Configuring OpenStack SDK Applications¶

Environment Variables¶

openstacksdk honors all of the normal OS_* variables. It does not provide backwards compatibility to service-specific variables such as NOVA_USERNAME.

If you have OpenStack environment variables set, openstacksdk will produce a cloud config object named envvars containing your values from the environment. If you don’t like the name envvars, that’s ok, you can override it by setting OS_CLOUD_NAME.

Service specific settings, like the nova service type, are set with the default service type as a prefix. For instance, to set a special service_type for trove set

export OS_DATABASE_SERVICE_TYPE=rax:database

Config Files¶

openstacksdk will look for a file called clouds.yaml in the following locations:

. (the current directory)
$HOME/.config/openstack
/etc/openstack

The first file found wins.

You can also set the environment variable OS_CLIENT_CONFIG_FILE to an absolute path of a file to look for and that location will be inserted at the front of the file search list.

The keys are all of the keys you’d expect from OS_* - except lower case and without the OS prefix. So, region name is set with region_name.

Service specific settings, like the nova service type, are set with the default service type as a prefix. For instance, to set a special service_type for trove (because you’re using Rackspace) set:

database_service_type: 'rax:database'

Site Specific File Locations¶

In addition to ~/.config/openstack and /etc/openstack - some platforms have other locations they like to put things. openstacksdk will also look in an OS specific config dir

USER_CONFIG_DIR
SITE_CONFIG_DIR

USER_CONFIG_DIR is different on Linux, OSX and Windows.

Linux: ~/.config/openstack
OSX: ~/Library/Application Support/openstack
Windows: C:\Users\USERNAME\AppData\Local\OpenStack\openstack

SITE_CONFIG_DIR is different on Linux, OSX and Windows.

Linux: /etc/openstack
OSX: /Library/Application Support/openstack
Windows: C:\ProgramData\OpenStack\openstack

An example config file is probably helpful:

clouds:
  mtvexx:
    profile: https://vexxhost.com
    auth:
      username: mordred@inaugust.com
      password: XXXXXXXXX
      project_name: mordred@inaugust.com
    region_name: ca-ymq-1
    dns_api_version: 1
  mordred:
    region_name: RegionOne
    auth:
      username: 'mordred'
      password: XXXXXXX
      project_name: 'shade'
      auth_url: 'https://montytaylor-sjc.openstack.blueboxgrid.com:5001/v2.0'
  infra:
    profile: rackspace
    auth:
      username: openstackci
      password: XXXXXXXX
      project_id: 610275
    regions:
    - DFW
    - ORD
    - IAD

You may note a few things. First, since auth_url settings are silly and embarrassingly ugly, known cloud vendor profile information is included and may be referenced by name or by base URL to the cloud in question if the cloud serves a vendor profile. One of the benefits of that is that auth_url isn’t the only thing the vendor defaults contain. For instance, since Rackspace lists rax:database as the service type for trove, openstacksdk knows that so that you don’t have to. In case the cloud vendor profile is not available, you can provide one called clouds-public.yaml, following the same location rules previously mentioned for the config files.

regions can be a list of regions. When you call get_all_clouds, you’ll get a cloud config object for each cloud/region combo.

As seen with dns_service_type, any setting that makes sense to be per-service, like service_type or endpoint or api_version can be set by prefixing the setting with the default service type. That might strike you funny when setting service_type and it does me too - but that’s just the world we live in.

Auth Settings¶

Keystone has auth plugins - which means it’s not possible to know ahead of time which auth settings are needed. openstacksdk sets the default plugin type to password, which is what things all were before plugins came about. In order to facilitate validation of values, all of the parameters that exist as a result of a chosen plugin need to go into the auth dict. For password auth, this includes auth_url, username and password as well as anything related to domains, projects and trusts.

Splitting Secrets¶

In some scenarios, such as configuration management controlled environments, it might be easier to have secrets in one file and non-secrets in another. This is fully supported via an optional file secure.yaml which follows all the same location rules as clouds.yaml. It can contain anything you put in clouds.yaml and will take precedence over anything in the clouds.yaml file.

# clouds.yaml
clouds:
  internap:
    profile: internap
    auth:
      username: api-55f9a00fb2619
      project_name: inap-17037
    regions:
    - ams01
    - nyj01
# secure.yaml
clouds:
  internap:
    auth:
      password: XXXXXXXXXXXXXXXXX

SSL Settings¶

When the access to a cloud is done via a secure connection, openstacksdk will always verify the SSL cert by default. This can be disabled by setting verify to False. In case the cert is signed by an unknown CA, a specific cacert can be provided via cacert. WARNING: verify will always have precedence over cacert, so when setting a CA cert but disabling verify, the cloud cert will never be validated.

Client certs are also configurable. cert will be the client cert file location. In case the cert key is not included within the client cert file, its file location needs to be set via key.

# clouds.yaml
clouds:
  regular-secure-cloud:
    auth:
      auth_url: https://signed.cert.domain:5000
      ...
  unknown-ca-with-client-cert-secure-cloud:
    auth:
      auth_url: https://unknown.ca.but.secure.domain:5000
      ...
    key: /home/myhome/client-cert.key
    cert: /home/myhome/client-cert.crt
    cacert: /home/myhome/ca.crt
  self-signed-insecure-cloud:
    auth:
      auth_url: https://self.signed.cert.domain:5000
      ...
    verify: False

Note for parity with openstack command-line options the insecure boolean is also recognised (with the opposite semantics to verify; i.e. True ignores certificate failures). This should be considered deprecated for verify.

