Lazy entry

[tonybaloney]

Introduce a convenience method to the libcloud module for getting drivers

Description

I find the current mechanism for fetching drivers a little cumbersome, 2 namespaces to import. After using the requests library I really like the module __init__ accessors for common attributes. The most common factory is get_driver and the most common enum is the Provider enum.

This code allows for this example:

import libcloud
cls = libcloud.get_driver(libcloud.DriverType.COMPUTE, libcloud.DriverType.COMPUTE.RACKSPACE)

Status

• done, ready for review

Checklist (tick everything that applies)

• Code linting (required, can be done after the PR checks)
• Documentation
• Tests
• ICLA (required for bigger changes)

[Kami]

I'm not too opinionated about of and I'm fine with the overall change and "external API".

[Kami]

Good idea to be consistent and inherit from object even if it's just used as an ENUM class.

[tonybaloney]

@Kami updated

[Kami]

I think it would also be good to include type in the error message.

[Kami]

And test for it would be nice :)

Besides that, LGTM, 👍

[Kami]

Would also be good to be update upgrade notes if want this to be a preferred approach for retrieving a driver down the road :)

For that though, it might be worth soliciting feedback and reaching consensus from more people.

[erjohnso]

Looks good to me. A good follow-on would be to update site docs / examples for this new approach.

[JamieCressey]

Observation from an outsider...

If you're defining a provider class as libcloud.DriverType.SERVICE.PROVIDER. Can we not determine the service from the provider, negating the requirement to also provide a service object, therefore simplifying the instantiation from:

cls = libcloud.get_driver(libcloud.DriverType.COMPUTE, libcloud.DriverType.COMPUTE.RACKSPACE)

to:

cls = libcloud.get_driver(libcloud.DriverType.COMPUTE.RACKSPACE)

Just a thought, either way seems much cleaner than the current method.

[tonybaloney]

@JamieCressey that would be better using the Enum base type in Python 3.4+ but once it has been called, its already been converted into the value (string), and there's no difference in values between storage.Providers.RACKSPACE and loadbalancer.Providers.RACKSPACE, they're both 'rackspace'.
Instead I created seperate factory methods, get_compute_driver, get_storage_driver with the type inbuilt.
There are some cases where people might want to generate a driver dynamically without knowing the type, so get_driver is there as a catch-all.

[tonybaloney]

I'm pushing this in unless any serious objections?

[tonybaloney]

merging