outposts/proxy: fix additionalHeaders not being set

closes #1050

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

outpost/pkg/proxy/proxy.go

@@ -446,15 +446,17 @@ func (p *OAuthProxy) addHeadersForProxying(rw http.ResponseWriter, req *http.Req
 			username = session.Email
 		}
 		authVal := b64.StdEncoding.EncodeToString([]byte(username + ":" + password))
+		p.logger.WithField("username", username).Trace("setting http basic auth")
 		req.Header["Authorization"] = []string{fmt.Sprintf("Basic %s", authVal)}
 	}
 	// Check if user has additional headers set that we should sent
-	if additionalHeaders, ok := userAttributes["additionalHeaders"].(map[string]string); ok {
+	if additionalHeaders, ok := userAttributes["additionalHeaders"].(map[string]interface{}); ok {
+		p.logger.WithField("headers", additionalHeaders).Trace("setting additional headers")
 		if additionalHeaders == nil {
 			return
 		}
 		for key, value := range additionalHeaders {
-			req.Header.Set(key, value)
+			req.Header.Set(key, toString(value))
 		}
 	}
 }

outpost/pkg/proxy/utils.go

@@ -3,6 +3,7 @@ package proxy
 import (
 	"net"
 	"net/http"
+	"strconv"
 )
 
 var xForwardedHost = http.CanonicalHeaderKey("X-Forwarded-Host")
@@ -18,3 +19,16 @@ func getHost(req *http.Request) string {
 	}
 	return hostOnly
 }
+
+// toString Generic to string function, currently supports actual strings and integers
+func toString(in interface{}) string {
+	switch v := in.(type) {
+	case string:
+		return v
+	case *string:
+		return *v
+	case int:
+		return strconv.Itoa(v)
+	}
+	return ""
+}