Merge pull request #115 from rackspace/gh-112-openstack-env-vars

Provide API for building AuthOptions from env vars.
diff --git a/acceptance/18-osutil-authentication.go b/acceptance/18-osutil-authentication.go
new file mode 100644
index 0000000..936f376
--- /dev/null
+++ b/acceptance/18-osutil-authentication.go
@@ -0,0 +1,17 @@
+package main
+
+import (
+	"github.com/rackspace/gophercloud"
+	"github.com/rackspace/gophercloud/osutil"
+)
+
+func main() {
+	provider, authOptions, err := osutil.AuthOptions()
+	if err != nil {
+		panic(err)
+	}
+	_, err = gophercloud.Authenticate(provider, authOptions)
+	if err != nil {
+		panic(err)
+	}
+}
diff --git a/osutil/auth.go b/osutil/auth.go
new file mode 100644
index 0000000..60a5f0b
--- /dev/null
+++ b/osutil/auth.go
@@ -0,0 +1,59 @@
+package osutil
+
+import (
+	"fmt"
+	"github.com/rackspace/gophercloud"
+	"os"
+)
+
+var (
+	nilOptions = gophercloud.AuthOptions{}
+
+	// ErrNoAuthUrl errors occur when the value of the OS_AUTH_URL environment variable cannot be determined.
+	ErrNoAuthUrl = fmt.Errorf("Environment variable OS_AUTH_URL needs to be set.")
+
+	// ErrNoUsername errors occur when the value of the OS_USERNAME environment variable cannot be determined.
+	ErrNoUsername = fmt.Errorf("Environment variable OS_USERNAME needs to be set.")
+
+	// ErrNoPassword errors occur when the value of the OS_PASSWORD environment variable cannot be determined.
+	ErrNoPassword = fmt.Errorf("Environment variable OS_PASSWORD or OS_API_KEY needs to be set.")
+)
+
+// AuthOptions fills out a gophercloud.AuthOptions structure with the settings found on the various OpenStack
+// OS_* environment variables.  The following variables provide sources of truth: OS_AUTH_URL, OS_USERNAME,
+// OS_PASSWORD, OS_TENANT_ID, and OS_TENANT_NAME.  Of these, OS_USERNAME, OS_PASSWORD, and OS_AUTH_URL must
+// have settings, or an error will result.  OS_TENANT_ID and OS_TENANT_NAME are optional.
+//
+// The value of OS_AUTH_URL will be returned directly to the caller, for subsequent use in
+// gophercloud.Authenticate()'s Provider parameter.  This function will not interpret the value of OS_AUTH_URL,
+// so as a convenient extention, you may set OS_AUTH_URL to, e.g., "rackspace-uk", or any other Gophercloud-recognized
+// provider shortcuts.  For broad compatibility, especially with local installations, you should probably
+// avoid the temptation to do this.
+func AuthOptions() (string, gophercloud.AuthOptions, error) {
+	provider := os.Getenv("OS_AUTH_URL")
+	username := os.Getenv("OS_USERNAME")
+	password := os.Getenv("OS_PASSWORD")
+	tenantId := os.Getenv("OS_TENANT_ID")
+	tenantName := os.Getenv("OS_TENANT_NAME")
+
+	if provider == "" {
+		return "", nilOptions, ErrNoAuthUrl
+	}
+
+	if username == "" {
+		return "", nilOptions, ErrNoUsername
+	}
+
+	if password == "" && apiKey == "" {
+		return "", nilOptions, ErrNoPassword
+	}
+
+	ao := gophercloud.AuthOptions{
+		Username:   username,
+		Password:   password,
+		TenantId:   tenantId,
+		TenantName: tenantName,
+	}
+
+	return provider, ao, nil
+}
diff --git a/osutil/region.go b/osutil/region.go
new file mode 100644
index 0000000..f7df507
--- /dev/null
+++ b/osutil/region.go
@@ -0,0 +1,9 @@
+package osutil
+
+import "os"
+
+// Region provides a means of querying the OS_REGION_NAME environment variable.
+// At present, you may also use os.Getenv("OS_REGION_NAME") as well.
+func Region() string {
+	return os.Getenv("OS_REGION_NAME")
+}
diff --git a/service_catalog.go b/service_catalog.go
index a439935..e6cf4a0 100644
--- a/service_catalog.go
+++ b/service_catalog.go
@@ -1,32 +1,36 @@
 package gophercloud
 
 import (
+	"os"
 	"strings"
 )
 
