Add header Injector

pkg/apis/options/util/util.go

@@ -0,0 +1,26 @@
+package util
+
+import (
+	"encoding/base64"
+	"errors"
+	"io/ioutil"
+	"os"
+
+	"github.com/oauth2-proxy/oauth2-proxy/v7/pkg/apis/options"
+)
+
+// GetSecretValue returns the value of the Secret from its source
+func GetSecretValue(source *options.SecretSource) ([]byte, error) {
+	switch {
+	case len(source.Value) > 0 && source.FromEnv == "" && source.FromFile == "":
+		value := make([]byte, base64.StdEncoding.DecodedLen(len(source.Value)))
+		decoded, err := base64.StdEncoding.Decode(value, source.Value)
+		return value[:decoded], err
+	case len(source.Value) == 0 && source.FromEnv != "" && source.FromFile == "":
+		return []byte(os.Getenv(source.FromEnv)), nil
+	case len(source.Value) == 0 && source.FromEnv == "" && source.FromFile != "":
+		return ioutil.ReadFile(source.FromFile)
+	default:
+		return nil, errors.New("secret source is invalid: exactly one entry required, specify either value, fromEnv or fromFile")
+	}
+}