Support configurations for cloudproviders

Cloud providers may need specific configurations to run properly (e.g.
authentication parameters, uri, etc.).

This patch adds the simplest implementation for passing configurations
to cloudproviders: a new apiserver -cloud_config flag to specify the
path to an arbitrary configuration file.

Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>

cmd/apiserver/apiserver.go

@@ -22,6 +22,7 @@ import (
 	"flag"
 	"net"
 	"net/http"
+	"os"
 	"strconv"
 	"time"
 
@@ -39,6 +40,7 @@ var (
 	address                     = flag.String("address", "127.0.0.1", "The address on the local server to listen to. Default 127.0.0.1")
 	apiPrefix                   = flag.String("api_prefix", "/api/v1beta1", "The prefix for API requests on the server. Default '/api/v1beta1'")
 	cloudProvider               = flag.String("cloud_provider", "", "The provider for cloud services.  Empty string for no provider.")
+	cloudConfigFile             = flag.String("cloud_config", "", "The path to the cloud provider configuration file.  Empty string for no configuration file.")
 	minionRegexp                = flag.String("minion_regexp", "", "If non empty, and -cloud_provider is specified, a regular expression for matching minion VMs")
 	minionPort                  = flag.Uint("minion_port", 10250, "The port at which kubelet will be listening on the minions.")
 	healthCheckMinions          = flag.Bool("health_check_minions", true, "If true, health check minions and filter unhealthy ones. [default true]")
@@ -63,6 +65,37 @@ func verifyMinionFlags() {
 	}
 }
 
+func initCloudProvider(name string, configFilePath string) cloudprovider.Interface {
+	var config *os.File
+
+	if name == "" {
+		glog.Info("No cloud provider specified.")
+		return nil
+	}
+
+	if configFilePath != "" {
+		var err error
+
+		config, err = os.Open(configFilePath)
+		if err != nil {
+			glog.Fatalf("Couldn't open cloud provider configuration %s: %#v",
+				configFilePath, err)
+		}
+
+		defer config.Close()
+	}
+
+	cloud, err := cloudprovider.GetCloudProvider(name, config)
+	if err != nil {
+		glog.Fatalf("Couldn't init cloud provider %q: %#v", name, err)
+	}
+	if cloud == nil {
+		glog.Fatalf("Unknown cloud provider: %s", name)
+	}
+
+	return cloud
+}
+
 func main() {
 	flag.Parse()
 	util.InitLogs()
@@ -75,17 +108,7 @@ func main() {
 		glog.Fatalf("-etcd_servers flag is required.")
 	}
 
-	cloud, err := cloudprovider.GetCloudProvider(*cloudProvider)
+	cloud := initCloudProvider(*cloudProvider, *cloudConfigFile)
-	if err != nil {
-		glog.Fatalf("Couldn't init cloud provider %q: %#v", *cloudProvider, err)
-	}
-	if cloud == nil {
-		if len(*cloudProvider) > 0 {
-			glog.Fatalf("Unknown cloud provider: %s", *cloudProvider)
-		} else {
-			glog.Info("No cloud provider specified.")
-		}
-	}
 
 	podInfoGetter := &client.HTTPPodInfoGetter{
 		Client: http.DefaultClient,

pkg/cloudprovider/gce/gce.go

@@ -18,6 +18,7 @@ package gce_cloud
 
 import (
 	"fmt"
+	"io"
 	"io/ioutil"
 	"net"
 	"net/http"
@@ -40,7 +41,7 @@ type GCECloud struct {
 }
 
 func init() {
-	cloudprovider.RegisterCloudProvider("gce", func() (cloudprovider.Interface, error) { return newGCECloud() })
+	cloudprovider.RegisterCloudProvider("gce", func(config io.Reader) (cloudprovider.Interface, error) { return newGCECloud() })
 }
 
 func getProjectAndZone() (string, string, error) {

pkg/cloudprovider/plugins.go

@@ -17,13 +17,17 @@ limitations under the License.
 package cloudprovider
 
 import (
+	"io"
 	"sync"
 
 	"github.com/golang/glog"
 )
 
 // Factory is a function that returns a cloudprovider.Interface.
-type Factory func() (Interface, error)
+// The config parameter provides an io.Reader handler to the factory in
+// order to load specific configurations. If no configuration is provided
+// the parameter is nil.
+type Factory func(config io.Reader) (Interface, error)
 
 // All registered cloud providers.
 var providersMutex sync.Mutex
@@ -44,13 +48,15 @@ func RegisterCloudProvider(name string, cloud Factory) {
 
 // GetCloudProvider creates an instance of the named cloud provider, or nil if
 // the name is not known.  The error return is only used if the named provider
-// was known but failed to initialize.
+// was known but failed to initialize. The config parameter specifies the
-func GetCloudProvider(name string) (Interface, error) {
+// io.Reader handler of the configuration file for the cloud provider, or nil
+// for no configuation.
+func GetCloudProvider(name string, config io.Reader) (Interface, error) {
 	providersMutex.Lock()
 	defer providersMutex.Unlock()
 	f, found := providers[name]
 	if !found {
 		return nil, nil
 	}
-	return f()
+	return f(config)
 }

pkg/cloudprovider/vagrant/vagrant.go

@@ -20,6 +20,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"net"
 	"net/http"
@@ -38,7 +39,7 @@ type VagrantCloud struct {
 }
 
 func init() {
-	cloudprovider.RegisterCloudProvider("vagrant", func() (cloudprovider.Interface, error) { return newVagrantCloud() })
+	cloudprovider.RegisterCloudProvider("vagrant", func(config io.Reader) (cloudprovider.Interface, error) { return newVagrantCloud() })
 }
 
 // SaltToken is an authorization token required by Salt REST API.