add ProviderClient.Reauthenticate() function

[majewsky]

If a user wants to do their own HTTP requests and reauthenticate in case of 401 responses, they can already use ProviderClient.ReauthFunc(), but that function is not thread-safe. This commit provides a safer alternative by pulling the relevant piece of code out of ProviderClient.Request().

For #742.

[theopenlab-ci]

Build failed.

• gophercloud-unittest : FAILURE in 1m 29s
• gophercloud-acceptance-test : SUCCESS in 27m 42s

[coveralls]

Coverage increased (+0.007%) to 73.221% when pulling f0a5d28 on sapcc:make-reauth-public into 9746ef6 on gophercloud:master.

[theopenlab-ci]

Build succeeded.

• gophercloud-unittest : SUCCESS in 1m 30s
• gophercloud-acceptance-test : SUCCESS in 57m 54s

[majewsky]

Any opinion? I would like to have this merged soon since I want to rely on this in a library that I'm currently building.

[majewsky]

@jrperritt What do you think about this?

[jrperritt]

I can take a look at this tomorrow. At first glance, it looks reasonable to me.

[jrperritt]

This looks good to me. @jtopjian what do you think?

[jtopjian]

If I understand this correctly, and forgive me if I'm being dense, the idea here is to call client.Reauthenticate() and never call client.ReauthFunc() directly?

[jrperritt]

@jtopjian right, I think the goal is to have thread-safe re-authentication without having to use ProviderClient.Request. It'd enable a user to, say, use a different library for the HTTP calls.

Otherwise, @majewsky , is there any reason to export the Reauthenticate method?

[majewsky]

As you said. My usecase is a custom Swift client library: I tried to build it on top of ProviderClient.Request at first, but found it too limiting. I tried patching around it for a while (e.g. I set OkCodes to a 500-element slice with codes 100..599 to avoid Gophercloud's error handling and get the bare http.Response in all cases), but in the end, it emerged that the only thing I really want to re-use from Gophercloud is the authentication parts. For reference, this is the interface between my library and Gophercloud: https://github.com/majewsky/schwift/blob/master/gopherschwift/package.go#L69-L105 - This is already using the Reauthenticate method proposed here. I'm using my fork for development at the moment.

[jrperritt]

OK, thanks. Sorry it took so long for me to get around to this