Add version checking to some SDK elements

[wojtek0806]

Some of the functionalities are not available in versions < 12.0, therefore they should not attempt to execute if utilized with BIGIP versions < 12

[wojtek0806]

@channel

I have been thinking about how do we implement this, and we could go with setting up icontrol version to: 12.0.0 similiar way have done so in FDB:

self._meta_data['icontrol_version'] = '12.0.0'

This however will not prevent the user to send the data over the wire, however in the Pythonic spirit we could implement error catching in the code, and deal with it accordingly. In this instance when we attempt to force unknown version we get 500 error message:

{"code":500,"message":"Can't find specified cli schema data for 12.0.0","errorStack":[]}

So we can either display informative warning or have code do something (the something yet to be determined).

Another solution wis to upon first connection to the bigip, we determine its TMOS version and set a variable to specific value. Then we could manipulate some of the lazy attributes in organizing collections to either "show" or "hide" respective classes.

If anyone has any other ideas I would like to hear them :)

[wojtek0806]

Issue Review: This issue will require changing v12 specific classes not to execute at all or catch exceptions from REST. Awaiting peer feedback re above comments

[zancas]

We should stick to the pattern of protecting the network from unnecessary traffic where possible. This means we should NOT use the "Ask Forgiveness Not Permission" pattern here.

I think a self._meta_data['version'] = # is the correct data structure.
There is a nice side-effect of sending a request during ManagementRoot construction, it makes the () always send a request, when used in the SDK. Currently ManagementRoot construction is the sole exception to that rule.

I don't like exceptions. Please implement a request in the construction of the ManagementRoot that obtains the version of the device and assigns self._meta_data['version'] to its value.

[zancas]

The scope of this issue is restricted to implementing the general mechanism as discussed above, and testing it in a few cases. Implementing specific cases should be tracked in separate specific issues.

This is because many specific cases are likely part of classes that are not yet implemented at all.

[wojtek0806]

There is no way to get the version of the device upon first connection. You need to send a REST query to find that out, after connection has been established. Also Pythonic way is to allow and deal with exceptions which is what we need to do here

[zancas]

I agree that we should submit a request to the device during construction/instantiation of the ManagementRoot object, see my comment above: #379 (comment)

Using exception handling is not relevant to this part of the design.

[wojtek0806]

So how do you want to get device's version? BIGIP will not send that kind of information to you. And querying a device for this each time we connect is inefficient

[wojtek0806]

and i was talking about exception handling at the class level not connection. The only way i see this working is if we keep track of version information per each host we connect, so even if we tear down connection we store it when connecting second time

[zancas]

Hmmm
Maybe a gist is the right thing...