Merge lp:~jtv/juju-core/mpv-singleton into lp:~maas-maintainers/juju-core/maas-provider-skeleton

[Jeroen T. Vermeulen]

Instantiate & register the MAAS environment provider. Make maasEnvironProvider, instead of *maasEnvironProvider, implement EnvironProvider.

This was cargo-culted off the EC2 provider: create a singleton instance of the maasEnvironProvider, and register it.

There is a difference, discussed with John Meinel: where the EC2 and OpenStack providers create a singleton instance but then register a separate instance, this code really uses just a single instance. We believe this is what the EC2 code intended. The OpenStack provider was cargo-culted off that one, so the fact that it does the same thing as the EC2 one is not particularly significant.

Jeroen

[Jeroen T. Vermeulen (jtv)]

We discussed this some more, with Roger Peppe as well. Turns out the singleton is really just a holdover from the time before Environ.Provider(). That simplifies things a bit. Environ.Provider() can just hand out pointers to instances it creates on the fly.

=== modified file 'environs/maas/environ.go'
--- environs/maas/environ.go	2013-01-29 09:51:16 +0000
+++ environs/maas/environ.go	2013-01-31 08:38:21 +0000
@@ -97,5 +97,5 @@
 }
 
 func (*maasEnviron) Provider() environs.EnvironProvider {
-	panic("Not implemented.")
+	return &maasEnvironProvider{}
 }

=== modified file 'environs/maas/environprovider.go'
--- environs/maas/environprovider.go	2013-01-31 06:27:18 +0000
+++ environs/maas/environprovider.go	2013-01-31 08:38:21 +0000
@@ -8,25 +8,26 @@
 
 type maasEnvironProvider struct{}
 
+// maasEnvironProvider implements EnvironProvider.
 var _ environs.EnvironProvider = (*maasEnvironProvider)(nil)
 
-func (*maasEnvironProvider) Open(cfg *config.Config) (environs.Environ, error) {
+func (maasEnvironProvider) Open(cfg *config.Config) (environs.Environ, error) {
 	log.Printf("environs/maas: opening environment %q.", cfg.Name())
 	return NewEnviron(cfg)
 }
 
-func (*maasEnvironProvider) Validate(cfg, old *config.Config) (*config.Config, error) {
+func (maasEnvironProvider) Validate(cfg, old *config.Config) (*config.Config, error) {
 	return cfg, nil
 }
 
-func (*maasEnvironProvider) SecretAttrs(*config.Config) (map[string]interface{}, error) {
-	panic("Not implemented.")
-}
-
-func (*maasEnvironProvider) PublicAddress() (string, error) {
-	panic("Not implemented.")
-}
-
-func (*maasEnvironProvider) PrivateAddress() (string, error) {
+func (maasEnvironProvider) SecretAttrs(*config.Config) (map[string]interface{}, error) {
+	panic("Not implemented.")
+}
+
+func (maasEnvironProvider) PublicAddress() (string, error) {
+	panic("Not implemented.")
+}
+
+func (maasEnvironProvider) PrivateAddress() (string, error) {
 	panic("Not implemented.")
 }