running programs have written their contents to disk
The file system does not have any “dirty” buffers: where programs have issued the command to write to disk, but the operating system has not yet done the write
To ensure that important services have written their contents to disk (such as databases), we recommend that you read the documentation for those applications to determine what commands to issue to have them sync their contents to disk. If you are unsure how to do this, the safest approach is to simply stop these running services normally.
To deal with the “dirty” buffer issue, we recommend using the sync command before snapshotting:
# sync
Running sync writes dirty buffers (buffered blocks that have been
modified but not written yet to the disk block) to disk.
Just running sync is not enough to ensure that the file system is
consistent. We recommend that you use the fsfreeze tool, which halts
new access to the file system, and create a stable image on disk that is
suitable for snapshotting. The fsfreeze tool supports several file
systems, including ext3, ext4, and XFS. If your virtual machine instance
is running on Ubuntu, install the util-linux package to get
fsfreeze:
Note
In the very common case where the underlying snapshot is done via LVM, the filesystem freeze is automatically handled by LVM.
# apt-get install util-linux
If your operating system doesn’t have a version of fsfreeze
available, you can use xfs_freeze instead, which is available on
Ubuntu in the xfsprogs package. Despite the “xfs” in the name,
xfs_freeze also works on ext3 and ext4 if you are using a Linux kernel
version 2.6.29 or greater, since it works at the virtual file system
(VFS) level starting at 2.6.29. The xfs_freeze version supports the
same command-line arguments as fsfreeze.
Consider the example where you want to take a snapshot of a persistent
block storage volume, detected by the guest operating system as
/dev/vdb and mounted on /mnt. The fsfreeze command accepts two
arguments:
- -f
Freeze the system
- -u
Thaw (unfreeze) the system
To freeze the volume in preparation for snapshotting, you would do the following, as root, inside the instance:
# fsfreeze -f /mnt
You must mount the file system before you run the fsfreeze command.
When the fsfreeze -f command is issued, all ongoing transactions in the file system are allowed to complete, new write system calls are halted, and other calls that modify the file system are halted. Most importantly, all dirty data, metadata, and log information are written to disk.
Once the volume has been frozen, do not attempt to read from or write to the volume, as these operations hang. The operating system stops every I/O operation and any I/O attempts are delayed until the file system has been unfrozen.
Once you have issued the fsfreeze command, it is safe to perform
the snapshot. For example, if the volume of your instance was named
mon-volume and you wanted to snapshot it to an image named
mon-snapshot, you could now run the following:
$ openstack image create mon-snapshot --volume mon-volume
When the snapshot is done, you can thaw the file system with the following command, as root, inside of the instance:
# fsfreeze -u /mnt
If you want to back up the root file system, you can’t simply run the preceding command because it will freeze the prompt. Instead, run the following one-liner, as root, inside the instance:
# fsfreeze -f / && read x; fsfreeze -u /
After this command it is common practice to call openstack image create from your workstation, and once done press enter in your instance shell to unfreeze it. Obviously you could automate this, but at least it will let you properly synchronize.
Ensuring Snapshots of Windows Guests Are Consistent
Obtaining consistent snapshots of Windows VMs is conceptually similar to obtaining consistent snapshots of Linux VMs, although it requires additional utilities to coordinate with a Windows-only subsystem designed to facilitate consistent backups.
Windows XP and later releases include a Volume Shadow Copy Service (VSS) which provides a framework so that compliant applications can be consistently backed up on a live filesystem. To use this framework, a VSS requestor is run that signals to the VSS service that a consistent backup is needed. The VSS service notifies compliant applications (called VSS writers) to quiesce their data activity. The VSS service then tells the copy provider to create a snapshot. Once the snapshot has been made, the VSS service unfreezes VSS writers and normal I/O activity resumes.
QEMU provides a guest agent that can be run in guests running on KVM hypervisors. This guest agent, on Windows VMs, coordinates with the Windows VSS service to facilitate a workflow which ensures consistent snapshots. This feature requires at least QEMU 1.7. The relevant guest agent commands are:
- guest-file-flush
Write out “dirty” buffers to disk, similar to the Linux
syncoperation.- guest-fsfreeze
Suspend I/O to the disks, similar to the Linux
fsfreeze -foperation.- guest-fsfreeze-thaw
Resume I/O to the disks, similar to the Linux
fsfreeze -uoperation.
To obtain snapshots of a Windows VM these commands can be scripted in sequence: flush the filesystems, freeze the filesystems, snapshot the filesystems, then unfreeze the filesystems. As with scripting similar workflows against Linux VMs, care must be used when writing such a script to ensure error handling is thorough and filesystems will not be left in a frozen state.
Instances in the Database¶
While instance information is stored in a number of database tables, the table you most likely need to look at in relation to user instances is the instances table.
The instances table carries most of the information related to both running and deleted instances. It has a bewildering array of fields; for an exhaustive list, look at the database. These are the most useful fields for operators looking to form queries:
The
deletedfield is set to1if the instance has been deleted andNULLif it has not been deleted. This field is important for excluding deleted instances from your queries.The
uuidfield is the UUID of the instance and is used throughout other tables in the database as a foreign key. This ID is also reported in logs, the dashboard, and command-line tools to uniquely identify an instance.A collection of foreign keys are available to find relations to the instance. The most useful of these —
user_idandproject_idare the UUIDs of the user who launched the instance and the project it was launched in.The
hostfield tells which compute node is hosting the instance.The
hostnamefield holds the name of the instance when it is launched. The display-name is initially the same as hostname but can be reset using the nova rename command.
A number of time-related fields are useful for tracking when state changes happened on an instance:
created_atupdated_atdeleted_atscheduled_atlaunched_atterminated_at
Good Luck!¶
This section was intended as a brief introduction to some of the most useful of many OpenStack commands. For an exhaustive list, please refer to the OpenStack Administrator Guide. We hope your users remain happy and recognize your hard work! (For more hard work, turn the page to the next chapter, where we discuss the system-facing operations: maintenance, failures and debugging.)