Cache Settings¶

Accessing a cloud is often expensive, so it’s quite common to want to do some client-side caching of those operations. To facilitate that, openstacksdk understands passing through cache settings to dogpile.cache, with the following behaviors:

Listing no config settings means you get a null cache.
cache.expiration_time and nothing else gets you memory cache.
Otherwise, cache.class and cache.arguments are passed in

Different cloud behaviors are also differently expensive to deal with. If you want to get really crazy and tweak stuff, you can specify different expiration times on a per-resource basis by passing values, in seconds to an expiration mapping keyed on the singular name of the resource. A value of -1 indicates that the resource should never expire. Not specifying a value (same as specifying 0) indicates that no caching for this resource should be done. openstacksdk only caches GET request responses for the queries which have non-zero expiration time defined. Caching key contains url and request parameters, therefore no collisions are expected.

The expiration time key is constructed (joined with .) in the same way as the metrics are emmited:

service type
meaningful resource url segments (i.e. /servers results in servers, /servers/ID results in server, /servers/ID/metadata/KEY results in server.metadata

Non GET requests cause cache invalidation based on the caching key prefix so that i.e. PUT request to /images/ID will invalidate all images cache (list and all individual entries). Moreover it is possible to explicitly pass _sdk_skip_cache parameter to the proxy._get function to bypass cache and invalidate what is already there. This is happening automatically in the wait_for_status methods where it is expected that resource is going to change some of the attributes over the time. Forcing complete cache invalidation can be achieved calling conn._cache.invalidate.

openstacksdk does not actually cache anything itself, but it collects and presents the cache information so that your various applications that are connecting to OpenStack can share a cache should you desire.

cache:
  class: dogpile.cache.pylibmc
  expiration_time: 3600
  arguments:
    url:
      - 127.0.0.1
  expiration:
    server: 5
    flavor: -1
    compute.servers: 5
    compute.flavors: -1
    image.images: 5
clouds:
  mtvexx:
    profile: vexxhost
    auth:
      username: mordred@inaugust.com
      password: XXXXXXXXX
      project_name: mordred@inaugust.com
    region_name: ca-ymq-1
    dns_api_version: 1

openstacksdk can also cache authorization state (token) in the keyring. That allow the consequent connections to the same cloud to skip fetching new token. When the token gets expired or gets invalid openstacksdk will establish new connection.

cache:
  auth: true

MFA Support¶

MFA support requires a specially prepared configuration file. In this case a combination of 2 different authorization plugins is used with their individual requirements to the specified parameteres.

clouds:
  mfa:
    auth_type: "v3multifactor"
    auth_methods:
      - v3password
      - v3totp
    auth:
      auth_url: https://identity.cloud.com
      username: user
      user_id: uid
      password: XXXXXXXXX
      project_name: project
      user_domain_name: udn
      project_domain_name: pdn

IPv6¶

IPv6 is the future, and you should always use it if your cloud supports it and if your local network supports it. Both of those are easily detectable and all friendly software should do the right thing.

However, sometimes a cloud API may return IPv6 information that is not useful to a production deployment. For example, the API may provide an IPv6 address for a server, but not provide that to the host instance via metadata (configdrive) or standard IPv6 autoconfiguration methods (i.e. the host either needs to make a bespoke API call, or otherwise statically configure itself).

For such situations, you can set the force_ipv4, or OS_FORCE_IPV4 boolean environment variable. For example:

clouds:
  mtvexx:
    profile: vexxhost
    auth:
      username: mordred@inaugust.com
      password: XXXXXXXXX
      project_name: mordred@inaugust.com
    region_name: ca-ymq-1
    dns_api_version: 1
  monty:
    profile: fooprovider
    force_ipv4: true
    auth:
      username: mordred@inaugust.com
      password: XXXXXXXXX
      project_name: mordred@inaugust.com
    region_name: RegionFoo

The above snippet will tell client programs to prefer the IPv4 address and leave the public_v6 field of the Server object blank for the fooprovider cloud . You can also set this with a client flag for all clouds:

client:
  force_ipv4: true

Per-region settings¶

Sometimes you have a cloud provider that has config that is common to the cloud, but also with some things you might want to express on a per-region basis. For instance, Internap provides a public and private network specific to the user in each region, and putting the values of those networks into config can make consuming programs more efficient.

To support this, the region list can actually be a list of dicts, and any setting that can be set at the cloud level can be overridden for that region.

clouds:
  internap:
    profile: internap
    auth:
      password: XXXXXXXXXXXXXXXXX
      username: api-55f9a00fb2619
      project_name: inap-17037
    regions:
    - name: ams01
      values:
        networks:
        - name: inap-17037-WAN1654
          routes_externally: true
        - name: inap-17037-LAN6745
    - name: nyj01
      values:
        networks:
        - name: inap-17037-WAN1654
          routes_externally: true
        - name: inap-17037-LAN6745

Configuring OpenStack SDK Applications