 // ApiCriteria provides one or more criteria for the SDK to look for appropriate endpoints.
 // Fields left unspecified or otherwise set to their zero-values are assumed to not be
 // relevant, and do not participate in the endpoint search.
+//
+// Name specifies the desired service catalog entry name.
+// Type specifies the desired service catalog entry type.
+// Region specifies the desired endpoint region.
+// If unset, Gophercloud will try to use the region set in the
+// OS_REGION_NAME environment variable.  If that's not set,
+// region comparison will not occur.  If OS_REGION_NAME is set
+// and IgnoreEnvVars is also set, OS_REGION_NAME will be ignored.
+// VersionId specifies the desired version of the endpoint.
+// Note that this field is matched exactly, and is (at present)
+// opaque to Gophercloud.  Thus, requesting a version 2
+// endpoint will _not_ match a version 3 endpoint.
+// The UrlChoice field inidicates whether or not gophercloud
+// should use the public or internal endpoint URL if a
+// candidate endpoint is found.
+// IgnoreEnvVars instructs Gophercloud to ignore helpful environment variables.
 type ApiCriteria struct {
-	// Name specifies the desired service catalog entry name.
-	Name string
-
-	// Type specifies the desired service catalog entry type.
-	Type string
-
-	// Region specifies the desired endpoint region.
-	Region string
-
-	// VersionId specifies the desired version of the endpoint.
-	// Note that this field is matched exactly, and is (at present)
-	// opaque to Gophercloud.  Thus, requesting a version 2
-	// endpoint will _not_ match a version 3 endpoint.
-	VersionId string
-
-	// The UrlChoice field inidicates whether or not gophercloud
-	// should use the public or internal endpoint URL if a
-	// candidate endpoint is found.
-	UrlChoice int
+	Name          string
+	Type          string
+	Region        string
+	VersionId     string
+	UrlChoice     int
+	IgnoreEnvVars bool
 }
 
 // The choices available for UrlChoice.  See the ApiCriteria structure for details.
@@ -42,6 +46,9 @@
 // set to "").
 func FindFirstEndpointByCriteria(entries []CatalogEntry, ac ApiCriteria) EntryEndpoint {
 	rgn := strings.ToUpper(ac.Region)
+	if (rgn == "") && !ac.IgnoreEnvVars {
+		rgn = os.Getenv("OS_REGION_NAME")
+	}
 
 	for _, entry := range entries {
 		if (ac.Name != "") && (ac.Name != entry.Name) {
@@ -53,7 +60,7 @@
 		}
 
 		for _, endpoint := range entry.Endpoints {
-			if (ac.Region != "") && (rgn != strings.ToUpper(endpoint.Region)) {
+			if (rgn != "") && (rgn != strings.ToUpper(endpoint.Region)) {
 				continue
 			}
 
diff --git a/service_catalog_test.go b/service_catalog_test.go
index 52e2388..b78f01f 100644
--- a/service_catalog_test.go
+++ b/service_catalog_test.go
@@ -1,55 +1,68 @@
 package gophercloud
 
 import (
+	"os"
 	"testing"
 )
 
-func TestFindFirstEndpointByCriteria(t *testing.T) {
-	endpoint := FindFirstEndpointByCriteria([]CatalogEntry{}, ApiCriteria{Name: "test"})
-	if endpoint.PublicURL != "" {
-		t.Error("Not expecting to find anything in an empty service catalog.")
-		return
-	}
+// TestFFEBCViaEnvVariable exercises only those calls where a region
+// parameter is required, but is provided by an environment variable.
+func TestFFEBCViaEnvVariable(t *testing.T) {
+	changeRegion("RGN")
 
-	endpoint = FindFirstEndpointByCriteria(
-		[]CatalogEntry{
-			{Name: "test"},
-		},
-		ApiCriteria{Name: "test"},
-	)
-	if endpoint.PublicURL != "" {
-		t.Error("Even though we have a matching entry, no endpoints exist")
-		return
-	}
-
-	endpoint = FindFirstEndpointByCriteria(
+	endpoint := FindFirstEndpointByCriteria(
 		catalog("test", "compute", "http://localhost", "", ""),
 		ApiCriteria{Name: "test"},
 	)
-	if endpoint.PublicURL != "http://localhost" {
-		t.Error("Looking for an endpoint by name but without region or version ID should match first entry endpoint.")
+	if endpoint.PublicURL != "" {
+		t.Error("If provided, the Region qualifier must exclude endpoints with missing or mismatching regions.")
 		return
 	}
 
 	endpoint = FindFirstEndpointByCriteria(
-		catalog("test", "compute", "http://localhost", "", ""),
-		ApiCriteria{Type: "compute"},
+		catalog("test", "compute", "http://localhost", "rgn", ""),
+		ApiCriteria{Name: "test"},
 	)
 	if endpoint.PublicURL != "http://localhost" {
-		t.Error("Looking for an endpoint by type but without region or version ID should match first entry endpoint.")
+		t.Error("Regions are case insensitive.")
 		return
 	}
 
 	endpoint = FindFirstEndpointByCriteria(
-		catalog("test", "compute", "http://localhost", "", ""),
-		ApiCriteria{Type: "identity"},
+		catalog("test", "compute", "http://localhost", "rgn", ""),
+		ApiCriteria{Name: "test", VersionId: "2"},
 	)
 	if endpoint.PublicURL != "" {
-		t.Error("Returned mismatched type.")
+		t.Error("Missing version ID means no match.")
 		return
 	}
 
 	endpoint = FindFirstEndpointByCriteria(
+		catalog("test", "compute", "http://localhost", "rgn", "3"),
+		ApiCriteria{Name: "test", VersionId: "2"},
+	)
+	if endpoint.PublicURL != "" {
+		t.Error("Mismatched version ID means no match.")
+		return
+	}
+
+	endpoint = FindFirstEndpointByCriteria(
+		catalog("test", "compute", "http://localhost", "rgn", "2"),
+		ApiCriteria{Name: "test", VersionId: "2"},
+	)
+	if endpoint.PublicURL != "http://localhost" {
+		t.Error("All search criteria met; endpoint expected.")
+		return
+	}
+}
+
+// TestFFEBCViaRegionOption exercises only those calls where a region
+// parameter is specified explicitly.  The region option overrides
+// any defined OS_REGION_NAME environment setting.
+func TestFFEBCViaRegionOption(t *testing.T) {
+	changeRegion("Starfleet Command")
+
+	endpoint := FindFirstEndpointByCriteria(
 		catalog("test", "compute", "http://localhost", "", ""),
 		ApiCriteria{Name: "test", Region: "RGN"},
 	)
@@ -93,10 +106,59 @@
 		t.Error("All search criteria met; endpoint expected.")
 		return
 	}
+}
+
+// TestFFEBCWithoutRegion exercises only those calls where a region
+// is irrelevant.  Just to make sure, though, we enforce Gophercloud
+// from paying any attention to OS_REGION_NAME if it happens to be set.
+func TestFindFirstEndpointByCriteria(t *testing.T) {
+	endpoint := FindFirstEndpointByCriteria([]CatalogEntry{}, ApiCriteria{Name: "test", IgnoreEnvVars: true})
+	if endpoint.PublicURL != "" {
+		t.Error("Not expecting to find anything in an empty service catalog.")
+		return
+	}
+
+	endpoint = FindFirstEndpointByCriteria(
+		[]CatalogEntry{
+			{Name: "test"},
+		},
+		ApiCriteria{Name: "test", IgnoreEnvVars: true},
+	)
+	if endpoint.PublicURL != "" {
+		t.Error("Even though we have a matching entry, no endpoints exist")
+		return
+	}
+
+	endpoint = FindFirstEndpointByCriteria(
+		catalog("test", "compute", "http://localhost", "", ""),
+		ApiCriteria{Name: "test", IgnoreEnvVars: true},
+	)
+	if endpoint.PublicURL != "http://localhost" {
+		t.Error("Looking for an endpoint by name but without region or version ID should match first entry endpoint.")
+		return
+	}
+
+	endpoint = FindFirstEndpointByCriteria(
+		catalog("test", "compute", "http://localhost", "", ""),
+		ApiCriteria{Type: "compute", IgnoreEnvVars: true},
+	)
+	if endpoint.PublicURL != "http://localhost" {
+		t.Error("Looking for an endpoint by type but without region or version ID should match first entry endpoint.")
+		return
+	}
+
+	endpoint = FindFirstEndpointByCriteria(
+		catalog("test", "compute", "http://localhost", "", ""),
+		ApiCriteria{Type: "identity", IgnoreEnvVars: true},
+	)
+	if endpoint.PublicURL != "" {
+		t.Error("Returned mismatched type.")
+		return
+	}
 
 	endpoint = FindFirstEndpointByCriteria(
 		catalog("test", "compute", "http://localhost", "ord", "2"),
-		ApiCriteria{Name: "test", VersionId: "2"},
+		ApiCriteria{Name: "test", VersionId: "2", IgnoreEnvVars: true},
 	)
 	if endpoint.PublicURL != "http://localhost" {
 		t.Error("Sometimes, you might not care what region your stuff is in.")
@@ -119,3 +181,10 @@
 		},
 	}
 }
+
+func changeRegion(r string) {
+	err := os.Setenv("OS_REGION_NAME", r)
+	if err != nil {
+		panic(err)
+	}
+}