os-client-config

os-client-config is a library for collecting client configuration for using an OpenStack cloud in a consistent and comprehensive manner. It will find cloud config for as few as 1 cloud and as many as you want to put in a config file. It will read environment variables and config files, and it also contains some vendor specific default values so that you don't have to know extra info to use OpenStack

• If you have a config file, you will get the clouds listed in it
• If you have environment variables, you will get a cloud named 'envvars'
• If you have neither, you will get a cloud named 'defaults' with base defaults

Environment Variables

os-client-config 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, os-client-config 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

os-client-config will look for a file called clouds.yaml in the following locations:

• Current Directory
• ~/.config/openstack
• /etc/openstack

The first file found wins.

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'

An example config file is probably helpful:

clouds:
  mordred:
    cloud: hp
    auth:
      username: mordred@inaugust.com
      password: XXXXXXXXX
      project_name: mordred@inaugust.com
    region_name: region-b.geo-1
    dns_service_type: hpext:dns
    compute_api_version: 1.1
  monty:
    auth:
      auth_url: https://region-b.geo-1.identity.hpcloudsvc.com:35357/v2.0
      username: monty.taylor@hp.com
      password: XXXXXXXX
      project_name: monty.taylor@hp.com-default-tenant
    region_name: region-b.geo-1
    dns_service_type: hpext:dns
  infra:
    cloud: rackspace
    auth:
      username: openstackci
      password: XXXXXXXX
      project_id: 610275
    region_name: DFW,ORD,IAD

You may note a few things. First, since auth_url settings are silly and embarrasingly ugly, known cloud vendors are included and may be referrenced by name. 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, os-client-config knows that so that you don't have to.

Also, region_name 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. os-client-config 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.

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, os-client-config understands passing through cache settings to dogpile.cache, with the following behaviors:

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

os-client-config 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
  max_age: 3600
  arguments:
    url:
      - 127.0.0.1
clouds:
  mordred:
    cloud: hp
    auth:
      username: mordred@inaugust.com
      password: XXXXXXXXX
      project_name: mordred@inaugust.com
    region_name: region-b.geo-1
    dns_service_type: hpext:dns

Usage

The simplest and least useful thing you can do is: :

python -m os_client_config.config

Which will print out whatever if finds for your config. If you want to use it from python, which is much more likely what you want to do, things like:

Get a named cloud. :

import os_client_config

cloud_config = os_client_config.OpenStackConfig().get_one_cloud(
    'hp', 'region-b.geo-1')
print(cloud_config.name, cloud_config.region, cloud_config.config)

Or, get all of the clouds. :: import os_client_config

cloud_config = os_client_config.OpenStackConfig().get_all_clouds() for cloud in cloud_config: print(cloud.name, cloud.region, cloud.config)