feat(mcp): log tool call (hide sensitive HTTP headers) (#225)

manusa · web-flow · commit 9cc7192d4dc4 · 2025-07-31T15:36:34.000+02:00
Signed-off-by: Marc Nuri &lt;marc@marcnuri.com&gt;
diff --git a/pkg/mcp/mcp.go b/pkg/mcp/mcp.go
@@ -190,7 +190,7 @@ func toolCallLoggingMiddleware(next server.ToolHandlerFunc) server.ToolHandlerFu
 		klog.V(5).Infof("mcp tool call: %s(%v)", ctr.Params.Name, ctr.Params.Arguments)
 		if ctr.Header != nil {
 			buffer := bytes.NewBuffer(make([]byte, 0))
-			if err := ctr.Header.Write(buffer); err == nil {
+			if err := ctr.Header.WriteSubset(buffer, map[string]bool{"Authorization": true, "authorization": true}); err == nil {
 				klog.V(7).Infof("mcp tool call headers: %s", buffer)
 			}
 		}
diff --git a/pkg/mcp/mcp_tools_test.go b/pkg/mcp/mcp_tools_test.go
@@ -1,6 +1,7 @@
 package mcp
 
 import (
+	"github.com/mark3labs/mcp-go/client/transport"
 	"github.com/mark3labs/mcp-go/mcp"
 	"k8s.io/utils/ptr"
 	"regexp"
@@ -140,16 +141,39 @@ func TestToolCallLogging(t *testing.T) {
 			}
 		})
 	})
-	testCaseWithContext(t, &mcpContext{logLevel: 7}, func(c *mcpContext) {
+	before := func(c *mcpContext) {
+		c.clientOptions = append(c.clientOptions, transport.WithHeaders(map[string]string{
+			"Accept-Encoding":   "gzip",
+			"Authorization":     "Bearer should-not-be-logged",
+			"authorization":     "Bearer should-not-be-logged",
+			"a-loggable-header": "should-be-logged",
+		}))
+	}
+	testCaseWithContext(t, &mcpContext{logLevel: 7, before: before}, func(c *mcpContext) {
 		_, _ = c.callTool("configuration_view", map[string]interface{}{
 			"minified": false,
 		})
 		t.Run("Logs tool call headers", func(t *testing.T) {
-			expectedLog := "mcp tool call headers: Accept-Encoding: gzip"
+			expectedLog := "mcp tool call headers: A-Loggable-Header: should-be-logged"
 			if !strings.Contains(c.logBuffer.String(), expectedLog) {
 				t.Errorf("Expected log to contain '%s', got: %s", expectedLog, c.logBuffer.String())
 			}
 		})
-
+		sensitiveHeaders := []string{
+			"Authorization",
+			// TODO: Add more sensitive headers as needed
+		}
+		t.Run("Does not log sensitive headers", func(t *testing.T) {
+			for _, header := range sensitiveHeaders {
+				if strings.Contains(c.logBuffer.String(), header) {
+					t.Errorf("Log should not contain sensitive header '%s', got: %s", header, c.logBuffer.String())
+				}
+			}
+		})
+		t.Run("Does not log sensitive header values", func(t *testing.T) {
+			if strings.Contains(c.logBuffer.String(), "should-not-be-logged") {
+				t.Errorf("Log should not contain sensitive header value 'should-not-be-logged', got: %s", c.logBuffer.String())
+			}
+		})
 	})
 }

Original file line number	Diff line number	Diff line change
`@@ -190,7 +190,7 @@ func toolCallLoggingMiddleware(next server.ToolHandlerFunc) server.ToolHandlerFu`
`190`	`190`	`klog.V(5).Infof("mcp tool call: %s(%v)", ctr.Params.Name, ctr.Params.Arguments)`
`191`	`191`	`if ctr.Header != nil {`
`192`	`192`	`buffer := bytes.NewBuffer(make([]byte, 0))`
`193`		`- if err := ctr.Header.Write(buffer); err == nil {`
	`193`	`+ if err := ctr.Header.WriteSubset(buffer, map[string]bool{"Authorization": true, "authorization": true}); err == nil {`
`194`	`194`	`klog.V(7).Infof("mcp tool call headers: %s", buffer)`
`195`	`195`	`}`
`196`	`196`	`}`