Rename PACK_ to CNB_

This change updates the code to examine CNB_ environment variables instead of
PACK_ environment variables.  Where PACK_ was previously used, it still exists
as a fallback to be removed once the lifecycle has been updated and released.

[buildpacks/spec#38]

Signed-off-by: Ben Hale <bhale@pivotal.io>

services/credentials.go

@@ -18,6 +18,7 @@ package services
 
 import (
 	"encoding/json"
+	"sort"
 )
 
 // Credentials is the collection of credential keys.
@@ -38,5 +39,6 @@ func (c *Credentials) UnmarshalJSON(text []byte) error {
 		*c = append(*c, key)
 	}
 
+	sort.Strings(*c)
 	return nil
 }

services/services_test.go

@@ -91,7 +91,7 @@ func TestServices(t *testing.T) {
 					Tags:         []string{"postgres", "postgresql", "relational"},
 				},
 				{
-					Credentials:  services.Credentials{"hostname", "username", "password"},
+					Credentials:  services.Credentials{"hostname", "password", "username"},
 					InstanceName: "mysendgrid",
 					Label:        "sendgrid",
 					Plan:         "free",

stack/stack.go

@@ -25,11 +25,15 @@ import (
 
 type Stack string
 
-// DefaultStack creates a new instance of Stack, extracting the name from the PACK_STACK_ID environment variable.
+// DefaultStack creates a new instance of Stack, extracting the name from the CNB_STACK_ID environment variable.
 func DefaultStack(logger logger.Logger) (Stack, error) {
-	s, ok := os.LookupEnv("PACK_STACK_ID")
+	s, ok := os.LookupEnv("CNB_STACK_ID")
 	if !ok {
-		return "", fmt.Errorf("PACK_STACK_ID not set")
+		s, ok = os.LookupEnv("PACK_STACK_ID")  // TODO: Remove once PACK_STACK_ID removed from lifecycle
+	}
+
+	if !ok {
+		return "", fmt.Errorf("CNB_STACK_ID not set")
 	}
 
 	stack := Stack(s)

stack/stack_test.go

@@ -33,18 +33,26 @@ func TestStack(t *testing.T) {
 
 		g := NewGomegaWithT(t)
 
+		it("extracts value from CNB_STACK_ID", func() {
+			defer internal.ReplaceEnv(t, "CNB_STACK_ID", "test-stack-name")()
+
+			g.Expect(stack.DefaultStack(logger.Logger{})).To(Equal(stack.Stack("test-stack-name")))
+		})
+
 		it("extracts value from PACK_STACK_ID", func() {
 			defer internal.ReplaceEnv(t, "PACK_STACK_ID", "test-stack-name")()
 
 			g.Expect(stack.DefaultStack(logger.Logger{})).To(Equal(stack.Stack("test-stack-name")))
 		})
 
-		it("returns error when PACK_STACK_ID not set", func() {
+		it("returns error when CNB AND PACK_STACK_ID not set", func() {
+			defer internal.ProtectEnv(t, "CNB_STACK_ID")()
 			defer internal.ProtectEnv(t, "PACK_STACK_ID")()
+			g.Expect(os.Unsetenv("CNB_STACK_ID")).Should(Succeed())
 			g.Expect(os.Unsetenv("PACK_STACK_ID")).Should(Succeed())
 
 			_, err := stack.DefaultStack(logger.Logger{})
-			g.Expect(err).To(MatchError("PACK_STACK_ID not set"))
+			g.Expect(err).To(MatchError("CNB_STACK_ID not set"))
 		})
 	}, spec.Report(report.Terminal{}))
 }