Add support for fetcing private key from an environment variable

appsTransport.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net/http"
+	"os"
 	"strconv"
 	"time"
 
@@ -36,6 +37,15 @@ func NewAppsTransportKeyFromFile(tr http.RoundTripper, appID int64, privateKeyFi
 	return NewAppsTransport(tr, appID, privateKey)
 }
 
+// NewAppsTransportKeyFromEnv returns a AppsTransport using a private key from environment variable.
+func NewAppsTransportKeyFromEnv(tr http.RoundTripper, appID int64, privateKeyEnv string) (*AppsTransport, error) {
+	privateKey, ok := os.LookupEnv(privateKeyEnv)
+	if !ok {
+		return nil, fmt.Errorf("private key environment variable %s empty", privateKeyEnv)
+	}
+	return NewAppsTransport(tr, appID, []byte(privateKey))
+}
+
 // NewAppsTransport returns a AppsTransport using private key. The key is parsed
 // and if any errors occur the error is non-nil.
 //

appsTransport_test.go

@@ -31,6 +31,17 @@ func TestNewAppsTransportKeyFromFile(t *testing.T) {
 	}
 }
 
+func TestNewAppsTransportKeyFromEnv(t *testing.T) {
+	if err := os.Setenv("KEY", string(key)); err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	_, err := NewAppsTransportKeyFromEnv(&http.Transport{}, appID, "KEY")
+	if err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+}
+
 type RoundTrip struct {
 	rt func(*http.Request) (*http.Response, error)
 }

transport.go

@@ -8,6 +8,7 @@ import (
 	"io"
 	"io/ioutil"
 	"net/http"
+	"os"
 	"sync"
 	"time"
 
@@ -60,6 +61,15 @@ func NewKeyFromFile(tr http.RoundTripper, appID, installationID int64, privateKe
 	return New(tr, appID, installationID, privateKey)
 }
 
+// NewKeyFromFile returns a Transport using a private key from environment variable.
+func NewKeyFromEnv(tr http.RoundTripper, appID, installationID int64, privateKeyEnv string) (*Transport, error) {
+	privateKey, ok := os.LookupEnv(privateKeyEnv)
+	if !ok {
+		return nil, fmt.Errorf("private key environment variable %s empty", privateKeyEnv)
+	}
+	return New(tr, appID, installationID, []byte(privateKey))
+}
+
 // Client is a HTTP client which sends a http.Request and returns a http.Response
 // or an error.
 type Client interface {

transport_test.go

@@ -136,6 +136,17 @@ func TestNewKeyFromFile(t *testing.T) {
 	}
 }
 
+func TestNewKeyFromENV(t *testing.T) {
+	if err := os.Setenv("KEY", string(key)); err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	_, err := NewKeyFromEnv(&http.Transport{}, appID, installationID, "KEY")
+	if err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+}
+
 func TestNew_appendHeader(t *testing.T) {
 	var headers http.Header
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {