Keep the groupId from ec2 permission groups.

Keep the groupId from ec2 permission groups.

If ec2 tells us only group Id values, and not Names, then we need to be
able to reproduce this when wanting to revoke permissions.

https://code.launchpad.net/~thumper/juju-core/more-ipperms/+merge/159994

(do not edit description out of merge proposal)

[thumper, 2013-04-22 00:25:25]

Please take a look.

[rog, 2013-04-22 07:30:11]

Thanks very much for getting to the bottom of this issue. This does not LGTM
though because I don't believe the fix is correct (see below). Also, if the live
tests didn't fail, we could do with a test please.

https://codereview.appspot.com/8649047/diff/1/environs/ec2/ec2.go
File environs/ec2/ec2.go (right):

https://codereview.appspot.com/8649047/diff/1/environs/ec2/ec2.go#newcode921
environs/ec2/ec2.go:921: groupId   string
I'm not sure this is right.

We use the permKey as unique key representing a group permission - the
permissions passed into ensureGroup have perms with only the group name set, so
they won't compare equal to permissions with the group id set, so this breaks
the logic in that function.

I think the right fix is probably to use groupId exclusively. This means that
the ensureGroup in setUpGroups needs to change, because the group perms refer
back to the group itself, and we can't provide its id before we've created it.
So I suggest creating the jujuGroupName group with no permissions before calling
ensureGroup using SourceGroups with the appropriate id filled out.

This means an extra round trip when starting an instance, but that's probably no
big deal compared to the amount of time it takes anyway.