From c7e6c9ebec6c9498901b040752f3ece4d9984373 Mon Sep 17 00:00:00 2001
From: Hans Hasselberg <me@hans.io>
Date: Mon, 8 Jun 2020 10:10:08 +0200
Subject: [PATCH] http: use default minsize for gzip handler. (#7354)

Fixes #6306
---
 agent/agent_endpoint_test.go | 37 +++++++++++++++++++++++++++++++++
 agent/http.go                | 13 ++++++++++--
 agent/http_test.go           | 40 ++++++++++++++++++++++++++++++++++++
 3 files changed, 88 insertions(+), 2 deletions(-)

diff --git a/agent/agent_endpoint_test.go b/agent/agent_endpoint_test.go
index facfb0ea3f..c91c1d49cf 100644
--- a/agent/agent_endpoint_test.go
+++ b/agent/agent_endpoint_test.go
@@ -4451,6 +4451,43 @@ func TestAgent_Monitor(t *testing.T) {
 		})
 	})
 
+	t.Run("stream compressed unstructured logs", func(t *testing.T) {
+		// The only purpose of this test is to see something being
+		// logged. Because /v1/agent/monitor is streaming the response
+		// it needs special handling with the compression.
+		retry.Run(t, func(r *retry.R) {
+			req, _ := http.NewRequest("GET", "/v1/agent/monitor?loglevel=debug", nil)
+			// Usually this would be automatically set by transport content
+			// negotiation, but since this call doesn't go through a real
+			// transport, the header has to be set manually
+			req.Header["Accept-Encoding"] = []string{"gzip"}
+			cancelCtx, cancelFunc := context.WithCancel(context.Background())
+			req = req.WithContext(cancelCtx)
+
+			resp := httptest.NewRecorder()
+			go a.srv.Handler.ServeHTTP(resp, req)
+
+			args := &structs.ServiceDefinition{
+				Name: "monitor",
+				Port: 8000,
+				Check: structs.CheckType{
+					TTL: 15 * time.Second,
+				},
+			}
+
+			registerReq, _ := http.NewRequest("PUT", "/v1/agent/service/register", jsonReader(args))
+			if _, err := a.srv.AgentRegisterService(nil, registerReq); err != nil {
+				t.Fatalf("err: %v", err)
+			}
+
+			// Wait until we have received some type of logging output
+			require.Eventually(t, func() bool {
+				return len(resp.Body.Bytes()) > 0
+			}, 3*time.Second, 100*time.Millisecond)
+			cancelFunc()
+		})
+	})
+
 	t.Run("stream JSON logs", func(t *testing.T) {
 		// Try to stream logs until we see the expected log line
 		retry.Run(t, func(r *retry.R) {
diff --git a/agent/http.go b/agent/http.go
index 222d18e73b..58c7a2c41a 100644
--- a/agent/http.go
+++ b/agent/http.go
@@ -258,8 +258,17 @@ func (s *HTTPServer) handler(enableDebug bool) http.Handler {
 			metrics.MeasureSince(key, start)
 		}
 
-		gzipWrapper, _ := gziphandler.GzipHandlerWithOpts(gziphandler.MinSize(0))
-		gzipHandler := gzipWrapper(http.HandlerFunc(wrapper))
+		var gzipHandler http.Handler
+		minSize := gziphandler.DefaultMinSize
+		if pattern == "/v1/agent/monitor" {
+			minSize = 0
+		}
+		gzipWrapper, err := gziphandler.GzipHandlerWithOpts(gziphandler.MinSize(minSize))
+		if err == nil {
+			gzipHandler = gzipWrapper(http.HandlerFunc(wrapper))
+		} else {
+			gzipHandler = gziphandler.GzipHandler(http.HandlerFunc(wrapper))
+		}
 		mux.Handle(pattern, gzipHandler)
 	}
 
diff --git a/agent/http_test.go b/agent/http_test.go
index 56025966e5..7424fd6e32 100644
--- a/agent/http_test.go
+++ b/agent/http_test.go
@@ -18,6 +18,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/NYTimes/gziphandler"
 	"github.com/hashicorp/consul/agent/structs"
 	tokenStore "github.com/hashicorp/consul/agent/token"
 	"github.com/hashicorp/consul/api"
@@ -462,6 +463,45 @@ func TestUIResponseHeaders(t *testing.T) {
 	}
 }
 
+func TestAcceptEncodingGzip(t *testing.T) {
+	t.Parallel()
+	a := NewTestAgent(t, "")
+	defer a.Shutdown()
+
+	// Setting up the KV to store a short and a long value
+	buf := bytes.NewBuffer([]byte("short"))
+	req, _ := http.NewRequest("PUT", "/v1/kv/short", buf)
+	resp := httptest.NewRecorder()
+	_, err := a.srv.KVSEndpoint(resp, req)
+	require.NoError(t, err)
+
+	// this generates a string which is longer than
+	// gziphandler.DefaultMinSize to trigger compression.
+	long := fmt.Sprintf(fmt.Sprintf("%%0%dd", gziphandler.DefaultMinSize+1), 1)
+	buf = bytes.NewBuffer([]byte(long))
+	req, _ = http.NewRequest("PUT", "/v1/kv/long", buf)
+	resp = httptest.NewRecorder()
+	_, err = a.srv.KVSEndpoint(resp, req)
+	require.NoError(t, err)
+
+	resp = httptest.NewRecorder()
+	req, _ = http.NewRequest("GET", "/v1/kv/short", nil)
+	// Usually this would be automatically set by transport content
+	// negotiation, but since this call doesn't go through a real
+	// transport, the header has to be set manually
+	req.Header["Accept-Encoding"] = []string{"gzip"}
+	a.srv.Handler.ServeHTTP(resp, req)
+	require.Equal(t, 200, resp.Code)
+	require.Equal(t, "", resp.Header().Get("Content-Encoding"))
+
+	resp = httptest.NewRecorder()
+	req, _ = http.NewRequest("GET", "/v1/kv/long", nil)
+	req.Header["Accept-Encoding"] = []string{"gzip"}
+	a.srv.Handler.ServeHTTP(resp, req)
+	require.Equal(t, 200, resp.Code)
+	require.Equal(t, "gzip", resp.Header().Get("Content-Encoding"))
+}
+
 func TestContentTypeIsJSON(t *testing.T) {
 	t.Parallel()
 	a := NewTestAgent(t, "")